AAOS Orthopedic MCQs (Set 1): Spine Disorders, Sports Medicine & Arthroplasty | 2026 Board Review

The symptoms are consistent with tarsal tunnel syndrome. Ganglion cysts are a well-known cause of tarsal tunnel syndrome. The MRI scans show a high intensity, well-circumscribed mass in the tarsal tunnel that is consistent with a fluid-filled cyst. Patients usually respond well to excision of the ganglion and resolution of the tarsal tunnel symptoms. The surrounding fat is a different signal intensity on the MRI scans, which rules out a lipoma. Synovial cell sarcoma has a heterogeneous appearance on an MRI scan. Metastatic tumors are most commonly found in the osseous structures of the foot, not the soft tissues. Rozbruch SR, Chang V, Bohne WH, et al: Ganglion cysts of the lower extremity: An analysis of 54 cases and review of the literature. Orthopedics 1998;21:141-148. Llauger J, Palmer J, Monill JM, et al: MR imaging of benign soft-tissue masses of the foot and ankle. Radiographics 1998;18:1481-1498.

The most common complication associated with tarsometatarsal joint injury is posttraumatic arthritis. In one series, symptomatic arthritis developed in 25% of the patients and half of those went on to fusion. In another series, 26% had painful arthritis. Initial treatment should consist of shoe modification, inserts, and anti-inflammatory drugs. Fusion is reserved for failure of nonsurgical management. Hardware failure may occur, but it is clinically unimportant. Kuo RS, Tejwani NC, DiGiovanni CW, et al: Outcome after open reduction and internal fixation of Lisfranc joint injuries. J Bone Joint Surg Am 2000;82:1609-1618. Arntz CT, Veith RG, Hansen ST Jr: Fractures and fracture-dislocations of the tarsometatarsal joint. J Bone Joint Surg Am 1988;70:173-181.

The patient has symptomatic primary osteoarthritis of the elbow with multiple loose bodies. Given his age and occupation, an elbow arthroplasty is not an option. Arthroscopic debridement and removal of loose bodies has been shown to be effective for osteoarthritis of the elbow. Gramstad GD, Galatz LM: Management of elbow osteoarthritis. J Bone Joint Surg Am 2006;88:421-430.

The pectoralis major insertion is just lateral to the long head of the biceps tendon. Medial to the biceps is the insertion for the teres major and latissimus dorsi. The short head of the biceps originates on the coracoid process. The subscapularis inserts on the lesser tuberosity just medial to the biceps.

Unopposed action of the tibialis anterior with weakness of the peroneus longus will lead to a dorsal bunion and supination deformity. Overpull of the gastrocnemius-soleus complex and posterior tibialis with weakness of the peroneus brevis will cause equinovarus deformity. A strong posterior tibialis with weakness of the peroneals will cause varus of the hindfoot. Unopposed peroneus brevis and incompetence of the posterior tibialis will lead to a flatfoot deformity. The etiology of a cavus foot is complex, but findings usually include a contracted plantar fascia and weakness of the tibialis anterior. Drennan JC (ed): The Child's Foot and Ankle. New York, NY, Raven Press, 1992, pp 289-302.

The patient has patellar tendinitis (jumper's knee). It is a common overuse condition seen in runners, volleyball players, soccer players, and jumpers but can be seen in any activity in which repeated extension of the knee is required. In the acute setting, the pain is well localized and there is tenderness and sometimes swelling of the tendon. MRI is recommended for evaluating chronic cases and for surgical planning. In the acute phases, ice, rest, and avoidance of the offending activity are recommended. Weakness of the quadriceps and hamstring muscle are thought to contribute to this problem; therefore, stretching and isometric exercise in a limited range of motion are important. Complete rest and intratendinous injections of steroids are detrimental to tendon physiology. Stanish WD, Rubinovich RM, Curwin S: Eccentric exercise in chronic tendinitis. Clin Orthop 1986;208:65-68.

The superior ulnar collateral, inferior ulnar collateral, and posterior ulnar recurrent arteries provide consistent vascular supply to the ulnar nerve. This supply is segmental in nature. No identifiable direct anastomosis is seen between the superior ulnar collateral and the posterior ulnar recurrent arteries. The inferior ulnar collateral artery provides the only direct vascularization to the nerve and is located in the region just proximal to the cubital tunnel. The segmental nature of the blood supply to the ulnar nerve underscores the importance of its preservation during transposition.

While difficult to appreciate on the AP radiograph of the shoulder, the increased physeal signal demonstrated on the axial MRI scan is consistent with a nondisplaced growth plate fracture. A comparison radiograph of the left shoulder also could be considered and the injured shoulder evaluated for physeal widening. Proximal humeral fractures in children are somewhat unusual, representing less than 1% of all fractures seen in children and only 3% to 6% of all epiphyseal fractures. Physeal injuries are classified according to the Salter-Harris classification scheme. Salter-Harris type I fractures represent approximately 25% of physeal injuries to the proximal humerus in adolescents. The proximal humeral physis is responsible for 80% of the longitudinal growth of the humerus; therefore, there is tremendous potential for remodeling of fractures in this region. Management for nondisplaced Salter-Harris type I fractures is limited to a short period of immobilization followed by a gradual return to activities as clinical symptoms resolve. Curtis RJ, Rockwood CA Jr: Fractures and dislocations of the shoulder in children, in Rockwood CA Jr, Matsen FA III (eds): The Shoulder. Philadelphia, PA, WB Saunders, 1990, pp 991-1007.

Solitary bone lesions require biopsy, for there is the possibility that the lesion may represent a primary bone sarcoma, which will necessitate a different treatment plan. This is especially true in patients with remote histories of cancer. The most likely cause of a lytic bone lesion in a patient older than age 40 years is a metastatic lesion. Rougraff BT, Kneisl JS, Simon MA: Skeletal metastases of unknown origin: A prospective study of a diagnostic strategy. J Bone Joint Surg Am 1993;75:1276-1281.

Clerical error leading to acute hemolysis and even death occurs in 1:12,000 to 1:50,000 transfusions. Bacterial contamination leading to sepsis/shock occurs in 1:1 million transfusions. HIV transmission is approximately 1:500,000 transfusions and hepatitis C is 1:103,000 transfusions. Anaphylactic reactions occur in 1:150,000 transfusions. Aubuchon JP, Birkmeyer JD, Busch MP: Safety of the blood supply in the United States: Opportunities and controversies. Ann Intern Med 1997;127:904-909.

The most important aspect in the decision for surgery in an acetabular fracture is the ability of the femoral head to remain concentrically reduced under the dome in AP and Judet oblique views of the pelvis. If this parameter is present, then the need for surgery is determined by other aspects such as fragmentation, age, incongruity, and displacement. If the head remains stable under the dome without traction, there is sufficient acetabular dome to provide stability, and nonsurgical treatment may be appropriate. Tile M: Assessment and management of acetabular fractures, in Tile M (ed): Pelvic and Acetabular Fractures, ed 2. Baltimore, MD, Williams and Wilkins, 1995, pp 305-354. Letournel E: Acetabular fractures: Classification and management. Clin Orthop 1980;151:81-106.

While injury of the distal radial metaphysis is a rather common occurrence, the incidence of physeal arrest is only about 4% to 5% of patients. While injury of the distal physis of the ulna is rare, the incidence of physeal arrest is greater than 50% in fractures of this structure. These patients need to be followed closely both clinically and radiographically to look for the signs of distal ulnar/physeal arrest such as loss of the prominence of the ulna and ulnar deviation of the hand. Radiographically, progressive shortening of the ulna is observed. Nelson OA, Buchanan JR, Harrison CS: Distal ulnar growth arrest. J Hand Surg Am 1984;9:164-170.

