Arab Orthopaedic Board MCQs - Part 4

During a total knee arthroplasty, after making the bone cuts and inserting trial components, the knee is found to be symmetrically tight in both full extension and 90 degrees of flexion. Which of the following is the most appropriate next step in management?

A 6-week-old female infant is being treated with a Pavlik harness for developmental dysplasia of the hip (DDH). At her 2-week follow-up, the mother notes that the infant has stopped kicking her right leg. Examination reveals decreased active knee extension, but active hip flexion is maintained. What is the most appropriate next step in management?

A 22-year-old collegiate rugby player presents with recurrent anterior shoulder instability. A 3D CT scan of the shoulder demonstrates 28% anterior glenoid bone loss and an engaging Hill-Sachs lesion. Which of the following surgical interventions is most appropriate to prevent recurrent dislocation?

A 14-year-old boy presents with progressive knee pain. Radiographs demonstrate a permeative diaphyseal lesion in the femur with a laminated 'onion-skin' periosteal reaction. Histology reveals sheets of small round blue cells. Which of the following chromosomal translocations is most characteristic of this tumor?

A 55-year-old Asian male presents with progressive hand clumsiness and broad-based gait. Cervical spine CT demonstrates continuous ossification of the posterior longitudinal ligament (OPLL) from C3 to C6. The K-line, drawn from the mid-point of the spinal canal at C2 to C7 on a sagittal MR image, demonstrates that the OPLL mass lies posterior to the line (a 'K-line negative' cervical spine). Which surgical approach is most highly recommended?

When utilizing the Ponseti method for the correction of idiopathic clubfoot, which of the following represents the correct sequence of deformity correction?

A 28-year-old male sustains a closed, isolated mid-shaft humerus fracture after a fall. In the emergency department, he is noted to have a dense radial nerve palsy that was present immediately following the injury. Radiographs show a displaced Holstein-Lewis type fracture. What is the most appropriate initial management of the radial nerve palsy?

A 60-year-old patient with long-standing poorly controlled diabetes presents with a unilaterally red, hot, and swollen foot. There is no history of trauma or skin ulceration. Radiographs reveal extensive periarticular debris, bony fragmentation, and joint subluxation at the midfoot. According to the Eichenholtz classification, what stage of Charcot arthropathy does this represent?

Recombinant human bone morphogenetic protein-2 (rhBMP-2) signals primarily through serine/threonine kinase receptors. Which of the following intracellular signaling molecules is directly phosphorylated following rhBMP-2 receptor activation to initiate osteoblastic gene transcription?

A 45-year-old active male underwent a total hip arthroplasty using a ceramic-on-ceramic bearing surface. Two years postoperatively, he complains of an audible squeaking sound during hip flexion. Radiographic evaluation shows normal implant fixation. Which of the following component positions is most strongly associated with the development of squeaking in this bearing type?

Which of the following locations of a scaphoid fracture is associated with the highest rate of avascular necrosis and non-union, and what is the anatomic basis for this?

A 25-year-old athlete undergoes a physical examination after a knee injury. The 'dial test' reveals 15 degrees of increased external rotation of the tibia compared to the contralateral side when the knee is flexed to 30 degrees. However, when the knee is flexed to 90 degrees, the external rotation is symmetric bilaterally. This examination pattern indicates an isolated injury to which of the following structures?

A 35-year-old male is brought to the trauma bay following a high-speed motorcycle collision. Pelvic radiographs reveal symphyseal diastasis of 3.5 cm and widening of both the anterior and posterior aspects of the sacroiliac joint. Based on the Young-Burgess classification, what injury pattern is present and what is the primary source of life-threatening hemorrhage typically associated with this specific pattern?

A 68-year-old male presents with bilateral lower extremity pain and cramping that worsens with walking and improves when he pushes a shopping cart. He undergoes stationary bicycle testing. Which of the following findings would most specifically differentiate neurogenic claudication from vascular claudication during this test?

In the flexor tendon anatomy of the hand, the flexor digitorum superficialis (FDS) tendon splits to allow the flexor digitorum profundus (FDP) tendon to pass through. This anatomic structural decussation is known as Camper's chiasm. In which flexor tendon zone is Camper's chiasm located?

Denosumab is often utilized in the medical management of surgically unsalvageable or recurrent Giant Cell Tumors of Bone (GCTB). What is the specific mechanism of action of this medication?

