General Orthopedics Board Review 2026: High-Yield MCQs (Set 6)

<span class="exp-title">Detailed Explanation</span><div markdown="1">The radiographs and CT scan reveal osteoarthritis with posterior subluxation and posterior bone loss. Total shoulder arthroplasty with reaming of the high side to neutralize the glenoid surface has been shown to yield better results than hemiarthroplasty. The amount of bone loss in this patient does not require posterior glenoid augmentation. Reverse total shoulder arthroplasty is indicated for rotator cuff tear arthropathy; therefore, it is not applicable. Arthroscopic debridement has yielded poor results with advanced osteoarthritis and posterior subluxation. Results from glenoid osteotomy have been variable and glenoid osteotomy is not indicated with associated osteoarthritis. Iannotti JP, Norris TR: Influence of preoperative factors on outcome of shoulder arthroplasty for glenohumeral osteoarthritis. J Bone Joint Surg Am 2003;85:251-258.

<span class="exp-title">Detailed Explanation</span><div markdown="1">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.

<span class="exp-title">Detailed Explanation</span><div markdown="1">The radioscaphocapitate ligament is the prime stabilizer between the radius and capitate, preventing ulnar translocation of the carpus. Its oblique orientation prevents the carpus from drifting ulnarly. This stout ligament must be protected when excising the scaphoid. Stern PJ, Agabegi SS, Kiefhaber TR, et al: Proximal row carpectomy. J Bone Joint Surg Am 2005;87:166-174.

<span class="exp-title">Detailed Explanation</span><div markdown="1">The patient has nonunions of the metatarsal fractures and a hallux valgus deformity with arthritic changes. To address all of the findings, management should consist of open treatment of the metatarsal nonunions and hallux metatarsophalangeal arthrodesis. Cast immobilization and a bone stimulator are unlikely to be beneficial at this time. Isolated correction of the hallux valgus deformity will not address the metatarsal nonunions or the arthritis at the hallux metatarsophalangeal joint. Kitaoka HB, Patzer GL: Arthrodesis versus resection arthroplasty for failed hallux valgus operations. Clin Orthop 1998;347:208-214. McGarvey WC, Braly WG: Bone graft in hindfoot arthrodesis: Allograft vs autograft. Orthopedics 1996;19:389-394.

<span class="exp-title">Detailed Explanation</span><div markdown="1">The femoral component should be implanted with enough external rotation to facilitate patellar tracking. Proper tracking requires a normal Q angle and is affected by axial and rotational alignment of the femur and tibia. An excessive Q angle can result from internal rotation of either component, medialization of the tibial tray, or lateralization of the patellar component. Beaty JH (ed): Orthopaedic Knowledge Update 6. Rosemont, IL, American Academy of Orthopaedic Surgeons, 1999, pp 559-582.

<span class="exp-title">Detailed Explanation</span><div markdown="1">All of the tissues noted above are stronger than native ACL. Although it is often thought that the bone-patellar tendon-bone graft is the strongest when selecting a graft source for ACL reconstruction, biomechanical studies show that the quadruple semitendinosus and gracilis tendons are the strongest of the tissues listed. Woo SL, Hollis JM, Adams DJ, et al: Tensile properties of the human femur-anterior cruciate ligament-tibia complex: The effects of specimen age and orientation. Am J Sports Med 1991;19:217-225. Staubli HU, Schatzmann L, Brunner P, et al: Quadriceps tendon and patellar ligament cryosectional anatomy and structural properties in young adults. Knee Surg Sports Traumatol Arthrosc 1996;4:100-110.

<span class="exp-title">Detailed Explanation</span><div markdown="1">Bisphosphonates have been reported to reduce the incidence of new osseous lesions and prevent an increase in size of existing lesions. Zoledronic acid has been reported in clinical trials to decrease the skeletal complications of patients with multiple myeloma and with bone metastases from solid tumors. Results also have demonstrated that zoledronic acid delays the initial onset of bone complications by more than 2 months in patients with non-small-cell lung cancer and other solid tumors. In two placebo-controlled clinical studies of zoledronic acid conducted in patients with bone metastases from prostate cancer or other solid tumors, there was a decrease in the number of patients with skeletal-related events compared to placebo, and the time to the first skeletal-related event was delayed. Mundy GR, Yoneda T: Bisphosphonates as anticancer drugs. N Engl J Med 1998;339:398-400.

<span class="exp-title">Detailed Explanation</span><div markdown="1">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.

<span class="exp-title">Detailed Explanation</span><div markdown="1">The initial stages of posterior tibial tendon insufficiency, where the deformity remains supple, may be treated with bracing or an orthotic for pain relief. The Arizona brace was introduced in 1988, and assists in pain relief and deformity correction by minimizing hindfoot valgus alignment, lateral calcaneal displacement, and medial ankle collapse. It is particularly helpful in those patients with advanced disease that cannot tolerate an ankle-foot orthosis. All other choices are incorrect because of the addition of lateral posting, which is not advantageous in valgus deformities. The addition of medial posting to any of the above choices would render them correct alternatives. A heel lift is applicable in Achilles tendon disorders, not posterior tibial tendon disorders. Chao W, Wapner KL, Lee TH, et al: Nonoperative management of posterior tibial tendon dysfunction. Foot Ankle Int 1996;17:736-741.

<span class="exp-title">Detailed Explanation</span><div markdown="1">Stress fractures in female long distance runners are frequently associated with the Female Athletic Triad. The triad consists of osteoporosis, amenorrhea, and altered eating habits. A thorough menstrual history, including age of menarche, history of amenorrhea, and use of oral contraceptives, is imperative. Amenorrhea leads to osteoporosis and predisposes the athlete to fractures. An MRI of the hip is not necessary because a fracture is evident on the radiograph. Serum calcium levels are normal in osteoporosis, a family history would be noncontributory, and it is highly unlikely that a contralateral hip radiograph will yield useful information. Bennell KL, Malcolm SA, Thomas SA, et al: Risk factors for stress fractures in track and field athletes: A twelve-month prospective study. Am J Sports Med 1996;24:810-818.

<span class="exp-title">Detailed Explanation</span><div markdown="1">Motor impulses to the triceps, wrist flexion and elbow extension, and sensation to the middle finger are associated most commonly with the C7 root. Hoppenfeld S: Physical Examination of the Spine and Extremities. Upper Saddle River, NJ, Prentice Hall, 1976, p 125.

<span class="exp-title">Detailed Explanation</span><div markdown="1">Gouty arthritis, pseudogout, and infection can all present with inflammatory arthritis and periarticular erosions. Strongly negative birefringent crystals are seen in gout. The histologic image shows elongated "needle-like" crystals of gout. Epidermal inclusion cysts are rarely painful and usually have a history of localized penetrating trauma. Hamilton W, Breedman KB, Haupt HM, Lackman R: Knee pain in a 40-year-old man. Clin Orthop 2001;383:282-285,290-292.

<span class="exp-title">Detailed Explanation</span><div markdown="1">Lung carcinoma most often has a lytic radiographic appearance. Bladder and prostate carcinoma are usually blastic. Breast carcinoma can be both blastic and lytic. Thyroid carcinoma may be difficult to visualize radiographically and may be seen only on MRI scans. Metastatic osteosarcomas typically produce bone. 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.

<span class="exp-title">Detailed Explanation</span><div markdown="1">Ample evidence supports an increased rate of degenerative arthritis in the ACL-deficient knee. Several variables play a role in the development of the arthritis, but the integrity of the meniscus has been shown to be the single most important factor. O'Brien WR: Degenerative arthritis of the knee following anterior cruciate ligament injury: Role of the meniscus. Sports Med Arthroscopy Rev 1993;1:114-118. Fetto JF, Marshall JL: The natural history and diagnosis of anterior cruciate ligament insufficiency. Clin Orthop 1980;147:29-38.

