Orthopedic Board Review MCQs (2026 Edition) - Part 9

Correct Answer: C

In a young individual with a chronic dislocation of the elbow and heterotopic bone formation, the treatment of choice is open reduction, heterotopic bone excision, anterior and posterior capsular releases, and a dynamic hinged fixator to begin protected early postoperative range of motion. It is important to understand that the fixator protects the reconstruction and allows early range of motion, but it does not maintain the reduction and should not be expected to do so. Pin fixation across the elbow delays early motion and is not recommended.

Correct Answer: B

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.

Correct Answer: C

The figure shows the missing pedicle or 'winking owl' sign that is characteristic of tumor involvement of the cortical bone of the pedicle. None of the other pathologic processes commonly gives this radiographic picture. Thinned, but not missing pedicles, have been described as a normal variant.

Correct Answer: B

The dynamic forces acting to maintain the position of the proximal phalanx at the head of the metatarsal are a balance between the extensor digitorum longus and the weaker intrinsic muscles. With hyperextension at the metatarsophalangeal joint, the intrinsic muscles become less efficient as plantar flexors. Consequently, the hyperextension deformity progresses in the metatarsophalangeal joint as the opposition of the intrinsic muscles to the extensor tendon lessens.

Correct Answer: B

The histology shows small round blue cells that are typical of Ewing's sarcoma. Ewing's sarcoma has been noted to have a consistent genetic translocation t(11;22). Although Ewing's sarcoma frequently occurs in the diaphysis, it can occur in the metaphysis.

Correct Answer: C

The patient has a midstem periprosthetic fracture, which commonly results in loosening of the prosthesis. Although the patient reported a fall, her history is also consistent with preexisting loosening of the prosthesis. Chronic infection has been shown in up to 16% of these fractures; however, the patient's work-up revealed no infection.

Correct Answer: B

Compression of the suprascapular nerve by a ganglion cyst is a well-documented cause of pain and weakness in the shoulder. Isolated involvement of the infraspinatus indicates that the area of entrapment is at the spinoglenoid notch and not the suprascapular notch. The suprascapular nerve innervates the supraspinatus before passing through the spinoglenoid notch to innervate the infraspinatus.

Correct Answer: D

The histologic finding of spicules of woven bone without osteoblastic rimming in a bland fibrous background is diagnostic of fibrous dysplasia. Observation is indicated in the absence of symptoms, impending fracture, or deformity. Fibrous dysplasia most commonly occurs in the proximal femur.

Correct Answer: C

The fracture is a both-column fracture in the Judet/Letournel classification. Both the anterior and posterior columns are separately broken and displaced. However, the defining feature of a both-column pattern is that all articular fragments are on fracture fragments and no joint surface is left intact to the axial skeleton above.

Correct Answer: B

The patient has Kienbock's disease (osteonecrosis of the lunate), which presents with boggy synovitis of the wrist, decreased range of motion, and often normal radiographs early on. This disease process is classically associated with an ulnar-negative variant. An MRI scan, revealing a low-intensity signal in the lunate, is the best diagnostic tool for early Kienbock's disease.

Correct Answer: C

In a young individual with a chronic dislocation of the elbow and heterotopic bone formation, the treatment of choice is open reduction, heterotopic bone excision, anterior and posterior capsular releases, and a dynamic hinged fixator. The primary purpose of the fixator is to protect the reconstruction and allow early protected range of motion. It does not maintain the reduction on its own and should not be expected to do so. Rigid immobilization or pin fixation across the joint delays early motion and is contraindicated.

Correct Answer: B

The underlying diagnosis is multiple myeloma, presenting with a large lucent lesion in the peritrochanteric region of the proximal femur. After prophylactic internal fixation to address the impending pathologic fracture, 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 comprehensive medical management.

Correct Answer: D

The 'winking owl' sign is characteristic of tumor involvement of the cortical bone of the pedicle, leading to a missing pedicle on an AP radiograph. None of the other pathologic processes or anatomical structures commonly give this specific radiographic picture. Thinned, but not missing, pedicles have been described as a normal variant, but complete absence is highly suspicious for metastatic disease or tumor.