Articular cartilage is a highly specialized tissue structured into four distinct zones. Which of the following best describes the orientation of Type II collagen fibers and the morphology of chondrocytes in the deep (radial) zone of articular cartilage?

A 13-year-old obese male presents with a 4-week history of right groin and thigh pain. Physical examination reveals obligatory external rotation of the right hip upon passive hip flexion. Radiographs confirm a stable Slipped Capital Femoral Epiphysis (SCFE). If single-screw in situ fixation is planned, what is the ideal position of the screw within the epiphysis to minimize complications?

A 24-year-old football player sustains an axial load injury to a plantarflexed foot. Weight-bearing AP radiographs demonstrate a small bony avulsion fragment in the first intermetatarsal space (the 'fleck sign'). This radiographic finding represents an avulsion of the Lisfranc ligament. What are the correct anatomic attachments of the intact Lisfranc ligament?

A 35-year-old healthy female sustains a displaced femoral neck fracture with a highly vertical fracture line (Pauwels Type III) after a high-energy fall. In selecting the optimal internal fixation construct for this specific fracture pattern to minimize the risk of varus collapse and non-union, biomechanical studies favor which of the following?

A 62-year-old man with cervical myelopathy secondary to ossification of the posterior longitudinal ligament (OPLL) from C3-C6 is planned for surgery. Lateral radiographs demonstrate a C2-C7 lordosis of 5 degrees, and the OPLL mass exceeds the K-line (K-line negative). Which surgical option is strictly contraindicated?

A 15-year-old boy presents with a destructive diaphyseal lesion of the femur with a large soft tissue mass. Biopsy shows uniform small round blue cells. Cytogenetic analysis reveals a t(11;22)(q24;q12) translocation. Which of the following fusion genes is responsible for the pathogenesis of this tumor?

A 58-year-old woman presents with groin pain and a palpable mass 4 years after a metal-on-metal total hip arthroplasty. Serum cobalt and chromium levels are significantly elevated. A Metal Artifact Reduction Sequence (MARS) MRI shows a large cystic periarticular collection. Histologic analysis of the tissue during revision surgery would most likely demonstrate:

A 35-year-old manual laborer presents with progressive wrist pain. Radiographs reveal a scaphoid nonunion with radioscaphoid arthritis and capitolunate arthritis. The radiolunate joint is spared. This corresponds to Scaphoid Nonunion Advanced Collapse (SNAC) Stage III. Which of the following is the most appropriate surgical treatment?

A 55-year-old diabetic male presents with a swollen, erythematous, and warm right foot without open ulcers. Radiographs show fragmentation, debris, and subluxation of the tarsometatarsal joints. According to the modified Eichenholtz classification, what is the current stage and the most appropriate initial management?

A 24-year-old football player sustains a knee dislocation (Schenck KD-III) after a high-velocity tackle. On examination, the foot is cool with diminished dorsalis pedis and posterior tibial pulses. His Ankle-Brachial Index (ABI) is 0.7. What is the most appropriate next step in management after emergent closed reduction of the knee?

A 13-year-old obese boy presents with left hip pain and an obligatory external rotation of the thigh during hip flexion. He is diagnosed with a stable slipped capital femoral epiphysis (SCFE). Which of the following is a recognized strong absolute or relative indication for prophylactic pinning of the asymptomatic contralateral hip?

A 42-year-old male sustains a severe closed bicondylar tibial plateau fracture (Schatzker VI). Initial management includes a spanning external fixator. During definitive fixation 10 days later via dual incisions, which surgical principle must be strictly adhered to minimize the risk of wound complications?

According to the 2018 International Consensus Meeting (ICM) criteria for Periprosthetic Joint Infection (PJI), which of the following findings alone represents a major criterion confirming the diagnosis of PJI in a total knee arthroplasty?

A 45-year-old man presents with a painful shoulder. Imaging reveals a large cartilaginous tumor in the proximal humerus with endosteal scalloping and soft tissue extension. Biopsy confirms a Grade II chondrosarcoma. Molecular testing is most likely to reveal a mutation in which of the following genes?

A 68-year-old female presents with chronic severe right shoulder pain and an inability to actively elevate her arm past 40 degrees (pseudoparalysis). Radiographs demonstrate superior migration of the humeral head with an acromiohumeral interval of 3 mm and severe glenohumeral osteoarthritis (Hamada Grade 4). What is the most appropriate surgical treatment?