<span class="exp-title">Detailed Explanation</span><div markdown="1">Osteonecrosis of major joints can occur in patients exposed to corticosteroids, alcohol, and antiseizure medications, as well as patients with hemaglobulinopathy, such as sickle cell anemia. In addition, patients with primary APS who had not taken corticosteroids were also found to be at high risk for osteonecrosis of the hip. In one study of 30 patients with primary APS, asymptomatic osteonecrosis was evident in 20%. A recent article has also found a high association between idiopathic osteonecrosis of the hip and collagen II mutation. None of the other conditions has been shown to be associated with a higher risk of osteonecrosis. Tektonidou MG, Malagari K, Vlachoyiannopoulos PG, et al: Asymptomatic avascular necrosis in patients with primary antiphospholipid syndrome in the absence of corticosteroid use: A prospective study by magnetic resonance imaging. Arthritis Rheum 2003;48:732-736.

<span class="exp-title">Detailed Explanation</span><div markdown="1">Glenoid dysplasia is an uncommon anomaly that usually has a benign course but may result in shoulder pain, arthritis, or multidirectional instability. Shoulder pain and instability often improve with shoulder strengthening exercises. Wirth MA, Lyons FR, Rockwood CA Jr: Hypoplasia of the glenoid: A review of sixteen patients. J Bone Joint Surg Am 1993;75:1175-1184.

<span class="exp-title">Detailed Explanation</span><div markdown="1">The MRI scan reveals a posterior labral detachment. This injury is the result of a posteriorly directed force and is common to football players in blocking positions. Although this injury can occur with trauma in all types of athletes, it is seen with relative frequency in football. Treatment is aimed at labral repair with posterior capsulorrhaphy. Both open and arthroscopic techniques can be used. Misamore GW, Facibene WA: Posterior capsulorrhaphy for the treatment of traumatic recurrent posterior subluxations of the shoulder in athletes. J Shoulder Elbow Surg 2000;9:403-408.

<span class="exp-title">Detailed Explanation</span><div markdown="1">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.

<span class="exp-title">Detailed Explanation</span><div markdown="1">A Hawkins III fracture-dislocation generally presents with posteromedial displacement with the deltoid ligament intact. Therefore, the only remaining blood supply is the deltoid branch of the artery of the tarsal canal originating from the posterior tibial artery. Often, the medial malleolus is fractured, assisting in reduction and visualization of fracture reduction. If the medial malleolus is intact, a medial malleolus osteotomy allows visualization of the reduction without compromising the last remaining blood supply to the talus. Mulfinger GL, Trueta J: The blood supply of the talus. J Bone Joint Surg Br 1970;52:160-167.

<span class="exp-title">Detailed Explanation</span><div markdown="1">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.

<span class="exp-title">Detailed Explanation</span><div markdown="1">The most significant impact on long-term survival is the presence or absence of identifiable metastatic disease on initial presentation. All of these factors have been shown to be predictive of long-term survival to varying degrees. Enneking WF, Spanier SS, Goodman MA: A system for the surgical staging of musculoskeletal sarcoma. Clin Orthop Relat Res 1980;153:106-120.

<span class="exp-title">Detailed Explanation</span><div markdown="1">History and physical examination are still the gold standard for diagnosis of an interdigital neuroma. Ultrasound and MRI may be helpful adjuncts but are dependent on equipment and operator expertise. Web space injection may be helpful for diagnostic and therapeutic purposes. Electromyography and nerve conduction velocity studies are of little benefit for distal lesions. Richardson EG (ed): Orthopaedic Knowledge Update: Foot and Ankle 3. Rosemont, IL, American Academy of Orthopaedic Surgeons, 2004, pp 145-147.

<span class="exp-title">Detailed Explanation</span><div markdown="1">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.

<span class="exp-title">Detailed Explanation</span><div markdown="1">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.

<span class="exp-title">Detailed Explanation</span><div markdown="1">A bone-producing lesion in the metaphysis of an adolescent is most likely an osteosarcoma. The radiographs show a distal femoral bone-producing lesion extending into the surrounding soft tissues. The histologic appearance consists of pleomorphic cells producing osteoid. Ewing's sarcoma and metastatic neuroblastoma do not produce a matrix. Chondrosarcoma is a radiographically destructive lesion with calcification and cartilage cells on histologic section. An osteochondroma is a benign cartilage lesion that is continuous with the medullary cavity of the underlying bone and extends into a bony lesion and covered by a cartilage cap. Unni KK: Dahlin's Bone Tumors: General Aspects and Data on 11,087 Cases, ed 5. Philadelphia, PA, Lippincott-Raven, 1996, pp 143-160.

<span class="exp-title">Detailed Explanation</span><div markdown="1">The theoretic advantage of a metal-to-bone articulation with the acromion is that there is a greater arc in which a smooth metal surface contacts the glenoid and acromion. This may improve pain and function, but no studies have evaluated this to date. One study showed results comparable to that of a standard hemiarthroplasty. There are no other biomechanic advantages. Visotsky JL, Basamania C, Seebauer L, et al: Cuff tear arthropathy: Pathogenesis, classification, and algorithm for treatment. J Bone Joint Surg Am 2004;86:35-40.

<span class="exp-title">Detailed Explanation</span><div markdown="1">Unilateral sacralization of the fifth lumbar vertebra was first described by Bertolotti in 1917. Bertolotti's syndrome is present in 12% to 21% of the population. The altered biomechanics have been postulated to cause low back pain by placing increased stress on the adjacent cephalad disk, thus contributing to accelerated degenerative disk disease at this level. It has also been found that the neoarticulation between the enlarged transverse process and the sacrum and/or ilium may be a source of neural impingement on the exited L5 nerve root and results in radicular pain syndrome. Brault and associates reported on a case treated surgically at the Mayo Clinic, in which the pain generator was found to be the contralateral facet joint. Brault JS, Smith J, Currier BL: Partial lumbosacral transitional vertebra resection for contralateral facetogenic pain. Spine 2001;26:226-229. Quinlan JF, Duke D, Eustace S: Bertolotti's syndrome: A cause of back pain in young people. J Bone Joint Surg Br 2006;88:1183-1186.

<span class="exp-title">Detailed Explanation</span><div markdown="1">Although the imaging studies are consistent with a unicameral bone cyst, aneurysmal bone cyst, or giant cell tumor, the histology shows small round blue cells that are typical of Ewing's sarcoma. Although Ewing's sarcoma frequently occurs in the diaphysis, it can occur in the metaphysis.

<span class="exp-title">Detailed Explanation</span><div markdown="1">Although not as common as arterial injury, venous thrombosis secondary to trauma of the subclavian or axillary vein can be problematic; therefore, venous duplex ultrasound scanning is the diagnostic study of choice. Arteriography may not show venous thrombosis in the venous run-off phase. The clinical history does not fit the usual presentation of a compartment syndrome or complex regional pain syndrome.

<span class="exp-title">Detailed Explanation</span><div markdown="1">When treating thoracolumbar spine fractures, the major advantage of using the TLSO is greater rotational control. Levine AM (ed): Orthopaedic Knowledge Update: Trauma. Rosemont, IL, American Academy of Orthopaedic Surgeons, 1996, pp 347-349. Krompinger WJ, Fredrickson BE, Mino DE, Yuan HA: Conservative treatment of fractures of the thoracic and lumbar spine. Orthop Clin North Am 1986;17:161-170.

