Orthopedic Sport Review | Dr Hutaif Sports Medicine Rev -...

The images reveal a medium-sized tear of the rotator cuff. As more clinical studies are published comparing double-row with single-row rotator cuff repair, it has become clear that the retear rate is lower with a double-row construct for small and medium-sized tears. This may be attributable to the stronger time-zero repair construct that double-row repair provides. No study to date has demonstrated a significant difference in clinical outcomes (functional and pain scores at any time) or time to healing between the two techniques.

Posterior shoulder instability is a rare form of instability that often presents with pain rather than feelings of instability. It often occurs in young athletes during activities that put the shoulder in an “at-risk position” (flexion, adduction, internal rotation). Repetitive microtrauma can lead to posterior shoulder instability such as seen in football linemen. Swinging a bat or golf club places the lead arm in a flexed, adducted, and internally rotated position, which can lead to posterior translation of the humeral head that is forcibly reduced in follow-through, as seen in this patient. The glenohumeral joint relies on static and dynamic stabilizers. Static stabilizers help prevent instability at the end ranges of motion when the ligaments are taut. Dynamic stabilizers work to prevent subluxation at midranges of motion, at which the ligaments are lax. The rotator cuff is integral as a dynamic stabilizer of the shoulder. It works through a process called concavity compression. The four muscles of the rotator cuff compress the humeral head into the concavity of the glenoid-labrum. This prevents the humeral head from subluxing during the midranges of motion. Of the four rotator cuff muscles, the subscapularis is most important at preventing posterior subluxation. This patient has posterior instability, and various surgical techniques may be indicated depending on findings. Arthroscopic labral repair is indicated for anterior instability. Arthroscopic posterior labral repair is indicated for this patient because he has a posterior labral tear and posterior instability. If a patient has ligamentous laxity (not seen in this scenario because sulcus and Beighton sign findings would be negative), a posterior capsular shift with rotator interval closure is indicated. If a patient has excessive glenoid retroversion (not seen in this scenario with 5 degrees of retroversion), a posterior opening-wedge osteotomy is appropriate. The most common complication seen after arthroscopic posterior labral repair is stiffness, followed by recurrent instability
and degenerative joint disease.

The MRI scan shows a bony Bankart lesion involving <20% of the glenoid joint surface. A recent series reported high success rates after arthroscopic treatment when the defect is incorporated into the repair. Anterior bony deficiencies occupying >25% to >30% of the glenoid joint surface treated with soft-tissue repair only are associated with high recurrence rates. In these patients, an open or arthroscopic coracoid transfer or structural iliac crest graft should be considered. Open reduction and internal fixation has been reported for treatment of large acute glenoid rim fractures but is not recommended for recurrent anterior shoulder instability in the setting of a 10% glenoid rim fracture.

This clinical scenario describes a patient with an isolated injury affecting the infraspinatus muscle. The anatomic location of such a lesion would be at the spinoglenoid notch, at which the suprascapular nerve may be compressed distal to its innervation of the supraspinatus but proximal to the infraspinatus innervation. A calcified transverse scapular ligament would also affect the suprascapular nerve but is proximal to the innervation of both muscles. Quadrilateral space syndrome would affect innervation of the deltoid (and teres minor). Parsonage-Turner syndrome is a more diffuse, and often severely painful, brachial plexus neuropathy.

The posterior and superior acromioclavicular ligaments provide the most restraint to posterior translation of the acromioclavicular joint and must be preserved during a Mumford procedure. Anterior and superior acromioclavicular joint ligaments are the opposite of the preferred response and prevent anterior translation of the clavicle. Injuries to the conoid and trapezoid ligaments are more pronounced with grade III or higher acromioclavicular separations, with superior migration of the clavicle relative to the acromion.

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DISCUSSION:
The patient has undergone a Latarjet procedure as shown in the radiographs. After harvesting the coracoid graft, care must be taken to not place too much tension on or dissect excessively near the musculocutaneous nerve. The nerve is encountered 5 cm distal to the coracoid as it enters the conjoint tendon. The lateral antebrachial cutaneous nerve is the terminal branch of the musculocutaneous nerve and; therefore, injury can cause decreased sensation in the lateral forearm.

This patient had an eccentric muscle contraction (muscle lengthening while contracting) of his biceps muscle while trying to stop a defender from getting around him. This in turn caused failure of the distal biceps tendon, as evidenced by pain in the antecubital fossa, lack of elbow supination strength, and his positive biceps active test finding (supination/pronation of the forearm showing no motion of the biceps muscle belly). Eccentric contractors
have the highest potential for building strength but also are at highest risk for injury. Concentric (muscle shortening with contraction), isometric (no change in muscle length with contracture), and isokinetic (constant velocity of muscle contraction with a variable force) do not describe the mechanism detailed. The loss of distal biceps attachment will result in loss of elbow supination strength in flexion (the biceps is the only supinator to cross the elbow) while still retaining elbow flexion (albeit weakened) because of the other elbow flexors (brachioradialis and brachialis). Consequently, treatment should be anatomic repair of the distal biceps insertion, which can be performed with a 2-incision or 1-incision technique. Although all of the listed complications have been reported with these techniques, LABC neuropraxia is by far the most common. Radiographs show that this athlete’s injury was repaired using a 1-incision technique with a cortical fixation device and a radial bone tunnel. This technique has gained favor because of its decreased incidence of heterotopic ossification and radioulnar synostosis compared with the 2-incision technique. The most troubling complication for most surgeons is the development of a posterior interosseous nerve (PIN) palsy, which this patient clearly demonstrates in addition to the more common LABCN upon postsurgical examination. Because the LABCN injury is typically a neuropraxia from retraction, a period of observation is indicated. PIN injury can result from excessive traction during surgical exposure or from entrapment by the fixation button. Considering the anatomy of the PIN, successful recovery of the nerve typically progresses based on the distance from the origin of the nerve to the muscle indicated. The extensor indicis proprius (EIP) muscle is the most distal muscle innervated and can be expected to recover last. First to return would be the EDC
followed by the ECU, EDQ, and, finally, the EIP.

The radiographs show severe osteoarthritis of the shoulder. The best surgical option would be an arthroplasty. The major determining factor for which type of arthroplasty to choose is the integrity of the rotator cuff tendons.
Although the radiographs do not reveal any obvious signs of rotator cuff failure, the patient had had an open Bankart 20 years ago. The integrity of the subscapularis tendon following a previous open shoulder procedure is crucial in deciding which type of arthroplasty to consider. Range of motion and infraspinatus strength do not affect the decision-making process, assuming the rotator cuff is intact. Activity level can be important when deciding whether to proceed with an arthroplasty, but it is not as important as the rotator cuff integrity when choosing which
arthroplasty to use.

This patient has a mechanism of injury and MRI scan consistent with a posterior labral tear and posterior instability. Flexion, adduction, and internal rotation produce a net posterior vector on the glenohumeral joint and should reproduce this patient's symptoms. Pain or instability with the arm elevated in the scapular plane describes an impingement sign. Pain or instability with the arm in external rotation and abduction describes the apprehension sign. Pain or instability with the arm in flexion and abduction is a _nonspecific finding._

Little League shoulder is a physeal injury increasingly seen in young throwers. The primary treatment is refraining from throwing with rehabilitation, followed by a throwing program. The risk of recurrence is approximately 7%. The risk of recurrence is three times higher in athletes with glenohumeral internal rotation deficit. Hyperlaxity,
rotator cuff weakness, and increased height have not been shown to correlate with recurrent symptoms.

The mechanism of injury/dislocation is most consistent with anterior glenohumeral joint instability. The axial cuts of the MR arthrogram reveals an anteroinferior labral tear, as well as a posterior labral tear. A Hill-Sachs lesion is also consistent with anterior glenohumeral joint instability. At the time of examination under anesthesia, this patient exhibited 2+ anterior and 2+ posterior glenohumeral joint instability. Patients with pan-labral tears and 270° tears can be challenging to diagnose, because patients can report anterior or posterior shoulder instability alone. The
physical examination and advanced imaging in these patients are crucial in directing appropriate treatment.

There is much debate in the literature regarding optimal techniques for treatment of shoulder instability. Barring other factors or concomitant pathology, however, there is no persuasive literature to suggest routine use of bone augmentation for contact athletes. Extensive labral involvement (here specifically implying posterior labral involvement, as well) will require a more extensive repair but does not, in and of itself, suggest the necessity for
glenoid bone augmentation. A large Hill-Sachs lesion may be an indication for glenoid augmentation, primarily if it is in a location/orientation that engages the anterior glenoid rim. These are referred to as “off-track” lesions. Of these choices, the strongest indication for a Latarjet coracoid transfer or similar bone augmentation (other options include iliac crest autograft or distal tibial allograft) is high-grade glenoid bone loss. Classically, this is performed through an open approach, although arthroscopic techniques are increasing in popularity. Although the critical amount of bone loss is debated, most surgeons and studies suggest a cut-off of approximately 20% to 25%, above
which isolated soft-tissue stabilization alone is less likely to be successful in the long-term.

This patient had an eccentric muscle contraction (muscle lengthening while contracting) of his biceps muscle while trying to stop a defender from getting around him. This in turn caused failure of the distal biceps tendon, as evidenced by pain in the antecubital fossa, lack of elbow supination strength, and his positive biceps active test finding (supination/pronation of the forearm showing no motion of the biceps muscle belly). Eccentric contractors have the highest potential for building strength but also are at highest risk for injury. Concentric (muscle shortening with contraction), isometric (no change in muscle length with contracture), and isokinetic (constant velocity of muscle contraction with a variable force) do not describe the mechanism detailed. The loss of distal biceps attachment will result in loss of elbow supination strength in flexion (the biceps is the only supinator to cross the
elbow) while still retaining elbow flexion (albeit weakened) because of the other elbow flexors (brachioradialis and brachialis). Consequently, treatment should be anatomic repair of the distal biceps insertion, which can be performed with a 2-incision or 1-incision technique. Although all of the listed complications have been reported with these techniques, LABC neuropraxia is by far the most common. Radiographs show that this athlete’s injury was repaired using a 1-incision technique with a cortical fixation device and a radial bone tunnel. This technique has gained favor because of its decreased incidence of heterotopic ossification and radioulnar synostosis compared with the 2-incision technique. The most troubling complication for most surgeons is the development of a posterior interosseous nerve (PIN) palsy, which this patient clearly demonstrates in addition to the more common LABCN upon postsurgical examination. Because the LABCN injury is typically a neuropraxia from retraction, a period of observation is indicated. PIN injury can result from excessive traction during surgical exposure or from entrapment by the fixation button. Considering the anatomy of the PIN, successful recovery of the nerve typically progresses based on the distance from the origin of the nerve to the muscle indicated. The extensor indicis proprius (EIP) muscle is the most distal muscle innervated and can be expected to recover last. First to return would be the EDC
followed by the ECU, EDQ, and, finally, the EIP.