A 40-year-old male undergoes electromyography (EMG) for suspected cubital tunnel syndrome. The nerve conduction study demonstrates a drop in the amplitude of the compound muscle action potential (CMAP) when stimulating the ulnar nerve at the elbow while recording from the abductor digiti minimi (ADM). However, the CMAP recorded from the first dorsal interosseous (FDI) is normal. This discrepancy is most likely explained by which anatomic variant?

A 65-year-old female presents with neurogenic claudication and L4-L5 degenerative spondylolisthesis. She is scheduled for surgery. According to the SPORT trial data, comparing surgical versus non-operative treatment for degenerative spondylolisthesis, which of the following statements is true regarding long-term (4-year) outcomes?

A 30-year-old male is brought to the trauma bay after a motorcycle crash. His blood pressure is 70/40 mmHg, HR 135 bpm. FAST exam is negative. Pelvic radiograph shows an AP Compression Type III (APC-III) pelvic ring injury. A pelvic binder is applied, but the patient remains hemodynamically unstable despite massive transfusion protocol initiation. What is the most appropriate next step in management?

Bone morphogenetic proteins (BMPs) play a crucial role in osteoinduction during fracture healing. Following the binding of BMPs to their serine/threonine kinase cell surface receptors, which family of intracellular signaling molecules is directly phosphorylated to translocate to the nucleus and regulate gene transcription?

A 50-year-old overweight woman complains of medial foot pain and an inability to perform a single-leg heel rise. Examination shows a flexible flatfoot with forefoot abduction. Radiographs reveal unroofing of the talonavicular joint without arthritic changes. Which of the following surgical procedures is most commonly indicated for this Stage IIB adult-acquired flatfoot deformity?

A 6-month-old female with developmental dysplasia of the hip (DDH) has failed 6 weeks of treatment in a Pavlik harness, with the left hip remaining persistently dislocated on ultrasound. What is the most appropriate next step in management?

A 28-year-old carpenter sustains a volar laceration to his index finger over the proximal phalanx, transecting both the FDS and FDP tendons (Zone II). He undergoes a primary 4-strand core suture repair with epitendinous running suture. Which of the following rehabilitation protocols has been shown to maximize tendon excursion while minimizing the risk of rupture and adhesions in the early postoperative period?

In posterior-stabilized (PS) total knee arthroplasty, the cam-and-post mechanism is designed to substitute for the resected posterior cruciate ligament (PCL). Which of the following best describes the intended kinematic effect of cam-post engagement during deep flexion?

A 32-year-old female presents with a large, lytic, eccentrically located epiphyseal lesion in her distal femur. Biopsy reveals multinucleated giant cells in a background of mononuclear stromal cells. She is prescribed denosumab prior to surgical intervention to downstage the tumor. What is the precise mechanism of action of denosumab in treating this tumor?

A 2-year-old child presents with anterolateral bowing of the tibia and a pseudoarthrosis is identified on radiographs. Which of the following gene mutations is most strongly associated with this condition?

A 30-year-old male is brought to the trauma bay in hemorrhagic shock following a motorcycle collision. Radiographs demonstrate an anteroposterior compression (APC) type III pelvic ring injury. A circumferential pelvic binder is applied. To achieve the most effective reduction and mechanical stabilization, over which anatomic structure should the binder be centered?

A 45-year-old manual laborer presents with chronic wrist pain. Radiographs reveal a scaphoid nonunion with arthritic changes present in the radioscaphoid and capitolunate joints. The radiolunate joint is completely spared. Which of the following is the most appropriate motion-preserving surgical intervention?

A 25-year-old athlete sustains a multiligamentous knee injury (KD-III) following a high-energy tackling injury. The knee is reduced in the emergency department. The patient has palpable dorsalis pedis and posterior tibial pulses. The ankle-brachial index (ABI) is measured at 0.85. What is the most appropriate next step in management?

A 55-year-old female with a metal-on-metal total hip arthroplasty presents with groin pain and swelling. A MARS MRI demonstrates a cystic soft tissue mass around the hip. A revision is performed, and histologic examination of the tissue reveals aseptic lymphocyte-dominated vasculitis-associated lesions (ALVAL). This histological finding is primarily characterized by:

A 35-year-old unrestrained driver is involved in a high-speed motor vehicle collision. Cervical spine imaging reveals a Levine-Edwards Type IIA traumatic spondylolisthesis of the axis (Hangman's fracture). The fracture shows severe angulation with minimal translation. Which of the following treatments is absolutely contraindicated in the management of this specific fracture pattern?

