Orthopedic Surgery Board Exam: 100 High-Yield MCQs (Set 924)

26b 26c The mechanism of injury, physical examination, and radiographs indicate a "high" ankle sprain with disruption of the distal tibiofibular ligaments and interosseous membrane. These injuries typically involve pronation and external rotation forces. In addition, recovery is significantly delayed, often requiring 6 to 8 weeks to heal. Radiographs obtained months after recovery often show calcification within the distal syndesmosis, which is not typically symptomatic. This patient has gross instability, resulting in a high incidence of chronic diastasis and subluxation leading to impaired function. Treatment should consist of reduction and stabilization with a transsyndesmotic screw because this injury demonstrates a widened syndesmosis. Boytim MJ, Fisher DA, Neumann L: Syndesmotic ankle sprains. Am J Sports Med 1991;19:294-298.

Symphyseal widening of greater than 2.5 cm and less than 5 cm denotes an AP II injury and a rotationally unstable pelvis. An AP II pelvic ring injury is best treated with anterior open reduction and internal fixation. Nonsurgical management is reserved for AP I injuries. Pelvic binders are used only acutely and should not be used for definitive management. Iliosacral screws usually are not necessary in the acute management of AP II injuries. Matta JM: Indications for anterior fixation of pelvic fractures. Clin Orthop Relat Res 1996;329:88-96. Templeman DC, Schmidt AH, Sems AS, et al: Diastasis of the symphysis pubis: Open reduction internal fixation, in Wiss D (ed): Masters Techniques in Orthopaedic Surgery-Fractures, ed 2. Philadelphia, PA, Lippincott Williams and Wilkins, 2006, pp 639-648.

The radiographs show a bone-producing lesion in the distal femoral metaphysis in this case of classic osteosarcoma presenting in the most common location, the distal femur. The coronal MRI scan reveals a marrow-occupying lesion with extension into the soft tissues. The histology shows osteoid production by pleomorphic cells consistent with an osteosarcoma. Ewing's sarcoma is a bone tumor characterized by uniform small blue cells on histology. Rhabdomyosarcoma is the most common childhood soft-tissue sarcoma. Osteomyelitis has an inflammatory appearance on histology. Malignant fibrous histiocytoma of bone has a lytic radiographic appearance and a pleomorphic storiform pattern without osteoid on histology. Wold LE, Adler CP, Sim FH, et al: Atlas of Orthopedic Pathology, ed 2. Philadelphia, PA, WB Saunders, 2003, p 179.

MRI-arthrography has been shown to be an accurate technique for assessing the glenoid labrum in patients with suspected labral tears. Often standard MRI technique will not identify labral lesions. The use of MRI-arthrography with an intra-articular injection of gadolinium provides improved visualization of labral lesions. Bencardino and associates demonstrated a sensitivity of 89%, a specificity of 91%, and an accuracy of 90% in detecting labral lesions. SLAP lesions can be visualized on coronal oblique sequences as a deep cleft between the superior labrum and the glenoid that extends well around and below the biceps anchor. Often, contrast will diffuse into the labral fragment, causing it to appear ragged or indistinct. Applegate GR, Hewitt M, Snyder SJ, et al: Chronic labral tears: Value of magnetic resonance arthrography in evaluating the glenoid labrum and labral-bicipital complex. Arthroscopy 2004;20:959-963. Bencardino JT, Beltran J, Rosenberg ZS, et al: Superior labrum anterior-posterior lesions: Diagnosis with MR arthrography of the shoulder. Radiology 2000;214:267-271.

The patient has a severe Sanders type 4 calcaneus fracture. By far the most common complication associated with surgical treatment of calcaneus fractures is wound dehiscence. Sanders R: Displaced intra-articular fractures of the calcaneus. J Bone Joint Surg Am 2000;82:225-250.

The most common finding at exploration of an inappropriately placed pedicle screw is displacement of the nerve. Pedicle breach is common, ranging from 2% to 20%, but most are asymptomatic. All of the choices are possible, but in a large series conducted by Lonstein and associates, the authors reported that displacement of the root, most often medial, was the most common finding. Laceration, contusion, or transfixion usually was not seen. Spinal fluid leakage occurs less frequently and is not expected in the minimal broach illustrated. Esses SI, Sachs BL, Dreyzin V: Complications associated with the technique of pedicle screw fixation: A selected survey of ABS members. Spine 1993;18:2231-2238. Laine T, Lund T, Ylikoski M, et al: Accuracy of pedicle screw insertion with and without computer assistance: A randomised controlled clinical study in 100 consecutive patients. Eur Spine J 2000;9:235-240.

The patient has anterior interosseous nerve palsy. Initial management should consist of splinting followed by observation; surgical decompression may be required if there is no improvement in the functional deficit in 6 months. Anterior interosseous nerve palsy is classically described as an inability to flex the interphalangeal joint of the thumb because of flexor pollicis longus paralysis and a weakness or inability to flex the distal interphalangeal joint of the index finger because of weakness and/or paralysis of the flexor digitorum profundus to the index finger. There has been some controversy in the literature as to whether this represents a true peripheral compression neuropathy or neuritis. Recent recommendations have been to extend the period of observation from 3 to 6 months before surgical decompression, as most cases will resolve within 6 months. Miller-Breslow A, Terrono A, Millender LH: Nonoperative treatment of anterior interosseous nerve paralysis. J Hand Surg Am 1990;15:493-496.

The patient has a slipped capital femoral epiphysis (SCFE) at a younger than average age (average age 13.5 years for boys and 12.0 years for girls); therefore, an etiology that is not idiopathic must be considered. Hypothyroidism can result in a SCFE, but these children typically fall into the category of less than the 10th percentile for height. SCFE may develop in children with a growth hormone deficiency who have undergone hormonal replacement. Osteodystrophy caused by chronic renal failure may result in a SCFE, but the bone quality is markedly osteopenic on radiographs and the children are chronically ill with both low height and weight percentiles. An elevated estrogen level results in physeal closure and is protective to physeal slippage. Therefore, this child will most likely have normal laboratory values. Loder RT, Hensinger RN: Slipped capital femoral epiphysis associated with renal failure osteodystrophy. J Pediatr Orthop 1997;17:205-211.

The radiograph reveals an avulsion of the ischial apophysis, most likely the result of violent contraction of the attached hamstring tendons (semimembranosus, semitendinosus, and long head of the biceps femoris). The short head of the biceps femoris arises from the linea aspera on the posterior femur. The pectineus and adductor longus attach to the pubic portion of the pelvis. The piriformis runs from the sacrum to the femur. Woodburne RT (ed): Essentials of Human Anatomy. New York, NY, Oxford University Press, 1978, pp 542-545.

The radiograph shows a complete extrusion of the talus. Reimplantation of the talus after wound debridement has been reported to be safe and successful, and provides for flexibility with any future reconstructive procedures. Smith CS, Nork SE, Sangeorzan BJ: The extruded talus: Results of reimplantation. J Bone Joint Surg Am 2006;88:2418-2424.

Congenital dislocation of the knee is an uncommon deformity that varies in presentation from simple hyperextension to complete anterior dislocation of the tibia on the femur. Treatment varies with the age at presentation and the severity of the deformity. Most authors recommend early nonsurgical management. A recent study of 24 congenital knee dislocations in 17 patients found that satisfactory results were obtained in most instances using closed treatment. Based on their findings, the authors concluded that immediate reduction or serial casting should be performed when the patient is seen early after birth. If the patient is seen late and correction cannot be achieved by serial casting, traction followed by closed or open reduction may be necessary. Early percutaneous quadriceps recession has been described for complex congenital knee dislocations associated with underlying disorders, such as arthrogryposis and Ehlers-Danlos syndrome. Ko JY, Shih CH, Wenger DR: Congenital dislocation of the knee. J Pediatr Orthop 1999;19:252-259. Johnson E, Audell R, Oppenheim WL: Congenital dislocation of the knee. J Pediatr Orthop 1987;7:194-200.

