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Arab Orthopaedic Board MCQs - Part 31

27 Apr 2026 123 min read 85 Views
Arab Ortho Board MCQs - Part 30

Key Takeaway

This topic focuses on Arab Orthopaedic Board MCQs - Part 31, Practice Arab Orthopaedic Board MCQs Part 31. Review orthopedic surgery questions 1501 to 1550 for your board exam preparation.

Arab Orthopaedic Board MCQs - Part 31

Comprehensive 100-Question Exam


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Question 1

A 35-year-old male sustains an APC-III pelvic ring injury. During the anterior surgical approach (ilioinguinal), massive hemorrhage occurs near the superior pubic ramus. Which vascular structures most likely represent the 'corona mortis' that was injured?





Explanation

The corona mortis ('crown of death') is an anatomical variant representing an anastomosis between the obturator vessels (internal iliac system) and the external iliac or inferior epigastric vessels. It crosses the superior pubic ramus and is highly susceptible to injury during anterior pelvic approaches (e.g., ilioinguinal or Stoppa approaches), which can result in life-threatening hemorrhage.

Question 2

What specific genetic mutation is strongly associated with the pathogenesis of multiple enchondromatosis (Ollier disease and Maffucci syndrome)?





Explanation

Somatic mosaic mutations in the isocitrate dehydrogenase (IDH1 and IDH2) genes are the primary drivers of Ollier disease and Maffucci syndrome. EXT1/EXT2 mutations are associated with Multiple Hereditary Exostoses. GNAS1 mutations are linked to fibrous dysplasia (McCune-Albright syndrome). RUNX2 is associated with cleidocranial dysplasia, and COL1A1 with osteogenesis imperfecta.

Question 3

In comparing bone-patellar tendon-bone (BTB) autograft to hamstring autograft for primary Anterior Cruciate Ligament (ACL) reconstruction, which of the following is a statistically higher risk specifically associated with the BTB graft?





Explanation

Bone-patellar tendon-bone (BTB) autografts are historically known for excellent bony incorporation and stability but carry a well-documented, statistically significant higher risk of harvest-site morbidity, specifically anterior knee pain and discomfort while kneeling, compared to hamstring autografts.

Question 4

A 6-week-old female is treated with a Pavlik harness for developmental dysplasia of the hip (DDH). At the 2-week follow-up, the mother notes the child is not kicking the left leg. Examination reveals absent active knee extension on the left. The hips are positioned in 120 degrees of flexion. What is the most likely cause of this finding?





Explanation

Femoral nerve palsy is a known complication of the Pavlik harness, typically caused by hyperflexion of the hips (usually >100-110 degrees), which compresses the femoral nerve against the inguinal ligament. The treatment is temporary harness removal or adjustment to reduce flexion, with recovery usually occurring within a few days to weeks.

Question 5

During a neurologic exam of a 65-year-old male with neck pain and clumsy hands, the examiner aggressively flicks the distal phalanx of the middle finger, resulting in involuntary flexion of the interphalangeal joint of the thumb and index finger. This clinical sign indicates compression of which neurological structure or tract?





Explanation

The maneuver described is Hoffman's sign, which is an upper motor neuron (UMN) sign indicating cervical spinal cord compression (cervical myelopathy). The corticospinal tract is the descending motor pathway; its compression leads to hyperreflexia and pathologic reflexes like Hoffman's and Babinski signs.

Question 6

Which of the following is the most unique potential complication associated with ceramic-on-ceramic total hip arthroplasty bearing surfaces compared to highly cross-linked polyethylene bearing surfaces?





Explanation

Squeaking is a unique, specific complication of ceramic-on-ceramic (CoC) bearing surfaces, occurring in up to 10% of patients. It is often related to component malposition (e.g., edge loading), stripe wear, or micro-separation. Osteolysis is more common with conventional polyethylene, and ALVAL/trunnionosis is typically associated with metal-on-metal or modular metallic junctions.

Question 7

The primary blood supply to the proximal pole of the scaphoid enters the bone at which specific anatomical location?