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The axial MRI scan reveals a subluxated biceps tendon. In the study by Koh and associates, 85% of patients with a biceps subluxation on MRI were found to have a subscapularis tear at the time of arthroscopy. These are not always obvious on the MRI, and close inspection of the leading edge/upper border of the subscapularis tendon at the time of arthroscopy is necessary. Although supraspinatus tears, SLAP tears, and Bankart tears can all occur in conjunction with a biceps subluxation, none have been shown to be strongly correlated with this pathology, nor as
specific to this pathology.

This patient has a massive rotator cuff tear resulting in disruption of the transverse force couple between the subscapularis anteriorly and the infraspinatus and teres minor posteriorly. These muscles provide dynamic shoulder stability throughout active elevation, and loss of the force couple produces a pathologic increase in translation of the humeral head and decreased active abduction. Active shoulder elevation <90 degrees in the presence of full passive motion is termed pseudoparalysis. The most common neurologic deficit after shoulder dislocation is isolated injury to the axillary nerve. This patient's sensory examination suggests that the axillary nerve is intact. Cervical radiculopathy is less common after shoulder dislocation but has been reported. Conflicting evidence exists regarding the contribution of the long head of the biceps tendon to glenohumeral stability. One study reported minimal electromyographic activity in the biceps during ten basic shoulder motions.

This patient had an eccentric muscle contraction (muscle lengthening while contracting) of his biceps muscle while trying to stop a defender from getting around him. This in turn caused failure of the distal biceps tendon, as evidenced by pain in the antecubital fossa, lack of elbow supination strength, and his positive biceps active test finding (supination/pronation of the forearm showing no motion of the biceps muscle belly). Eccentric contractors have the highest potential for building strength but also are at highest risk for injury. Concentric (muscle shortening with contraction), isometric (no change in muscle length with contracture), and isokinetic (constant velocity of muscle contraction with a variable force) do not describe the mechanism detailed. The loss of distal biceps attachment will result in loss of elbow supination strength in flexion (the biceps is the only supinator to cross the elbow) while still retaining elbow flexion (albeit weakened) because of the other elbow flexors (brachioradialis and brachialis). Consequently, treatment should be anatomic repair of the distal biceps insertion, which can be performed with a 2-incision or 1-incision technique. Although all of the listed complications have been reported with these techniques, LABC neuropraxia is by far the most common. Radiographs show that this athlete’s injury was repaired using a 1-incision technique with a cortical fixation device and a radial bone tunnel. This technique has gained favor because of its decreased incidence of heterotopic ossification and radioulnar synostosis compared with the 2-incision technique. The most troubling complication for most surgeons is the development of a posterior interosseous nerve (PIN) palsy, which this patient clearly demonstrates in addition to the more common LABCN upon postsurgical examination. Because the LABCN injury is typically a neuropraxia from retraction, a period of observation is indicated. PIN injury can result from excessive traction during surgical exposure or from entrapment by the fixation button. Considering the anatomy of the PIN, successful recovery of the nerve typically progresses based on the distance from the origin of the nerve to the muscle indicated. The extensor indicis proprius (EIP) muscle is the most distal muscle innervated and can be expected to recover last. First to return would be the EDC
followed by the ECU, EDQ, and, finally, the EIP.

Posterior shoulder instability is a rare form of instability that often presents with pain rather than feelings of instability. It often occurs in young athletes during activities that put the shoulder in an “at-risk position” (flexion, adduction, internal rotation). Repetitive microtrauma can lead to posterior shoulder instability such as seen in football linemen. Swinging a bat or golf club places the lead arm in a flexed, adducted, and internally rotated position, which can lead to posterior translation of the humeral head that is forcibly reduced in follow-through, as seen in this patient. The glenohumeral joint relies on static and dynamic stabilizers. Static stabilizers help prevent instability at the end ranges of motion when the ligaments are taut. Dynamic stabilizers work to prevent subluxation at midranges of motion, at which the ligaments are lax. The rotator cuff is integral as a dynamic stabilizer of the shoulder. It works through a process called concavity compression. The four muscles of the rotator cuff compress the humeral head into the concavity of the glenoid-labrum. This prevents the humeral head from subluxing during the midranges of motion. Of the four rotator cuff muscles, the subscapularis is most important at preventing posterior subluxation. This patient has posterior instability, and various surgical techniques may be indicated depending on findings. Arthroscopic labral repair is indicated for anterior instability. Arthroscopic posterior labral repair is indicated for this patient because he has a posterior labral tear and posterior instability. If a patient has ligamentous laxity (not seen in this scenario because sulcus and Beighton sign findings would be negative), a posterior capsular shift with rotator interval closure is indicated. If a patient has excessive glenoid retroversion (not seen in this scenario with 5 degrees of retroversion), a posterior opening-wedge osteotomy is appropriate. The most common complication seen after arthroscopic posterior labral repair is stiffness, followed by recurrent instability
and degenerative joint disease.

The radiograph reveals a widened lateral physis at the proximal humerus, consistent with a physeal stress fracture or “Little Leaguer’s shoulder.” Numerous studies have established that children and adolescents are particularly prone to such overuse injuries. With regard to baseball participation, a major contributor is over-pitching, i.e., excessive numbers of pitches, excessive innings pitched, and insufficient rest days. Altered range of rotational motion, a gradual adaptation to the increased stresses of throwing, can predispose to long-term injury, especially internal impingement and labral pathology. A unicameral or aneurysmal bone cyst can often occur in the proximal humerus, but has a distinct radiographic appearance and would predispose to fracture. There is evidence that breaking pitches place increased stresses on the elbow and shoulder, but it remains controversial whether such
throws should be avoided at certain ages.

The patient has recurrent instability and is at a high rate of further dislocations due to his young age. Therefore, therapy and bracing are unlikely to decrease his dislocation rate. The radiographs are normal, and there is no Hill-Sachs lesion or bony Bankart lesion. His instability severity index score is 3, and; therefore, a bony procedure such as Latarjet is not necessary. Furthermore, the rate of complication following a Latarjet procedure, especially nerve
injury and hardware problems, exceeds that of arthroscopic Bankart repair.

This athlete has a symptomatic posterior-superior labral tear, spinoglenoid notch cysts, and subsequent suprascapular nerve compression, as evidenced by the atrophy of the infraspinatus muscle on sagittal T1 MRI. The cyst is located at the spinoglenoid notch and is compressing the suprascapular nerve after it has innervated the supraspinatus but before innervation of the infraspinatus; hence, the atrophy of infraspinatus on examination and imaging. Compression of the suprascapular nerve at the suprascapular notch would lead to weakness and atrophy of both the supraspinatus and infraspinatus. The lower subscapular nerve innervates the teres major, as well as, with the upper subscapular nerve, the _subscapularis. The teres minor is innervated by the axillary nerve._

This patient is experiencing soreness over his medial (ulnar) collateral ligament. Valgus overload is likely to reproduce his symptoms and is most pronounced during the late cocking phase of the throwing cycle. In windup, very little elbow torque is required. In early cocking, the arm is getting loaded, and maximum valgus is not yet achieved at the elbow. In acceleration and deceleration, more force is _generated at the level of the shoulder joint._

Posterior shoulder instability is a rare form of instability that often presents with pain rather than feelings of instability. It often occurs in young athletes during activities that put the shoulder in an “at-risk position” (flexion, adduction, internal rotation). Repetitive microtrauma can lead to posterior shoulder instability such as seen in football linemen. Swinging a bat or golf club places the lead arm in a flexed, adducted, and internally rotated position, which can lead to posterior translation of the humeral head that is forcibly reduced in follow-through, as seen in this patient. The glenohumeral joint relies on static and dynamic stabilizers. Static stabilizers help prevent instability at the end ranges of motion when the ligaments are taut. Dynamic stabilizers work to prevent subluxation at midranges of motion, at which the ligaments are lax. The rotator cuff is integral as a dynamic stabilizer of the shoulder. It works through a process called concavity compression. The four muscles of the rotator cuff compress the humeral head into the concavity of the glenoid-labrum. This prevents the humeral head from subluxing during the midranges of motion. Of the four rotator cuff muscles, the subscapularis is most important at preventing posterior subluxation. This patient has posterior instability, and various surgical techniques may be indicated depending on findings. Arthroscopic labral repair is indicated for anterior instability. Arthroscopic posterior labral repair is indicated for this patient because he has a posterior labral tear and posterior instability. If a patient has ligamentous laxity (not seen in this scenario because sulcus and Beighton sign findings would be negative), a posterior capsular shift with rotator interval closure is
indicated. If a patient has excessive glenoid retroversion (not seen in this scenario with 5 degrees of retroversion), a posterior opening-wedge osteotomy is appropriate.

In younger active patients, tendon transfer is considered a preferable treatment option. The patient has failed a course of nonoperative management. Subacromial decompression may offer pain relief but may not be advisable in a patient with rotator cuff deficient shoulder. A total shoulder arthroplasty requires functionality of the supraspinatus and infraspinatus. A reverse total shoulder is an option to alleviate pain and perhaps improve forward flexion height and strength; however, reverse arthroplasty would not improve external rotation in this patient, and there is concern for longevity of the implant in younger _patient populations._

Figures 1 and 2 show a full thickness distal biceps tendon rupture with proximal retraction. Edema is seen along the course of the distal biceps tendon, and the axial cut demonstrates the absence of tendon at the radial tuberosity. The sagittal cut demonstrates the stump of the proximally retracted biceps tendon. The biceps muscle contour is abnormal in appearance, demonstrating the classic “popeye” deformity. Nonsurgical treatment options result in predictable loss of supination and elbow flexion strength that is not desirable. A local corticosteroid injection would not improve strength, and there is no evidence to support the use of a PRP injection.