Correct Answer: A

The imaging and histology (small round blue cells) are diagnostic of Ewing's sarcoma. Ewing's sarcoma is characteristically associated with the t(11;22) genetic translocation. Other translocations listed correspond to different sarcomas: t(X;18) is seen in synovial sarcoma, t(12;16) in myxoid liposarcoma, and t(2;13) in alveolar rhabdomyosarcoma.

Correct Answer: C

The radial nerve lies directly on the anterior elbow capsule at the midportion of the capitellum. It is at significant risk for injury when capsular excision or release is performed in this specific region during elbow arthroscopy.

Correct Answer: B

The radiographs demonstrate a proximal third (proximal pole) scaphoid fracture. Proximal pole fractures are optimally approached via a dorsal approach to ensure proper reduction and allow for a compression screw to be placed perpendicular to the fracture plane. Fractures of the scaphoid waist can be approached either volarly or dorsally.

Correct Answer: B

The imaging and histology are diagnostic of fibrous dysplasia. The classic histologic finding of fibrous dysplasia is spicules of woven bone (often described as 'Chinese characters') without osteoblastic rimming, set in a bland fibrous background. Observation is indicated in the absence of symptoms, impending fracture, or severe deformity.

Correct Answer: C

The defining feature of a both-column acetabular fracture is that all articular fragments are detached from the intact axial skeleton (ilium/sacrum). While both the anterior and posterior columns are broken, the complete dissociation of the articular surface from the intact ilium is the hallmark of this specific fracture pattern.

Correct Answer: C

The patient has a displaced four-part proximal humerus fracture. Given her advanced age and the presence of osteopenia, the risk of osteonecrosis of the humeral head and failure of internal fixation is high. Therefore, a cemented hemiarthroplasty is the treatment of choice. ORIF may be indicated in younger individuals with good bone quality.

Correct Answer: D

The radiographs demonstrate a degenerative collapse of the midfoot through the tarsometatarsal joints with significant forefoot abduction. Because the primary pathology and deformity are at the tarsometatarsal articulation, a midfoot arthrodesis is the required surgical intervention. Procedures targeting the hindfoot (like triple arthrodesis or lateral column lengthening) would not address the primary site of arthritis and deformity.

Correct Answer: C

In the surgical management of chronic elbow dislocation with heterotopic ossification (HO), the treatment of choice is open reduction, HO excision, capsular release, and application of a dynamic hinged fixator. The fixator's primary role is to protect the soft-tissue reconstruction and allow early protected range of motion. It does not maintain the reduction itself, nor does it prevent HO recurrence. Pin fixation across the joint would delay early motion and is contraindicated.

Correct Answer: B

The patient has multiple myeloma with an impending pathologic fracture of the proximal femur, which requires prophylactic internal fixation with a locked intramedullary nail. Postoperatively, treatment with bisphosphonates and radiation therapy is indicated to decrease the risk of future pathologic fractures and provide local tumor control. Bisphosphonates inhibit osteoclast-mediated bone resorption, which is heavily upregulated in multiple myeloma.

Correct Answer: C

The 'winking owl' sign on an AP radiograph of the spine is caused by the absence or destruction of a pedicle. This is highly characteristic of tumor involvement (often metastatic) destroying the cortical bone of the pedicle. Infections and inflammatory processes typically involve the disc space and endplates rather than isolated pedicle destruction.

Correct Answer: A

The clinical, radiographic, and histologic findings (small round blue cells) are diagnostic of Ewing's sarcoma. Ewing's sarcoma is characterized by the t(11;22) chromosomal translocation, which results in the EWS-FLI1 fusion protein. t(X;18) is seen in synovial sarcoma, t(12;16) in myxoid liposarcoma, and t(2;13) in alveolar rhabdomyosarcoma.