Explanation

The major blood supply to the scaphoid is derived from the dorsal carpal branch of the radial artery, which enters the scaphoid at the dorsal ridge (distal to the waist) and flows in a retrograde fashion (distal to proximal). This retrograde blood supply explains why proximal pole fractures have a high rate of avascular necrosis and nonunion.

Question 8

A 45-year-old female presents with painful hallux valgus. Weight-bearing radiographs reveal a Hallux Valgus Angle (HVA) of 38 degrees and an Intermetatarsal Angle (IMA) of 16 degrees. The first tarsometatarsal (TMT) joint shows no hypermobility and no signs of arthritis. Which of the following procedures is most appropriate?





Explanation

An IMA greater than 15 degrees signifies a severe deformity that generally cannot be fully corrected with a distal osteotomy alone (like a Chevron). A proximal osteotomy (crescentic, Ludloff, or Scarf) is indicated for larger IM angles. A Lapidus (TMT fusion) is typically indicated when there is concurrent first TMT hypermobility or osteoarthritis, which is absent in this patient.

Question 9

Which of the following fracture fixation constructs relies primarily on intramembranous ossification (primary bone healing) rather than endochondral ossification for fracture healing?





Explanation

Absolute stability constructs (lag screws, compression plates) eliminate interfragmentary motion, allowing for primary bone healing. Primary bone healing occurs via cutting cones and Haversian remodeling (intramembranous ossification) without intermediate cartilage or visible fracture callus. Intramedullary nails, casting, bridge plating, and external fixators permit relative stability, leading to secondary bone healing via endochondral ossification (callus formation).

Question 10

A 40-year-old male sustains a Schatzker IV tibial plateau fracture with a predominant posteromedial coronal split fragment. To adequately buttress this fragment, which surgical approach is most appropriate?





Explanation

A Schatzker IV fracture often involves a medial plateau fracture, frequently with a posteromedial shear fragment. Because screws/plates must be applied to the apex of the deformity to achieve an anti-glide (buttress) effect, a posteromedial approach is required to place a plate on the posterior aspect of the medial tibial condyle.

Question 11

A 65-year-old male presents with back pain and hypercalcemia. Radiographs show multiple 'punched-out' lytic lesions in the skull and vertebrae. Serum protein electrophoresis reveals an M-spike. Which of the following laboratory findings is most characteristic of this disease's specific effect on bone turnover?





Explanation

In multiple myeloma, malignant plasma cells secrete factors (like DKK1, MIP-1 alpha) that stimulate osteoclasts but heavily inhibit osteoblast differentiation and activity. Therefore, despite massive bone destruction (high N-telopeptide, high calcium), osteoblast-specific markers like alkaline phosphatase and osteocalcin remain surprisingly normal or low.

Question 12

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





Explanation

Prophylactic pinning of the contralateral hip in SCFE is controversial but is strongly indicated in patients with underlying endocrine disorders (hypothyroidism, growth hormone deficiency, renal osteodystrophy) or previous radiation therapy, as these patients have a much higher risk of bilateral disease (up to 100% in some endocrine subgroups) compared to idiopathic cases.

Question 13

Which of the following patient history or physical examination findings is most specific for neurogenic claudication (lumbar spinal stenosis) as opposed to vascular claudication?





Explanation

The 'shopping cart sign' is highly specific for neurogenic claudication. Leaning forward (flexion of the lumbar spine) increases the cross-sectional area of the spinal canal and neural foramina, relieving compression on the nerve roots. Vascular claudication is exacerbated by muscle exertion (like stationary biking) regardless of posture and is relieved quickly by simply resting (standing still).

Question 14

A laceration of the flexor digitorum profundus (FDP) and flexor digitorum superficialis (FDS) tendons in 'Zone II' is notoriously difficult to treat, historically termed 'no man's land'. What specific anatomical landmarks define the proximal and distal boundaries of flexor tendon Zone II?





Explanation

Zone II of the flexor tendon system begins proximally at the level of the A1 pulley (distal palmar crease) and ends distally at the insertion of the FDS tendon on the middle phalanx. Both FDS and FDP tendons are tightly constrained within the fibro-osseous sheath here, making repairs highly prone to adhesion formation.