<span class="exp-title">Detailed Explanation</span><div markdown="1">The radiographs show a lytic lesion in the right proximal tibia that has a high fluid content based on the MRI findings. The radiographic appearance is consistent with either telangiectatic osteosarcoma or aneurysmal bone cyst. Low-magnification histology shows a lesion resembling an aneurysmal bone cyst, with blood lakes separated by cellular septa. However, high-magnification shows severe cytologic atypia, indicative of a telangiectatic osterosarcoma. The appropriate treatment is neoadjuvant chemotherapy followed by wide resection and reconstruction of the lesion. Unni KK: Dahlin's Bone Tumors: General Aspects and Data on 11,087 Cases, ed 5. Philadelphia, PA, Lippincott-Raven, 1996, pp 143-160.

<span class="exp-title">Detailed Explanation</span><div markdown="1">Chondroblastomas are benign cartilage lesions frequently seen in adolescents or young adults. They are found in the epiphyseal or apophyseal regions of bones. The radiograph shows a radiolucent lesion with mineralization and a well-marginated rim of reactive bone. The lesion is composed of sheets of immature chondroblasts (polygonal cells with a clear, bluish cytoplasm and a small round central nucleus). In some regions, classic "chicken-wire" matrix calcifications and a "cobblestone" pattern of cell arrangement may be seen. Treatment consists of curettage and bone grafting. Campanacci M: Bone and Soft Tissue Tumors, ed 2. New York, NY, Springer-Verlag, 1999, pp 247-264.

<span class="exp-title">Detailed Explanation</span><div markdown="1">Because the patient has sustained a major high-energy injury to the pelvic ring, it can be assumed that there is serious bleeding or hemodynamic instability related to a pelvic vascular injury. The goal of intervention at this time is to assist in the resuscitative effort and to stop the bleeding. All attempts at providing fluid and blood are important, but without cessation of the bleeding continued loss occurs and significant problems can ensue such as coagulopathy and multiple organ failure. Noninvasive methods of stabilizating the pelvic ring should be used to stop the bleeding. These methods include wrapping a sheet around the pelvis or using commercially available belts, vacuum beanbags, or pneumatic shock garments. This will provide time to prepare for arteriography and/or external fixation. The next step is debatable but in view of negative findings for intra-abdominal blood, arteriography performed with the pelvis reduced using noninvasive methods would be ideal. Bassam D, Cephas GA, Ferguson KA, Beard LN, Young JS: A protocol for the initial management for unstable pelvic fractures. Am Surg 1998;64:862-867. Levine AM (ed): Orthopaedic Knowledge Update: Trauma. Rosemont, IL, American Academy of Orthopaedic Surgeons, 1996, pp 217-226.

<span class="exp-title">Detailed Explanation</span><div markdown="1">Plastic deformation of viscoelastic tissues represents deformation of the soft tissues to the point of failure. The lining up of collagen fibers would be in the "toe region" of the curve, which, in the case of the FSU, would be mainly in the neutral zone. Elastin is a minor contributor to the composition of the ligaments and would be protected by the stiffer collagen fibers. The transition between flexion and extension occurs in the neutral zone, and reversible elongation occurs in the elastic zone. Fardon DF, Garfin SR, Abitbol J, et al (eds): Orthopaedic Knowledge Update: Spine 2. Rosemont, IL, American Academy of Orthopaedic Surgeons, 2002, pp 15-23.

<span class="exp-title">Detailed Explanation</span><div markdown="1">Bisphosphonates are a class of drugs that act to inhibit osteoclast resorption of bone. It has been shown that patients with multiple myeloma who are treated with bisphosphonates have fewer pathologic fractures than patients who are not treated with bisphosphonates. Vitamin D and calcium are considered appropriate for patients who are at risk for the development of osteoporosis, as is estrogen in selected women. Chelating agents and progesterones have no use in the treatment of patients with multiple myeloma or osteoporosis. Berenson JR: Bisphosphonates in multiple myeloma. Cancer 1997;15:1661-1667.

<span class="exp-title">Detailed Explanation</span><div markdown="1">Vascular injuries occur in approximately 20% to 35% of knee dislocations, of which one third are posterior. Recognition of the vascular injury is essential. Normal pulses or normal capillary refill do not preclude an arterial injury, and arteriography should be considered in all knee dislocations. If the leg is ischemic, the arteriogram should be circumvented and the patient taken directly to the operating room. The risk of muscle fibrosis, contracture, or vascular insufficiency, and the need for amputation increase significantly when ischemia exceeds 6 hours. This patient has ischemia and is considered a vascular emergency. As such, delays for a thorough examination of the ligament, MRI scans, and even an arteriogram are unwarranted. Concurrent ligamentous repair and reconstruction should be deferred until vascular stability has been achieved. Kremchek TE, Welling RE, Kremchek EJ: Traumatic dislocation of the knee. Orthop Rev 1989;18:1051-1057.

<span class="exp-title">Detailed Explanation</span><div markdown="1">The ulnar nerve is more prone to neuropathy than the radial or median nerves for many reasons. It has the greatest longitudinal excursion required to accommodate elbow range of motion, subjecting it to potential traction forces. The dimensions of the entrance of the cubital tunnel change with elbow motion, potentially causing compression in flexion. For these two reasons, the ulnar nerve is subjected to both compression and traction during elbow motion. Although it passes between two muscle heads as it enters the forearm, so do the median and radial nerves. Finally, the vascular supply is adequate because of the anastamoses between the superior ulnar collateral artery, the posterior ulnar recurrent artery, and the inferior ulnar collateral artery. Norris TR (ed): Orthopaedic Knowledge Update: Shoulder and Elbow. Rosemont, IL, American Academy of Orthopaedic Surgeons, 1997, pp 369-378. Prevel CD, Matloub HS, Ye Z, Sanger JR, Yousif NJ: The extrinsic blood supply of the ulnar nerve at the elbow: An anatomic study. J Hand Surg Am 1993;18:433-438.

<span class="exp-title">Detailed Explanation</span><div markdown="1">While many low-demand patients with injuries to the ulnar collateral ligament can be treated nonsurgically, Jobe and associates described two situations in which ulnar collateral ligament reconstruction is indicated: (1) an acute complete rupture in a competitive athlete who uses the upper extremities extensively and who wishes to remain active; and (2) chronic pain or instability that does not improve after at least 3 months of nonsurgical management. Rarely is direct surgical repair of the ligament possible or able to withstand the valgus stresses applied to the elbow. Most authors recommend surgical reconstruction of the ulnar collateral ligament using a palmaris longus, plantaris, or fourth toe extensor tendon from the fourth autograft. Andrews JR, Jelsma RD, Joyce ME, et al: Open surgical procedures for injuries to the elbow in throwers. Oper Tech Sports Med 1994;4:109-133. Jobe FW, Kvitne RS: Elbow instability in the athlete. Instr Course Lect 1991;40:17-23.

<span class="exp-title">Detailed Explanation</span><div markdown="1">Bisphosphonates are indicated in the treatment of osteoporosis. They have been shown to reduce the incidence of vertebral and extremity fractures in patients with a T-score of less than -1.

<span class="exp-title">Detailed Explanation</span><div markdown="1">The sheath of the psoas muscle or the iliopectineal fascia separates the more lateral iliopsoas muscle and the femoral nerve from the more medially located iliac vessels. This fascia has to be taken down to enter the true pelvis. Masquelet AC, McCullough CJ, Tubiana R: An Atlas of Surgical Exposures of the Lower Extremity. Philadelphia, PA, JB Lippincott, 1993. Letournel E, Judet R: Fractures of the Acetabulum, ed 2. Berlin, Germany, Springer Verlag, 1993.