The radiographs show fractures of the coronoid and radial head. The medial collateral ligament has been avulsed from the ulnar insertion, and there is a valgus opening on the medial side. The lateral collateral ligament is always disrupted in elbow dislocations and fracture-dislocations that occur secondary to falls. This is known as the terrible triad injury (dislocation and fractures of the coronoid and radial head); it has a very poor prognosis because of its propensity for recurrent or persistent instability and late arthritis. The principle in treating this injury is to repair all of the injured parts or protect them with a hinged external fixator until they heal. Norris TR (ed): Orthopaedic Knowledge Update: Shoulder and Elbow. Rosemont, IL, American Academy of Orthopaedic Surgeons, 1997, pp 345-354. Kasser JR (ed): Orthopaedic Knowledge Update 5. Rosemont, IL, American Academy of Orthopaedic Surgeons, 1996, pp 283-294.

Typically, posterior spinal fusion to the pelvis is recommended for patients with spinal muscular atrophy and advanced scoliosis. Examination for lower extremity muscle contractures is important because the contractures may interfere with good sitting balance. Anterior release and fusion usually are not advised. Diaphragmatic pacing is not indicated because diaphragm function usually is not affected. Patients with spinal muscular atrophy usually are not ambulatory or only marginally ambulatory at the time of scoliosis surgery; therefore, gait analysis usually is not relevant. While a muscle biopsy may have a role in the diagnosis of this disorder, it plays no subsequent role in determining life expectancy or the value of spinal surgery. Daher YH, Lonstein JE, Winter RB, Bradford DS: Spinal surgery in spinal muscular atrophy. J Pediatr Orthop 1985;5:391-395.

A total hip arthroplasty using the posterior approach has resulted in hip dislocation under certain circumstances. Reconstruction of the external rotator/capsular complex is recognized as a stability-enhancing mechanism for the posterior approach. During the procedure, the acetabular component should be placed in 15 to 20 degrees of anteversion and approximately 45 degrees of abduction. Relative retroversion is a risk factor for posterior dislocation. High abduction angles result in edge loading of the polyethylene and possible early failure, as well as an increased risk of dislocation. Smaller diameter heads and skirted neck extensions used together decrease the range of motion that is allowed before impingement occurs, and this can result in dislocation. Shorter neck lengths generally result in soft-tissue envelope laxity. If laxity occurs, increased offset, neck length, or both can improve stability. Pellicci PM, Bostrom M, Poss R: Posterior approach to total hip replacement using enhanced posterior soft tissue repair. Clin Orthop 1998;355:224-228.

There is a negative change of calcium balance with a decrease in intestinal absorption and an increase in urinary calcium loss. The reduction of intestinal absorption is accompanied by reduced circulating concentrations of total, but not free 1,25-dihydroxyvitamin D. However, estrogen may also directly regulate intestinal calcium resorption independent of vitamin D. Tubular resorption of calcium is higher in the presence of estrogen. Studies of the levels of PTH in the presence of estrogen are controversial. Oh KW, Rhee EJ, Lee WY, et al: The relationship between circulating osteoprotegerin levels and bone mineral metabolism in healthy women. Clin Endocrinol (Oxf) 2004;61:244-249.

The most common cause of recurrent dislocation following total hip arthroplasty continues to be component malposition. Component malposition should be addressed prior to any other treatment options, such as increasing soft-tissue tension with increased femoral offset or greater trochanteric advancement. A larger femoral head size may help, but correcting the component malposition should give more predictable results. A retroverted acetabular component should be revised to 15 degrees to 20 degrees of anteversion, matching the patient's anatomy with an abduction angle close to 45 degrees. Daly PJ, Morrey BF: Operative correction of an unstable total hip arthroplasty. J Bone Joint Surg Am 1992;74:1334-1343. Jolles BM, Zangger P, Leyvraz PF: Factors predisposing to dislocation after primary total hip arthroplasty: A multivariate analysis. J Arthroplasty 2002;17-282-288.

The arrow points to the biceps femoris, which is inserted onto the fibula. The biceps femoris lies at the posterolateral aspect of the thigh. The semimembranosus and the semitendinous lie at the posterior medial aspect of the thigh. Gray H: Anatomy of the Human Body. Philadelphia, PA, Lea and Febiger, 1918, 2000.

Posttraumatic osteolysis of the distal portion of the clavicle is a condition that can be a complication of acute or repetitive trauma. The distal end of the clavicle is frayed and resorbed. Resorption may occur after weeks or months. The end of the clavicle may reconstitute over a period of months, or the acromioclavicular joint may remain widened. The differential diagnosis for distal clavicular erosion also includes rheumatoid arthritis, hyperparathyroidism, neoplastic destruction, cleidocranial dysplasia, and pyknodysostosis. Acutely, a type 2 acromioclavicular joint injury does not result in erosion or resorption of the clavicle. Periosteal sleeve injuries radiographically mimic acromioclavicular joint dislocation. Rickets occurs only in childhood.

Nonsteroidal anti-inflammatory drugs (NSAIDs) have been shown to increase the risk of pseudarthrosis. In a controlled rabbit study, nonunions were reported with the use of toradol and indomethacin. NSAIDs are commonly used medications with the potential to diminish osteogenesis. Studies clearly have demonstrated inhibition of spinal fusion following the postoperative administration of several NSAIDs, including ibuprofen. Cigarette smoking is another potent inhibitor of spinal fusion. Glassman SD, Rose SM, Dimar JR, et al: The effect of postoperative nonsteroidal anti-inflammatory drug administration on spinal fusion. Spine 1998;23:834-838.

Doxorubicin is a chemotherapeutic agent that is best known for dose-limiting cardiotoxicity. This is related not only to the cumulative dose, but also the rate of infusion.

The CT scans show a burst fracture that results from an axial load injury. The radiographic hallmark of a burst fracture is compression of the posterior cortex of the vertebral body with retropulsion of bone into the spinal canal. AP radiographs often show widening of the interpedicular distance with a fracture of the lamina. Theiss SM: Thoracolumbar and lumbar spine trauma, in Stannard JP, Schmidt AH, Kregor PJ (eds): Surgical Treatment of Orthopaedic Trauma. New York, NY, Thieme, 2007, pp 179-207.

Proximal tibial osteotomy is appropriate for the younger and/or athletic patient who has mild to moderate medial compartment osteoarthritis. Relative contraindications include limited range of motion (eg, flexion contracture of 15 degrees), anatomic varus of greater than 10 degrees, advanced patellofemoral arthritis, and tibial subluxation. Inflammatory arthritides involve all the compartments and are a contraindication to osteotomies around the knee.

In general, a previously healthy patient with an acute onset of nontraumatic lower back pain does not need diagnostic imaging before proceeding with therapeutic treatment. In the absence of any "red flags" during the history and physical examination, such as trauma or constitutional symptoms (ie, fevers, chills, weight loss), the appropriate treatment for acute onset lower back pain is purely symptomatic treatment including limited analgesics and early range of motion. Diagnostic imaging is not necessary unless the initial treatment is unsuccessful and symptoms are prolonged. Miller and associates suggested that the use of radiographs can lead to better patient satisfaction but not necessarily better outcomes. Miller P, Kendrick D, Bentley E, et al: Cost effectiveness of lumbar spine radiographs in primary care patients with low back pain. Spine 2002;27:2291-2297.