The MRI reveals a large full thickness supraspinatus tear. A large, prospective study showed that physical therapy can be effective in the treatment of atraumatic full-thickness rotator cuff tears. Patient expectations regarding the role of rehabilitation were the strongest predictor of surgery. Other factors associated with surgery were higher activity level and not smoking. Anatomic features of the rotator
cuff tear and the severity of patient’s reported pain did not predict failure of nonoperative treatment. Patients who have low expectations regarding the effectiveness of physical therapy are more likely to fail nonoperative treatment.

The football player had bilateral weakness indicating that the injury was more significant than a stinger. Stingers present with unilateral symptoms, and if they resolve, an athlete can return to sports. However, bilateral symptoms indicate cervical spine pathology, such as spinal stenosis, and warrant an MRI scan of the cervical spine. Despite the patient being able to continue playing in the game and having symptom resolution, a cervical MRI scan should be performed prior to return to sports.

The MR image shows medial subluxation of the biceps tendon, which can be confused with an articular loose body. In the clinical scenario of biceps instability/subluxation, the rationale regarding tenodesis is to address the painful dislocation and subluxation of the biceps tendon from the bicipital groove. Biceps tendon subluxation is most frequently associated with subscapularis tendon pathology, which is indicated by the MRI and by a positive lift-off test. The MR image does not show a loose body or Bankart lesion. Patients with irreparable rotator cuff tears with a severe external rotation deficit and a deficient teres minor _may experience a better functional result with latissimus dorsi transfer._

Humerus fractures account for 11% of all fractures among snowboarders and are the second-most-common upper-extremity fracture after radius fractures (48%). Surgical fixation is recommended for fractures with residual displacement >5 mm, or >3 mm in active patients involved in frequent overhead activity. Malunion can result in a mechanical block to shoulder abduction or external rotation and altered rotator cuff mechanics, causing weakness. A rich arterial network provides a favorable healing environment for greater tuberosity fractures. Consequently, nonunion and osteonecrosis are uncommon.

A systematic review of case studies looking at the results of surgical treatment for femoroacetabular impingement shows good results for most patients, with the exception of those with preoperative radiographs showing osteoarthritis or Outerbridge grade III or grade IV cartilage damage noted intraoperatively. Both Byrd and Jones and Philippon and associates have shown good surgical results for this condition among professional athletes. Likewise, Fabricant and associates demonstrated good surgical results among adolescent patients with an average age of 17.6 years.

This patient has ischiofemoral impingement, in which there is abnormal contact between the lesser trochanter and the lateral border of the ischium. Patients typically present with posteriorly based hip pain and do not respond to intra-articular diagnostic injections. Examination can demonstrate pain with long strides, pain with palpation over the area, as well as reproduction of symptoms with the patient in the contralateral decubitus position and taking the affected hip into passive extension (ischiofemoral impingement test). MRI demonstrates a narrowed ischiofemoral space, as well as increased signal within the quadratus femoris muscle. The diagnosis can be confirmed with a diagnostic injection into this area. Treatment is typically nonsurgical, with surgical intervention consisting of resection of the lesser _trochanter reserved for refractory cases._

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This clinical scenario describes a patient with FAI attributable to pincer (acetabular) deformity. This form of FAI, which involves prominence of the anterosuperior acetabular lip, may be more common among women. Decreased range of motion and pain occur secondary to the abutment of the femoral head against the acetabular labrum and rim. Hip flexion, combined with adduction and internal rotation, recreates this contact and causes pain, but CAM or pincer etiology remains unknown. The differential diagnosis of hip pain in a young athlete includes femoral neck stress reaction/fracture, sacroiliac arthritis, intra-articular loose body, trochanteric bursitis, osteitis pubis, and hernia. No information presented in this scenario suggests any of these causes. Diagnosis of FAI is best performed via MR imaging, with an arthrogram increasing the sensitivity and specificity for labral pathology. Ultrasonography may be useful in the diagnosis of dysplasia or for dynamic assessment of a snapping hip, but ultrasonography is not commonly used to diagnose labral pathology. Although concomitant chondral lesions of the femoral head are uncommon, the forced leverage of the anterosuperior femoral neck upon the anterior acetabulum may result in a “contra-coup” chondral injury on the posteroinferior acetabulum. This is the most common location of chondral lesions in this scenario. Without bony resection to prevent further impingement, this patient will continue to experience symptoms. Because there is no evidence of femoral neck prominence (CAM lesion), there is no indication for osteoplasty of the femoral neck; resection of the pincer lesion is necessary. This will often require take-down of the labrum in this location. If possible, iatrogenic or traumatic labral tears should subsequently be repaired after pincer debridement because the labrum has _important functions for hip stability and maintenance of the suction seal of the joint._

This patient has cam-type femoroacetabular impingement. Decreased internal rotation and a positive impingement test (forced flexion, adduction, and internal rotation) are classic findings. The lack of pain with resisted hip flexion makes hip flexor strain unlikely, and the lack of tenderness at the greater trochanter renders trochanteric bursitis unlikely. Although athletic pubalgia can be a source of longstanding groin pain, he lacks the pain with a resisted sit-up and tenderness along the pubic ramus that is frequently noted in patients with pubalgia. His radiographs reveal a focal femoral neck prominence consistent with cam impingement, although pistol grip deformities and flattening of the lateral femoral head are often present as well. His MRI scan shows a labral tear, which is common in cam impingement. Surgical treatment for cam impingement can be effective for symptomatic patients. Even among high-level athletes, open surgical dislocation of the hip has been shown to have good results. Most patients with cam impingement can be treated with arthroscopic osteoplasty and achieve results comparable with those realized with open surgical dislocation. The literature describes success in terms of athletes returning to sports (even professional athletes) to be approximately 90% after arthroscopic treatment. Byrd and Jones described five patients who developed transient neurapraxias that resolved uneventfully. The patients in his series who had concomitant microfracture had a 92% return to sports within the follow-up period. Cam impingement has long been thought to be associated with a history of a slipped capital femoral epiphysis. The capitis in these patients is displaced posteriorly, resulting in a prominent anterior femoral neck and decreased hip internal rotation. Pincer impingement is associated with a deep acetabulum, such as protrusion acetabula and acetabular retroversion. A patient who underwent a _periacetabular osteotomy can develop a more retroverted acetabulum as well._

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This clinical scenario describes a patient with FAI attributable to pincer (acetabular) deformity. This form of FAI, which involves prominence of the anterosuperior acetabular lip, may be more common among women. Decreased range of motion and pain occur secondary to the abutment of the femoral head against the acetabular labrum and rim. Hip flexion, combined with adduction and internal rotation, recreates this contact and causes pain, but CAM or pincer etiology remains unknown. The differential diagnosis of hip pain in a young athlete includes femoral neck stress reaction/fracture, sacroiliac arthritis, intra-articular loose body, trochanteric bursitis, osteitis pubis, and hernia. No information presented in this scenario suggests any of these causes. Diagnosis of FAI is best performed via MR imaging, with an arthrogram increasing the sensitivity and specificity for labral pathology. Ultrasonography may be useful in the diagnosis of dysplasia or for dynamic assessment of a snapping hip, but ultrasonography is not commonly used to diagnose labral pathology. Although concomitant chondral lesions of the femoral head are uncommon, the forced leverage of the anterosuperior femoral neck upon the anterior acetabulum may result in a “contra-coup” chondral injury on the posteroinferior acetabulum. This is the most common location of chondral lesions in this scenario. Without bony resection to prevent further impingement, this patient will continue to experience symptoms. Because there is no evidence of femoral neck prominence (CAM lesion), there is no indication for osteoplasty of the femoral neck; resection of the pincer lesion is necessary. This will often require take-down of the labrum in this location. If possible, iatrogenic or traumatic labral tears should subsequently be repaired after pincer debridement because the labrum has _important functions for hip stability and maintenance of the suction seal of the joint._

An osteoid osteoma is a benign bone tumor. Osteoid osteomas tend to be small—typically <1.5 cm. Regardless of their size, they cause a large amount of reactive bone to form around them, and they make a new type of abnormal bone material called osteoid bone. This osteoid bone, along with the tumor
cells, forms the nidus of the tumor, which is easily identified on CT scans.

This clinical scenario describes a patient with FAI attributable to pincer (acetabular) deformity. This form of FAI, which involves prominence of the anterosuperior acetabular lip, may be more common among women. Decreased range of motion and pain occur secondary to the abutment of the femoral head against the acetabular labrum and rim. Hip flexion, combined with adduction and internal rotation, recreates this contact and causes pain, but CAM or pincer etiology remains unknown. The differential diagnosis of hip pain in a young athlete includes femoral neck stress reaction/fracture, sacroiliac arthritis, intra-articular loose body, trochanteric bursitis, osteitis pubis, and hernia. No information presented in this scenario suggests any of these causes. Diagnosis of FAI is best performed via MR imaging, with an arthrogram increasing the sensitivity and specificity for labral pathology. Ultrasonography may be useful in the diagnosis of dysplasia or for dynamic assessment of a snapping hip, but ultrasonography is not commonly
used to diagnose labral pathology. Although concomitant chondral lesions of the femoral head are uncommon, the forced leverage of the anterosuperior femoral neck upon the anterior acetabulum may result in a “contra-coup” chondral injury on the posteroinferior acetabulum. This is the most common location of chondral lesions in this scenario. Without bony resection to prevent further impingement, this patient will continue to experience symptoms. Because there is no evidence of femoral neck prominence (CAM lesion), there is no indication for osteoplasty of the femoral neck; resection of the pincer lesion is necessary. This will often require take-down of the labrum in this location. If possible, iatrogenic or traumatic labral tears should subsequently be repaired after pincer debridement because the labrum has _important functions for hip stability and maintenance of the suction seal of the joint._