<span class="exp-title">Detailed Explanation</span><div markdown="1">The radiograph shows posttraumatic tibiofibular synostosis. This condition typically follows an eversion (high) ankle sprain that results in disruption of the interosseous membrane. Ossification usually develops within 6 to 12 months after the injury. Return to sports is possible despite the lack of normal ankle dorsiflexion and mobility between the tibia and fibula. Surgical excision is reserved for persistent pain that fails to respond to nonsurgical management once the ossification is "cold" on bone scintigraphy. Whiteside LA, Reynolds FC, Ellsasser JC: Tibiofibular synostosis and recurrent ankle sprains in high performance athletes. Am J Sports Med 1978;6:204-208. Henry JH, Andersen AJ, Cothren CC: Tibiofibular synostosis in professional basketball players. Am J Sports Med 1993;21:619-622.

<span class="exp-title">Detailed Explanation</span><div markdown="1">In a recent analysis of 200 patients with tibial fractures, Bhandari and associates attempted to identify variables that were predictive of reoperation. The variables in the study were type of injury (fracture pattern), degree of open injury, mechanism of injury, cortical bone contact, postoperative complications, polytrauma, anti-inflammatory drug use, nail insertion technique (reamed versus nonreamed), smoking history, alcohol use, diabetes mellitus, peripheral vascular disease, age, disability status pre-injury, gender, surgeon, time to surgery, steroid use, phenytoin use, antibiotic use, anticoagulant use, and type of fixation used. Three variables were statistically significant predictors of reoperation to achieve bone union in the first postinjury year: transverse fracture pattern, open fracture, and cortical contact of 50% or less. Using these three variables, four reoperation risk groups were identified based on the number of these three variables present: 0, 1, 2, or 3. The risk for reoperation was 0%, 18%, 47%, and 94%, respectively. The authors concluded that these statistics can provide prognostic information to patients and help identify those high-risk patients where early intervention to achieve union is indicated. In addition, the data highlights the significance of achieving cortical contact at the time of initial fixation.

<span class="exp-title">Detailed Explanation</span><div markdown="1">Deficiency of the rotator cuff interval may be acquired or congenital. In this patient, extensive debridement of the rotator cuff interval capsule at the time of arthroscopy most likely is the cause of the defect seen on the MRI scan. Surgical closure of the defect is the treatment of choice. During the repair, the shoulder should be placed in 30 degrees of external rotation to avoid overtightening. Care should be taken to include the leading edge of both the supraspinatus and subscapularis tendons in the repair because the rotator cuff interval capsular tissue is likely to be of poor quality. Cole BJ, Rodeo SA, O'Brien SJ, et al: The anatomy and histology of the rotator interval capsule of the shoulder. Clin Orthop 2001;390:129-137.

<span class="exp-title">Detailed Explanation</span><div markdown="1">Dislocation of the long head of the biceps tendon is the result of a defect in the region of the rotator cuff interval, coracohumeral ligament-superior glenohumeral ligament pulley, or an associated tear of the medial insertion of the subscapularis tendon. In the case of an intra-articular dislocation of the long head of the biceps tendon associated with a tear of the subscapularis tendon, stabilization of the biceps tendon is difficult in this situation; therefore, biceps release or tenodesis and repair of the subscapularis tendon is the treatment of choice. Eakin CL, Faber KJ, Hawkins RJ, et al: Biceps tendon disorders in athletes. J Am Acad Orthop Surg 1999;7:300-310. Sethi N, Wright R, Yamaguchi K: Disorders of the long head of the biceps tendon. J Shoulder Elbow Surg 1999;8:644-654.

<span class="exp-title">Detailed Explanation</span><div markdown="1">The plain radiographs show a horizontal orientation of the C5 facet joint. The CT scan through C5 reveals an ipsilateral pedicle and lamina fracture (floating facet). This injury involves two adjacent motion segments and is extremely unstable. Lateral mass plates, with or without the purchase of the "floating facet," provide the best means of stabilization and should include the facet above (C4) and below (C6) the level of injury. Orthotic immobilization is insufficient for this particular injury. Halo vest treatment does not control the subaxial spine well and is of limited value. While simple midline (Rogers) wiring provides some tension band restoration, it is not optimal for rotational control. The use of lateral mass plates provides rotational stability. Another option would be anterior fusion and plating, which would save cervical segments. Levine AM, Mazel C, Roy-Camille R: Management of fracture separations of the articular mass using posterior cervical plating. Spine 1992;17:S447-S454. Levine AM: Facet fractures and dislocations, in Levine AM, Eismont FJ, Garfin S, Zigler JE (eds): Spine Trauma. Philadelphia, PA, WB Saunders, 1998, pp 360-362. Whitehill R, Richman JA, Glaser JA: Failure of immobilization of the cervical spine by the halo vest: A report of five cases. J Bone Joint Surg Am 1986;68:326-332.

<span class="exp-title">Detailed Explanation</span><div markdown="1">Appropriate treatment is based on multiple considerations, which include the chronicity of the dislocation, the amount of humeral head involvement, the medical condition, and functional limitations of the patient. It has been shown that shoulder arthroplasty for locked posterior dislocation provides pain relief and improved motion. Transfer of the lesser tuberosity with its attached subscapularis tendon into the defect is recommended for anteromedial humeral defects that are smaller than approximately 40% of the joint surface. Subscapularis transfer as described by McLaughlin and the modification thereof later described by Hawkins and associates in which the lesser tuberosity is transferred into the defect, have yielded good results if the defect is less than 40% of the humeral head. Prosthetic replacement is preferred for larger defects. If the dislocation is less than 3 weeks old and has less than 25% of humeral head involvement, closed reduction with the patient under general anesthesia should be attempted and the stability assessed by internally rotating the arm. If the arm can be safely internally rotated to the abdomen, then 6 weeks of immobilization in an orthosis that maintains the shoulder in slight extension and external rotation can yield a good result. If the dislocation has been present for more than 3 weeks, closed reduction becomes exceedingly difficult. Gerber C, Lambert SM: Allograft reconstruction of segmental defects of the humeral head for the treatment of chronic locked posterior dislocation of the shoulder. J Bone Joint Surg Am 1996;78:376-382. Spencer EE Jr, Brems JJ: A simple technique for management of locked posterior shoulder dislocations: Report of two cases. J Shoulder Elbow Surg 2005;14:650-652. Sperling JW, Pring M, Antuna SA, et al: Shoulder arthroplasty for locked posterior dislocation of the shoulder. J Shoulder Elbow Surg 2004;13:522-527. Hawkins RJ, Neer CS II, Pianta RM, et al: Locked posterior dislocation of the shoulder. J Bone Joint Surg Am 1987;69:9-18.

<span class="exp-title">Detailed Explanation</span><div markdown="1">The underlying diagnosis is multiple myeloma. Because the patient has a large lucent lesion in the peritrochanteric region of the left proximal femur, the risk of pathologic fracture is high. Consideration should be given to prophylactic internal fixation with a locked intramedullary rod. The lesion does not appear to be a sarcoma requiring wide resection and endoprosthetic reconstruction. Neither chemotherapy nor radiation therapy alone is likely to result in long-term stabilization of the proximal femur. Postoperative treatment with bisphosphonates and radiation therapy is indicated to decrease the risk of future pathologic fractures. The patient should also be referred to a medical oncologist for medical management. Menendez LR (ed): Orthopaedic Knowledge Update: Musculoskeletal Tumors. Rosemont, IL, American Academy of Orthopaedic Surgeons, 2002, p 364.