A 55-year-old male with long-standing poorly controlled diabetes presents with a swollen, erythematous, and warm left foot. He denies trauma. Radiographs of the foot show osteopenia and soft tissue swelling but no evidence of fracture, subluxation, or debris. MRI demonstrates bone marrow edema in the midfoot. What is the Eichenholtz stage of this patient's Charcot arthropathy?

A 14-year-old boy presents with progressive thigh pain. Radiographs reveal a destructive diaphyseal lesion in the femur with a 'lamellated' or 'onion-skin' periosteal reaction. Biopsy shows uniform small round blue cells. The most likely genetic translocation associated with this tumor results in a fusion gene that acts as an aberrant transcription factor. Which translocation is diagnostic?

In the study of orthopaedic biomechanics, viscoelastic materials such as ligaments and tendons display time-dependent behaviors. When a ligament is subjected to a constant, sustained load over a period of time, it will undergo progressive elongation. This phenomenon is known as:

A 13-year-old obese male underwent in situ single-screw fixation for a stable slipped capital femoral epiphysis (SCFE). Six months postoperatively, he complains of severe hip stiffness and pain. Examination reveals a rigid hip with severe loss of motion in all planes. Radiographs show a concentric joint space narrowing of the affected hip to less than 3 mm. What is the most likely diagnosis?

A 28-year-old man sustains a Pauwels type III fracture of the femoral neck. Based on the biomechanics of this fracture pattern, which of the following describes the primary deforming force acting at the fracture site?

A 32-year-old mechanic presents with an infected index finger after a puncture wound. You suspect pyogenic flexor tenosynovitis. Which of the following is NOT one of Kanavel's four cardinal signs of flexor tenosynovitis?

A 22-year-old rugby player undergoes surgical stabilization for recurrent anterior shoulder instability. Intraoperatively, he is noted to have an off-track, engaging Hill-Sachs lesion with subcritical glenoid bone loss. The surgeon decides to perform an arthroscopic Bankart repair with a remplissage. Which structure(s) is/are tenodesed into the humeral head defect during a remplissage?

In the design of a posterior-stabilized (PS) total knee arthroplasty (TKA), the tibial polyethylene insert features a central post that interacts with a cam on the femoral component. What is the primary biomechanical purpose of the cam-and-post mechanism during deep knee flexion?

During the neurological examination of a 60-year-old patient with suspected cervical spondylotic myelopathy, the examiner supports the patient's hand and forcefully flicks the distal phalanx of the middle finger into flexion. The patient exhibits a sudden reflexive flexion of the thumb and index finger. What is the name of this clinical sign?

The Lisfranc joint complex is crucial for midfoot stability. The Lisfranc ligament itself is the strongest stabilizing structure in this region. Between which two osseous structures does the primary intra-articular component of the Lisfranc ligament course?

A 35-year-old woman is diagnosed with an aggressive giant cell tumor (GCT) of the distal radius. Due to the size and proximity to the joint, she is treated with neoadjuvant denosumab prior to surgical curettage. What is the specific mechanism of action of denosumab in the treatment of GCT of bone?

Articular cartilage is composed of multiple zones, each with unique ultrastructural properties that provide mechanical resilience. Which zone is characterized by having the largest diameter collagen fibrils oriented perpendicular to the articular surface, as well as the highest concentration of proteoglycans?

A 6-week-old female infant is being treated for developmental dysplasia of the hip (DDH) with a Pavlik harness. At a follow-up visit, the mother notes the baby is no longer kicking her right leg. On examination, the infant exhibits absent active knee extension on the right side. Which nerve is most likely compressed due to improper positioning in the harness?

A 25-year-old male sustains a closed tibial shaft fracture. Twelve hours later, he complains of severe, unrelenting leg pain exacerbated by passive stretch of his toes. Compartment syndrome is suspected, and pressures are measured using a slit catheter. Which of the following pressure criteria (delta pressure) is universally considered the threshold indicating an absolute need for emergency fasciotomy?