Patients with diabetes mellitus are prone to infection, and surgical treatment of their infections frequently requires multiple procedures. The triad of poor wound healing, chronic neuropathy, and vascular disease contributes to the increased infection rate. Studies have demonstrated increased amputation rates in patients with diabetes mellitus who have renal failure or deep polymicrobial or gram-negative infections. Gonzalez MH, Bochar S, Novotny J, et al: Upper extremity infections in patients with diabetes mellitus. J Hand Surg Am 1999;24:682-686. Trumble TE (ed): Hand Surgery Update 3: Hand, Elbow, & Shoulder. Rosemont, IL, American Society for Surgery of the Hand, 2003, pp 433-457.

The complications of femoral neck fractures in children include osteonecrosis, malunion, nonunion, and premature physeal closure. It is presumed that the risk of osteonecrosis is directly related to the amount of displacement at the time of injury and is not affected by the type of treatment. The risk of the other complications can be decreased depending on the type of treatment. Anatomic reduction by either closed or open methods can reduce the risk of malunion. The addition of internal fixation allows for maintenance of the reduction. In young children who cannot comply with a partial or non-weight-bearing status, the addition of a spica cast gives added protection. Canale ST: Fractures of the hip in children and adolescents. Orthop Clin North Am 1990;21:341-352.

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.

Pelvic osteolysis in the presence of a well-fixed porous-coated socket is a recognized complication in total hip arthroplasty. The radiograph shows large lytic lesions superiorly adjacent to an acetabular screw and inferiorly extending into the ischium. It also reveals eccentricity of the femoral head with respect to the acetabular component, consistent with polyethylene wear. Koval KJ (ed): Orthopaedic Knowledge Update 7. Rosemont, IL, American Academy of Orthopaedic Surgeons, 2002, p 440.

Children with spastic diplegic cerebral palsy often have contractures of multiple joints. Because the gait abnormalities can be complex, isolated surgery is rarely indicated. To avoid compensatory deformities at other joints, it is preferable to correct all deformities in a single operation. Isolated heel cord lengthening in the presence of tight hamstrings and hip flexors will lead to progressive flexion at the hips and knees, thus worsening a crouched gait. Split posterior tibial tendon transfer is used for patients with hindfoot varus, which is not present in this patient. Gage JR: Distal hamstring lengthening/release and rectus femoris transfer, in Sussman MD (ed): The Diplegic Child. Rosemont, IL, American Academy of Orthopaedic Surgeons, 1992, pp 324-326.

The child has a trigger thumb deformity. A trigger thumb is a developmental mechanical problem rather than a congenital deformity. The anomaly generally is not noted at birth. A fixed flexion deformity of the IP joint of the thumb most commonly occurs in children in the first 2 years of life. A stretching and splinting program may correct the deformity in the first year of life, but nonsurgical management after age 3 years results in a success rate of only 50%. Release of the proximal annular pulley of the flexor sheath is recommended at this age. Tan AH, Lam KS, Lee EH: The treatment outcome of trigger thumb in children. J Pediatric Orthop B 2002;11:256-259. Slakey JB, Hennrikus WL: Acquired thumb flexion contracture in children: Congenital trigger thumb. J Bone Joint Surg Br 1996;78:481-483.

The patient has symptomatic postoperative heterotopic ossification after total hip arthroplasty. Postoperative prophylactic treatments include nonsteroidal anti-inflammatory drugs (usually indomethacin) or low-dose irradiation. The heterotopic ossification shown here is quite mature; therefore, nonsurgical management will not be successful. Surgical excision of grade III or IV heterotopic ossification should be followed with postoperative irradiation to minimize the chances of recurrence. Ayers DC, Evarts CM, Parkinson JR: The prevention of heterotopic ossification in high-risk patients by low-dose radiation therapy after total hip arthroplasty. J Bone Joint Surg Am 1986;68:1423-1430.

The association of a nail puncture wound with a gram-negative infection (Pseudomonas aeruginosa) has been attributed to the local environmental factors in shoes. Osteomyelitis is rare, occurring only in about 1% of patients. Tetanus prophylaxis should be given if it is not up to date. While the remaining organisms listed are periodically involved, they are more common in patients who are immunocompromised or who have diabetes mellitus. Therefore, obtaining a culture of the infected wound is appropriate in such individuals because of the multifactorial nature of the infection. Green NE, Bruno J III: Pseudomonas infections of the foot after puncture wounds. South Med J 1980;73:146-149.

Flexor tenosynovitis of the thumb flexor tendon sheath can spread proximally and form an abscess within the thenar space of the palm. The flexor pollicis longus tendon does not pass through the central space of the palm or the hypothenar space of the palm. The flexor pollicis longus tendon does pass through the carpal tunnel, but this is not a palmar space. The three palmar spaces include the hypothenar space, the thenar space, and the central space. The posterior adductor space would likely only be involved secondarily after spread from a thenar space infection. Hollinshead W: Anatomy for Surgeons: The Back and Limbs, ed 3. Philadelphia, PA, Harper and Row, 1982, vol 3, pp 478-479.

The history and findings are consistent with a diagnosis of a sprain of the medial collateral ligament (MCL) of the elbow; therefore, contrast-enhanced MRI is considered the most sensitive and specific study for accurately showing this injury. Arthroscopic visualization of the MCL is limited to the most anterior portion of the anterior bundle only; complete inspection of the MCL using the arthroscope is not possible. CT without the addition of contrast is of no value in this situation. Use of a technetium Tc 99m bone scan is limited to aiding in the diagnosis of occult fracture, a highly unlikely injury in this patient. There are no clinical indications for electromyography. Timmerman LA, Andrews JR: Undersurface tear of the ulnar collateral ligament in baseball players: A newly recognized lesion. Am J Sports Med 1994;22:33-36. Timmerman LA, Schwartz ML, Andrews JR: Preoperative evaluation of the ulnar collateral ligament by magnetic resonance imaging and computed tomography arthrography: Evaluation of 25 baseball players with surgical confirmation. Am J Sports Med 1994;22:26-32.

The radiographs reveal a predominantly lytic, destructive lesion of the distal femur, although there is a hint of some blastic change as well. The lesion has violated the cortex, and there is mineralization outside the cortex laterally. The lateral radiograph suggests a soft-tissue density. These aggressive changes on radiographs in this age group are strongly suggestive of osteosarcoma. Sanders TG, Parsons TW: Radiographic imaging of musculoskeletal neoplasia. Cancer Control 2001;8:221-231.

The grading of response to chemotherapy for osteosarcoma was introduced by Huvos and associates. Patients with tumors that show more than 90% necrosis after neoadjuvant chemotherapy are considered to have had a good response and have better survival rates than those with less than 90% necrosis. However, it should be noted that survival rates for patients with a poor response are still better than in patients who do not receive neoadjuvant chemotherapy. More recently, similar results have been reported in patients with Ewing's sarcoma. Chemotherapy is not typically used for giant cell tumor of bone. Meyers PA, Heller G, Healey J, Huvos A, Lane J, Marcove R, et al: Chemotherapy for nonmetastatic osteogenic sarcoma: The Memorial Sloan- Kettering experience. J Clin Oncol 1992;10:5-15.

Creatine is currently used as a nutritional supplement in an attempt to enhance athletic performance. The physiologic basis for its use is based on its conversion by CK to PCr, which acts as an energy reservoir in muscle cells for the production of ATP. A number of studies that examined the effect of creatine supplementation on performance concluded that while creatine does not increase peak force production, it can increase the amount of work done in the first few anaerobic short duration, maximal effort trials. The mechanism for this enhancement of work is unknown, but it is most likely secondary to the increase in the available PCr pool. Greenhaff PL: Creatine and its application as an ergogenic aid. Int J Sport Nutr 1995;5:S100-S110. Greenhaff PL, Casey A, Short AH, Harris R, Soderlund K, Hultman E: Influence of oral creatine supplementation on muscle torque during repeated bouts of maximal voluntary exercise in man. Clin Sci 1993;84:565-571. Trump ME, Heigenhauser GJ, Putman CT, Spriet LL: Importance of muscle phosphocreatine during intermittent maximal cycling. J Appl Physiol 1996;80:1574-1580.