<span class="exp-title">Detailed Explanation</span><div markdown="1">Type I collagen accounts for more than 90% of the total collagen content. Other minor collagens present include types II, III, V, and VI. Mow VC, Arnoczky SP, Jackson DW (eds): Knee Meniscus: Basic and Clinical Foundations. New York, NY, Raven Press, 1992, p 41.

<span class="exp-title">Detailed Explanation</span><div markdown="1">In most patients with symptomatic talocalcaneal coalition involving less than 50% of the subtalar joint, resection with fat graft interposition is preferred over a subtalar or triple arthrodesis, especially if reasonable range of motion can be achieved. This patient has a synchondrosis that is partially cartilaginous. Although patients may have a residual gait abnormality, most report pain relief after surgery. Scranton PE Jr: Treatment of symptomatic talocalcaneal coalition. J Bone Joint Surg Am 1987;69:533-539. Kitaoka HB, Wikenheiser MA, Schaughnessy WJ, et al: Gait abnormalities following resection of talocalcaneal coalition. J Bone Joint Surg Am 1997;79:369-374.

<span class="exp-title">Detailed Explanation</span><div markdown="1">The vascularity of the dorsal portion of the digital flexor tendons is considerably richer than the volar portion. The other regions are not preferentially more vascular. Hunter JM, Scheider LH, Makin EJ (eds): Tendon Surgery in the Hand. St Louis, MO, Mosby, 1987, pp 91-99.

<span class="exp-title">Detailed Explanation</span><div markdown="1">The radiograph demonstrates thickened trabeculae and thickened cortices in the left proximal femur compared to the right, and the bone scan shows increased uptake in this area. The MRI scans show thickened trabeculae with normal marrow signal. These findings are diagnostic of Paget's disease. Medical treatment, including bisphosphonates and calcitonin, is indicated for painful bone lesions. Hadjipavlou AG, Gaitanis IN, Kontakis GM: Paget's disease of the bone and its management. J Bone Joint Surg Br 2002;84:160-169.

<span class="exp-title">Detailed Explanation</span><div markdown="1">The pathology demonstrates a very cellular chondroid matrix with multinucleated forms, atypia, and myxomatous regions. This is most consistent with a myxoid chondrosarcoma. The radiograph shows a well-circumscribed lesion in the superior and medial aspect of the right acetabulum. The CT and MRI scans confirm these same findings with no evidence of matrix mineralization or significant surrounding edema. Unfortunately, in this location with this appearance, the radiographic differential diagnosis includes all the diagnoses listed. Terek RM: Recent advances in the basic science of chondrosarcoma. Orthop Clin North Am 2006;37:9-14. Donati D, El Ghoneimy A, Bertoni F, et al: Surgical treatment and outcome of conventional pelvic chondrosarcoma. J Bone Joint Surg Br 2005;87:1527-1530.

<span class="exp-title">Detailed Explanation</span><div markdown="1">Polyethylene particles generated as mechanical wear debris can be phagocytized by macrophages and enter a metabolically active state that releases cytokines, causing periprosthetic bone resorption. Significant osteolysis can occur in the pelvis with a porous-coated cementless socket without loosening of the component. If the acetabular component is modular, well positioned, well-designed with a good survivorship record, and remains undamaged after liner removal, the polyethylene liner can be exchanged and the lytic defects can be debrided and bone grafted. This implant is well positioned, has a good survivorship record, a good locking mechanism, and is modular. The hip arthroplasty needs to be aseptic for consideration of liner exchange. Maloney WJ, Herzwurm P, Paprosky W, Rubash HE, Engh CA: Treatment of pelvic osteolysis associated with a stable acetabular component inserted without cement as part of a total hip replacement. J Bone Joint Surg Am 1997;79:1628-1634.

<span class="exp-title">Detailed Explanation</span><div markdown="1">The patient initially has a distal third femoral fracture and a pulseless limb. The first step is to reduce the fracture and reassess the vascular status. Although the pulse returns, it feels different than the quality of the pulse in the contralateral uninjured extremity. There is a risk of a vascular injury with this fracture pattern due to tethering of the femoral vessels at the adductor hiatus; therefore, the vascular status needs further assessment since the pulses are not symmetrical. A physical examination is not very accurate in assessing whether a vascular injury is present; therefore, serial examinations are not appropriate. Angiography is very sensitive and specific but is time consuming and can cause complications secondary to the dye and the arterial puncture required to perform it. Duplex ultrasound is effective but is very operator-dependent and may not be available 24 hours a day. The ABI is easily performed and has been shown to be sensitive and specific. If the value is greater than 0.9, the negative predictive value is 99% and when the value is less than 0.9, it is 95% sensitive and 97% specific for a major arterial injury. It has been shown to be useful for blunt lower extremity injuries as well as knee dislocations. Levy BA, Zlowodzki MP, Graves M, et al: Screening for extremity arterial injury with the arterial pressure index. Am J Emerg Med 2005;23:689-695. Abou-Sayed H, Berger DL: Blunt lower-extremity trauma and politeal artery injuries: Revisiting the case for selective arteriography. Arch Surg 2002;137:585-589.

<span class="exp-title">Detailed Explanation</span><div markdown="1">The overriding factor determining treatment in this case is the appearance of the surgical wound. Based on MacPhearson's work, this "C" wound is best managed with two-stage exchange. The functional outcome is markedly diminished following a knee arthrodesis compared to revision knee arthroplasty. Harwin SF: The diagnosis and management of infected total knee replacement. Seminars Arthroplasty 2002;13:9-22. Goldmann RT, Scuderi GR, Insall JN: 2-stage reimplantation for infected total knee replacement. Clin Orthop 1996;331:118-124.

<span class="exp-title">Detailed Explanation</span><div markdown="1">The etiology of osteochondritis dissecans of the capitellum is somewhat unclear. However, trauma has been implicated in this disease process. Gymnasts who load their upper extremities during tumbling and throwing athletes with repetitive trauma during the throwing motion are common patient subgroups in which osteochondritis dissecans of the elbow is seen. This often occurs in the adolescent age population. Baumgarten TE, Andrews JR, Satterwhite YE: The arthroscopic classification and treatment of osteochondritis dissecans of the capitellum. Am J Sports Med 1998;26:520-523.

<span class="exp-title">Detailed Explanation</span><div markdown="1">A calcaneal deformity of the foot may occur in children who have low lumbar myelomeningocele. Strong dorsiflexors overcome a weak or absent gastrocnemius-soleus complex, leading to downward growth of the calcaneal apophysis. The deformity is usually progressive and does not respond to nonsurgical management. Most authorities recommend transfer of the tibialis anterior muscle through the interosseous membrane to the posterior aspect of the calcaneus. This procedure has been reported to be effective in limiting progression of the deformity. An extra-articular subtalar arthodesis, a treatment option for valgus deformity of the hindfoot, is not indicated. Similarly, Achilles tendon tenodesis to the fibula, an option for managing valgus of the ankle, is not indicated. Calcaneal osteotomy may be used in older children with severe calcaneal deformity. Stott NS, Zionts LE, Gronley JK, Perry J: Tibialis anterior transfer for calcaneal deformity: A postoperative gait analysis. J Pediatr Orthop 1996;16:792-798.