In the pathogenesis of acute Charcot neuroarthropathy, pro-inflammatory cytokines play a critical role in increasing the expression of which of the following, leading to amplified osteoclastogenesis?

A 40-year-old male sustains a traumatic spondylolisthesis of the axis (Hangman's fracture) following a motor vehicle collision. Radiographs show severe angulation with minimal translation. Flexion imaging demonstrates an increase in angulation, while extension reduces it. According to the Levine and Edwards classification, what is the most appropriate management?

Which of the following factors is the most critical determinant of the initial tensile strength of a flexor tendon repair in Zone II?

Denosumab is highly effective in the management of unresectable Giant Cell Tumor (GCT) of bone. What is the specific cellular target of this monoclonal antibody?

In a patient presenting with a unilateral slipped capital femoral epiphysis (SCFE), which of the following is considered the strongest indication for prophylactic in situ pinning of the contralateral asymptomatic hip?

When comparing a 10-mm Bone-Patellar Tendon-Bone (BTB) autograft to a quadrupled hamstring autograft for Anterior Cruciate Ligament (ACL) reconstruction, which of the following statements regarding initial graft biomechanics is true?

A 35-year-old male sustains a closed pelvic ring injury. Examination reveals a large, fluctuant swelling over the greater trochanteric region with overlying skin bruising. Aspiration yields serosanguinous fluid. What is the precise anatomic location of this fluid collection in a Morel-Lavallee lesion?

Which of the following bone graft substitutes possesses osteoinductive properties but lacks both osteogenic and osteoconductive properties when used alone in its standard powder form?

A 55-year-old female presents with an audible 'squeaking' sound coming from her hip 3 years after a Total Hip Arthroplasty. Radiographs show a well-fixed, ceramic-on-ceramic bearing surface. Which of the following component position factors is most strongly associated with the development of this phenomenon?

During the extended deltopectoral approach for open reduction and internal fixation of a proximal humerus fracture, the axillary nerve must be protected during plate placement. What is the typical average distance of the axillary nerve from the tip of the greater tuberosity?

A 32-year-old male manual laborer presents with chronic dorsal wrist pain. Radiographs demonstrate sclerosis and severe fragmentation of the lunate, with proximal migration of the capitate and a radioscaphoid angle of 65 degrees. He is noted to have ulnar minus variance. Which Lichtman stage of Kienbock's disease does this represent?

Which of the following factors is the strongest independent predictor of non-union in the conservative management of a Type II odontoid fracture?

In the Ponseti method for the treatment of idiopathic clubfoot, sequential correction of the deformity components must be strictly followed to avoid creating a 'rocker-bottom' deformity. What is the correct sequence of deformity correction?

A 40-year-old male undergoes a percutaneous repair of an acute Achilles tendon rupture. Post-operatively, he complains of numbness over the lateral aspect of his heel and foot. Which nerve was most likely injured, and what is its anatomic relationship to the Achilles tendon at the level of the repair?

A 14-year-old boy presents with a permeative lytic lesion in the diaphysis of the femur with an associated 'onion-skin' periosteal reaction. A biopsy confirms Ewing sarcoma. Which of the following cytogenetic abnormalities is most characteristic of this diagnosis?

During a posterior-stabilized Total Knee Arthroplasty, trial reduction reveals that the knee is well-balanced in full extension but is excessively tight in 90 degrees of flexion. Which of the following is the most appropriate intraoperative option to exclusively address this imbalance?

A 19-year-old female collegiate swimmer presents with bilateral shoulder pain and a sensation of 'slipping' during her freestyle stroke. Examination reveals a positive sulcus sign bilaterally, positive apprehension and relocation tests, and generalized ligamentous laxity. What is the primary focus of the initial non-operative rehabilitation program?

Articular cartilage is divided into distinct zones, each with a unique structure and function. Which structure delineates the boundary between the deep (radial) zone and the calcified cartilage zone, and plays a biomechanical role in resisting shear stresses?

A 30-year-old male presents with a complex intra-articular distal femur fracture. Axial CT imaging demonstrates an isolated coronal plane fracture of the lateral femoral condyle. What is the appropriate eponymous name for this specific fracture pattern?

A 4-month-old infant with Developmental Dysplasia of the Hip (DDH) has been treated with a Pavlik harness for 4 weeks. Ultrasound reveals a persistently dislocated left hip. What is the most appropriate next step in management?