This patient has cam-type femoroacetabular impingement. Decreased internal rotation and a positive impingement test (forced flexion, adduction, and internal rotation) are classic findings. The lack of pain with resisted hip flexion makes hip flexor strain unlikely, and the lack of tenderness at the greater trochanter renders trochanteric bursitis unlikely. Although athletic pubalgia can be a source of long-
standing groin pain, he lacks the pain with a resisted sit-up and tenderness along the pubic ramus that is frequently noted in patients with pubalgia. His radiographs reveal a focal femoral neck prominence consistent with cam impingement, although pistol grip deformities and flattening of the lateral femoral head are often present as well. His MRI scan shows a labral tear, which is common in cam impingement. Surgical treatment for cam impingement can be effective for symptomatic patients. Even among high-level athletes, open surgical dislocation of the hip has been shown to have good results. Most patients with cam impingement can be treated with arthroscopic osteoplasty and achieve results comparable with those realized with open surgical dislocation. The literature describes success in terms of athletes returning to sports (even professional athletes) to be approximately 90% after arthroscopic treatment. Byrd and Jones described five patients who developed transient neurapraxias that resolved uneventfully. The patients in his series who had concomitant microfracture had a 92% return to sports within the follow-up period. Cam impingement has long been thought to be associated with a history of a slipped capital femoral epiphysis. The capitis in these patients is displaced posteriorly, resulting in a prominent anterior femoral neck and decreased hip internal rotation. Pincer impingement is associated with a deep acetabulum, such as protrusion acetabula and acetabular retroversion. A patient who underwent a
periacetabular osteotomy can develop a more retroverted acetabulum as well.

This patient has cam-type femoroacetabular impingement. Decreased internal rotation and a positive impingement test (forced flexion, adduction, and internal rotation) are classic findings. The lack of pain with resisted hip flexion makes hip flexor strain unlikely, and the lack of tenderness at the greater
trochanter renders trochanteric bursitis unlikely. Although athletic pubalgia can be a source of longstanding groin pain, he lacks the pain with a resisted sit-up and tenderness along the pubic ramus that is frequently noted in patients with pubalgia. His radiographs reveal a focal femoral neck prominence consistent with cam impingement, although pistol grip deformities and flattening of the lateral femoral head are often present as well. His MRI scan shows a labral tear, which is common in cam impingement. Surgical treatment for cam impingement can be effective for symptomatic patients. Even among high-level athletes, open surgical dislocation of the hip has been shown to have good results. Most patients with cam impingement can be treated with arthroscopic osteoplasty and achieve results comparable with those realized with open surgical dislocation. The literature describes success in terms of athletes returning to sports (even professional athletes) to be approximately 90% after arthroscopic treatment. Byrd and Jones described five patients who developed transient neurapraxias that resolved uneventfully. The patients in his series who had concomitant microfracture had a 92% return to sports within the follow-up period. Cam impingement has long been thought to be associated with a history of a slipped capital femoral epiphysis. The capitis in these patients is displaced posteriorly, resulting in a prominent anterior femoral neck and decreased hip internal rotation. Pincer impingement is associated with a deep acetabulum, such as protrusion acetabula and acetabular retroversion. A patient who underwent a _periacetabular osteotomy can develop a more retroverted acetabulum as well._

This clinical scenario describes a patient with FAI attributable to pincer (acetabular) deformity. This form of FAI, which involves prominence of the anterosuperior acetabular lip, may be more common among women. Decreased range of motion and pain occur secondary to the abutment of the femoral head against the acetabular labrum and rim. Hip flexion, combined with adduction and internal rotation, recreates this contact and causes pain, but CAM or pincer etiology remains unknown. The differential diagnosis of hip pain in a young athlete includes femoral neck stress reaction/fracture, sacroiliac arthritis, intra-articular loose body, trochanteric bursitis, osteitis pubis, and hernia. No information presented in this scenario suggests any of these causes. Diagnosis of FAI is best performed via MR imaging, with an arthrogram increasing the sensitivity and specificity for labral pathology. Ultrasonography may be useful in the diagnosis of dysplasia or for dynamic assessment of a snapping hip, but ultrasonography is not commonly used to diagnose labral pathology. Although concomitant chondral lesions of the femoral head are uncommon, the forced leverage of the anterosuperior femoral neck upon the anterior acetabulum may result in a “contra-coup” chondral injury on the posteroinferior acetabulum. This is the most common location of chondral lesions in this scenario. Without bony resection to prevent further impingement, this patient will continue to experience symptoms. Because there is no evidence of femoral neck prominence (CAM lesion), there is no indication for osteoplasty of the femoral neck; resection of the pincer lesion is necessary. This will often require take-down of the labrum in this location. If possible, iatrogenic or traumatic labral tears should subsequently be repaired after pincer debridement because the labrum has _important functions for hip stability and maintenance of the suction seal of the joint._

This patient has a classic presentation of postmeniscectomy medial compartment arthritis. The appropriate diagnostic study is weight-bearing radiographs to confirm the diagnosis. An MRI scan will reveal medial compartment arthritis but will not provide information about alignment. A CT scan would be appropriate to detect an occult fracture; however, this condition is not suspected in this clinical scenario. Ultrasonography can provide information about fluid collection around the knee or a deep vein thrombosis; however, these conditions also are not suspected in this clinical scenario. Because the patient has a correctable deformity (gaps 3 mm with valgus stress), and his symptoms are localized to the involved
compartment, a trial of a medial unloader brace is appropriate both diagnostically and therapeutically. If unloading the medial compartment resolves the patient’s symptoms, he would be an excellent candidate for an osteotomy. An MRI scan may be obtained to evaluate ligamentous integrity or to evaluate degenerative involvement of the lateral and patellofemoral compartment for presurgical planning of an osteotomy; however, the integrity of the medial meniscus has no clinical importance in a patient with severe medial compartment arthritis. A repeat corticosteroid injection is not indicated within 1 month of his last injection, and referral to pain management is not appropriate with other options available to help this patient. A VPHTO is the appropriate intervention considering the patient’s young age, high-functional occupation, examination, radiographic findings, and response to medial unloader bracing. A revision knee arthroscopy would be appropriate for a recurrent medial meniscus tear, but not appropriate in a patient with severe medial compartment arthritis. The patient’s young age and high functional requirements are contraindications to TKA. The presence of severe arthritis is a contraindication to medial meniscus transplant. The patient is a candidate for a VPHTO. The technical options include a medial opening-wedge or a lateral closing-wedge osteotomy. Both techniques have advantages and disadvantages; however, a medial opening-wedge osteotomy is contraindicated in a smoker because of concern for nonunion. As a result, current smoking history is the only factor listed that would influence the technique used. The history of prior arthroscopy has no relevance in the decision about which type of osteotomy is appropriate. Normal BMI is between 18.5 and 24.9, so this patient’s BMI is considered normal and would not affect the surgical technique (if this patient were obese, a lateral closing-wedge osteotomy would be considered, but this is controversial). His age of 40 years is an indication for HTO _but does not influence technique._

The images provided reveal a posterior cruciate ligament (PCL) disruption with an intact anterior cruciate ligament (ACL). Common diagnostic findings for a PCL tear include a positive posterior drawer test, positive reverse pivot shift, positive quadriceps active test, and positive posterior sag. A positive Lachman test, which would indicate a torn ACL, would not be expected to be positive. A false-positive result for a Lachman test can arise with a torn PCL because of the overall increased anterior-posterior translation; _this must be avoided by careful attention to initial resting position and station of the knee._

This is a rupture of the anterolateral ligament complex and a portion of the IT band. This injury is highly correlated with a complete ACL injury. In the MRI, the curvilinear or elliptic bone fragment (Segond fracture) projected parallel to the lateral aspect of the tibial plateau, the lateral capsular sign, is seen. The lateral capsular sign is also associated with ACL tears. Thus, this is an MRI showing a complete ACL _tear._

The images show a full-thickness cartilage defect with significant bony involvement >4 cm2. Microfracture should be considered for lesions <2 cm2 without an underlying osseous defect. Autologous chondrocyte implantation, although used for lesions between 1 and 10 cm2, should be restricted for defects with minimal (<8 mm depth) bone loss. Osteochondral allograft transfer with the mosaicplasty technique (transfer of multiple plugs) would be well-suited for this large defect with significant osseous involvement. Dejour trochleoplasty is performed for patellar instability to correct trochlear dysplasia and _would not be indicated in this case._

The MRI scan shows a posterior horn medial meniscus root avulsion with bony edema at the tibial root insertion. The radiograph shows no significant degenerative changes. If left untreated, posterior meniscal
root tears lead to progressive degenerative changes as a result of the altered tibiofemoral contact pressures and areas. Nonsurgical treatment including injections, physical therapy, and unloader braces are more _appropriate in the older patient with pre-existing advanced degenerative changes._

This patient’s examination and history indicate recurrent patellar dislocations. Radiographs show an osseous or osteochondral loose fragment. There is no evidence of an obvious nondisplaced fracture or physeal changes. In the setting of suspected patella dislocation or subluxation with loose fragment seen on radiograph, an MRI is indicated. Lateral release alone is seldom indicated in a knee that is normal before injury. The examination and MRI do not indicate a need for medial collateral ligament repair. Treatment should consist of arthroscopy or arthrotomy and attempted internal fixation of this fragment. If fixation is not possible, the loose body can be removed. Normal TT-TG values, an increased lateral patellar glide, and a history of recurrent patellar dislocations after trauma suggest MPFL incompetence and the need for reconstruction.