11b Protection of the superior laryngeal nerve is critical in a professional singer. The nerve is easily injured with retraction when using vertical extension of common anterior surgical approaches to gain exposure to the C2-3 level. McAfee and associates reported on 17 patients with C1-2 and C2-3 pathology. They used a modified submandibular approach as an anterior retropharyngeal exposure with modification of the superior extension of the Smith-Robinson technique that allows visualization of the superior laryngeal nerve and surrounding structures. No incidences of superior laryngeal nerve injury were recorded. The transoral approach should be avoided because of the high rate of infection and limited exposure. McAfee PC, Bohlman HH, Reilly LH Jr, Robinson RA, Southwick WO, Nachlas NE: The anterior retropharyngeal approach to the upper part of the cervical spine. J Bone Joint Surgery Am 1987;69:1371-1383.

Acetabular screws are inserted to supplement fixation. The acetabular component can be divided into four quadrants. Anatomic studies have shown that screws placed in the anterior superior and anterior inferior quadrants of the cup may injure the external iliac vein and obturator artery, respectively. Posterior superior and posterior inferior placement (in screws greater than 25 mm) may injure the sciatic nerve or the superior gluteal artery. The common iliac artery is proximal to the acetabulum and is at least risk for injury from acetabular screw placement.

The differential diagnosis includes septic hip and transient synovitis. Both disorders may present with a joint effusion. The increased teardrop distance and loss of range of motion implies that there is excess fluid in the joint. While the other tests can confirm this, only aspiration can characterize the fluid further, thereby indicating the etiology of the effusion. Provided there is enough fluid obtained at aspiration, the joint fluid should be sent for Gram stain, culture, cell count, glucose, and protein studies.

The history, examination, and surgical findings are most consistent with plantar fibromatosis. Plantar fibromatosis is a benign tumor of the plantar fascia that consists chiefly of fibromyoblasts. These cells produce excessive collagen and are similar to the cells found in the palmar fascia of patients with Dupuytren's contracture of the hand. The myocyte, synovial cell, and osteocyte all produce their respective individual tissue types but do not contribute to the formation of a plantar fibromatosis. The T-cell is an important immunologic cell that is most affected in patients with HIV.

Although considered benign bone lesions, lung metastases can develop in giant cell tumors and chondroblastomas. These often can be treated with multiple thoracotomies, resulting in long-term survival. Roberts PF, Taylor JG: Multifocal benign chondroblastomas: Report of a case. Hum Pathol 1980;11:296-298.

Ewing's sarcoma is characterized by small round blue cells. Lesions with a similar appearance include lymphoma, primitive neuroectodermal tumor, rhabdomyosarcoma, small cell lung tumor, and metastatic neuroblastoma. Karyotyping, immunohistochemistry, and electron microscopy can help differentiate these lesions.

The patient has a significantly displaced medial epicondyle fracture. The only absolute indication for surgical treatment is irreducible incarceration in the joint. Nonsurgical management usually results in a painless nonunion with good elbow function and little elbow instability. Prolonged immobilization should be avoided to prevent stiffness. Tardy ulnar nerve palsy and cubitus varus are not complications of medial epicondyle fractures. Chamber HG, Wilkins KE: Part IV: Apophyseal injuries of the distal humerus, in Rockwood CA Jr, Wilkins KE, Beaty JH (eds): Fractures in Children, ed 4. Philadelphia, PA, Lippincott-Raven, 1996, vol 3, pp 801-812.

The peroneus brevis and peroneus longus muscles are the main evertors of the hindfoot. As they descend along the posterior fibula, they pass through the retromalleolar sulcus, formed by the concavity of the retromalleolar fibula. This sulcus is deepened by a fibrocartilaginous rim. The superior peroneal retinaculum covers the fibular groove and stabilizes the peroneal tendons within the retromalleolar sulcus. It originates from the posterolateral ridge of the fibula and inserts onto the lateral calcaneus. Richardson EG (ed): Orthopaedic Knowledge Update: Foot and Ankle 3. Rosemont, IL, American Academy of Orthopaedic Surgeons, 2003, pp 81-89.

31b The arthroscopic views show the lateral side of the ankle as demonstrated by the presence of the tibiofibular articulation. As is typical in chronic anterolateral impingement, synovitis overlies the anteroinferior band of the tibiofibular ligament, the most distal portion of the anterior syndesmosis. Hypertrophic scar formed on or in this ligament can impinge on the lateral margin of the talar dome and has been associated with chronic anterolateral ankle pain. Bassett FH III, Gates HS III, Billys JB, et al: Talar impingement by the anteroinferior tibiofibular ligament: A cause of chronic pain in the ankle after inversion sprain. J Bone Joint Surg Am 1990;72:55-59.

The superficial portion of the MCL contributes 57% and 78% of medial stability at 5 degrees and 25 degrees of knee flexion, respectively. The deep MCL and posteromedial capsule act as secondary restraints at full knee extension. The anterior cruciate ligament and PCL also provide secondary resistance to valgus loads.

This fracture, known as a pilon fracture, represents comminution of the base of the middle phalanx with both palmar and dorsal cortical disruption. The treatment method that allows the best function and fewest complications is indirect reduction achieved through specific dynamic splinting or the use of specifically designed proximal interphalangeal joint external fixators. Early mobilization can be achieved by either of these techniques. Volar plate arthroplasty is indicated for a simple fracture-dislocation of the proximal interphalangeal joint with comminution of the volar fracture fragment and dorsal dislocation of the remaining articular surface. Open reduction and internal fixation or percutaneous pinning adds surgical risks and scarring and typically will not provide added stability. Cast immobilization will not achieve the goal of early range of motion. Stern PJ, Roman RJ, Kiefhaber TR, McDonough JJ: Pilon fractures of the proximal interphalangeal joint. J Hand Surg Am 1991;16:844-850.

Avulsion fractures of the tibial spine are rare injuries that result from rapid deceleration or hyperextension of the knee in skeletally immature individuals. This injury is the equivalent of ruptures of the anterior cruciate ligament in adults. These fractures are classified as types 1 through 3. Type 1 is a minimally displaced fracture, type 2 fractures have an intact posterior hinge, and type 3 fractures have complete separation. The radiograph demonstrates a completely displaced, or type III, tibial spine avulsion. Surgical reduction is indicated in type 2 fractures that fail to reduce with knee extension and in all type 3 fractures. Reduction may be arthroscopic or open, with fixation of the bony fragment using a method that maintains physeal integrity and prevents later growth arrest. Preferred techniques would be with suture or an intra-epiphyseal screw Wiley JJ, Baxter MP: Tibial spine fractures in children. Clin Orthop 1990;255:54-60. Mulhall KJ, Dowdall J, Grannell M, et al: Tibial spine fractures: An analysis of outcome in surgically treated type III injuries. Injury 1999;30:289-292. Owens BD, Crane GK, Plante T, et al: Treatment of type III tibial intercondylar eminence fractures in skeletally immature athletes. Am J Orthop 2003;32:103-105.

Because the man is only recently removed from his injury and is judged capable of returning to work with some restrictions, the term that best describes his work status is temporary partial disability.

Suprascapular nerve palsy is a fairly uncommon yet well-known cause of shoulder pain and weakness. A variety of causes have been described, including compression by a ganglion cyst, an anomalous or thickened superior transverse scapular ligament, a humeral and scapular fracture, and traction or kinking of the nerve in the suprascapular notch. In this patient, the injury is most likely caused by traction or compression of the nerve in the suprascapular notch as the result of positioning during abdominal surgery; therefore, the studies of choice are electromyography and nerve conduction velocity studies. While MRI of the cervical spine may be of some value in ruling out a radiculopathy, the clinical history does not support such a cause for this condition. Rengachary SS, Neff JP, Singer PA, Brackett CE: Suprascapular entrapment neuropathy: A clinical, anatomical, and comparative study. Part 1: Clinical study. Neurosurgery 1979;5:441-446. Rengachary SS, Burr D, Lucas S, Hassanein KM, Mohn MP, Matzke H: Suprascapular entrapment neuropathy: A clinical, anatomical and comparative study. Part 2: Anatomical study. Neurosurgery 1979;5:447-451.

Traumatic posterior instability is a common finding in football players, especially in the blocking positions as well as in the defensive linemen and linebackers. A traumatic blow to the outstretched arm results in posterior glenohumeral forces. Labral detachment at the glenoid rim is common. Patients report slipping or pain with posteriorly directed pressure. Rarely do these patients have true dislocations that require reduction; however, recurrent episodes of subluxation or pain are not uncommon. Posterior repair has been shown to be successful in the treatment of traumatic instability. Bottoni CR, Franks BR, Moore JH, et al: Operative stabilization of posterior shoulder instability. Am J Sports Med 2005;33:996-1002. Williams RJ III, Strickland S, Cohen M, et al: Arthroscopic repair for traumatic posterior shoulder instability. Am J Sports Med 2003;31:203-209.