<span class="exp-title">Detailed Explanation</span><div markdown="1">The posterior circumflex artery provides blood supply only to the posterior portion of the greater tuberosity and a small posteroinferior portion of the humeral head. The humeral head is supplied primarily by the anterolateral ascending branch of the anterior circumflex artery; the terminal branch of this artery is termed the arcuate artery. Norris TR (ed): Orthopaedic Knowledge Update: Shoulder and Elbow 2. Rosemont, IL, American Academy of Orthopaedic Surgeons, 2002, pp 267-274.

<span class="exp-title">Detailed Explanation</span><div markdown="1">The posterior atlanto-dens interval represents the space available for the spinal cord and a distance of less than 14 mm is predictive of neurologic progression, thus warranting consideration for fusion, even in the absence of symptoms.

<span class="exp-title">Detailed Explanation</span><div markdown="1">The patient's findings are consistent with an intermediate form of spinal muscular atrophy. Children with this condition appear normal at birth but are not able to walk. The disorder affects anterior horn cells. Fasciculations may be present, but deep tendon reflexes are typically absent. The development of scoliosis is almost universal with this type of spinal muscular atrophy. More than 90% of patients with spinal muscular atrophy have deletions in the telomeric survival motor neuron gene. Peripheral myelin protein 22 is abnormal in Charcot-Marie-Tooth type IA. Connexin 32 is abnormal in the X-linked type of Charcot-Marie-Tooth disease. Neurofibromin is affected in neurofibromatosis type 1. Friedreich's ataxia is secondary to a disorder of frataxin. Buckwalter JA, Einhorn TA, Simon SR (eds): Orthopaedic Basic Science, ed 2. Rosemont, IL, American Academy of Orthopaedic Surgeons, 2000, pp 111-131.

<span class="exp-title">Detailed Explanation</span><div markdown="1">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.

<span class="exp-title">Detailed Explanation</span><div markdown="1">The patient has a nondisplaced stress fracture of the tarsal navicular. Weight bearing is associated with a high rate of nonunion; therefore, management should consist of immobilization and no weight bearing for 8 weeks. Delayed union or nonunion is treated by excision of sclerotic fracture margins and bone grafting, with or without internal fixation. Generally, CT should be repeated to document healing before permitting a return to sports. Beaty JH (ed): Orthopaedic Knowledge Update 6. Rosemont, IL, American Academy of Orthopaedic Surgeons, 1999, pp 597-612.

<span class="exp-title">Detailed Explanation</span><div markdown="1">Spinal cord injury in skeletally immature patients almost always leads to the development of paralytic spinal deformity. The age at injury is the most important factor affecting the development of scoliosis. Spinal cord injury that occurs more than 1 year prior to skeletal maturity is almost always followed by the development of scoliosis. In one study, scoliosis developed in 100% of children who were younger than age 10 years at the time of spinal cord injury. Scoliosis can occur after injury at any level. Spasticity is often a contributing factor. Up to two thirds of patients who have paralytic scoliosis prior to skeletal maturity will eventually require surgery for curve control. Mayfield JK, Erkkila JC, Winter RB: Spine deformity subsequent to acquired childhood spinal cord injury. J Bone Joint Surg Am 1981;63:1401-1411. Lancourt JE, Dickson JH, Carter RE: Paralytic spinal deformity following traumatic spinal cord injury in children and adolescents. J Bone Joint Surg Am 1981;63:47-53.

<span class="exp-title">Detailed Explanation</span><div markdown="1">These are classic findings of osteonecrosis of the hip. The radiograph reveals the subchondral sclerotic pattern commonly seen in osteonecrosis and is quite extensive in this patient. The MRI scan reveals the typical serpentine-like region of low signal intensity with a central zone where the signal is similar to fat. Resnick D (ed): Diagnosis of Bone and Joint Disorders. Philadelphia, PA, WB Saunders, 2002, pp 3160-3162.

<span class="exp-title">Detailed Explanation</span><div markdown="1">Alumina is the hardest of all the materials listed. Clinical retrieval demonstrates resistance to scratching from third-body debris.

<span class="exp-title">Detailed Explanation</span><div markdown="1">Esler and associates evaluated the use of manipulation under anesthesia in 47 knees. Manipulation was considered when intensive physical therapy failed to increase flexion to more than 80 degrees. The mean time from arthroplasty to manipulation was 11.3 weeks, and the mean active flexion before manipulation was 62 degrees. One year later, the mean gain was 33 degrees. Definite sustained gains in flexion were achieved even when manipulation was performed 4 or more months after arthroplasty. An additional 21 patients who met the criteria for manipulation declined the procedure, and despite continued physical therapy, they showed no significant increase in knee flexion.

<span class="exp-title">Detailed Explanation</span><div markdown="1">Displaced clavicular fractures lateral to the coracoid process (Neer type II and III) are best managed nonsurgically with sling immobilization and physical therapy, starting with pendulum exercises and progressing to active-assisted exercises when comfortable. Supervised therapy should be performed for 3 months or until full painless motion is achieved. In one study by Robinson and Cairns, this form of treatment provided patients with a 86% chance of avoiding a secondary reconstructive procedure. Robinson CM, Cairns DA: Primary nonoperative treatment of displaced lateral fractures of the clavicle. J Bone Joint Surg Am 2004;86:778-782.

<span class="exp-title">Detailed Explanation</span><div markdown="1">The MRI scans reveal a postoperative infection. Observation and antibiotics are not appropriate choices. There is a large fluid collection and this requires decompression because the patient has neurologic changes. There is considerable debate regarding the removal of hardware. Many contend that biofilm on the implants can harbor the infection. However, these complications usually can be treated with serial irrigations, debridements, and IV antibiotics. The incidence of infection has been widely studied with varying rates in fusions with instrumentation. Rates appear to be increased with instrumentation, yet these infections usually can be managed without hardware removal. Glassman SD, Dimar JR, Puno RM, et al: Salvage of instrumental lumbar fusions complicated by surgical wound infection. Spine 1996;21:2163-2169.

<span class="exp-title">Detailed Explanation</span><div markdown="1">An isotropic material is one that has similar mechanical properties regardless of the orientation of the material. Examples of isotropic materials include metals, plastics, and methacrylate. Most biologic tissues are anisotropic, meaning their mechanical properties alter depending on the materials' orientation to the applied stress.

<span class="exp-title">Detailed Explanation</span><div markdown="1">The first rule of total knee arthroplasty is to restore the joint line to its original location. This will ensure optimal patellofemoral biomechanics and will facilitate ligament balancing. Changes on the tibial side affect both the flexion and extension gaps equally. Changes in femoral component sizing or position affect the flexion gap only. Tibial changes affect both the flexion and extension gaps. To convert a tight extension gap to a normal flexion gap, more distal femur needs to be resected. Vince KG: Revision knee arthroplasty technique. Instr Course Lect 1993;42:325-339.

<span class="exp-title">Detailed Explanation</span><div markdown="1">Tibial tubercle avulsion is an injury of the adolescent knee that most often occurs just before the end of growth. The fracture usually occurs with jumping, either at push-off or landing. This patient has a type III injury. In type III injuries, the articular surface is disrupted, and meniscal injury and compartment syndrome can occur. Open reduction is the treatment of choice, and anterior fasciotomy should be considered prophylactically at the time of surgery. Although the fracture heals with an anterior epiphysiodesis of the proximal tibia, little growth remains in this patient and no special handling of the physis is warranted. Ogden JA, Tross RB, Murphy MJ: Fractures of the tibial tuberosity in adolescents. J Bone Joint Surg Am 1980;62:205-215.