The MRI scan shows significant dural ectasia, which is seen in more than 60% of patients with Marfan syndrome. It is also relatively common in patients with neurofibromatosis, but this patient has no skin lesions. It has also been described in Ehlers-Danlos syndrome but is less common. Ahn NU, Sponseller PD, Ahn UM, Nallamshetty L, Kuszyk BS, Zinreich SJ: Dural ectasia is associated with back pain in Marfan' syndrome. Spine 2000;25:1562-1568.

Several studies have shown that sitting ability by age 2 years is highly prognostic of walking. Molnar and Gordon reported that children not sitting independently by age 2 years had a poor prognosis for walking. Wu and associates reported that children sitting without support by age 2 years had an odds ratio of 26:1 of walking compared with those unable to sit. This was far higher than the odds ratios for cerebral palsy location, motor dysfunction, crawling, creeping, scooting, or rolling. Molnar GE, Gordon SU: Cerebral palsy: Predictive value of selected clinical signs for early prognostication of motor function. Arch Phys Med Rehabil 1976;57:153-158.

Biopsy of the soft-tissue component is often diagnostic. Alternatively, in centers with pathologists familiar with bone tumors, needle biopsy is usually successful. The principles of biopsy of bone tumors include avoiding contamination of uninvolved structures and compartments, taking the most direct path to the tumors, making an excisable biopsy tract, and obtaining diagnostic tissue. Transverse biopsy incisions should be avoided because they hinder the definitive surgical procedure. Peabody TD, Simon MA: Making the diagnosis: Keys to a successful biopsy in children with bone and soft-tissue tumors. Orthop Clin North Am 1996;27:453-459. Mankin HJ, Mankin CJ, Simon MA: The hazards of the biopsy, revisited. Members of the Musculoskeletal Tumor Society. J Bone Joint Surg Am 1996;78:656-663.

Linazolid is the first agent of the oxazolidinone group of antibiotics and is very active against methicillin-sensitive Staphylococus aureus, S epidermidis, and vancomycin-resistant enterococci. The drug has no gram-negative activity. Linazolid inhibits protein synthesis by blocking formation of the 70S ribosomal translation complex. This mechanism of action is unique to the oxazolidinones. Rybak MJ, Cappelletty DM, Moldovan T, et al: Comparative in vitro activities and postantibiotic effects of the oxazolidinone compounds eperezolid (PNU-100592) and linezolid (PNU-100766) versus vancomycin against Staphylococcus aureus, coagulase-negative staphylococci, Enterococcus faecalis, and Enterococcus faecium. Antimicrob Agents Chemother 1998;42:721-724.

Malunion of the talus is a devastating complication that leads to malpositioning of the foot and subsequent arthrosis of the subtalar joint complex. This is considered an avoidable complication in that accurate surgical reduction will minimize its development. Posttraumatic arthritis of the subtalar joint, osteonecrosis of the talus, posttraumatic arthritis of the ankle joint, and complex regional pain syndrome all may develop as a result of the initial traumatic event and may not be avoidable despite anatomic reduction. Rockwood and Green's Fractures in Adults, ed 5. Philadelphia, PA, Lippincott, Williams and Wilkins, 2001, pp 2091-2132.

The radius of curvature of the distal femur is greater over the distal aspect of the lateral femoral condyle than the distal aspect of the medial femoral condyle. As the femur rolls posteriorly during early knee flexion, both condyles undergo similar angular changes equal to the amount of flexion. With a similar amount of angular rotation, the sphere with the larger radius experiences greater net rollback, producing a pivoting motion. Although the anterior cruciate ligament plays a role in producing tibial rotations, the posterior cruciate ligament does not play a significant role in producing such rotations. Similarly, the tibial tubercle does not play a significant role in producing normal rotations of the femur relative to the tibia. The popliteus may also play a role in producing rotational pivots, as might differential laxity of the medial and lateral collateral ligaments in early knee flexion. Pellicci PM, Tria AJ Jr, Garvin KL (eds): Orthopaedic Knowledge Update: Hip and Knee Reconstruction 2. Rosemont, IL, American Academy of Orthopaedic Surgeons, 2000, pp 239-240.

Symptoms of activity-related low back pain, physical findings of pain with extension, lateral bending, and resuming an upright position, and relative hamstring tightness are consistent with spondylolysis. While the initial diagnostic work-up should include plain radiographs of the lumbosacral spine, the findings may be negative because it can take weeks or months for the characteristic changes to become apparent. SPECT has been a useful adjunct in the diagnosis of spondylolysis when plain radiographs are negative. Since the patient's pain is activity related and she is otherwise healthy, evaluation for infection is not indicated. Because the neurologic examination is normal, electromyography, nerve conduction velocity studies, and MRI are not indicated. CT can be used in those instances in which SPECT and bone scans are negative. Ciullo JV, Jackson DW: Pars interarticularis stress reaction, spondylolysis, and spondylolisthesis in gymnasts. Clin Sports Med 1985;4:95-110. Collier BD, Johnson RP, Carrera GF, et al: Painful spondylolysis or spondylolisthesis studied by radiography and single photon emission computed tomography. Radiology 1985;154:207-211. Jackson DW, Wiltse LL, Cirincione RT: Spondylolysis in the female gymnast. Clin Orthop 1976;117:68-73.

The radiographs show well-fixed components of a posterior cruciate-retaining total knee replacement. The relative position of the femoral component is anteriorly subluxated relative to the tibial component. The AP radiograph shows that the articular space is markedly asymmetric, indicating either failure or fracture of the polyethylene or subluxation of the femur relative to the tibia. The patient's symptoms suggest a failure of the posterior cruciate ligament that is consistent with the radiographic findings; therefore, the treatment of choice is revision to a posterior cruciate-substituting implant.

By placing the forearm at neutral rotation, as shown in Figures 43c and 43d, the distal fragment has become malrotated by 90 degrees. This is evident by the fact that the bicipital tuberosity is rotated 90 degrees to the radial styloid. Normally, it should be directly opposite (180 degrees) to the radial styloid. The correct alignment was present in the original radiographs shown in Figures 43a and 43b. Another clue to the malrotation in the postreduction radiographs is the difference in the diameters of the opposing radial shafts. To correct this rotational malalignment, the distal fragment needs to be remanipulated into supination so that it is correctly aligned with the supinated proximal radius. Evans EM: Fractures of the radius and ulna. J Bone Joint Surg Br 1951;33:548-561.

The patient has an AP I pelvic ring disruption with minimal symphyseal widening. The best treatment is nonsurgical management and weight bearing as tolerated. This will help close the anterior pelvic ring during the healing process. Pelvic binders are excellent for acute treatment of widely displaced pelvic fractures but are not recommended for long-term use. Open reduction and internal fixation is not indicated for this injury and furthermore, the posterior ring is not injured. Matta JM: Indications for anterior fixation of pelvic fractures. Clin Orthop Relat Res 1996;329:88-96. Templeman DC, Schmidt AH, Sems SA, 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.