25b 25c 25d The radiograph shows a lytic lesion in the left periacetabular area consistent with chondrosarcoma. A large soft-tissue mass is present along with extension through the supra-acetabular region and pubic ramus. The histology shows a hypercellular lesion infiltrating through the bony trabeculae with a basophilic cytoplasm. This is classified as a grade 2 chondrosarcoma. The treatment of a pelvic chondrosarcoma is wide resection via either an internal hemipelvectomy or amputation. Chondrosarcoma requires surgical resection for control and does not traditionally respond to chemotherapy or external beam irradiation therapy. Pring M, Weber, KL, Unni KK, et al: Chondrosarcoma of the pelvis: A review of sixty-four cases. J Bone Joint Surg 2001;83:1630-1642.

Compression of the suprascapular nerve by a ganglion cyst is a well-documented cause of pain and weakness in the shoulder. Isolated involvement of the infraspinatus indicates that the area of entrapment is at the spinoglenoid notch and not the suprascapular notch. The majority of ganglion cysts found in the shoulder are related to tears of the labrum. When such a compressive lesion is found, decompression can be accomplished through either an open or arthroscopic approach. Several authors have shown the value of arthroscopy in the treatment of this condition. It has been shown that it is technically possible to decompress a paralabral ganglion cyst using arthroscopy; this method is usually followed by repair of the torn labrum. Alternatively, arthroscopic repair of the labrum can be performed and the cyst may be aspirated at the time of surgery. Open cyst excision through a posterior approach is also an acceptable method of treatment. Schickendantz MS, Ho CP: Suprascapular nerve compression by a ganglion cyst: Diagnosis by magnetic resonance imaging. J Shoulder Elbow Surg 1993;2:110-114. Thompson RC, Schneider W, Kennedy T: Entrapment neuropathy of the inferior branch of the suprascapular nerve by ganglia. Clin Orthop 1982;166:185-187.

Congenital scoliosis in an infant warrants evaluation of the renal, cardiac, and neurologic systems because frequently there is concurrent pathology. Progression in this instance is possible but not certain; therefore, progression must be documented prior to any surgical intervention. Close observation with serial radiographs every 4 to 6 months is appropriate. All of the surgical options listed may be reasonable choices in the future, but cardiac evaluation is the most important issue at this time. Basu PS, Elsebaie H, Noordeen MH: Congenital spinal deformity: A comprehensive assessment at presentation. Spine 2002;27:2255-2259.

The history and presentation are consistent with type I Charcot-Marie-Tooth (CMT), the most common form of hereditary peripheral motor sensory neuropathy. Type I CMT is the most common, occurring in 50% of patients with CMT, and is characterized by marked slowing of motor neuron velocities, and inconsistent slowing of sensory neuron velocities. Peroneus longus to brevis transfer is indicated to release the overpull of the peroneus longus, and restore the eversion and dorsiflexion function of the peroneus brevis. A lateralizing calcaneal osteotomy with proximal translation is indicated to correct heel varus given that the Coleman block only allows for partial correction of heel varus. Proximal translation of the posterior tuber corrects for the increased calcaneal dorsiflexion, improving the lever arm for the triceps surae. A medial column closing wedge osteotomy is often required to correct a rigid, or semirigid plantar flexed first ray to allow for a balanced, plantigrade foot. Triple arthrodesis is indicated for rigid, arthritic hindfoot deformities. Transfer of the posterior tibial tendon to the tibialis anterior is not indicated since it is an out-of-phase transfer. Transfer of the posterior tibial tendon, when performed, should be to the lateral aspect of the foot. A medializing calcaneal osteotomy would accentuate the heel varus. There is no indication for Botox in CMT; Botox injection of the calf would further weaken push-off during gait. Bracing of a progressive semirigid or rigid deformity is not recommended. Younger AS, Hansen ST Jr: Adult cavovarus foot. J Am Acad Orthop Surg 2005;13:302-315. Sammarco GJ, Taylor R: Cavovarus foot treated with combined calcaneus and metatarsal ostetotomies. Foot Ankle Int 2001;22:19-30.

46b These lesions are emboli related to the cardiac surgery, and the patient is already on anticoagulation medication. The foot reveals no signs consistent with gangrene or infection. Unless the patient shows local or systemic signs of sepsis, the best management is observation. It is unlikely that formal debridement will be necessary. Bowker JH, Pfeiffer MA (eds): The Diabetic Foot. St Louis, MO, Mosby, 2001, pp 219-260.

This pattern of injury is consistent with an unrecognized compartment syndrome of the anterior and lateral compartments. Transfer of the PTT through a long incision in the interosseous membrane corrects the foot drop deformity, and allows adequate dorsiflexion provided that the tendon to be transferred has a strength of 5/5. Muscles/tendons typically lose one grade of strength after transfer. Transfer into the tendons at the level of the ankle prevents overtensioning or pullout of a PTT tendon that is not long enough. Debridement of the scarred muscle in the anterior compartment decreases the risk of scarring down to the tendon transfer. Transfer of the peroneus longus is not preferred given its relative lack of strength and line of pull. Continued therapy and bracing are unlikely to lead to further improvement at 2 years after injury. An ankle fusion would correct the foot drop but would not address the tendon imbalances between the tibialis anterior and the peroneus longus, and the PTT and the peroneus brevis. Hansen ST Jr: Functional Reconstruction of the Foot and Ankle. Philadelphia, PA, Lippincott Williams & Wilkins, 2000, p 192. Atesalp AS, Yildiz C, Komurcu M, et al: Posterior tibial tendon transfer and tendo-Achilles lengthening for equinovarus foot deformity due to severe crush injury. Foot Ankle Int 2002;23:1103-1106. Scott AC, Scarborough N: The use of dynamic EMG in predicting the outcome of split posterior tibial tendon transfers in spastic hemiplegia. J Pediatr Orthop 2006;26:777-780.

The radiographs show osteochondritis dissecans of the capitellum and a loose body in the anterior compartment. Arthroscopic removal is indicated because symptoms referable to the loose body are present. Baumgarten TE: Osteochondritis dissecans of the capitellum. Sports Med Arthroscopy Rev 1995;3:219-223.

The on-field evaluation and management of the seriously injured athlete requires advance preparation and planning. It is imperative that the health care team have a game plan in place and the proper equipment readily available. The initial step consists of stabilizing the head and neck by manually holding the head and neck in a neutral position. Then, in the following order, check for breathing, pulses, and level of consciousness. If the athlete is breathing, simply remove the mouth guard and maintain the airway. If the athlete is not breathing, the face mask must be removed and the chin strap left in place. An open airway must be established, followed by assisted breathing. CPR is only instituted when breathing and circulation are compromised. If the athlete is unconcious or has a suspected cervical spine injury, the helmet must not be removed until the athlete has been transported to an appropriate facility and the cervical spine has been completely evaluated. McSwain NE, Garnelli RL: Helmet removal from injured patients. Bull Am Coll Surg 1997;82:42-44. Vegso JJ, Lehman RC: Field evaluation and management of head and neck injuries. Clin Sports Med 1987;6:1-15.

The radiograph reveals the classic "bump" that is seen in patients with femoroacetabular impingement (FAI). Ganz and associates described two types of FAI. This patient has cam impingement, which describes a nonspherical femoral head being forced into the acetabulum during hip motion and resulting in labral and chondral injury. Hip arthroscopy and labral debridement is unlikely to control the symptoms because the underlying anatomic abnormality is often difficult to address with arthroscopy. The treatment involves surgical dislocation of the hip with preservation of the blood supply to the femoral head, removal of the asphericity on the femoral side (femoral osteoplasty), and removal of the acetabular rim (acetabular osteoplasty) if the latter is found to contribute to impingement. Ganz R, Gill TJ, Gautier E, et al: Surgical dislocation of the adult hip a technique with full access to the femoral head and acetabulum without the risk of avascular necrosis. J Bone Joint Surg Br 2001;83:1119-1124. Ganz R, Parvizi J, Beck M, et al: Femoroacetabular impingement: A cause for early osteoarthritis of the hip. Clin Orthop 2003;417:112-120.