The clinical description and MR image point to an injury to the posterior cruciate ligament (PCL). This ligament is thought to be primarily composed of anterolateral and posteromedial bundles, with the former tightening in flexion and the latter in extension. Because of alterations in knee kinematics and increased varus alignment in PCL insufficiency, contact stresses and cartilage loads increase in the patellofemoral and medial compartments. Although good outcomes may be obtained with transtibial, open inlay, and arthroscopic inlay techniques, one major difference is the creation of the “killer-turn” during the transtibial approach. This sharp turn in the graft as it emerges from the tibia appears to lead to more pronounced attenuation and thinning of the graft during cyclic loading. The scenario describes a patient with chronic PCL and posterolateral corner (PLC) injury, as evidenced by the varus thrust and abnormal Dial test finding. A valgus-producing osteotomy may be effective, and, in fact, may be the only treatment necessary to address chronic PLC injury. Accordingly, an opening lateral osteotomy would not be appropriate. Of the remaining responses, an osteotomy that increases tibial slope would also address the PCL deficiency by reducing posterior tibial sag. Vascular injury is an uncommon, but potentially devastating, complication associated with PCL surgery and may occur regardless of the technique used. Numerous strategies have been described to reduce the risk, including use of a posteromedial accessory incision to allow finger retraction of the popliteal neurovascular bundle, oscillating drills to prevent excessive soft-tissue entanglement, and tapered (rather than square) drill bits that may minimize cut-out of sharp edges as drilling reaches the posterior tibial cortex. Knee extension lessens, rather than increases,
the distance between the posterior tibia and the neurovascular bundle and increases, not lessens, risk for _vascular injury._

Lateral closing wedge (LCW) and medial opening wedge (MOW) high-tibial osteotomies (HTOs) can both correct varus knee alignment and stabilize the ACL–deficient knee. Increasingly, HTO is being proposed as a singular or concomitant procedure with ACL reconstruction for restoring knee stability and as a more reliable slope correction. LCW HTO demonstrates more reliable slope correction than does MOW HTO. Revision ACL with BTB allograft and meniscal transplant will not help early arthritis in varus alignment. Distal femoral osteotomy is usually considered for valgus knee. Pure sagittal osteotomy _would not help the patient’s medial knee pain, arthritis, and malalignment._

This patient underwent an ACL reconstruction that has now failed. Based on his examination, he also has a posterolateral corner injury. Because this concomitant injury was not treated, the patient had undue strain on his graft, resulting in ultimate failure. Hamstring grafts are as effective as other graft types for ACL reconstruction. The medial meniscus provides secondary stabilization to the knee; however, this patient has a missed lateral ligamentous injury, and meniscus tears do not result in the development of a varus thrust. An unrecognized PCL tear likely results in mild-to-moderate medial and patellofemoral osteoarthritis without significant lateral laxity and thrust.

This patient has likely sustained an isolated PCL injury. The examination is consistent with a grade II injury to the PCL. In this scenario, the best initial option is nonsurgical treatment and return to play as symptoms subside and strength improves. Physical therapy with a focus on quadriceps strengthening and delayed PCL reconstruction is not the answer because this patient can likely be treated without surgery. The absence of valgus laxity and negative dial testing findings suggest that an injury to the posteromedial and posterolateral corners has not occurred. Initial nonsurgical treatment is indicated for this patient. If he completes rehabilitation and experiences persistent disability with anterior and/or medial knee discomfort or senses the knee is "loose," PCL reconstruction should be considered at that time.

The patient has a symptomatic cartilage lesion of his medial femoral condyle, which has not responded to nonsurgical measures, and he failed a prior arthroscopy with debridement. Based on his examination and imaging, he is ligamentously stable, has normal mechanical alignment, and has intact menisci, making him a candidate for a cartilage restoration procedure. The accompanying MRI also indicates subchondral bone involvement with increased T2 signal underlying the cartilage defect. Osteochondral allograft is the only choice that addresses both the cartilage defect, as well as compromised subchondral bone. Depending on lesion size, osteochondral autograft transfer may also be considered, but this is not presented as an answer choice.Given the radiographic finding of neutral mechanical alignment, bracing would be less effective, and the patient has already tried extensive physical therapy. Lack of malalignment also excludes tibial osteotomy as a preferred answer choice. Microfracture is best for small cartilage lesions without _significant bone marrow involvement._

This patient has a classic presentation of postmeniscectomy medial compartment arthritis. The appropriate diagnostic study is weight-bearing radiographs to confirm the diagnosis. An MRI scan will reveal medial compartment arthritis but will not provide information about alignment. A CT scan would be appropriate to detect an occult fracture; however, this condition is not suspected in this clinical scenario. Ultrasonography can provide information about fluid collection around the knee or a deep vein thrombosis; however, these conditions also are not suspected in this clinical scenario. Because the patient has a correctable deformity (gaps 3 mm with valgus stress), and his symptoms are localized to the involved compartment, a trial of a medial unloader brace is appropriate both diagnostically and therapeutically. If unloading the medial compartment resolves the patient’s symptoms, he would be an excellent candidate for an osteotomy. An MRI scan may be obtained to evaluate ligamentous integrity or to evaluate degenerative involvement of the lateral and patellofemoral compartment for presurgical planning of an osteotomy; however, the integrity of the medial meniscus has no clinical importance in a patient with severe medial compartment arthritis. A repeat corticosteroid injection is not indicated within 1 month of his last injection, and referral to pain management is not appropriate with other options available to help this patient. A VPHTO is the appropriate intervention considering the patient’s young age, high-functional occupation, examination, radiographic findings, and response to medial unloader bracing. A revision knee arthroscopy would be appropriate for a recurrent medial meniscus tear, but not appropriate in a patient with severe medial compartment arthritis. The patient’s young age and high functional requirements are contraindications to TKA. The presence of severe arthritis is a contraindication to medial meniscus transplant. The patient is a candidate for a VPHTO. The technical options include a medial opening-wedge or a lateral closing-wedge osteotomy. Both techniques have advantages and disadvantages; however, a medial opening-wedge osteotomy is contraindicated in a smoker because of concern for nonunion. As a result, current smoking history is the only factor listed that would influence the technique used. The history of prior arthroscopy has no relevance in the decision about which type of osteotomy is appropriate. Normal BMI is between 18.5 and 24.9, so this patient’s BMI is considered normal and would not affect the surgical technique (if this patient were obese, a lateral closing-wedge osteotomy would be considered, but this is controversial). His age of 40 years is an indication for HTO _but does not influence technique._

This patient likely has a physeal injury to the distal femoral physis. Stress radiographs or an MRI scan will most reliably reveal this diagnosis. The growth plate, when injured, is most commonly fractured through the hypertrophic zone of cartilage, its weakest point. This patient is optimally treated in a _cylindrical or long-leg cast._

The clinical description and MR image point to an injury to the posterior cruciate ligament (PCL). This ligament is thought to be primarily composed of anterolateral and posteromedial bundles, with the former tightening in flexion and the latter in extension. Because of alterations in knee kinematics and increased varus alignment in PCL insufficiency, contact stresses and cartilage loads increase in the patellofemoral and medial compartments. Although good outcomes may be obtained with transtibial, open inlay, and arthroscopic inlay techniques, one major difference is the creation of the “killer-turn” during the transtibial approach. This sharp turn in the graft as it emerges from the tibia appears to lead to more pronounced attenuation and thinning of the graft during cyclic loading. The scenario describes a patient with chronic PCL and posterolateral corner (PLC) injury, as evidenced by the varus thrust and abnormal Dial test finding. A valgus-producing osteotomy may be effective, and, in fact, may be the only treatment necessary to address chronic PLC injury. Accordingly, an opening lateral osteotomy would not be appropriate. Of the remaining responses, an osteotomy that increases tibial slope would also address the PCL deficiency by reducing posterior tibial sag. Vascular injury is an uncommon, but potentially devastating, complication associated with PCL surgery and may occur regardless of the technique used.
Numerous strategies have been described to reduce the risk, including use of a posteromedial accessory incision to allow finger retraction of the popliteal neurovascular bundle, oscillating drills to prevent excessive soft-tissue entanglement, and tapered (rather than square) drill bits that may minimize cut-out of sharp edges as drilling reaches the posterior tibial cortex. Knee extension lessens, rather than increases, the distance between the posterior tibia and the neurovascular bundle and increases, not lessens, risk for _vascular injury._

The MR images show a tear through a discoid lateral meniscus. A discoid meniscus is caused by a failure of apoptosis during development in utero and is considered a congenital abnormality. Discoid menisci are prone to tearing and can be caused by minimal trauma. There is no known genetic cause for this condition. Radiographic findings that may be present in the setting of a discoid meniscus include lateral joint space widening, squaring of the lateral femoral condyle, and cupping of the lateral tibial plateau. Contralateral
discoid menisci are noted in 20% of patients. There are no other known associated conditions. Treatment of a symptomatic discoid meniscus should include partial meniscectomy and saucerization or repair.

This patient likely has a physeal injury to the distal femoral physis. Stress radiographs or an MRI scan will most reliably reveal this diagnosis. The growth plate, when injured, is most commonly fractured through the hypertrophic zone of cartilage, its weakest point. This patient is optimally treated in a cylindrical or long-leg cast.

The diagnostic criteria for chronic exertional compartment syndrome is pressure >15 mm Hg at rest, or
>30 mm Hg at 1 minute post exercise, or >20 mm Hg at 5 minutes post-exercise. The anterior and lateral compartments are the only ones that meet strict diagnostic criteria for chronic exertional compartment syndrome. The superficial posterior compartment, although close to meeting criteria, is not responsible _for the patient's symptoms and falls below current thresholds for diagnosis._

The MR image shows bone bruises (“kissing contusions”) consistent with an ACL tear. During the ACL subluxation event, the posterolateral tibial plateau subluxes anteriorly, making contact with the mid portion of the lateral femoral condyle and resulting in this characteristic bone bruise pattern on MRI. Randomized clinical trials comparing early accelerated versus nonaccelerated rehabilitation programs have demonstrated no significant differences in long-term results with regard to function, reinjury, and successful return to play. These studies did not address timing of return to play with an early accelerated rehabilitation program. At 2 and 3 years postsurgically, there are no differences in laxity, number of graft failures, or KOOS scores.