A destructive mixed lytic and blastic metaphyseal lesion with a large soft-tissue mass in an adolescent is most likely an osteosarcoma until proven otherwise. The epicenter of the tumor is on the surface of the bone, most likely involves the periosteum, and is more likely to be chondroblastic in nature. Parosteal osteosarcoma is a low-grade tumor, much more radiodense, usually smaller, and found in the posterior distal femur of middle-aged patients. Chondrosarcomas are distinctly rare in childhood.

The initial treatment consisting of oral antibiotics was appropriate but with progressive symptoms, surgical debridement is necessary. Ciprofloxacin is contraindicated in children, and at this stage, oral antibiotics are inadequate. Intravenous antibiotics may be necessary, but surgical debridement is paramount. Failure to respond to the initial management precludes further observation. Riegler HP, Routson T: Complications of deep puncture wounds of the foot. J Trauma 1979;19:18-22.

The patient has an avulsion of the flexor digitorum profundus. Treatment should include surgical exploration and tendon reinsertion. This is not an avulsion of the flexor digitorum superficialis because the patient's deficiency is the inability to flex the distal interphalangeal joint, not the proximal interphalangeal joint. Surgical release of the anterior interosseous nerve is not indicated because the flexor digitorum profundus of the ring finger is innervated by the ulnar nerve. A median nerve contusion causes wrist pain and/or numbness and tingling in the median nerve distribution. Strickland JW: Flexor tendons: Acute injuries, in Green DP, Hotchkiss RN, Pederson WC (eds): Green's Operative Hand Surgery, ed 4. Philadelphia, PA, 1999, pp 1851-1897.

The radiograph shows a type IIa Hangman's fracture, and the classic treatment is halo vest immobilization. Traction should be avoided in type IIa injuries because of the risk of overdistraction. A lesser form of immobilization such as a hard collar or a Minerva jacket can be used for nondisplaced (type I) fractures. Surgery generally is reserved for type III fractures (includes C2-3 facet dislocation), or extenuating circumstances such as multiple trauma or other fractures of the cervical spine that require surgical stabilization. Levine AM, Edwards CC: The management of traumatic spondylolisthesis of the axis. J Bone Joint Surg Am 1985;67:217-226.

The patient has a rotational stress fracture of the proximal humeral physis (Little Leaguer's shoulder). The symptoms of increasing pain with activity and relief with rest are typical of a stress injury. Treatment should consist of cessation of throwing activity but rehabilitation of the shoulder girdle muscles. The pitching technique should be evaluated as well. Barnett LS: Little League shoulder syndrome: Proximal humeral epiphyseolysis in the adolescent baseball pitchers: A case report. J Bone Joint Surg Am 1985;67:495-496.

Tarsal coalitions commonly present in the preadolescent age group as a rigid, planovalgus foot. Small coalitions of the calcaneonavicular joint or the middle facet of the talocalcaneal joint can be excised with interposition of fat or muscle tissue. Isolated calcaneocuboid joint coalitions are very rare. This patient has an associated large talocalcaneal coalition; therefore, resection is contraindicated. Surgery is warranted after failure of nonsurgical management, and because of the involvement of two joints, the only viable option for the severely symptomatic foot is triple arthrodesis. Vincent KA: Tarsal coalition and painful flatfoot. J Am Acad Orthop Surg 1998;6:274-281.

In patients with an osteomyelitic infection, radiographic findings at 1 to 5 days usually show soft-tissue swelling only. Seven to 14 days after symptoms begin, radiographs will most likely show the classic signs of acute osteomyelitis. Reactive bone formation would be expected by 6 months. Kasser JR (ed): Orthopaedic Knowledge Update 5. Rosemont, IL, American Academy of Orthopaedic Surgeons, 1996, pp 149-161.

Infantile tibia vara is a developmental condition characterized by a varus angulation of the proximal end of the tibia that is caused by a growth disturbance of the proximal medial physis. In a study of 42 affected extremities in 24 children younger than age 3 years, it was found that daytime ambulatory brace treatment favorably altered the natural history of tibia vara. Another study of 27 patients with stage II Langenskiöld disease found a success rate of 70% (improved alignment without the need for osteotomy) using brace treatment. These authors also noted that children with unilateral disease were more likely to obtain correction of the deformity compared with those with bilateral disease. In this patient, observation is not warranted because untreated tibia vara has a significant risk for progressive worsening. Osteotomy is best reserved for those patients who, despite bracing, do not show satisfactory clinical and radiographic improvement by age 4 years. Elevation of the medial tibial plateau is a treatment option for older patients who have more advanced disease. An MRI scan would not provide any useful clinical information at this time. Zionts LE, Shean CJ: Brace treatment of early infantile tibia vara. J Pediatr Orthop 1998;18:102-109. Richards BS, Katz DE, Sims JB: Effectiveness of brace treatment in early infantile Blount's disease. J Pediatr Orthop 1998;18:374-380.

The Allen and Ferguson mechanistic classification system is a useful tool for evaluating cervical spine injuries. Cervical fractures are classified as compressive extension, distractive extension, compressive flexion, distractive flexion, vertical compression, and lateral flexion. The patient has a distractive flexion injury.

Both myeloma and lymphoma are more responsive to radiation therapy. The other types of tumors are relatively more resistant to radiation. Doses of 25 to 50 Gy (2,500 to 5,000 cGy) are usually sufficient for myeloma and lymphoma, while carcinomas frequently require a higher dosage. Large cell lymphoma of bone is usually of B-cell origin and is treated with chemotherapy and radiation therapy. Simon MA, Springfield DS, et al: Surgery for Bone and Soft Tissue Tumors. Philadelphia, PA, Lippincott Raven, 1998, p 683.

The area of the tendon degeneration is greater than 50% of the width so a supplemental tendon transfer is needed. Debridement and repair alone do not provide adequate strength. Injection risks tendon rupture. Brisement is indicated for peritendinitis, not tendinosis. Nonsurgical management is unlikely to be of benefit after 12 months. Richardson EG (ed): Orthopaedic Knowledge Update: Foot and Ankle 3. Rosemont, IL, American Academy of Orthopaedic Surgeons, 2004, pp 94-95.

The findings are most consistent with a rupture of the anterior tibial tendon. The damaged area of tendon should be resected, followed by tendon reconstruction or tenodesis. The histology is not consistent with giant cell tumor of the tendon sheath, gout, or synovial sarcoma. Fibromatosis is characterized by a large number of spindle cells within the collagen background. Otte S, Klinger HM, Loreaz F, Haerer T: Operative treatment in case of closed rupture of the anterior tibial tendon. Arch Orthop Traum Surg 2002;122:188-190.

The MRI scans reveal a large postoperative hematoma causing significant thecal compression. An epidural hematoma with neurologic deficit is a surgical emergency requiring immediate evacuation of the hematoma. Although the incidence of postoperative epidural hematomas is rare, the consequences of a missed diagnosis can be catastrophic. Early recognition and evacuation are essential in preserving or restoring neurologic function. Uribe and associates attributed delayed postoperative hematomas to previous multiple lumbar surgeries as a possible contributing factor. Yi S, Yoon do H, Kim KN, et al: Postoperative spinal epidural hematoma: Risk factor and clinical outcome. Yonsei Med J 2006;47:326-332.

The loss of consciousness indicates a grade 2 concussion, which necessitates a 4-week period out of sport. The last week prior to return must be symptom-free and the athlete should not have symptoms in practice. Cantu RC: Return to play guidelines after a head injury. Clin Sports Med 1998;17:45-60.