Radiographs reveal malunion of a Monteggia fracture-dislocation. Dislocation of the posterior radial head is caused by the malunited ulnar fracture. The deformity includes shortening with an apex posterior angulation. In the acute setting, open reduction of the radial head rarely is necessary; however, in chronic dislocations, open reduction is required. Without ulnar osteotomy, recurrent radial head dislocation is likely.

Open reduction and transfer of the subscapularis and lesser tuberosity into the humeral head defect is the treatment of choice for chronic posterior dislocations in which the articular defect consists of 20% to 40% of the articular surfaces. Closed reduction can be used if the dislocation is recognized early and the articular defect is less than 20% of the articular surface. Humeral arthroplasty is reserved for patients with an articular defect that is greater than 45% to 50% of the head. Hawkins RJ, Neer CS II, Pianta RM, Mendoza FX: Locked posterior dislocation of the shoulder. J Bone Joint Surg Am 1987;69:9-18.

Os acromiale represents a failure of fusion of the anterior acromial apophysis and has been reported in approximately 8% of the population. Patients with a symptomatic os acromiale often report impingement-type symptoms with pain over the superior acromion, especially with overhead activities or sleeping. When nonsurgical management is unsuccessful, surgical options include excision, open reduction and internal fixation, and arthroscopic decompression. Kurtz CA, Humble BJ, Rodosky MW, et al: Symptomatic os acromiale. J Am Acad Orthop Surg 2006;14:12-19.

A high level of suspicion must be given for a fracture in any patient with ankylosing spondylitis who reports neck pain, even with minimal or no trauma. The neck should be immobilized in its normal position, which is often kyphotic, and plain radiographs should be obtained. If no obvious fracture is seen, CT with reconstruction should be obtained. The placement of in-line traction can have catastrophic effects because it may malalign the spine. Brigham CD: Ankylosing spondylitis and seronegative spondyloarthropathies, in Clark CR (ed): The Cervical Spine, ed 3. Philadelphia, PA, Lippincott Raven, 1998, pp 724-727.

All of the factors listed contribute to some extent to the pull-out strength of lumbar pedicle screws, but bone mineral density correlates most precisely. Wittenberg RH, Shea M, Swartz DE, et al: Importance of bone mineral density in instrumented spine fusions. Spine 1991;16:647-652.

The radiograph shows osteochondritis dissecans (OCD) of the capitellum, one manifestation of "pitcher's elbow." The lesion is nondisplaced, and healing is possible if the inciting throwing activities are curtailed. Long arm cast treatment may be reasonable for the noncompliant patient but should not exceed 6 weeks duration. Surgical treatment is indicated for loose bodies or cartilage flaps. Elbow OCD lesions are now being seen in younger children as more participate in organized sports, especially baseball and gymnastics. Bauer M, Jonsson K, Josefsson PO, et al: Osteochondritis dissecans of the elbow: A long-term follow-up study. Clin Orthop 1992;284:156-160. Takahara M, Ogino T, Sasaki I, et al: Long term outcome of osteochondritis dissecans of the humeral capitellum. Clin Orthop 1999;363:108-115.

The incidence of injury associated with horseback rising is estimated to be one per 350 riding hours to one per 1,000 riding hours. Of these injuries, approximately 15% to 27% are severe enough to warrant hospital admission. Significant and serious injuries in equestrian activities are associated with recreational riders and those not wearing a helmet. Head and spine injuries are more common in recreational and nonhelmeted riders. Extremity injuries are more common in professional and helmeted riders. Professional riders are less likely to be admitted to the hospital than recreational riders, and are about half as likely to be disabled at 6 months after injury as recreational riders. Lim J, Puttaswamy V, Gizzi M, et al: Pattern of equestrian injuries presenting to a Sydney teaching hospital. ANZ J Surg 2003;73:567-571.

Greater tuberosity anterior fractures associated with anterior glenohumeral dislocations respond very well to closed methods in the majority of patients. Closed reduction of the glenohumeral joint often anatomically reduces the greater tuberosity into its cancellous bed, without the need for open fixation or cuff repair. Once closed reduction of the joint is performed, tuberosity displacement and joint articulation should be evaluated radiographically with AP and scapular lateral views as well as an axillary view. The axillary view will not only definitively show the joint articulation but also demonstrate posterior displacement of the greater tuberosity missed on the AP and lateral views. If no or minimal (5 mm) displacement is found, then nonsurgical management consisting of a sling and gentle passive range-of-motion exercises can be instituted. Beaty JH (ed): Orthopaedic Knowledge Update 6. Rosemont, IL, American Academy of Orthopaedic Surgeons, 1999, pp 271-286.

The radiographs reveal both cement debonding at the lateral shoulder of the prosthesis and a cement mantle fracture. Both of these indicate a loose femoral component. The radiographs show a stress fracture with reactive bone on the lateral femoral cortex in conjunction with the cement mantle fracture. The acetabular component shows no evidence of loosening. Heterotopic bone usually is not a source of pain when it is Brooker grade I, as in this case. Parkinsonism generally is not associated with hip pain. Harris WH, McCarthy JC, O'Neill DA: Femoral component loosening using contemporary techniques of femoral cement fixation. J Bone Joint Surg Am 1982;64:1063-1067. Callaghan JJ, Rosenberg AG, Rubash H (eds): The Adult Hip. Philadelphia, PA, Lippincott-Raven, 1998, pp 960, 1228-1229.

The most likely diagnosis is a stress fracture of the calcaneus and is supported by the history of running, female gender, and amenorrhea. Reproducing pain with medial and lateral compression of the heel also supports the diagnosis. A bone scan or MRI would most likely confirm the diagnosis. Plantar fasciitis would result in pain on the bottom of the heel with point tenderness. The lack of other areas of involvement or other symptoms does not support a seronegative inflammatory arthritis. Tarsal tunnel syndrome and peripheral neuropathy are unlikely because of the normal neurologic examination. Beaty JH (ed): Orthopaedic Knowledge Update 6. Rosemont, IL, American Academy of Orthopaedic Surgeons, 1999, pp 597-612.

Stress fractures of the navicular are often seen in running and jumping sports. Whereas most individuals heal with nonsurgical management consisting of 6 weeks of casting, this gymnast has had pain for 1 year and nonsurgical management has failed. Open reduction with bone grafting is the preferred treatment. Quirk RM: Stress fractures of the navicular. Foot Ankle Int 1998;19:494-496.

41b Transolecranon fracture-dislocations are most effectively managed with open reduction and internal fixation, followed by early aggressive range of motion. Concomitant injury to the collateral ligament is rare, and stability is achieved by anatomic reconstruction of the olecranon fracture with rigid fixation. The need for collateral ligament repair or a hinged external fixator is uncommon in this fracture pattern.

The schematic labeled A best depicts the primary fracture line in a calcaneal fracture. The primary fracture line in an axial-loading fracture of the calcaneus occurs from superior-lateral to inferior-medial. This fracture line separates the calcaneus into sustentacular and tuberosity fragments and typically enters the subtalar joint through the posterior facet. Although additional fracture lines typically occur, the primary fracture line is almost always present. If surgical reduction is planned, reducing the primary fracture is always a key step. Macey LR, Benirschke SK, Sangeorzan BJ, Hansen ST: Acute calcaneal fractures: Treatment option and results. J Am Acad Orthop Surg 1994;2:36-43.

12b 12c Injury to the spinal accessory nerve can occur after penetrating trauma to the shoulder. Blunt trauma may also cause loss of trapezius function. Most commonly, surgical dissection in the posterior triangle of the neck, such as lymph node biopsy, may expose the nerve to possible damage. Surgical repair of the nerve may be considered up to 1 year after injury; after this time muscle transfer is usually associated with a better functional outcome. Steinman SP, Spinner RJ: Nerve problems in the shoulder, in Rockwood CA, Matsen FA, Wirth MA, et al (eds): The Shoulder. Philadelphia, PA, WB Saunders, 2004, vol 2, pp 1013-1015.

A number of bioabsorbable polymers are used in orthopaedic applications, and all have in common reports of foreign body reactions, which occur in more than 50% of patients in some series. In general, the high cost of these polymers is offset by the elimination of a second surgery to remove the implant. Bioabsorbable polymers are low strength in comparison to metallic alloys but of sufficient strength for many orthopaedic applications. The elastic modulus is not as high as many other orthopaedic biomaterials, making them suitable for applications where lower stiffness is an asset. Ambrose CG, Clanton TO: Bioabsorbable implants: Review of clinical experience in orthopedic surgery. Ann Biomed Eng 2004;32:171-177.