The MRI scans show that edema is noted on the femoral insertion of the ACL consistent with a high-grade or complete ACL tear. The ACL is not visualized on the sagittal view, although the torn meniscus can be seen in the notch. On the coronal image, there is an empty lateral wall sign indicating proximal
disruption of the ACL. The medial meniscus images show a disruption of normal meniscus morphology consistent with a bucket handle medial meniscus tear. Note the appearance on the sagittal MRI scan of what appears to be a second soft-tissue density in line with the PCL. This "double PCL" sign is highly _indicative of a displaced medial meniscus tear rather than a displaced lateral meniscus tear._

The MR image shows bone bruises (“kissing contusions”) consistent with an ACL tear. During the ACL subluxation event, the posterolateral tibial plateau subluxes anteriorly, making contact with the mid portion of the lateral femoral condyle and resulting in this characteristic bone bruise pattern on MRI. Randomized clinical trials comparing early accelerated versus nonaccelerated rehabilitation programs have demonstrated no significant differences in long-term results with regard to function, reinjury, and successful return to play. These studies did not address timing of return to play with an early accelerated rehabilitation program. At 2 and 3 years postsurgically, there are no differences in laxity, number of graft _failures, or KOOS scores._

OCD is an acquired lesion of the subchondral bone. Patients with OCD initially report nonspecific pain and variable amounts of swelling. Initial radiographs help identify the lesion and establish the status of the physes. An MRI scan is useful for assessing the potential for the lesion to heal with nonsurgical treatment. Nonsurgical treatment is appropriate for small, stable lesions in patients with open physes and focuses on activity restriction for 3 to 9 months. Surgical treatment is necessary for unstable or detached lesions. Stable lesions with intact articular cartilage can be treated with subchondral drilling to stimulate vascular ingrowth, with radiographic healing at an average of 4.4 months. Fixation is indicated for unstable or hinged lesions, and stabilization of the fragment can be achieved using a variety of implants through an arthroscopic or open approach. The fragment should be salvaged and the normal articular _surface restored whenever possible._

The MR images show a tear through a discoid lateral meniscus. A discoid meniscus is caused by a failure of apoptosis during development in utero and is considered a congenital abnormality. Discoid menisci are prone to tearing and can be caused by minimal trauma. There is no known genetic cause for this condition. Radiographic findings that may be present in the setting of a discoid meniscus include lateral joint space widening, squaring of the lateral femoral condyle, and cupping of the lateral tibial plateau. Contralateral discoid menisci are noted in 20% of patients. There are no other known associated conditions. Treatment _of a symptomatic discoid meniscus should include partial meniscectomy and saucerization or repair._

Surgical intervention of discoid meniscus is based on symptomatic patients. Complete discoid menisci are typically stable but are expected to have >4.5 times incidence of surgical intervention. Saucerization of symptomatic discoid meniscus is associated with better results with younger patients with increases of poor outcomes in adult-aged patients. Meniscal transplant may be an option, although long-term results _are unknown._

The radiograph reveals bony overgrowth of the microfracture site on the lateral femoral condyle. This occurs from violation of the subchondral plate during aggressive removal of the calcified cartilage layer during the microfracture. It is important during a microfracture to attempt to have a contained lesion and remove the calcified cartilage layer down to the subchondral plate, but avoid aggressively penetrating the _plate._

The MR images show a tear through a discoid lateral meniscus. A discoid meniscus is caused by a failure of apoptosis during development in utero and is considered a congenital abnormality. Discoid menisci are prone to tearing and can be caused by minimal trauma. There is no known genetic cause for this condition. Radiographic findings that may be present in the setting of a discoid meniscus include lateral joint space widening, squaring of the lateral femoral condyle, and cupping of the lateral tibial plateau. Contralateral discoid menisci are noted in 20% of patients. There are no other known associated conditions. Treatment _of a symptomatic discoid meniscus should include partial meniscectomy and saucerization or repair._

This athlete sustained an isolated PCL injury. The mechanism of injury is typical for a PCL injury. When a PCL injury is identified, one must rule out other ligamentous injuries to the knee. The patient has a stable examination to varus and valgus and a negative dial test, so the lateral collateral, medial collateral, and posterolateral corner (respectively) are intact. It is common to have increased anterior to posterior translation in isolated PCL injuries, even with an intact ACL, as the tibia will rest posterior to the medial femoral condyle. Treatment of isolated PCL injuries is typically nonoperative, with an initial focus on quadriceps strengthening. Hamstring strengthening and rehabilitation is added at a later time, as this places increased stress on the healing PCL. The images reveal an isolated PCL injury with intact menisci and ACL, ruling out ACL reconstruction using autograft tissue and PCL reconstruction using autograft tissue.

If the graft becomes tighter with knee flexion, the femoral attachment is too proximal. This error is referred to as “high and tight,” meaning that a high or proximal femoral attachment produces a graft that is too tight with knee flexion. If graft tension increases with increasing knee flexion, the result is loss of knee flexion or graft failure, increased contact forces resulting in patella femoral chondrosis, and possibly medial subluxation.

This patient has a classic presentation of postmeniscectomy medial compartment arthritis. The appropriate diagnostic study is weight-bearing radiographs to confirm the diagnosis. An MRI scan will reveal medial compartment arthritis but will not provide information about alignment. A CT scan would be appropriate to detect an occult fracture; however, this condition is not suspected in this clinical scenario. Ultrasonography can provide information about fluid collection around the knee or a deep vein thrombosis; however, these conditions also are not suspected in this clinical scenario. Because the patient has a correctable deformity (gaps 3 mm with valgus stress), and his symptoms are localized to the involved compartment, a trial of a medial unloader brace is appropriate both diagnostically and therapeutically. If unloading the medial compartment resolves the patient’s symptoms, he would be an excellent candidate for an osteotomy. An MRI scan may be obtained to evaluate ligamentous integrity or to evaluate degenerative involvement of the lateral and patellofemoral compartment for presurgical planning of an osteotomy; however, the integrity of the medial meniscus has no clinical importance in a patient with severe medial compartment arthritis. A repeat corticosteroid injection is not indicated within 1 month of his last injection, and referral to pain management is not appropriate with other options available to help this patient. A VPHTO is the appropriate intervention considering the patient’s young age, high-functional occupation, examination, radiographic findings, and response to medial unloader bracing. A revision knee arthroscopy would be appropriate for a recurrent medial meniscus tear, but not appropriate in a patient with severe medial compartment arthritis. The patient’s young age and high functional requirements are contraindications to TKA. The presence of severe arthritis is a contraindication to medial meniscus transplant. The patient is a candidate for a VPHTO. The technical options include a medial opening-wedge or a lateral closing-wedge osteotomy. Both techniques have advantages and disadvantages; however, a medial opening-wedge osteotomy is contraindicated in a smoker because of concern for nonunion. As a result, current smoking history is the only factor listed that would influence the technique used. The history of prior arthroscopy has no relevance in the decision about which type of osteotomy is appropriate. Normal BMI is between 18.5 and 24.9, so this patient’s BMI is considered normal and would not affect the surgical technique (if this patient were obese, a lateral closing-wedge osteotomy would be considered, but this is controversial). His age of 40 years is an indication for HTO but does not influence technique.

MR images reveal a posterior horn root tear of the medial meniscus. LaPrade and associates found that outcomes after posterior meniscal root repair significantly improved postoperatively and patient satisfaction was high, regardless of age or meniscal laterality. Patients aged <50 years had outcomes similar to those of patients ≥50 years, as did patients who underwent medial versus lateral root repair. In patients undergoing pullout fixation for posterior medial meniscus root tear, Chung and associates (in “Pullout Fixation of Posterior Medial Meniscus Root Tears”) found that patients with decreased meniscus extrusion at postoperative 1 year have more favorable clinical scores and radiographic findings at midterm follow-up than those with increased extrusion at 1 year. Krych and associates found that nonoperative treatment of medial meniscus posterior horn root tears is associated with poor clinical outcome, worsening arthritis, and a relatively high rate of arthroplasty at 5-year follow-up. Reconstruction would have no role _in the setting of a reparable meniscal root tear._

This patient sustained an isolated anterior cruciate ligament (ACL) injury based upon the mechanism described and examination findings. The finding that produces the “clunk” is the pivot-shift maneuver, which is positive in a knee with an incompetent ACL. With an ACL-deficient knee in full extension and internal rotation, the lateral tibial plateau subluxates anteriorly. As the knee is flexed, the lateral tibial plateau slides posteriorly into a reduced position, causing an audible clunk. Response D correctly describes the pathomechanics that result in the audible clunk heard during the pivot-shift maneuver. Responses A and B are incorrect because they describe the medial tibial plateau, which is not part of the pathomechanics of the pivot shift. Response C is incorrect because in extension, the lateral tibial plateau _is subluxated, not reduced._

The MR image is consistent with an episode of patellar instability with concomitant bruising of the medial patellar facet and lateral femoral condyle. The medial patellofemoral ligament appears torn and attenuated. Kita and associates reported that severe trochlear dysplasia is the most important predictor of residual patellofemoral instability after isolated medial patellofemoral ligament reconstruction. An increased TT-TG affected outcomes of patients with type D trochlear dysplasia (Dejour classification). Wagner and associates also found that high degrees of trochlear dysplasia correlate with poor clinical outcome due to graft overload in dysplastic situations. Other studies by Nelitz and associates and Matsushita and associates have also suggested that TT-TG distance did not reliably correlate with clinical outcome. Tibial slope would not affect recurrent patellar instability.

Technical failure is the most common reason for ACL reconstruction failure. Tunnel position is the most frequent cause for technical failure. Malpositioning of the tunnel affects the length of the graft, causing either decreased range of motion or increased graft laxity. Although graft choice is an important factor when planning an ACL reconstruction, overall outcomes with autograft tissues are fairly similar. Fixation of the graft at the femoral or tibial end is not as important as tunnel position.

After HTO, particularly in patients who have been immobilized after a closing-wedge osteotomy, patella baja is a common finding. This can precipitate anterior knee pain or patellofemoral pain syndrome. Recurrence of medial joint overload is incorrect because the patient has no medial joint complaints. Nonunion is less likely with a closing-wedge osteotomy and likely will not result in anterior knee pain.