Advances in development of new tumor markers and techniques of antigen retrieval have enhanced the sensitivity and reliability of identifying the primary source of metastasis. New markers such as CK7, CK20, CA125, and thyroid transcription factor-1 (TTF-1) can help to determine the origin of an adenocarcinoma or aid in the recognition of other tumors. In patients who do not have an obvious primary site of disease or screening radiographs, these new markers can help focus the search for and guide the treatment of the underlying lesion. CA125 is positive in patients with ovarian cancer, CK7 is positive in patients with breast and lung carcinoma, and CK20 is indicative of colon carcinoma if the CK7 marker is negative. Gastrointestinal stromal tumor (GIST) is positive for CD117 (c-kit) and CD34, whereas 75% of bronchogenic carcinomas are positive for TTF-1. Histochemical staining of the S100 protein family has been used for many years in the diagnosis of malignant melanoma. Recent markers HMB-45, MART-1, and Melan-A have proved to be useful in diagnosis of melanoma. S100B protein has been implicated in downregulation of p53 (oncosuppressor gene). Harpio R, Einarsson R: S100 proteins as cancer biomarkers with focus on S100B in malignant melanoma. Clin Biochem 2004;37:512-518.

The radiographs show a loose femoral component with an associated medial condyle distal femoral fracture. The treatment of choice is open reduction and internal fixation with revision of the femoral component because of the femoral component loosening. Moran MC, Brick GW, Sledge CB, et al: Supracondylar femoral fracture following total knee arthroplasty. Clin Orthop 1996;324:196-209. McLaren AC, DuPont JA, Schroeber DC: Open reduction internal fixation of supracondylar fractures above total knee arthroplasties using the intramedullary supracondylar rod. Clin Orthop 1994;302:194-198.

The patient has spinal muscular atrophy, type 2. This type is intermediate in severity between the Werdnig-Hoffmann type (type 1) and the Kugelberg-Welander type (type 3). It normally manifests itself between the ages of 3 and 15 months. Survival until adolescence is common. All three types of spinal muscular atrophy have been linked to the SMN gene at the 5q12.2-13.3 locus. DNA testing is available and is preferred to muscle biopsy because it is less invasive and more definitive. Biros I, Forrest S: Spinal muscular atrophy: Untangling the knot? J Med Genet 1999;36:1-8.

The ulnar collateral ligament is often difficult to visualize during elbow arthroscopy. It can be seen clearly in only 10% to 30% of elbow arthroscopies. All of the other structures should be easily and thoroughly seen and palpated during elbow arthroscopy. Johnson LL: Arthroscopic Surgery: Principles and Practice. St Louis, MO, CV Mosby, 1988.

Focal calcifications causing small radiopacities are found in 15% to 20% of synovial sarcomas. Their irregular contours differentiate them from the phleboliths found in a benign hemangioma. Ewing's sarcoma, clear cell sarcoma, and malignant fibrous histiocytoma do not commonly have calcifications within the lesions. Enzinger FM, Weiss SW: Soft Tissue Tumors, ed 3. St Louis, MO, Mosby, 1995, p 761.

The expected physiologic effects of anemia include an increased heart rate and increased cardiac output. The coronary blood flow requirement increases. There is a decrease in peripheral resistance and blood viscosity.

Osteosarcoma is the most common primary malignant tumor of bone in childhood, followed by Ewing's sarcoma. Rhabdomyosarcoma is a soft-tissue sarcoma of childhood. Chondrosarcoma rarely occurs in childhood. Osteochondroma is a benign tumor of bone. Simon MA, Springfield DS, et al: Osteogenic Sarcoma: Surgery for Bone and Soft Tissue Tumors. Philadelphia, PA, Lippincott Raven, 1998, p 266.

An inability to participate in athletics generally is considered an indication for continued symptomatic treatment only. All of the other answers suggest the possibility of more significant pathology that may require more urgent treatment. Frymoyer JW: Back pain and sciatica. N Engl J Med 1988;318:291-300.

A variety of methodologies have been used to decrease the need for homologous blood transfusions following THA. Some of the effective strategies include preoperative donation of autologous units, intraoperative salvage and recycling, preoperative injection of erythropoietin, and regional anesthesia. Cementless fixation and use of wound drains have been shown to increase the blood loss with THA. Huo MH, Paly WL, Keggi KJ: Effect of preoperative autologous blood donation and intraoperative and postoperative blood recovery on homologous blood transfusion requirement in cementless total hip replacement operation. J Am Coll Surg 1995;180:561-567. 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 patient requires an arthrodesis of the first metatarsophalangeal joint because of the abnormal neuromuscular forces. The more traditional bunionectomies such as a distal chevron bunionectomy, a proximal first metatarsal osteotomy, and a double osteotomy have a high failure rate because of the underlying Down syndrome. The Keller procedure is indicated for older, sedentary individuals and has little role in the management of a neuromuscular bunion. Coughlin MJ, Abdo RV: Arthodesis of the first metatarsophalangeal joint with Vitallium plate fixation. Foot Ankle Int 1994;15:18-28.

The work-up for a patient with an unknown primary lesion that is metastatic to bone includes a search for the primary tumor and other sites of metastasis. This involves conducting a thorough history and physical examination, appropriate laboratory studies, bone scan, chest radiograph, and CT of the chest, abdomen, and pelvis. In women, a mammogram may be indicated. CT of the brain is not necessary in the early stages of a metastatic work-up. Simon MA, Bartucci EJ: The search for the primary tumor in patients with skeletal metastases of unknown origin. Cancer 1986;58:1088-1095.

The radiographs reveal a blastic lesion of the proximal tibial metaphysis with cortical destruction, mineralization extending into the soft tissue laterally, indistinct margins, and destruction of the normal trabecular pattern. In this age group, with this aggressive appearance, osteosarcoma is the most likely diagnosis. Chondroblastoma and giant cell tumor are generally geographic and lytic. Chondrosarcoma is rare in this age group and would likely be a secondary lesion from an underlying chondroid tumor that is not present here. Whereas infection can have a wide variety of appearances, it tends to be more lytic in the acute presentation. Sanders TG, Parsons TW: Radiographic imaging of musculoskeletal neoplasia. Cancer Control 2001;8:221-231.

The patient has bilateral subluxated hips, with nearly vertical neck shaft angles; therefore, the treatment of choice is varus derotation osteotomy. Shortening of the bone on one or both sides may be necessary to allow adequate range of motion postoperatively. In patients this age and with this degree of bony deformity, soft-tissue releases are not likely to lead to hip stability. Botulinum toxin has been shown to be effective in the treatment of ankle equinus, but its efficacy in other areas has not been demonstrated as yet. The indications for obturator neurectomy are unclear at present. Proximal femoral resection is a salvage procedure for long-standing hip dislocations that are symptomatic and not reconstructable. Tylkowski CM, Rosenthal RK, Simon SR: Proximal femoral osteotomy in cerebral palsy. Clin Orthop 1980;151:183-192.

In adults, a direct blow on the acromion usually results in an acromioclavicular dislocation. In children, however, the usual injury from this mechanism is a physeal fracture of the lateral clavicle. The clavicular shaft fragment, analogous to the metaphyseal portion of a physeal fracture, herniates through the periosteum, leaving the distal periosteal sleeve in contact with the lateral (distal) physeal fragment. The treatment of choice is immobilization until the patient is pain-free. Falstie-Jensen S, Mikkelsen P: Pseudodislocation of the acromioclavicular joint. J Bone Joint Surg Br 1982;64:368-369.

Fractures through the cartilage on the inferior pole of the patella, the so-called sleeve fracture, are often difficult to diagnose because of the paucity of ossified bone visible on the radiographs. If the fracture is missed and the fragments are widely displaced, the patella may heal in an elongated configuration that may result in compromise of the extensor mechanism function. The treatment of choice is open reduction and internal fixation using a tension band wire technique to achieve close approximation of the fragments and restore full active knee extension. Heckman JD, Alkire CC: Distal patellar pole fractures: A proposed common mechanism of injury. Am J Sports Med 1984;12:424-428.