The radiographs show posterior instability caused by an absent posterior cruciate ligament. The tibia is significantly displaced posteriorly with respect to the femur. This can be demonstrated with a lateral radiograph obtained with the knee in flexion. The anterior cruciate ligament has been resected but is not responsible for the instability shown.

53b Celiac sprue results in rapid gastrointestinal transit and fatty stools that impair the absorption of calcium and vitamin D and result in nutritional-deficiency osteomalacia with secondary hyperparathyroidism. The radiographs show marked osteopenia with brown tumors. A pathologic fracture is seen in the proximal humerus through a large brown tumor. Serum findings include low or normal calcium, low phosphate, elevated alkaline phosphatase, low 1,25(OH)2D, and increased PTH levels. Secondary hyperparathyroidism is associated with a variety of conditions including malabsorption syndromes. Potts JT: Parathyroid hormone: Past and present. J Endocrinol 2005;187:311-325. Corazza GR, Di Stefano M, Maurino E, et al: Bones in coeliac disease: Diagnosis and treatment. Best Pract Res Clin Gastroenterol 2005;19:453-465.

Dislocation following total hip arthroplasty is twice as common in women than in men. It is more likely to occur in older patients. There is no clear association between dislocation and the method of fixation or the type of bearing, so long as the bearing diameter is the same.

Kinematic analysis of both menisci demonstrates anterior movement with extension and posterior movement with flexion. The lateral meniscus has more mobility than the medial meniscus because of less soft-tissue attachments. Insall JN, Scott WN (eds): Surgery of the Knee, ed 3. New York, NY, Churchill Livingstone, 2001, vol 1, p 474. Thompson WO, Thaete FL, Fu FH, et al: Tibial meniscal dynamics using 3D reconstructions of MR images, in Proceedings of the Orthopaedic Research Society 1990;389.

Although obesity can make brace or halo wear difficult, it has not been associated with an increased risk for nonunion. Carson GD, Heller JG, Abitbol JJ, et al: Odontoid fractures, in Levine AM, Eismont FJ, Garfin SR, et al (eds): Spine Trauma. Philadelphia, PA, WB Saunders, 1998, pp 235-238.

Based on the epiphyseal location and sharp, well-defined borders, the radiograph suggests chondroblastoma. Histologically, multinucleated giant cells are scattered among mononuclear cells. The nuclei are homogenous and contain a characteristic longitudinal groove. Although not seen here, "chicken-wire calcification" with a bland giant cell-rich matrix is also typical for chondroblastoma. Clear cell chondrosarcoma occurs in epiphyseal locations but has a more aggressive histologic pattern and occurs in an older age group. Giant cell tumors occur in the epiphysis but have a more uniform giant cell population histologically. Aneurysmal bone cyst often results in bone remodeling and has a different pathologic appearance. Osteonecrosis has a typical histologic pattern of empty lacunae and necrotic bone. Springfield DS, Capanna R, Gherlinzoni F, et al: Chondroblastoma: A review of seventy cases. J Bone Joint Surg Am 1985;67:748-755. Simon M, Springfield D, et al: Chrondroblastoma: Surgery for Bone and Soft Tissue Tumors. Philadelphia, PA, Lippincott Raven, 1998, p 190.

3b Although inadequate correction, obesity, patient age of older than 5 years and an increased metaphyseal-diaphyseal angle are all associated with a poorer outcome, the radiographs show a growth arrest of the medial tibial physis. If not recognized and treated with early surgery, progressive genu varum will occur with continued growth of the lateral physis. In addition to repeat osteotomy, options for treating the arrest include physeal bar resection or, as necessary, completion of the growth arrest by epiphyseodesis of the lateral physes, followed by a limb equalization procedure at a later date. Brooks WC, Gross RH: Genu varum in children: Diagnosis and treatment. J Am Acad Orthop Surg 1995;3:326-335. Herring JA: Tachdjian's Pediatric Orthopedics, ed 4. Philadelphia, PA, WB Saunders, 2002, pp 840-950.

The patient sustained a type I unstable fracture that requires debridement of superficial fragments from the sole and surgical stabilization. Low-velocity wounds less than 8 hours old are considered type I open fractures. In contrast, gunshot wounds with associated fractures more than 8 hours old are considered type II open fractures using the Gustilo and Anderson classification. Gustilo type I stable fractures due to gunshot wounds and seen within 8 hours can be treated with tetanus toxoid (if no history of immunization or booster within 5 years), surface irrigation, and casting or a hard sole shoe. Antibiotics are not required unless gross contamination is present. However, if the extent of contamination is unclear, or if a joint is penetrated, then routine antibiotic prophylaxis is recommended. Indications for surgery include: articular involvement, unstable fractures, presentation 8 or more hours after injury, tendon involvement, and superficial fragments in the palm or sole. Type I unstable fractures may be stabilized with internal or external fixation. Type II unstable fractures should be treated with external fixation and repeat debridements until clean. Holmes GB Jr: Gunshot wounds of the foot. Clin Orthop Relat Res 2003;408:86-91.

The carotid tubercle is usually located at the level of C6. The angle of the mandible is at C1-C2; the hyoid is at C4; the superior portion of the thyroid cartilage is C4-C5; and the cricoid cartilage is at C6. Smith GW, Robinson RA: The treatment of certain cervical-spine disorders by anterior removal of the intervertebral disc and interbody fusion. J Bone Joint Surg Am 1958;40:607.

17b 17c Parameters for first metatarsal fracture management are different than for shaft fractures of the central second, third, and fourth metatarsals. The first metatarsal carries a greater load and if malunited, can create transfer lesions by virtue of uneven weight distribution; therefore, nonsurgical management is not indicated for this patient. Percutaneous pinning is not as likely to result in an anatomic reduction as open reduction and internal fixation. As his livelihood depends on an expeditious return to function, the choice of open reduction and internal fixation allows for earlier motion and rehabilitation. Richardson EG (ed): Orthopaedic Knowledge Update: Foot and Ankle 3. Rosemont, IL, American Academy of Orthopaedic Surgeons, 2004, pp 64-65.

Surgical decompression and stabilization have been shown to be the most effective means of improving neurologic function. Decompression is most reliably done from the side of the compression, which is anterior in this patient. Harrington KD: Metastatic tumors of the spine: Diagnosis and treatment. J Am Acad Orthop Surg 1993;1:76-86.

Radiographic abnormalities such as coxa magna, coxa breva secondary to growth arrest, and coxa plana and acetabular deformities are associated with healed Legg-Calve-Perthes disease. Femoral heads that were flat yet congruent with the acetabulum are at risk for disabling arthritis in the sixth decade of life in 50% of these untreated patients. As the normal ball-and-socket joint deforms to a flattened cylinder, the hip loses abduction and rotation capability, while retaining flexion and extension potential. If the femoral head is flat and is not concentric with the acetabulum, early severe arthritis occurs. Hinge abduction and anterior impingement are known sequelae of a flat, incongruent femoral head.

An intramuscular lipoma is a benign soft-tissue lesion that can grow and has a small risk of progressing to a liposarcoma. Radiographs usually show a globular radiolucent mass adjacent to higher-density muscle tissue shadows. When the patient has symptoms and reports an increase in size of the mass, the treatment of choice after appropriate radiographic analysis is complete excision of the mass with marginal resection. Sampling error is a problem with fatty lesions and core or incisional biopsies are frequently unnecessary, especially if an MRI scan of the lesion shows signal intensity that matches subcutaneous fat on all sequences. Damron TA: What to do with deep lipomatous tumors. Instr Course Lect 2004;53:651-655. Gaskin CM, Helms CA: Lipomas, lipoma variants, and well-differentiated liposarcomas (atypical lipomas): Results of MRI evaluations of 126 consecutive fatty masses. Am J Roentgenol 2004;182:733-739.

The primary change that takes place in the aging spine is degeneration of the lumbar disks and loss of the overall lumbar lordosis. This also may be associated with osteopenic-related compression fractures. With these changes, the sagittal vertical line moves anteriorly relative to the sacrum; cervical scoliosis is uncommon and not part of the normal aging process. Overall kyphosis in the thoracic spine gradually increases, but the coronal balance remains essentially the same unless scoliosis develops. Gelb DE, Lenke LG, Bridwell KH, et al: An analysis of sagittal spinal alignment in 100 asymptomatic middle and older aged volunteers. Spine 1995;20:1351-1358.