Correct Answer: B

The patient has isolated infraspinatus atrophy and weakness in external rotation, which indicates compression of the suprascapular nerve after it has innervated the supraspinatus. This occurs at the spinoglenoid notch. Compression at the suprascapular notch would affect both the supraspinatus and infraspinatus muscles. The MRI shows a paralabral ganglion cyst, which is commonly associated with labral tears.

Correct Answer: C

The histologic description of 'Chinese character' spicules of woven bone lacking osteoblastic rimming, set within a bland fibrous background, is the classic hallmark of fibrous dysplasia. While the radiographic appearance can sometimes mimic other lesions, the histology is diagnostic. In asymptomatic patients without impending fracture, observation is appropriate.

Correct Answer: B

The diagnosis is osteosarcoma. The defining histologic feature of osteosarcoma is the direct production of osteoid (immature, unmineralized bone matrix) by malignant mesenchymal cells. The radiograph shows an aggressive, bone-forming lesion in the proximal humerus, typical of osteosarcoma in a pediatric patient.

Correct Answer: C

The images demonstrate a both-column acetabular fracture. The defining feature of a both-column fracture in the Judet-Letournel classification is that all articular fragments are detached from the intact axial skeleton (the intact portion of the ilium attached to the sacrum). The 'spur sign' is often seen on the obturator oblique view, representing the intact portion of the ilium.

Correct Answer: B

The patient has Kienböck's disease (avascular necrosis of the lunate). This condition is classically associated with ulnar negative variance, which is thought to increase the shear and compressive forces transmitted across the radiolunate joint, predisposing the lunate to microtrauma and subsequent avascular necrosis.

Correct Answer: B

The clinical presentation (night pain relieved by NSAIDs), radiographic appearance (cortically based lucent nidus with surrounding sclerosis), and histology (vascular stroma with plump osteoblasts and woven bone) are diagnostic of an osteoid osteoma. Percutaneous radiofrequency ablation (RFA), typically performed under CT guidance, has become the preferred and highly successful minimally invasive treatment for most osteoid osteomas.

Correct Answer: B

In a young individual with a chronic dislocation of the elbow and heterotopic bone formation, the treatment of choice is open reduction, heterotopic bone excision, anterior and posterior capsular releases, and a dynamic hinged fixator to begin protected early postoperative range of motion. It is important to understand that the fixator protects the reconstruction and allows early range of motion, but it does not maintain the reduction and should not be expected to do so. Pin fixation across the elbow delays early motion and is not recommended.

Correct Answer: B

Patients with one- or two-level anterior cervical diskectomies and fusions that have healed fully can return to play. Any loss of motion, persistent neurologic deficit, or significant adjacent segment degeneration may preclude a player from returning. The presence of hardware or a solid fusion is expected and does not contraindicate return to play.

Correct Answer: B

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. Postoperative treatment with bisphosphonates and radiation therapy is indicated to decrease the risk of future pathologic fractures. The lesion does not appear to be a sarcoma requiring wide resection and endoprosthetic reconstruction.

Correct Answer: C

The figure shows the missing pedicle or 'winking owl' sign that is characteristic of tumor involvement of the cortical bone of the pedicle. None of the other pathologic processes commonly gives this radiographic picture. Thinned, but not missing pedicles, have been described as a normal variant.

Correct Answer: B

The dynamic forces acting to maintain the position of the proximal phalanx at the head of the metatarsal are a balance between the extensor digitorum longus and the weaker intrinsic muscles. With hyperextension at the metatarsophalangeal joint, the intrinsic muscles become less efficient as plantar flexors. In the interphalangeal joints, the stronger flexors overpower the weaker intrinsic muscles, which act as the extensors. This combination of events leads to hyperextension at the metatarsophalangeal joint and flexion deformities at the interphalangeal joints, resulting in claw toe.

Correct Answer: B

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, as demonstrated in the provided imaging studies.

Correct Answer: C

The image shows a view of the radiocapitellar joint from an anterior medial portal. The radial nerve lies on the elbow capsule at the midportion of the capitellum. It is at risk for injury when capsular excision is performed in this region.