The patient has symptoms typical of Raynaud's phenomenon secondary to underlying vascular disease. The next most appropriate step in the management of this patient should be to perform contrast angiography on the involved upper extremity to look for proximal or distal arterial lesions or insufficiencies. MRI and contrast CT are not as specific as angiography for the identification of vascular lesions of the upper extremity. Although patients with primary Raynaud's vasospastic disease can have normal angiographic findings, they typically are younger than age 40 years, are female, and have normal results on an Allen test. Green DP, Hotchkiss RN, Pederson WC (eds): Operative Hand Surgery, ed 4. New York, NY, Churchill Livingstone, 1999, pp 2288-2290.

An acetabular reinforcement cage is required infrequently except when there is pelvic discontinuity in which there is no posterior column support of the acetabular cup. A larger cup inserted with cement and morselized bone graft is an effective technique for contained cavitary and anterior wall defects. Zone 1 osteolysis and a medial wall defect are essentially the same as a contained cavitary defect and can be reconstructed using cementless cups. Berry DJ, Lewallen DG, Hanssen A, Cabanela ME: Pelvic discontinuity in revision total hip arthroplasty. J Bone Joint Surg Am 1999;81:1692-1702.

The patient sustained a high-angle femoral neck fracture. The follow-up clinical findings and radiograph show that she now has a nonunion with failed internal fixation. The joint appears preserved. In a healthy, young patient, arthroplasty of the femoral head, although possible, is not ideal. Excellent healing and function can be obtained in 70% to 80% of patients with femoral neck nonunion with a valgus intertrochanteric osteotomy. Marti RK, Schuller HM, Raaymakers EL: Intertrochanteric osteotomy for non-union of the femoral neck. J Bone Joint Surg Br 1989;71:782-787.

The radiograph reveals primary osteoarthritis of the elbow; therefore, ulnohumeral arthroplasty is the preferred procedure. Patients with severely limited preoperative elbow extension of more than 60 degrees and flexion of less than 100 degrees are at risk for ulnar nerve dysfunction postoperatively and should undergo a concomitant ulnar nerve decompression. Nonsurgical methods are unlikely to improve his chronic condition. Elbow arthroplasty is contraindicated for patients in this age group and with this diagnosis. Antuna SA, Morrey BF, Adams RA, et al: Ulnohumeral arthroplasty for primary degenerative arthritis of the elbow: Long-term outcome and complications. J Bone Joint Surg Am 2002;84:2168-2173.

The patient has a chronic flexor tendon laceration. There are options to restore motion and strength; therefore, fusion is not necessary. Full range of motion is present so the soft tissues are suitable for a tendon transfer. A transfer of the flexor digitorum superficialis of the ring finger to the insertion of the flexor pollicis longus on the distal phalanx provides good results with a one-stage operation. Schneider LH, Wiltshire D: Restoration of flexor pollicis longus function by flexor digitorum superficialis transfer. J Hand Surg Am 1983;8:98-101.

The history and examination findings suggest an acute fracture of the hook of the hamate. The radiographic study considered most helpful in identifying this type of fracture is the carpal tunnel view. PA and lateral views of the wrist will not adequately visualize the hook of the hamate. Bruerton's view is intended for the assessment of the metacarpophalangeal joints. Pathology would not be suspected in the scaphoid, metacarpals, or the phalanges, so the scaphoid view and the PA, lateral, and oblique views of the hand would not be helpful. Green DP, Hotchkiss RN, Pederson WC (eds): Operative Hand Surgery, ed 4. New York, NY, Churchill Livingstone, 1999, p 855.

Tannenbaum and associates found that patients who had a joint replacement after an organ transplantation had a rate of infection of 19% (five of 27 joint replacements in 16 patients). They retrospectively reviewed the results of 35 joint (hip or knee) replacements in 19 patients who had an organ transplant. The patients received a standard immunosuppressive induction regimen at the time of the transplantation and were maintained on a combination of prednisone, azathioprine, and cyclosporin A. All patients received antibiotics perioperatively, but antibiotic-impregnated bone cement was not used for any procedure. Six joint replacements in three patients (median patient age of 48.2 years at the time of the arthroplasty) were performed before a renal transplantation. Twenty-four joint replacements in 14 patients (average patient age of 40.9 years at the time of the arthroplasty) were performed after an organ transplantation. Two patients, with an average age of 53.8 years at the time of the arthroplasty, each had a joint replacement both before and after a liver transplantation (a total of five joint replacements). The average duration of follow-up after the first joint replacement was 8.8 years (range, 1 to 23 years). An infection developed around the implant in five patients who had undergone the joint replacement after a transplantation. The average interval from implantation of the prosthesis until detection of the infection was 3.4 years (range, 1 to 6 years). Of two patients who underwent a liver transplant, one had Pseudomonas aeruginosa infection and the other Escherichia coli infection. Of three patients who underwent a renal transplantation, one was infected with Staphylococcus epidermidis, one with Enterococcus, and one with Serratia marcescens.

Congenital vertical talus is a fixed dorsal dislocation of the talonavicular joint with equinus of the ankle joint. The AP radiograph shows valgus of the midfoot and an increased talocalcaneal angle; the lateral radiograph shows a vertically positioned talus and equinus of the ankle joint, and the plantar flexion lateral view shows that the talonavicular joint does not reduce. A line drawn through the long axis of the talus passes below the long axis of the first metatarsal. Initial management should consist of serial casting to stretch the dorsal soft-tissue structures; surgery eventually will be required to reduce the talonavicular joint. The differential diagnosis of congenital vertical talus includes pes calcaneovalgus, flexible pes planus, and peroneal spastic flatfoot. Pes calcaneovalgus, flexible pes planus, congenital short Achilles tendon, and peroneal spastic flatfoot would not show resistent dorsal dislocation of the navicular on the plantar flexion view. Kodros SA, Dias LS: Single-stage surgical correction of congenital vertical talus. J Pediatr Orthop 1999;19:42-48.

The lateral cord terminates as the musculocutaneous nerve and also contributes sensory fibers to the median nerve. Involvement of the C6 root or upper trunk could potentially cause weakness of the infraspinatus and the brachioradialis. The middle trunk and the posterior cord do not contribute motor fibers to the thumb or sensory fibers to the thumb.

Combination drugs with activity against both aerobic and anaerobic organisms have been determined to be the best approach. The first-generation cephalosporins do not provide adequate coverage for gram-negative and anaerobic organisms. Gentamicin alone would not provide adequate activity against anaerobes, and there is the risk of renal and auditory toxicity. Pinzur MS, Slovenkai MD, Trepman E: Guidelines for diabetic foot care. Foot Ankle Int 1999;20:695-702.

Traumatic brain injury is considered to be either primary or secondary. Primary injury is direct or impact damage to the brain, and secondary injury can have intracranial or systemic causes. While treatment has little impact on primary brain injury, secondary brain injury can be avoided. There are also many causes of intracranial secondary brain injury, including intracranial hypertension or cerebral edema. There are many causes of systemic secondary brain injury, but none has a greater impact on outcome than hypotension or hypoxia. In fact, the occurrence of hypotension postinjury causes a 10- to 15-fold increase in mortality. In a series by Pietropaoli and associates, the mortality rate for head-injured patients that were normotensive during surgery was 25%, but if they were hypotensive the mortality rate was 82%. In the same series, the number of patients with a Glasgow Coma Scale score of either 4 or 5 dropped from 58% in those patients that were normotensive during surgery to 6% in those patients that became hypotensive during surgery. Efforts to avoid hypotension postinjury and especially during surgery should be of primary importance. Chesnut RM, Marshall LF, Klauber MR, et al: The role of secondary brain injury in determining outcome from severe head injury. J Trauma 1993;34:216-222. Pietropaoli JA, Rogers FB, Shackford SR, Wald SL, Schmoker JD, Zhuang J: The deleterious effects of intraoperative hypotension on outcome in patients with severe head injury. J Trauma 1992;33:403-407. Schmeling GJ, Schwab JP: Polytrauma care: The effect of head injuries and timing of skeletal fixation. Clin Orthop 1995;318:106-116.