The genitofemoral nerve and the sympathetic plexus consistently lie on the ventral surface of the psoas muscle. The ilioinguinal and iliohypogastric nerves are the most superior branches of the lumbar plexus and emerge along the upper lateral border of the psoas muscle traveling toward the quadratus lumborum. Both the obturator and femoral nerves are deep and lateral to the psoas muscle. Watkins RG (ed): Surgical Approaches to the Spine, ed 1. New York, NY, Springer-Verlag, 1983, p 107. Johnson R, Murphy M, Southwick W: Surgical approaches to the spine, in Herkowitz HH (ed): The Spine, ed 4. Philadelphia, PA, WB Saunders, 1992, p 1559.

Retrograde ejaculation is a sequela of injury to the superior hypogastric plexus. The structure needs protection, especially during anterior exposure of the lumbosacral junction. The use of monopolar electrocautery should be avoided in this region. The ideal exposure starts with blunt dissection just to the medial aspect of the left common iliac vein, sweeping the prevertebral tissues toward the patient's right side. Although erectile dysfunction can be seen after spinal surgery, it is not typically related to the surgical exposure because erectile function is regulated by parasympathetic fibers derived from the second, third, and fourth sacral segments that are deep in the pelvis and are not at risk with the anterior approach. The other choices are complications of spinal surgery but are not uniquely associated with an anterior L5-S1 exposure. Flynn JC, Price CT: Sexual complications of anterior fusion of the lumbar spine. Spine 1984;9:489-492. Watkins RG (ed): Surgical Approaches to the Spine, ed 1. New York, NY, Springer-Verlag, 1983, p 107.

The radiograph shows a complete acromioclavicular separation. Because the patient is a professional athlete who is unable to participate, surgery is indicated. Chronic separations, especially those with previous trauma from joint pinning, should be treated with resection of the distal clavicle and stabilization to the coracoid. Some type of biologic reconstruction of the coracoclavicular ligaments is generally recommended. Open repair of the ligaments is generally not possible in such a delayed fashion. Screw fixation alone will not provide a lasting solution as the screws usually need to be removed, leaving no fixation in place. Reconstruction using the coracoacromial ligament is generally recommended with coracoclavicular fixation to protect the repair while it heals. Nuber GW, Bowen MK: Disorders of the acromioclavicular joint: Pathophysiology, diagnosis and management, in Iannotti JP, Williams GR (eds): Disorders of the Shoulder: Diagnosis and Management. Philadelphia, PA, Lippincott Williams and Wilkins, 1999.

The initial management of a lumbar strain should consist of 2 to 3 days of bed rest when symptoms are severe, activity restrictions, and nonsteroidal anti-inflammatory drugs. It has been estimated that 60% to 80% of the adult population experiences back pain, with 2% to 5% affected yearly. Spontaneous improvement generally will occur within 4 weeks. Further study is indicated by the presence of radiculopathy, weakness, trauma, or suspicion of malignancy. Bigos S, Boyer O, Braen GR, et al: Acute low back pain in adults: Clinical practice guideline No. 14. AHCPR Publication No. 95-0642. Rockville, MD, Agency for Health Care Policy and Research, Public Health Service, US Department of Health and Human Services, December, 1994.

Osteoblastomas are benign lesions that represent less than 5% of benign bone tumors. Most lesions are located in the spine, followed by the femur, tibia, and skull. Patients with spinal lesions usually have pain that may be associated with scoliosis. The most common location in the spine is within the posterior elements.

The patient has a pronounced deformity with pain and degenerative arthritis; therefore, triple arthrodesis is the treatment of choice. Gastrocnemius or Achilles tendon lengthening may be a necessary adjunct to the triple arthrodesis, but alone is inadequate to allow for correction. Because the ankle-foot orthosis has failed to provide relief, a UCBL is not likely to help. Osteotomy procedures are designed for lesser deformities and well-preserved joints. Nunley JA, Pfeffer GB, Sanders RW, et al (eds): Advanced Reconstruction: Foot and Ankle. Rosemont, IL, American Academy of Orthopaedic Surgeons, 2004, pp 115-120.

Patients with Becker muscular dystrophy have an abnormality in dystrophin, but unlike patients with Duchenne muscular dystrophy, some dystrophin is present. As a result, the progression of muscle weakness is slower, with the diagnosis typically made after age 8 years. Similar to patients with Duchenne muscular dystrophy, patients with Becker muscular dystrophy have pseudohypertrophy of the calves, markedly increased creatine kinase levels, and X-linked transmission of the condition. In addition, these patients are more prone to cardiomyopathy; a condition that should be carefully evaluated if any surgery is required. Patients with spinal muscular atrophy also have proximal muscle weakness, but the onset of weakness occurs earlier in childhood. These patients also have absent deep tendon reflexes and fasciculations, but pseudohypertrophy is absent and creatine kinase levels are normal. Patients with Emery-Dreifuss dystrophy may have a similar clinical picture to Becker's muscular dystrophy, but pseudohypertrophy is absent and creatine kinase levels are only mildly elevated. In addition, neck extension, elbow flexion, and ankle equinus contractures develop at an early age. Limb girdle dystrophy is a group of progressive muscular dystrophies that is not associated with pseudohypertrophy or a significant elevation of creatine kinase levels. Guillain-Barre syndrome is a condition associated with results from postinfectious demyelination of the peripheral nerve. These patients have the acute onset of weakness, hypotonia, and areflexia; creatine kinase levels are normal. Sussman MD: Muscular dystrophy, in Fitzgerald RH, Kaufer H, Malkani AL (eds): Orthopaedics. St Louis, MO, Mosby, 2002, pp 1573-1583.

Gradual dessication of the disk begins in the third decade as glycosaminoglycan levels within the nucleus begin to decline. The original water content of 88% decreases to 70% in the sixth decade and beyond. As glycosaminoglycan content decreases, there is a corresponding increase in noncollagen glycoprotein. Happey F, Weissman A, Naylor A: Polysaccharide content of the prolapsed nucleus pulposus of the human intervertebral disc. Nature 1961;192:868. Naylor A, Shentall R: Biomechanical aspects of intervertebral discs in aging and disease, in Jayson M (ed): The Lumbar Spine and Back Pain. New York, NY, Grune and Stratton Inc, 1976, pp 317-326.

7b The MRI scan shows a Segond fracture, which is a small avulsion of the lateral joint capsule from the anterolateral aspect of the proximal tibia. It is almost always associated with anterior cruciate ligament rupture and often with a tear of either the medial or lateral meniscus. Goldman AB, Pavlov H, Rubenstein D: The Segond fracture of the proximal tibia: A small avulsion that reflects major ligamentous damage. Am J Roentgenol 1988;151:1163-1167. Sanders TG, Miller MD: A systematic approach to magnetic resonance imaging interpretation of sports medicine injuries of the knee. Am J Sports Med 2005;33:131-148.

Following failure of physical therapy and pharmacologic management in a patient with complex regional pain syndrome, the management of choice is sympathetic blocks. While continued physical therapy would be assistive, sympathetic blocks allow a more rapid relief of symptoms. Neurostimulation is not appropriate at this stage because of its invasive nature. Cepeda MS, Lau J, Carr DB: Defining the therapeutic role of local anesthetic sympathetic blockade in complex regional pain syndrome: A narrative and systematic review. Clin J Pain 2002;18:216-233. Perez RS, Kwakkel G, Zuurmond WW, et al: Treatment of reflex sympathetic dystrophy (CRPS type 1): A research synthesis of 21 randomized clinical trials. J Pain Symptom Manage 2001;21:511-526. Tran KM, Frank SM, Raja SN, et al: Lumbar sympathetic block for sympathetically maintained pain changes in cutaneous temperatures and pain perception. Anesth Analg 2000;90:1396-1401.