Correct Answer: B

Compression of the suprascapular nerve by a ganglion cyst is a well-documented cause of pain and weakness in the shoulder. Isolated involvement of the infraspinatus indicates that the area of entrapment is at the spinoglenoid notch and not the suprascapular notch. Entrapment at the suprascapular notch would affect both the supraspinatus and infraspinatus muscles.

Correct Answer: B

Displaced fractures of the scaphoid are best treated with compression screw fixation. Proximal third (proximal pole) fractures, as seen in this patient, are optimally approached via a dorsal approach to ensure proper reduction and compression. Fractures of the scaphoid waist can be approached either by a volar or a dorsal approach.

Correct Answer: B

The imaging studies demonstrate fibrous dysplasia. Although the classic radiographic appearance of fibrous dysplasia is one of a central metaphyseal lesion with ground glass matrix, it is not unusual to see either a more radiodense-appearing lesion or a more peripheral location. The histologic finding of spicules of woven bone without osteoblastic rimming in a bland fibrous background is diagnostic of fibrous dysplasia.

Correct Answer: C

In a young individual with a chronic dislocation of the elbow and heterotopic bone formation, the treatment of choice is open reduction, heterotopic bone excision, anterior and posterior capsular releases, and a dynamic hinged fixator to begin protected early postoperative range of motion. It is important to understand that the fixator protects the reconstruction and allows early range of motion, but it does not maintain the reduction and should not be expected to do so. Pin fixation across the elbow delays early motion and is not recommended.

Correct Answer: B

Patients with one- or two-level anterior cervical diskectomies and fusions that have healed fully can return to play. Any loss of motion, persistent neurologic deficit, or significant adjacent segment degeneration may preclude a player from returning. The presence of instrumentation or a solid fusion are not contraindications to return to play.

Correct Answer: B

Because the patient has a large lucent lesion in the peritrochanteric region of the left proximal femur, the risk of pathologic fracture is high, and prophylactic internal fixation with a locked intramedullary rod is indicated. Postoperative treatment with bisphosphonates and radiation therapy is indicated to decrease the risk of future pathologic fractures. Neither chemotherapy nor radiation therapy alone is likely to result in long-term stabilization of the proximal femur.

Correct Answer: D

The figure shows the missing pedicle or 'winking owl' sign that is characteristic of tumor involvement of the cortical bone of the pedicle. None of the other pathologic processes commonly gives this radiographic picture. Thinned, but not missing pedicles, have been described as a normal variant.

Correct Answer: A

The imaging studies and histology showing small round blue cells are typical of Ewing's sarcoma. Ewing's sarcoma has been noted to have a consistent genetic translocation t(11;22). Other translocations include t(X;18) for synovial sarcoma and t(12;16) for myxoid liposarcoma.

Correct Answer: B

The imaging studies are consistent with fibrous dysplasia. The classic histologic finding of fibrous dysplasia is spicules of woven bone without osteoblastic rimming in a bland fibrous background (often described as 'Chinese characters'). Small round blue cells are seen in Ewing's sarcoma, malignant cells with osteoid in osteosarcoma, blood-filled spaces in aneurysmal bone cysts, and a central nidus with plump osteoblasts in osteoid osteoma.

Correct Answer: C

The patient has osteosarcoma. The radiograph suggests an aggressive primary tumor of bone, and the histology shows malignant cells surrounded by osteoid, which is classic for osteosarcoma. Ewing's sarcoma histologically consists of small round blue cells. Osteochondroma and periosteal chondroma have a different histologic pattern and a less aggressive radiographic appearance.

Correct Answer: C

The defining feature of a both-column acetabular fracture pattern is that all articular fragments are on fracture fragments and no joint surface is left intact to the axial skeleton above. While extension into the sacroiliac joint or comminution may be present, the complete detachment of the articular surface from the intact ilium is the hallmark of a both-column fracture.