<span class="exp-title">Detailed Explanation</span><div markdown="1">The photograph shows the characteristic attitude of the hand when an anterior interosseous nerve palsy is present. The patient is unable to flex the interphalangeal joint to the joint of the thumb. Anterior interosseous nerve palsies are often misdiagnosed as tendon ruptures. Schantz K, Reigels-Nielsen P: The anterior interosseous nerve syndrome. J Hand Surg Br 1992;17:510-512.

<span class="exp-title">Detailed Explanation</span><div markdown="1">The patient has a grade I isthmic spondylolisthesis at L5-S1. He has an L5 radiculopathy with foraminal stenosis. Any further treatment needs to include an arthrodesis and foraminal decompression. Isolated interbody fusion is contraindicated in patients with spondylolisthesis, as is total disk arthroplasty. Therefore, the best procedure is a posterior fusion with instrumentation and bone graft along with a foraminal decompression. Spivak JM, Connolly PJ (eds): Orthopaedic Knowledge Update: Spine 3. Rosemont, IL, American Academy of Orthopaedic Surgeons, 2006, pp 311-317.

<span class="exp-title">Detailed Explanation</span><div markdown="1">The patient has no clinical or observed signs of sepsis. The skin just proximal to the gangrenous tissue appears somewhat hyperemic and is clearly viable. These wounds should be managed much like burn wounds. Moist dressings should be used until the tissue clearly demarcates. Much of the insult may simply be superficial and only require late debridement. McAdams TR, Swenson DR, Miller RA: Frostbite: An orthopedic perspective. Am J Orthop 1999;28:21-26.

<span class="exp-title">Detailed Explanation</span><div markdown="1">Athletic pubalgia refers to a distinct syndrome of lower abdominal and adductor pain that is mostly commonly seen in high performance male athletes. This condition must be distinguished from others such as painful inflammation of the symphysis pubis, referred to as osteitis pubis. Symptoms attributable to the iliopsoas tendon are most commonly associated with snapping of the tendon. Stress fracture of the pubic ramus may cause symptoms in this area, but it is usually confirmed by imaging studies. Neurapraxia of the pudendal nerve is associated with pressure from the seat in cycling sports and also as a complication associated with traction during surgical procedures. Meyers WC, Foley DP, Garrett WE, Lohnes JH, Mandlebaum BR: Management of severe lower abdominal or inguinal pain in high-performance athletes: PAIN (Performing Athletes with Abdominal or Inguinal Neuromuscular Pain Study Group). Am J Sports Med 2000;28:2-8.

<span class="exp-title">Detailed Explanation</span><div markdown="1">The relationship between the distal articular surface of the first metatarsal head and the long axis of the first metatarsal is called the distal metatarsal articular angle. This angle has been validated by Richardson and associates to measure and determine the congruence of the first metatarsophalangeal joint. This angle is critical in determining the appropriate surgical procedure to perform on a patient with a bunion deformity because a congruent joint requires a procedure to maintain congruence of the articular surfaces following osteotomy. Therefore, a chevron becomes a biplanar chevron, and a Lapidus procedure adds a second osteotomy of the distal metatarsal to tilt the metatarsal head into a congruent location. Coughlin MJ: Juvenile hallux valgus: Etiology and treatment. Foot Ankle Int 1995;16:682-697. Steel MW III, Johnson KA, DeWitz MA, et al: Radiographic measurements of the normal foot. Foot Ankle 1980;1:151-158.

<span class="exp-title">Detailed Explanation</span><div markdown="1">The examination findings are consistent with subscapularis muscle weakness but normal supraspinatus and infraspinatus strength. The lift-off test and abdominal compression test are specific for subscapularis function. The MRI scan reveals a chronic avulsion and retraction of the subscapularis. The transverse image reveals a normal infraspinatus muscle, and the sagittal image reveals an atrophic subscapularis. Surgical repair of the isolated subscapularis tendon is indicated. Iannotti JP, Williams GR: Disorders of the Shoulder: Diagnosis and Management, ed 1. Philadelphia, PA, Lippincott Williams & Wilkins, 1999, pp 31-56.

<span class="exp-title">Detailed Explanation</span><div markdown="1">The radiographs show fragmentation of the inferior pole of the patella. This finding, along with the clinical presentation, is most consistent with Sindig-Larsen-Johansson disease. This is an overuse syndrome commonly seen in boys ages 9 to 11 years. The differential diagnosis includes bipartite patella and patellar sleeve fracture. Like most overuse syndromes, Sindig-Larsen-Johansson disease responds to activity modification and nonsteroidal anti-inflammatory drugs. While symptoms usually resolve with short periods of activity restriction, radiographic findings may persist. Stanitski CL: Anterior knee pain syndromes in the adolescent. J Bone Joint Surg Am 1993;75:1407-1416.

<span class="exp-title">Detailed Explanation</span><div markdown="1">Anterior dislocation is the most common type of sternoclavicular dislocation. The medial end of the clavicle is displaced anterior or anterosuperior to the anterior margin of the sternum. In a study by Omer, 31% of athletic injuries have been known to cause a dislocation of the sternoclavicular joint. The serendipity view can show this dislocation, as will CT of the chest. This view requires the x-ray beam to be aimed at the manubrium with 40 degrees of cephalic tilt. An anterior sternoclavicular joint dislocation will appear superiorly displaced, while a posterior sternoclavicular joint dislocation is inferiorly displaced on the serendipity view. Rockwood CA Jr, Matsen FA III (eds): The Shoulder. Philadelphia, PA, WB Saunders, 1998, vol 1, pp 566-572.

<span class="exp-title">Detailed Explanation</span><div markdown="1">TFCC tears are common in athletes. As the athlete braces for a fall, the wrist is most commonly in an extended position and the forearm is pronated. Cohen MS: Ligamentous injuries of the wrist in the athlete. Clin Sports Med 1998;17:533-552.

<span class="exp-title">Detailed Explanation</span><div markdown="1">The findings are consistent with an osteoblastoma. The radiographs show a bone-forming lesion of the distal humerus. The lesion has an osseous component extending out of the native cortex with a thin sclerotic border. The T2-weighted MRI scan shows the lesion extending anteriorly beyond the native cortex. No fluid-fluid levels are seen. Histology shows large osteoblasts producing osteoid and woven bone. The tissue between the spicules of bone and osteoid contains thin fibrous tissue and capillaries. Osteoid osteoma is a smaller lesion usually with sclerotic reactive bone around a small nidus. The histology differentiates osteoblastoma from osteosarcoma because no malignant cells are seen. There is no cartilage production or chondroblasts in the histologic specimen, eliminating chondroblastoma. Giant cell tumors of bone typically occur in a epiphyseal metaphyseal location, most commonly after skeletal maturity, and contain numerus giant cells. Menendez LR (ed): Orthopaedic Knowledge Update: Musculoskeletal Tumors. Rosemont, IL, American Academy of Orthopaedic Surgeons, 2002, pp 87-102.

<span class="exp-title">Detailed Explanation</span><div markdown="1">The studies reveal significant heterotopic ossification that appears to be mature. Following resection, the most reliable way to prevent recurrence is with low-dose external-beam radiation therapy. Bisphosphonate therapy can be considered; however, when terminated, heterotopic bone may reform. Heterotopic ossification is unrelated to the patient's endocrine status and is not associated with any metabolic abnormalities. Moore K, Goss K, Anglen J: Indomethacin versus radiation therapy for prophylaxis against heterotopic ossification in acetabular fracture. J Bone Joint Surg Br 1998;80:259.