The correct decision on return to sports participation after episodes of transient quadraparesis is controversial. Cantu and Mueller feel strongly that the loss of cerebrospinal fluid space about the spinal cord signifies an unacceptable risk for future spinal cord injury if the athlete returns to sports. However, Watkins and Torg and Lasgow have reported no evidence of increased spinal cord injury in athletes with narrow spinal canals, even in football. These authors suggest judgment be used in advising return to contact or high-energy sports and that the physician's responsibility is to give accurate and relevant information, allowing the athlete to make his or her own choice regarding return to sports participation. Cantu R, Mueller FO: Catastrophic spine injuries in football (1977-1989). J Spinal Disord 1990;3:227-231. Watkins RG: Neck injuries in football players. Clin Sports Med 1986;5:215-246. Torg JS, Lasgow SG: Criteria for return to contact activities following cervical spine injury. Clin Sports Med 1991;1:12-26.

Bilateral joint replacement, chronic disease, and preoperative autologous donation all increase the risk of needing blood. Young patients and a high hemoglobin level (greater than 15 g/dL) are considered clinical parameters that decrease the risk for requiring allogenic blood. Bierbaum BE, Callaghan JJ, Galante JO, Rubash HE, Tooms RE, Welch RB: An analysis of blood management in patients having a total hip or knee arthroplasty. J Bone Joint Surg Am 1999;81:2-10.

The incidence of recurrent disk herniation after a successful diskectomy is approximately 5% to 10%. Indications for surgical diskectomy for a recurrence are the same as for a primary diskectomy. Beaty JH (ed): Orthopaedic Knowledge Update 6. Rosemont, IL, American Academy of Orthopaedic Surgeons, 1999, pp 685-698.

Numerous clinical and basic science investigations have evaluated meniscal tear characteristics to identify factors that either promote or mitigate against meniscal healing. Complex tears have been noted to heal poorly, while longitudinal tears heal more predictably. Tear length, time from injury to repair, medial versus lateral meniscal tears, and the use of a fibrin clot have not been shown to consistently affect meniscal healing. However, rim width, the distance of the tear site from the peripheral meniscocapsular junction (vascular supply), has been shown to have a significant role in the ability of a meniscus repair to heal. DeHaven KE, Arnoczky SP: Meniscus repair: Basic science, indications for repair, and open repair. Instr Course Lect 1994;43:65-76.

Water is the most abundant component of articular cartilage with a wet weight of 65% to 80%. Of the water, 80% is at the surface and 65% at the deep zone. Collagen accounts for 10% to 20% of the wet weight, with type II collagen accounting for 90% to 95% of the total collagen content. Small amounts of types V, VI, IX, X, and XI collagen are also present. Proteoglycans comprise 10% to 15% of the wet weight of collagen. The remainder of the wet weight is made up of other collagens, noncollagenous proteins, and chondrocytes.

Achieving stability in chronic locked posterior dislocations of the shoulder remains a difficult challenge. Intraoperative measures include decreased humeral retroversion, anterior releases, and posterior capsular tightening. Postoperative rehabilitation is of equal importance. Immobilization in an external rotation brace (10 degrees to 15 degrees) with the arm at the side for 4 to 6 weeks is recommended to decrease tension in the posterior capsule. When passive range-of-motion exercises are instituted, they should be performed in the plane of the scapula to avoid stress posteriorly. Internal rotation and supine elevation should be avoided for similar reasons. Hawkins RJ, Neer CS II, Pianta RM, Mendoza FX: Locked posterior dislocation of the shoulder. J Bone Joint Surg Am 1987;69:9-18.

Acceptable alignment in both bone forearm fractures is related to age and location. In children younger than age 9 years, angulations of 15 degrees and malrotation of 45 degrees are acceptable. In children older than age 9 years, acceptable alignment is 10 degrees of angulation and 30 degrees of malrotation. Bayonet apposition is acceptable provided that the angular and rotational reductions are held within these guidelines. A long arm cast provides better control of deforming forces than a short arm cast. Do TT, Strub WM, Foad SL, et al: Reduction versus remodeling in pediatric distal forearm fractures: A preliminary cost analysis. J Pediatr Orthop B 2003;12:109-115. Flynn JM: Pediatric forearm fractures: Decision making, surgical techniques, and complications. Instr Course Lect 2002;51:355-360. Ring D, Waters PM, Hotchkiss RN, et al: Pediatric floating elbow. J Pediatr Orthop 2001;21:456-459.

The most likely diagnosis is Lyme disease because of the patient's recent vacation in an area with a high risk of exposure. The most effective treatment is doxycycline. Neu HC: A perspective on therapy of Lyme infection. Ann NY Acad Sci 1988;539:314-316.

The peroneus brevis is easily identified by its location behind the fibula and its distal muscle belly. Axial MRI images provide a reliable guide even when one of the peroneals is completely ruptured, subluxated out of the peroneal groove, or absent. Sarrafian SK: Anatomy of the Foot and Ankle: Descriptive, Topographic, Functional, ed 2. New York, NY, Lippincott, 1993, pp 234-235.

Persistent Horner's sign (ptosis, myosis, and anhydrosis) is a sign of proximal injury, usually avulsion of the roots from the cord which disrupts the sympathetic chain. Root rupture or avulsion proximal to the myelin sheath has less chance of healing. Two-month-old infants with persistent weakness in the other areas described may still have a good prognosis for recovery. Concurrent clavicle fracture has been shown to have no prognostic value. Clarke HM, Curtis CG: An approach to obstetrical brachial plexus injuries. Hand Clin 1995;11:563-581.

In patients with radial nerve injuries with closed humeral fractures, it has been reported that 85% to 95% spontaneously recover. Based on this premise, most surgeons favor expectant management of these injuries. Even if there is no evidence of recovery at 6 weeks, repeat electromyography at 12 weeks is advocated. If there is no clinical or electromyographic signs of recovery at 6 months, exploration is recommended. If the nerve is in continuity at the time of exploration, nerve action potentials are useful in helping determine the need for neurolysis, excision, and grafting, or if excision and repair is the best option. Pollock FH, Drake D, Bovill EG, et al: Treatment of radial neuropathy associated with fractures of the humerus. J Bone Joint Surg Am 1981;63:239-243.

The patient has a distal biceps rupture. While the distal biceps contributes to elbow flexion, its main function is forearm supination. Baker BE, Bierwagen D: Rupture of the distal tendon of the biceps brachii: Operative versus non-operative treatment. J Bone Joint Surg Am 1985;67:414-417. D'Arco P, Sitler M, Kelly J, et al: Clinical, functional, and radiographic assessments of the conventional and modified Boyd-Anderson surgical procedures for repair of distal biceps tendon ruptures. Am J Sports Med 1998;26:254-261.

The presence of any curve greater than 20 degrees in a nonambulatory patient with Duchenne muscular dystrophy is an indication for posterior fusion with instrumentation. Because of progressive cardiomyopathy and pulmonary deficiency, waiting until the curve is larger can increase the risk of pulmonary or cardiac complications during or following surgery. There is some disagreement as to whether all such fusions must extend to the pelvis. Bracing or other nonsurgical management is ineffective and is not indicated in this situation. Sussman M: Duchenne muscular dystrophy. J Am Acad Orthop Surg 2002;10:138-151.

59b 59c 59d This classic case of osteosarcoma illustrates the typical radiographic and histologic characteristics of this disease. The radiographs show an aggressive-appearing lesion of the distal femur. The lesion has both lytic and blastic areas. Periosteal reaction is present in the form of a Codman's triangle. The radiographs are highly suggestive of osteosarcoma. The photomicrographs show malignant spindle cells that produce osteoid, thus confirming the diagnosis of osteosarcoma. Treatment of osteosarcoma is multimodal including multi-agent chemotherapy and surgery (wide resection or amputation). Bacci G, Ferrari S, Bertoni F, et al: Long-term outcome for patients with nonmetastatic osteosarcoma of the extremity treated at the Instituto Ortopedico Rizzoli according to the Instituto Ortopedico Rizzoli/osteosarcoma-2 protocol: An updated report. J Clin Oncol 2000;18:4016-4037. Bielack SS, Kempf-Bielack B, Delling G, et al: Prognostic factors in high-grade osteosarcoma of the extremities or trunk: An analysis of 1,702 patients treated on neoadjuvant cooperative osteosarcoma study group protocols. J Clin Oncol 2002;20:776-790.