Correct Answer: B

The patient has Kienbock's disease (osteonecrosis of the lunate), which presents with boggy synovitis of the wrist, decreased range of motion, and increased density in the lunate body on radiographs. This disease process is classically associated with an ulnar-negative variant, which is thought to increase shear forces across the lunate.

Correct Answer: C

Based on the radiographic findings, the patient has melorheostosis, a rare, benign connective tissue disorder that is characterized by a cortical thickening of bone. It produces a 'dripping candle wax' appearance with dense hyperostosis that flows along the cortex. 'Smoke up a chimney' is associated with bone infarcts, 'sunburst' with osteosarcoma, and 'onion skin' with Ewing's sarcoma.

The area under the stress-strain curve in the elastic region represents the modulus of resilience, which is the energy absorbed by a material before yielding. The total area under the entire curve (elastic and plastic regions) represents the material's toughness.

In a pink, pulseless hand after adequate reduction of a supracondylar humerus fracture, observation is indicated because collateral circulation is sufficient. Vascular exploration is only required if the hand remains white and pulseless after fracture reduction.

T1 hypointensity on MRI indicates permanent cystic myelomalacia and cord atrophy, representing a poor prognosis for neurologic recovery after decompression. T2 hyperintensity alone indicates edema and has a variable prognosis.

The intact posterior sacroiliac ligamentous complex is the most vital structure for maintaining vertical stability of the pelvic ring. Disruption of these ligaments results in vertical shear instability.

BTB autografts are associated with a higher incidence of donor site morbidity, specifically anterior knee pain and difficulty kneeling, compared to hamstring autografts. Rates of graft rupture and osteoarthritis are broadly similar between the two.

A favorable histologic response to neoadjuvant chemotherapy in osteosarcoma is defined as greater than 90% tumor necrosis (Huvos Grade III or IV) at the time of surgical resection. This is strongly correlated with improved overall survival.

The most significant risk factor for AVN in slipped capital femoral epiphysis is an unstable slip, defined clinically by the patient's inability to bear weight. While timing of surgery and decompression are debated, instability remains the strongest predictor.

Varus collapse in bicondylar tibial plateau fractures is frequently caused by a failure to recognize, anatomically reduce, and adequately buttress the posteromedial coronal shear fragment. This fragment is critical for restoring the medial column stability.

Ceramic-on-ceramic bearings offer excellent wear characteristics but are uniquely associated with "squeaking" (an audible noise) in a small percentage of patients. This is often related to edge loading, micro-separation, or resonance within the hardware components.

The proximal pole of the scaphoid relies almost entirely on retrograde intraosseous blood flow from the dorsal carpal branch of the radial artery. Fractures in this region disrupt this blood supply, resulting in high rates of avascular necrosis and nonunion.

This patient presents with classic signs of cervical spondylotic myelopathy and MRI evidence of spinal cord injury (myelomalacia). Surgical decompression, such as an ACDF, is indicated to prevent further irreversible neurologic deterioration.

Intramedullary nailing is a load-sharing device that provides relative stability to the fracture site. This mechanical environment promotes secondary bone healing characterized by endochondral ossification and callus formation.

Anterior knee pain, especially with kneeling, is the most common complication following BTB autograft harvest for ACL reconstruction. It arises directly from morbidity at the patellar tendon donor site and altered patellofemoral mechanics.

The Lisfranc ligament connects the medial cuneiform to the base of the second metatarsal, stabilizing the tarsometatarsal joint complex. Rupture of this critical ligament leads to midfoot instability, radiographically evident as widening of the 1st-2nd intermetatarsal space.

The gold standard treatment for high-grade conventional osteosarcoma involves neoadjuvant chemotherapy to shrink the primary tumor and treat micrometastases, followed by wide surgical resection (limb salvage if feasible) and adjuvant chemotherapy.

Necrotizing fasciitis is a life-threatening surgical emergency. While broad-spectrum antibiotics are necessary, immediate radical surgical debridement of all necrotic tissue is the absolute most critical intervention to improve survival.