The MR images show a tear through a discoid lateral meniscus. A discoid meniscus is caused by a failure of apoptosis during development in utero and is considered a congenital abnormality. Discoid menisci are prone to tearing and can be caused by minimal trauma. There is no known genetic cause for this condition. Radiographic findings that may be present in the setting of a discoid meniscus include lateral joint space widening, squaring of the lateral femoral condyle, and cupping of the lateral tibial plateau. Contralateral discoid menisci are noted in 20% of patients. There are no other known associated conditions. Treatment _of a symptomatic discoid meniscus should include partial meniscectomy and saucerization or repair._

The structure shown is the posterolateral bundle of the anterior cruciate ligament (ACL). This bundle is optimally positioned in the knee to resist rotatory forces during terminal knee extension. "Resist anterior translation during knee flexion" best describes the anteromedial bundle. "Resist rotatory loads during knee flexion" is unlikely because the posterolateral bundle is tightest during knee extension. The posterior cruciate ligament, not the ACL, functions to resist posterior translation.

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DISCUSSION:
The MRI scan clearly reveals bone bruises in the mid lateral femoral condyle and posterior tibial plateau. These MRI findings are commonly associated with acute anterior cruciate ligament injuries. Therefore, the preferred answer would be a positive pivot shift examination. A positive posterior drawer and positive quad active test are associated with posterior cruciate ligament injuries. A positive dial test would be suggestive of a posterolateral instability of the knee.

Patellar tendinopathy is a relatively common condition in athletes for which repetitive jumping is the norm, especially volleyball and basketball athletes. The prevalence has been reported to be up to 32% in professional basketball players. Initial management is nonoperative in nature with eccentric exercises providing the most reliable clinical results. The other selections have not demonstrated consistent longterm results.

This patient has a classic presentation of postmeniscectomy medial compartment arthritis. The appropriate diagnostic study is weight-bearing radiographs to confirm the diagnosis. An MRI scan will reveal medial compartment arthritis but will not provide information about alignment. A CT scan would be appropriate to detect an occult fracture; however, this condition is not suspected in this clinical scenario. Ultrasonography can provide information about fluid collection around the knee or a deep vein thrombosis; however, these conditions also are not suspected in this clinical scenario. Because the patient has a correctable deformity (gaps 3 mm with valgus stress), and his symptoms are localized to the involved compartment, a trial of a medial unloader brace is appropriate both diagnostically and therapeutically. If unloading the medial compartment resolves the patient’s symptoms, he would be an excellent candidate for an osteotomy. An MRI scan may be obtained to evaluate ligamentous integrity or to evaluate degenerative involvement of the lateral and patellofemoral compartment for presurgical planning of an osteotomy; however, the integrity of the medial meniscus has no clinical importance in a patient with severe medial compartment arthritis. A repeat corticosteroid injection is not indicated within 1 month of his last injection, and referral to pain management is not appropriate with other options available to help this patient. A VPHTO is the appropriate intervention considering the patient’s young age, high-functional occupation, examination, radiographic findings, and response to medial unloader bracing. A revision knee arthroscopy would be appropriate for a recurrent medial meniscus tear, but not appropriate in a patient with severe medial compartment arthritis. The patient’s young age and high functional requirements are contraindications to TKA. The presence of severe arthritis is a contraindication to medial meniscus transplant. The patient is a candidate for a VPHTO. The technical options include a medial opening-wedge or a lateral closing-wedge osteotomy. Both techniques have advantages and disadvantages; however, a medial opening-wedge osteotomy is contraindicated in a smoker because of concern for nonunion. As a result, current smoking history is the only factor listed that would influence the technique used. The history of prior arthroscopy has no relevance in the decision about which type of osteotomy is appropriate. Normal BMI is between 18.5 and 24.9, so this patient’s BMI is considered normal and would not affect the surgical technique (if this patient were obese, a lateral closing-wedge osteotomy would be considered, but this is controversial). His age of 40 years is an _indication for HTO but does not influence technique._

This patient likely has a physeal injury to the distal femoral physis. Stress radiographs or an MRI scan will most reliably reveal this diagnosis. The growth plate, when injured, is most commonly fractured through the hypertrophic zone of cartilage, its weakest point. This patient is optimally treated in a _cylindrical or long-leg cast._

The patient has sustained a proximal third tibia and fibula fracture, sometimes referred to as a "boot top" fracture when sustained while alpine skiing. These fractures frequently fall into apex anterior and valgus
angulation as shown in the radiographs. Great care needs to be taken during intramedullary nailing to avoid fixing the fracture in a malreduced position. The use of Poller blocking screws in the posterior and lateral aspects of the proximal fragment can help to avoid this complication (posterior screw prevents flexion deformity while lateral screw prevents valgus deformity). Additional technical pearls include starting with a more lateral entry point for the guidewire, placing a provisional unicortical plate prior to nailing to maintain the reduction, or using a suprapatellar entry nail to allow for fixation with the knee in _a semi-extended position._

The clinical description and MR image point to an injury to the posterior cruciate ligament (PCL). This ligament is thought to be primarily composed of anterolateral and posteromedial bundles, with the former tightening in flexion and the latter in extension. Because of alterations in knee kinematics and increased varus alignment in PCL insufficiency, contact stresses and cartilage loads increase in the patellofemoral and medial compartments. Although good outcomes may be obtained with transtibial, open inlay, and arthroscopic inlay techniques, one major difference is the creation of the “killer-turn” during the transtibial approach. This sharp turn in the graft as it emerges from the tibia appears to lead to more pronounced attenuation and thinning of the graft during cyclic loading. The scenario describes a patient with chronic PCL and posterolateral corner (PLC) injury, as evidenced by the varus thrust and abnormal Dial test finding. A valgus-producing osteotomy may be effective, and, in fact, may be the only treatment necessary to address chronic PLC injury. Accordingly, an opening lateral osteotomy would not be
appropriate. Of the remaining responses, an osteotomy that increases tibial slope would also address the PCL deficiency by reducing posterior tibial sag. Vascular injury is an uncommon, but potentially devastating, complication associated with PCL surgery and may occur regardless of the technique used. Numerous strategies have been described to reduce the risk, including use of a posteromedial accessory incision to allow finger retraction of the popliteal neurovascular bundle, oscillating drills to prevent excessive soft-tissue entanglement, and tapered (rather than square) drill bits that may minimize cut-out of sharp edges as drilling reaches the posterior tibial cortex. Knee extension lessens, rather than increases, the distance between the posterior tibia and the neurovascular bundle and increases, not lessens, risk for _vascular injury._

The clinical description and MR image point to an injury to the posterior cruciate ligament (PCL). This ligament is thought to be primarily composed of anterolateral and posteromedial bundles, with the former tightening in flexion and the latter in extension. Because of alterations in knee kinematics and increased varus alignment in PCL insufficiency, contact stresses and cartilage loads increase in the patellofemoral and medial compartments. Although good outcomes may be obtained with transtibial, open inlay, and arthroscopic inlay techniques, one major difference is the creation of the “killer-turn” during the transtibial approach. This sharp turn in the graft as it emerges from the tibia appears to lead to more pronounced attenuation and thinning of the graft during cyclic loading. The scenario describes a patient with chronic PCL and posterolateral corner (PLC) injury, as evidenced by the varus thrust and abnormal
Dial test finding. A valgus-producing osteotomy may be effective, and, in fact, may be the only treatment necessary to address chronic PLC injury. Accordingly, an opening lateral osteotomy would not be appropriate. Of the remaining responses, an osteotomy that increases tibial slope would also address the PCL deficiency by reducing posterior tibial sag. Vascular injury is an uncommon, but potentially devastating, complication associated with PCL surgery and may occur regardless of the technique used. Numerous strategies have been described to reduce the risk, including use of a posteromedial accessory incision to allow finger retraction of the popliteal neurovascular bundle, oscillating drills to prevent excessive soft-tissue entanglement, and tapered (rather than square) drill bits that may minimize cut-out of sharp edges as drilling reaches the posterior tibial cortex. Knee extension lessens, rather than increases, the distance between the posterior tibia and the neurovascular bundle and increases, not lessens, risk for _vascular injury._

This patient’s examination and history indicate recurrent patellar dislocations. Radiographs show an osseous or osteochondral loose fragment. There is no evidence of an obvious nondisplaced fracture or physeal changes. In the setting of suspected patella dislocation or subluxation with loose fragment seen on radiograph, an MRI is indicated. Lateral release alone is seldom indicated in a knee that is normal before injury. The examination and MRI do not indicate a need for medial collateral ligament repair.
Treatment should consist of arthroscopy or arthrotomy and attempted internal fixation of this fragment. If fixation is not possible, the loose body can be removed. Normal TT-TG values, an increased lateral patellar glide, and a history of recurrent patellar dislocations after trauma suggest MPFL incompetence _and the need for reconstruction._

The clinical description and MR image point to an injury to the posterior cruciate ligament (PCL). This ligament is thought to be primarily composed of anterolateral and posteromedial bundles, with the former tightening in flexion and the latter in extension. Because of alterations in knee kinematics and increased varus alignment in PCL insufficiency, contact stresses and cartilage loads increase in the patellofemoral and medial compartments. Although good outcomes may be obtained with transtibial, open inlay, and arthroscopic inlay techniques, one major difference is the creation of the “killer-turn” during the transtibial approach. This sharp turn in the graft as it emerges from the tibia appears to lead to more pronounced attenuation and thinning of the graft during cyclic loading. The scenario describes a patient with chronic PCL and posterolateral corner (PLC) injury, as evidenced by the varus thrust and abnormal Dial test finding. A valgus-producing osteotomy may be effective, and, in fact, may be the only treatment necessary to address chronic PLC injury. Accordingly, an opening lateral osteotomy would not be appropriate. Of the remaining responses, an osteotomy that increases tibial slope would also address the PCL deficiency by reducing posterior tibial sag. Vascular injury is an uncommon, but potentially devastating, complication associated with PCL surgery and may occur regardless of the technique used.
Numerous strategies have been described to reduce the risk, including use of a posteromedial accessory incision to allow finger retraction of the popliteal neurovascular bundle, oscillating drills to prevent excessive soft-tissue entanglement, and tapered (rather than square) drill bits that may minimize cut-out of sharp edges as drilling reaches the posterior tibial cortex. Knee extension lessens, rather than increases, the distance between the posterior tibia and the neurovascular bundle and increases, not lessens, risk for vascular injury.