Because the patient's shoulders are overtensioned anteriorly, premature osteoarthritis may develop. This may create obligate translation posteriorly and increase the interarticular pressure of the humeral head against the glenoid. Patients should achieve 20 degrees to 30 degrees of external rotation with the elbow at the side. Late degenerative arthritis following a Putti-Platt procedure is associated with significant restriction of external rotation. This patient's shoulder has a reduced risk of anterior instability, rotator cuff tear, and internal impingement because of the limitation of motion. Hawkins RJ, Angelo RL: Glenohumeral osteoarthritis: A late complication of the Putti-Platt repair. J Bone Joint Surg Am 1990;72:1193-1197.

The MRI scan shows a dislocated peroneus brevis tendon with disruption of the peroneal retinaculum. This injury is commonly seen in skiers and is the result of peroneal contraction with the ankle everted and dorsiflexed. Nonsurgical management is rarely successful; therefore, repair of the peroneal retinaculum is the treatment of choice. Eckert WR, Davis EA Jr: Acute rupture of the peroneal retinaculum. J Bone Joint Surg Am 1976;58:670-672. Murr S: Dislocation of the peroneal tendons with marginal fracture of the lateral malleolus. J Bone Joint Surg Br 1961;43:563-565.

The history is most consistent with a plantar fibroma. The nodules typically are located within the substance of the plantar aponeurosis. The clinical appearance is usually diagnostic without the need for advanced imaging studies. While the lesion may be prominent and painful to direct palpation, the anatomic location is usually off of the weight-bearing surface. Observation with or without an accommodative orthotic is the treatment of choice. Recurrence is common following attempted excision. Sammarco GJ, Mangone PG: Classification and treatment of plantar fibromatosis. Foot Ankle Int 2000;21:563-569.

Pitchers tend to have a decrease in internal rotation and an increase in external rotation. The increase in external rotation is felt to be multifactorial. An increase in humeral retroversion occurs from repeated throwing. This results in increased soft-tissue stretching and results in a posterior capsular contracture. Meister K, Buckley B, Batts J: The posterior impingement sign: Diagnosis of rotator cuff and posterior labral tears secondary to internal impingement in overhand athletes. Am J Orthop 2004;33:412-415.

The patient has sustained an iatrogenic injury to the lateral ulnar collateral ligament. This injury has been reported after lateral approaches to the elbow. The orbicular, annular, and lateral radial collateral ligaments have a much less important role in lateral elbow stability. The anterior band of the ulnar collateral ligament is on the medial side of the elbow and is important for valgus stability. O'Driscoll SW, Bell DF, Morrey BF: Posterolateral rotatory instability of the elbow. J Bone Joint Surg Am 1991;73:440-446.

Persistent pain at the fracture site in the absence of infection is most likely due to a nonunion, best detected by CT. Walsh and DiGiovanni reported on a series of closed rotational fibular fractures in which nonunions were detected by CT in the absence of standard ankle radiographic findings. Repeat immobilization would not be appropriate at this late date. Pain management/sympathetic blocks would be considered if the patient displayed pain with light touch and disproportionate pain consistent with a complex mediated pain syndrome. Acupuncture would be expected to be of limited benefit. Walsh EF, DiGiovanni C: Fibular nonunion after closed rotational ankle fracture. Foot Ankle Int 2004;25:488-495.

The area of the tendon degeneration is greater than 50% of the width so a supplemental tendon transfer is needed. Debridement and repair alone do not provide adequate strength. Injection risks tendon rupture. Brisement is indicated for peritendinitis, not tendinosis. Nonsurgical management is unlikely to be of benefit after 12 months. Richardson EG (ed): Orthopaedic Knowledge Update: Foot and Ankle 3. Rosemont, IL, American Academy of Orthopaedic Surgeons, 2004, pp 94-95.

The patient has a presumed metastatic bone tumor. The approach to evaluating a patient with a bone tumor of unknown primary origin is to obtain laboratory studies that include a CBC, an erythrocyte sedimentation rate, a serum protein electrophoresis, a calcium level, a urinalysis, and a prostate-specific antigen. In addition, a bone scan, a radiograph of the chest, and CT scans of the chest and abdomen should be obtained. These evaluations can identify the primary site in 85% of patients. GI studies rarely are of diagnostic value. Prophylactic stabilization is contraindicated until a diagnosis is confirmed by histology. Frassica FJ, Frassica DA, McCarthy EF, Riley LH III: Metastatic bone disease: Evaluation, clinicopathologic features, biopsy, fracture risk, nonsurgical treatment, and supportive management. Instr Course Lect 2000;49:453-459.

Patients with chronic ACL-deficient knees typically have lower than normal net quadriceps activity during the middle portion of the stance phase; the net moment about the knee reverses from one that demands quadriceps activity to one that demands increased hamstring activity. This type of gait is termed "quadriceps avoidance." This avoidance is believed to be a functional adaptation to reduce anterior tibial translation, and it is most prevalent as the knee moves from 45 degrees of flexion toward full extension, the arc of motion through which the ACL is most responsible for stability. Hurwitz DE, Andriacchi TP, Bush-Joseph CA, Bach BR Jr: Functional adaptations in patients with ACL-deficient knees. Exerc Sport Sci Rev 1997;25:1-20. Andriacchi TP, Birac D: Functional testing in the anterior cruciate ligament-deficient knee. Clin Orthop 1993;288:40-47.

The patient has a dislocation of the elbow with displaced coronoid process and radial head fractures. The elbow is extremely unstable after this injury, and recurrent dislocation in a splint is the most common early complication. Skeletal stabilization of the fractures is required to restore stability of the joint. Characteristics of the fractures will determine the techniques required to restore stability. Ring D, Jupiter JB, Zilberfarb J: Posterior dislocation of the elbow with fractures of the radial head and coronoid. J Bone Joint Surg Am 2002;84:547-551.

A C6-7 herniation affects the C7 root. The C7 root has the middle finger as its predominant sensory distribution. Its motor function is the triceps, wrist extension, and finger metacarpophalangeal extension. The reflex is the triceps. Magee D: Principles and concepts, in Orthopedic Physical Assessment, ed 3. Philadelphia, PA, WB Saunders, 1997, pp 1-18.

Nonsurgical management of a symptomatic accessory navicular should be attempted prior to surgery. Good relief is often obtained with a semi-rigid orthosis with a medial arch support. Myerson MS: Foot and Ankle Disorders. Philadelphia, PA, WB Saunders, 2000, p 655.

The patient has spinal shock. Steroid administration and MRI are appropriate therapeutic and diagnostic procedures. Myelography with CT is of little value unless there is an unusual skeletal variant. Spinal cord-evoked potentials have no value. The best method to determine the patient's neurologic recovery is repeated physical examinations over the first 48 to 72 hours. Spivak JM, Connolly PF (eds): Orthopaedic Knowledge Update: Spine 3. Rosemont, IL, American Academy of Orthopaedic Surgeons, 2006, pp 183-184.