<span class="exp-title">Detailed Explanation</span><div markdown="1">The imaging studies show a comminuted lateral talar process fracture. This injury is often missed on plain radiographs; therefore, CT provides the best method of diagnostic evaluation. The most likely long-term sequela of this injury is subtalar joint arthrosis. Although this injury involves the fibular gutter region, progression to true ankle arthritis is unlikely. There does not appear to be any association with this injury and chronic mechanical instability of the ankle or disruption of the superior peroneal retinaculum and subsequent peroneal tendon instability. Entrapment of the flexor hallucis longus tendon may occur with fractures of the sustentaculum tali but not with injuries of the lateral talar process. Surgical management includes open reduction and internal fixation versus excision; the goal is preservation of the large articular surface fragments. In this patient, there is significant comminution and early fragment excision may be the best option for acute treatment. Tucker DJ, Feder JM, Boylan JP: Fractures of the lateral process of the talus: Two case reports and a comprehensive literature review. Foot Ankle Int 1998;19:641-646.

<span class="exp-title">Detailed Explanation</span><div markdown="1">All of the muscles are innervated by the peroneal nerve with the exception of the tibialis posterior which is innervated by the tibial nerve. Tibialis posterior function is best tested with resistance to plantar flexion and inversion.

<span class="exp-title">Detailed Explanation</span><div markdown="1">During the late acceleration phase of throwing, the triceps forcibly contracts, extending the elbow as the ball is released. Normally, this force is absorbed by the anterior capsule and the brachialis and biceps muscles. However, if the ulnar collateral ligament is insufficient, the elbow will be in a subluxated position during extension and cause impaction of the olecranon and the olecranon fossa posteromedially. Over time, osteophyte formation is likely to occur. Conway JE, Jobe FW, Glousman RE, Pink M: Medial instability of the elbow in throwing athletes: Treatment by repair or reconstruction of the ulnar collateral ligament. J Bone Joint Surg Am 1992;74:67-83.

<span class="exp-title">Detailed Explanation</span><div markdown="1">The motor dysfunction in Charcot-Marie-Tooth disease involves the tibialis anterior muscle. Charcot-Marie-Tooth disorders most commonly cause distal motor dysfunction in the foot intrinsics, anterior compartment musculature, and peroneals. There is evidence that the peroneus brevis is affected selectively and the peroneus longus is spared. This is based on clinical muscle testing, muscle cross-sections on MRI, and electrodiagnostic testing. Mann RA, Missirian J: Pathophysiology of Charcot-Marie-Tooth disease. Clin Orthop 1988;234:221-228.

<span class="exp-title">Detailed Explanation</span><div markdown="1">The patient has a prefractured stage of congenital pseudarthrosis of the tibia and is at risk for fracture. The PTB orthosis may prevent or delay the fracture. Osteotomy is frequently complicated by nonunion. When established nonunion does not respond to intramedullary nailing and bone grafting, vascularized grafting may succeed. Amputation is a salvage procedure. Murray HH, Lovell WW: Congenital pseudarthrosis of the tibia: A long-term follow-up study. Clin Orthop 1982;166:14-20.

<span class="exp-title">Detailed Explanation</span><div markdown="1">The history and laboratory findings are consistent with osteomyelitis of the patella. The radiograph reveals bone destruction in the patella; therefore, the next most appropriate step is open biopsy and debridement of the site. Aspiration of the knee joint may be needed to rule out septic arthritis prior to patellar debridement. With this amount of bone destruction, surgical debridement is helpful to obtain cultures and to remove necrotic material. Administering antibiotics without any prior culture increases the risk of negative cultures later and a potentially incorrect choice of antibiotic. A neoplasm should be included in the differential. It would be inappropriate to initiate chemotherapy and radiation therapy without a biopsy-confirmed diagnosis. A bone scan is likely to demonstrate uptake, but radiographs have already localized the abnormality to the patella. Morrisy RT: Bone and joint sepsis, in Morrissy RT, Weinstein SL (eds): Lovell and Winter's Pediatric Orthopaedics, ed 5. Philadelphia, PA, Lippincott Williams & Wilkins, 2001, pp 466-470.

<span class="exp-title">Detailed Explanation</span><div markdown="1">The patient has an L5 radiculopathy secondary to an L4-5 disk herniation that is compressing the traversing L5 nerve root.

<span class="exp-title">Detailed Explanation</span><div markdown="1">Nondisplaced transverse fractures of the phalanges are stable. Immobilization in the intrinsic plus position will prevent MCP joint stiffness. Displaced oblique fractures are more at risk for instability. Stern PJ: Fractures of the metacarpals and phalanges, in Green DP, Hotchkiss RN, Pederson WC, et al (eds): Green's Operative Hand Surgery, ed 5. Philadelphia, PA, Elsevier, 2005, p 281.

<span class="exp-title">Detailed Explanation</span><div markdown="1">In a recent study on restoration of motion following zone I and zone II flexor tendon repairs in children, age was found to have no effect on the results of zone II tendon repairs. Early passive motion offered no better results than immobilization for 3 weeks. Immobilization for more than 4 weeks correlated with poorer results.

<span class="exp-title">Detailed Explanation</span><div markdown="1">Osteopenia, decreased bone mass without fracture risk as defined by the WHO criteria for diagnosis of osteoporosis, is when a woman's T-score is within -1 to -2.5 SD. The T-score represents a comparison to young normals or optimum peak density. The Z-score represents a comparison of BMD to age-matched normals. Measurements of bone mineral density (BMD) at various skeletal sites help in predicting fracture risk. Hip BMD best predicts fracture of the hip, as well as fractures at other sites.

<span class="exp-title">Detailed Explanation</span><div markdown="1">The size of the rotator cuff tear in both anteroposterior and mediolateral dimensions has been found to correlate best with outcome. Older patient age and rupture of the long head of the biceps tend to be associated with larger tears and, therefore, may be associated indirectly with a poorer outcome. Iannotti JP: Full-thickness rotator cuff tears: Factors affecting surgical outcome. J Am Acad Orthop Surg 1994;2:87-95.

<span class="exp-title">Detailed Explanation</span><div markdown="1">Because the patient is skeletally mature with a curve of less than 40 degrees, there is no benefit to bracing and surgery is not indicated. Management should consist of observation and follow-up radiographs in 6 months. Lonstein JE, Carlson JM: The prediction of curve progression in untreated idiopathic scoliosis during growth. J Bone Joint Surg Am 1984;66:1061-1071.

<span class="exp-title">Detailed Explanation</span><div markdown="1">The Watson-Jones approach to the hip uses the intermuscular interval between the gluteus medius and the tensor fascia lata. This is not a true internervous plane, as both muscles are supplied by the superior gluteal nerve. Hoppenfeld S, deBoer P: Surgical Exposures in Orthopaedics: The Anatomic Approach. Philadelphia, PA, JB Lippincott, 1984, pp 316-332.

<span class="exp-title">Detailed Explanation</span><div markdown="1">The radiographs demonstrate persistent widening of the medial clear space with an ossicle. This represents soft-tissue interposition-scar tissue, the deltoid ligament, or the posterior tibialis tendon. Physical therapy will not improve the symptomatic malalignment. Hardware removal would be indicated for pain localized to the lateral fibula. Repeat syndesmotic screw fixation alone will not reduce the malalignment. Deltoid ligament repair may be necessary but will need to be combined with debridement of the medial ankle and syndesmosis, as well as repeat placement of one or more syndesmotic screws to maintain the reduction. Weening B, Bhandari M: Predictors of functional outcome following transsyndesmotic screw fixation of ankle fractures. J Orthop Trauma 2005;19:102-108.