Multiple biomechanical studies have investigated the contribution of the Gould modification with the Broström anatomic repair for chronic ankle instability. No studies to date have demonstrated a statistically significant difference in initial ankle stability with inclusion of the Gould modification or augmentation of the repair with a mobilized lateral portion of the extensor retinaculum. No clear association exists between the Broström-Gould repair technique and risk for nerve injury, postsurgical range of motion, or incidence of osteoarthritis on long-term follow-up.

The anterior drawer test is performed with the ankle in 10° of plantar flexion, which results in the greatest amount of translation. The test investigates the integrity of the anterior talofibular ligament with a key distance of translation being 8 to 10 mm. While the patient is sitting and has her knees flexed over the edge of a table or bench, the physician uses one hand to stabilize the distal leg and with the other hand applies an anterior force to the heel in an attempt to gap the talus anteriorly from under the tibia. The anterior talofibular ligament and calcaneofibular ligament are both compromised based on the examination findings. The anterior drawer test result reflects injury to the anterior talofibular ligament and a possible injury to the calcaneofibular ligament. A lateral talar tilt test angle measurement >15° degrees reflects a rupture of both anterior talofibular ligament and calcaneofibular ligaments. The
diagnosis is a severe lateral ligament complex sprain. This is optimally managed with early mobilization and a guided rehabilitation program that emphasizes proprioceptive stability.

The anterior drawer test is performed with the ankle in 10° of plantar flexion, which results in the greatest amount of translation. The test investigates the integrity of the anterior talofibular ligament with a key distance of translation being 8 to 10 mm. While the patient is sitting and has her knees flexed over the edge of a table or bench, the physician uses one hand to stabilize the distal leg and with the other hand applies an anterior force to the heel in an attempt to gap the talus anteriorly from under the tibia. The anterior talofibular ligament and calcaneofibular ligament are both compromised based on the examination findings. The anterior drawer test result reflects injury to the anterior talofibular ligament and a possible injury to the calcaneofibular ligament. A lateral talar tilt test angle measurement >15° degrees reflects a rupture of both anterior talofibular ligament and calcaneofibular ligaments. The diagnosis is a severe lateral ligament complex sprain. This is optimally managed with early mobilization and a guided rehabilitation program that emphasizes proprioceptive stability.

The anterior drawer test is performed with the ankle in 10° of plantar flexion, which results in the greatest amount of translation. The test investigates the integrity of the anterior talofibular ligament with a key distance of translation being 8 to 10 mm. While the patient is sitting and has her knees flexed over the edge of a table or bench, the physician uses one hand to stabilize the distal leg and with the other hand applies an anterior force to the heel in an attempt to gap the talus anteriorly from under the tibia. The
anterior talofibular ligament and calcaneofibular ligament are both compromised based on the examination findings. The anterior drawer test result reflects injury to the anterior talofibular ligament and a possible injury to the calcaneofibular ligament. A lateral talar tilt test angle measurement >15° degrees reflects a rupture of both anterior talofibular ligament and calcaneofibular ligaments. The diagnosis is a severe lateral ligament complex sprain. This is optimally managed with early mobilization _and a guided rehabilitation program that emphasizes proprioceptive stability._

The radiographs reveal medial clear space widening and an oblique proximal fibula fracture (best seen on the lateral view overlapping the tibia). This is consistent with an unstable syndesmotic injury. Operative repair of the syndesmosis with reduction and fixation is warranted. Immobilization is the best option for a stable syndesmotic injury. Physical therapy and MRI are not warranted given the findings on the _radiographs._

Ice hockey injuries demand a thorough assessment because they have the potential to be significant. In hockey players, bone injuries in the foot and ankle can be missed or improperly diagnosed through routine radiographic imaging. MRI can display bone injuries that are not found radiographically; this is because _some fractures and contusions involve the medial ankle and midfoot bones._

Mild traumatic brain injury is common in the adolescent child. Neuropsychological examination is widely used but, in this case, the patient is asymptomatic and has no baseline testing. There is a limited role for MRI in the recovery process of concussions. Furthermore, higher levels of physical/cognitive activity should be avoided due to their potential to increase total recovery time. In this scenario, a graduated return to activity is most appropriate thus, the next appropriate step is to start light aerobic activity.

CTE is a neurodegenerative disease that occurs years or decades after recovery from acute or postacute effects of head trauma. The exact relationship between concussion and CTE is not entirely clear; however, early behavioral manifestations of CTE have been described by family and providers to include apathy, irritability, and suicidal ideation. For some patients, cognitive difficulty such as poor episodic memory and executive function may be the first signs of CTE. Onset most often occurs in midlife after athletes have completed their sports careers, with mean age of onset at 42 years. The effects on the brain are degenerative, leading to a permanent state of derangement. Autopsy findings demonstrate multiple gross pathological findings. The condition is more common among contact athletes.

The National Collegiate Athletic Association's (NCAA) 2011 revised health and safety guidelines regarding concussion management recommend no return to play on the same day of an injury. In particular, athletes sustaining a concussion should not return to play the same day as their injury. Before resuming exercise, athletes must be asymptomatic or returned to baseline symptoms at rest and have no
symptoms with cognitive effort. They must be off of medications that could mask or alter concussion symptoms. Neurocognitive testing can be a helpful tool in determining brain function even after all symptoms of concussion have resolved. With a comparison baseline test, this evaluation, in conjunction with a physician's examination, may reduce risk for second impact syndrome. The athlete's clinical neurologic examination findings (cognitive, cranial nerve, balance testing) must return to baseline before resuming exercise. Research has shown that among youth athletes, it may take longer for tested functions to return to baseline (compared with the recovery rate in adult athletes). Brain MRI scan has no role in evaluating athletes for return to play in this situation.

This patient has sustained a significant concussion or minor brain injury. Although all answer options reflect important steps in her management, the initial primary concern in any player who is confused or combative is protection of the cervical spine until formal clearance can be performed. This patient requires immediate immobilization, collar placement, and, ultimately, transportation to a hospital. Cervical immobilization should be achieved before transport, given her complaints of neck pain and inability to provide a reliable examination.

Complete immobilization of the cervical spine is critical for athletes with a suspected cervical spine or spinal cord injury. The spinal cord in the subaxial spine is especially sensitive to motion, and removal of protective gear such as the helmet and shoulder pads presents an unacceptable risk for progressive neurologic injury in the setting of a potentially unstable cervical spine injury. Removal of the face mask alone is typically performed to improve access to an athlete's airway. Protective equipment often prevents
proper placement of a hard cervical collar, and the spine board offers a variety of options for safe cervical spine immobilization of helmeted athletes without a hard cervical collar. The log-roll and lift-and-slide techniques allow for the safe transfer of an athlete to a spine board while maintaining appropriate manual stabilization of the cervical spine.

Data collected in research studies fall into one of two categories—continuous or discrete. Continuous data can be displayed on a curve. Examples include height, weight, and time recorded in a 40-yard dash. Discrete data represent data that fall into specific categories such as gender or the presence or absence of a risk factor. ANOVA is used to determine statistical significance in mean values of continuous data when there are more than two independent samples. The 2-sample _t_ test compares mean values of continuous data between two independent groups. The Chi-square test and Fisher's exact tests are tests used to analyze discrete data.

The images illustrate a large unstable osteochondral lesion of the medial femoral condyle. Radiographs and MR images clearly show deep subchondral bone involvement. The appropriate choice of surgery is OCA transplantation, which is indicated for primary treatment of large cartilage lesions, osteochondral lesions, and salvage procedure from failed prior cartilage surgery. Correction of mechanical axis malalignment, ligamentous insufficiency, and meniscal deficiency should also be addressed. ACI alone or an arthroscopic microfracture procedure would not address the bone defect, leaving an uneven articular surface. Although an osteotomy may be a viable choice, a distal femoral varus osteotomy would increase the contact pressure in the medial compartment and worsen the situation. The histologic anatomy of articular cartilage is well described. The superficial layer or lamina splendens contains a small amount of proteoglycan with collagen fibrils arranged parallel to the articular surface. In contrast, the deep zone contains the largest-diameter collagen fibrils, oriented perpendicular to the joint surface, and the highest _concentration of proteoglycans._

Figure 1 reveals medial scapular winging secondary to weakness of the serratus anterior, which is innervated by the long thoracic nerve. Damage to the long thoracic nerve can occur via repetitive stretching, compression, or iatrogenic injury during a surgical procedure. Lateral thoracic winging is caused by weakness of the trapezius, which is innervated by cranial nerve XI (spinal accessory nerve). The direction of scapular winging is judged by the upper medial border of the scapula. Observation of a period of at least 6 months with serratus anterior strengthening while the nerve recovers is the mainstay _of treatment for medial scapular winging._

Heat exhaustion and heat stroke reflect varying degrees of heat illness, with both marked by increased heat production with impaired heat dissipation. Heat exhaustion typically involves a core body temperature between 37°C (98.6°F) and 40°C (104°F) and usually presents with heavy sweating, as well as nausea; vomiting; headache; fainting; weakness; and cold or clammy skin. Fatigue, malaise, and dizziness may occur, but necessary to the diagnosis is normal mentation and stable neurologic status. Heat stroke is defined by a core body temperature >40°C (>104°F) and disturbances of the central nervous system, such as confusion, irritability, ataxia, and even coma. Heat exhaustion is a less urgent scenario and can usually be treated with rest, elevation, and rehydration. Heat stroke, confirmed here by the presence of mental status changes, is a more critical situation. The most important immediate step is rapid body cooling through whatever means are available, as this has been clearly shown to improve outcomes. Ideally, a whole body ice bath would be used, with ice towels, ice packs, cold water, and air fans all utilized if needed. Emergency department transportation and rehydration may be considered as well but are not as important as immediate lowering of body temperature. Anti-pyretics have no role in this process.

The hockey player is suffering from commotio cordis, in which a cardiac arrhythmia occurs after a sudden blunt impact to the chest. Treatment of commotio cordis is defibrillation. As the time to defibrillation increases, the likelihood of survival decreases. In animal models, chest protectors have not shown efficacy
against ventricular fibrillation. The velocity of the projectile (most commonly baseball, hockey puck or lacrosse ball) has also not been shown to alter survival.