The sagittal image reveals increased signal and decreased size of the supraspinatus and infraspinatus muscles, indicating muscle atrophy. The rotator cuff tendon signal is normal. The subscapularis and teres minor muscles are unaffected. Muscular dystrophy and thoracic outlet syndrome would be expected to have a more global effect. Although muscular atrophy can occur in the setting of a rotator cuff tear, the coronal image shows an intact supraspinatus. The suprascapular nerve supplies the supraspinatus and infraspinatus muscles. Therefore, suprascapular nerve entrapment would result in atrophy of these muscles with sparing of the surrounding musculature. Any lesion within the suprascapular notch, including neoplastic disease, a venous varix, or neuroma, can place pressure on the suprascapular nerve. Suprascapular nerve entrapment most commonly results from extension of a paralabral cyst or ganglion, often with associated labral pathology. Spinal accessory nerve disruption would show trapezius muscle atrophy. Resnick D, Kang HS (eds): Internal Derangement of Joints: Emphasis on MR Imaging. Philadelphia, PA, WB Saunders, 1997, pp 308-317.

Several studies have documented the satisfactory outcomes of total elbow arthroplasty when osteosynthesis is not feasible for fixation of a distal humerus fracture, particularly in the physiologically older patient with low functional demands. Total elbow arthroplasty should be considered when a comminuted intra-articular distal humerus fracture occurs in a woman older than age 65 years, particularly with such associated comorbidities as systemic steroid use, osteoporosis, or rheumatoid arthritis. Kamineni S, Morrey BF: Distal humeral fractures treated with noncustom total elbow replacement. J Bone Joint Surg Am 2004;86:940-947. Frankle MA, Herscovici D Jr, DiPasquale TG, et al: A comparison of open reduction and internal fixation and primary total elbow arthroplasty in the treatment of intraarticular distal humerus fractures in women older than 65. J Orthop Trauma 2003;17:473-480.

Most children with amyoplasia are ambulatory and when a decrease in function occurs because of a severe contracture, it must be addressed. A radical posterior soft-tissue release, including the posterior knee capsule and often the collateral ligaments and the posterior cruciate ligament, is needed to obtain extension. After the age of 1 year, aggressive physical therapy will do little to correct a contracture. Botulinum toxin A is indicated for spasticity and is contraindicated with severe contractures. Supracondylar femoral extension osteotomy works well, but will remodel at an average rate of 1 degree per month, which is not considered ideal in a young patient. Gradual correction with a circular ring external fixator is an option, but a soft-tissue release will also most likely be needed for a contracture of this severity. Sarwark JF, MacEwen GD, Scott CI Jr: Amyoplasia (a common form of arthrogryposis). J Bone Joint Surg Am 1990;72:465-469. DelBello DA, Watts HG: Distal femoral extension osteotomy for knee flexion contracture in patients with arthrogryposis. J Pediatr Orthop 1996;16:122-126.

There is almost universal acceptance that an athlete may return to play after blunt head trauma only if he or she is totally asymptomatic. Mild residual symptoms are considered an absolute contraindication for return to play. Returning to play after a cardiovascular challenge or sport-specific activities is permitted on the pretext that the athlete is totally asymptomatic prior to these maneuvers. Neuropsychiatric testing is being used more frequently to monitor residual cognitive effects after head trauma. It has not been used as a return to play criterion. Garrick J (ed): Orthopaedic Knowledge Update: Sports Medicine 3. Rosemont, IL, American Academy of Orthopaedic Surgeons, 2004, pp 29-48.

It is not uncommon for patients with ankylosing spondylitis to sustain extension-type fractures, most typically of the cervicothoracic junction. These fractures can appear nondisplaced or minimally displaced initially, making them difficult to diagnose. Because there is no mobility between vertebrae, fractures tend to occur more like those of a transverse fracture of a long bone. In addition, the vertebral bodies are vascular and their canals are relatively enclosed, making them vulnerable to epidural bleeding. The MRI scan reveals an epidural hematoma located posteriorly on the cord; therefore, the treatment of choice is surgical evacuation and a posterior laminectomy. Because of the intrinsic instability of such fractures at the time of the laminectomy, internal fixation and stabilization with a posterior fusion is warranted. A simple laminectomy will only increase instability, and control is unlikely with halo vest immobilization. An anterior procedure will not effectively treat the problem given the location of the hematoma. Consideration can be given to methylprednisolone and observation; however, this will not eradicate the problem. Bohlman HH: Acute fractures and dislocations of the cervical spine. J Bone Joint Surg Am 1979;61:1119-1142.

Tears of the pectoralis major tendon are frequently missed during examination. MRI provides excellent visualization of the tendon if the study extends low enough down the arm. The pectoralis major tendon inserts on the crest of the greater tubercle of the humerus, just lateral to the long head of the biceps tendon. The latissimus dorsi tendon inserts medial to the long head of the biceps tendon on the lesser tubercle. The subscapularis tendon inserts on the lesser tuberosity more proximally. The deltoid insertion is more distal. Connell DA, Potter HG, Sherman MF, et al: Injuries of the pectoralis major muscle: Evaluation with MR imaging. Radiology 1999;210:785-791. Carrino JA, Chandnanni VP, Mitchell DB, et al: Pectoralis major muscle and tendon tears: Diagnosis and grading using magnetic resonance imaging. Skeletal Radiol 2000;29:305-313.

IGF-I, formerly known as somatomedin-C, possibly acts by both paracrine and endocrine hormone pathways. The products of the GH-IGF-I system induce proliferation without maturation of the growth plate and thus induce linear skeletal growth. The action of the thyroid hormone axis is via an active metabolite that enters target cells and signals a nuclear receptor to stimulate both proliferation and maturation of the growth plate. Increased amounts of the active steroid hormone metabolite promote proliferation and maturation of the growth plate. Calcitonin inhibits bone resorption. Binder G, Grauer ML, Wehner AV, et al: Outcome in tall stature: Final height and psychological aspects in 220 patients with and without treatment. Eur J Pediatr 1997;156:905-910. Wang J, Zhou J, Cheng CM, et al: Evidence supporting dual, IGF-I-independent and IGF-I-dependent, roles for GH in promoting longitudinal bone growth. Endocrinol 2004;180:247-255.

Lubricin and SZP share a similar primary structure but may differ in posttranslational modifications with O-linked oligosaccharides. The primary physiologic function of SZP appears to be boundary lubrication. SZP does not influence interleukin-1, collagenase, or TIMP directly because these proteins are associated with articular cartilage turnover. Hlavacek M: The influence of the acetabular labrum seal, intact articular superficial zone and synovial fluid thixotropy on squeeze-film lubrication of a spherical synovial joint. J Biomech 2002;35:1325-1335.

The proposed mechanisms by which steroids such as methylprednisolone are thought to prevent neurologic deterioration by limiting secondary insult, include: decreasing the area of ischemia in the cord, reducing TNF-alpha expression and NF-kB binding activity, decreasing free radical oxidation and thus stabilizing cell and lysosomal membranes, and checking the influx of calcium into the injured cells, thus reducing cord edema. Slucky AV: Pathomechanics of spinal cord injury. Spine: State Art Rev 1999;13:409-417.

The radiograph and pathology are consistent with adamantinoma. While the mechanism underlying adamantinoma has not been identified, it is believed to be closely related to osteofibrous dysplasia, which may represent a precursor. The other diagnoses are not known to give rise to adamantinoma.

60b 60c 60d The patient has a large deep anterior thigh mass that has imaging characteristics of mature fat. Intramuscular lipomas are effectively treated with marginal resections with very low recurrence rates. Large lipomas often have small amounts of intralesional signal changes frequently representing trapped muscle fibers and do not necessitate more extensive margins. Gaskin CM, Helms CA: Lipomas, lipoma variants, and well-differentiated liposarcomas (atypical lipomas): Results of MRI evaluations of 126 consecutive fatty masses. Am J Roentgenol 2004;182:733-739.

The superior glenohumeral ligament identified as "A" in the figure functions primarily as a restraint to inferior glenohumeral translation of the adducted arm. The middle glenohumeral ligament is highly variable and pooly defined in up to 40% of the population and functions to restrain anterior translation of the externally rotated arm in the midrange of abduction. The anterior band of the inferior glenohumeral ligament is the primary restraint to anterior/inferior translation of the head with the shoulder abducted to 90 degrees and in maximum external rotation. Ticker JB, Bigliani LU, Soslowskiy LJ, et al: Inferior glenohumeral ligament: Geometric and strain-rate dependent properties. J Shoulder Elbow Surg 1996;5:269-279.