Question 15

During the trial phase of a total knee arthroplasty (TKA) using a gap balancing technique, the surgeon finds that the knee is excessively tight in flexion but perfectly balanced and stable in extension. Which of the following component or bony adjustments is the most appropriate next step?





Explanation

A knee that is tight in flexion but balanced in extension requires addressing the flexion gap without altering the extension gap. Options include decreasing the anteroposterior dimension of the femur (downsizing the femoral component), increasing the posterior tibial slope, or releasing the posterior cruciate ligament (if a CR knee is being used). Resecting more distal femur or releasing the posterior capsule would inappropriately loosen the extension gap.

Question 16

A 25-year-old male sustains a closed comminuted tibia fracture. Six hours later, he develops severe leg pain out of proportion to the apparent injury. Which of the following is considered the most sensitive and earliest clinical sign of acute compartment syndrome?





Explanation

Pain out of proportion and pain with passive stretch of the muscles within the affected compartment are the earliest and most sensitive clinical signs of acute compartment syndrome. Pulselessness, pallor, and paralysis are very late signs, at which point irreversible ischemic muscle and nerve damage has often already occurred.

Question 17

In the structural anatomy of normal articular hyaline cartilage, which zone contains the highest concentration of proteoglycans, the lowest water content, and chondrocytes that are arranged in vertical columns?





Explanation

The deep (radial) zone of articular cartilage is characterized by chondrocytes arranged in vertical columns perpendicular to the joint surface. It has the largest diameter collagen fibrils, the highest concentration of proteoglycans, and the lowest water content, providing high resistance to compressive forces.

Question 18

Recent high-level randomized controlled trials comparing operative and non-operative management of acute Achilles tendon ruptures, specifically when utilizing early functional rehabilitation protocols, demonstrate which of the following outcomes?





Explanation

Recent high-quality RCTs (e.g., Willits et al.) have shown that when early functional rehabilitation (early weight-bearing and ROM in a brace) is employed, the re-rupture rates between operative and non-operative management of acute Achilles ruptures are similar. However, operative management carries higher risks of surgical complications such as wound infections and nerve injuries.

Question 19

Which of the following biological or surgical factors provides the best prognosis for the successful healing of an isolated meniscal repair?





Explanation

Meniscal repair performed concurrently with ACL reconstruction has a higher healing rate than isolated meniscal repair. This is attributed to the intra-articular bleeding and marrow elements (containing stem cells and growth factors) released during the creation of the femoral and tibial tunnels, which biologically augment the meniscal healing environment.

Question 20

When treating an infant with an idiopathic congenital clubfoot (talipes equinovarus) utilizing the Ponseti method of serial casting, what is the correct sequence of deformity correction?





Explanation

The Ponseti method follows the CAVE sequence: Cavus is corrected first (by elevating the first ray to align the forefoot with the hindfoot), followed by Adduction, then Varus (which corrects simultaneously with adduction as the foot is abducted around the talar head). Equinus is corrected last, often requiring a percutaneous Achilles tenotomy (TAL).

Question 21

A 35-year-old male presents with chronic shoulder pain. Radiographs reveal a lytic lesion in the proximal humeral epiphysis. Biopsy demonstrates abundant clear cytoplasm, centrally located nuclei, and areas of conventional chondrosarcoma intimately associated with woven bone trabeculae. Immunohistochemistry is positive for S-100. Which of the following is the most likely diagnosis?





Explanation

Clear cell chondrosarcoma is a low-grade malignant cartilage tumor that typically occurs in the epiphysis of long bones (most commonly the proximal femur and humerus) in patients in their 3rd to 5th decades. It is distinguished from chondroblastoma, which also occurs in the epiphysis but usually in younger, skeletally immature patients, and has a different histologic profile (chicken-wire calcification, coffee-bean nuclei).

Question 22

In the treatment of open tibial shaft fractures, the use of recombinant human bone morphogenetic protein-2 (rhBMP-2) has been shown to decrease the need for secondary bone grafting. Which of the following intracellular signaling pathways is primarily activated by rhBMP-2?





Explanation

Bone morphogenetic proteins (BMPs), particularly BMP-2 and BMP-7, bind to cell surface serine/threonine kinase receptors. This receptor activation leads to the intracellular phosphorylation of Smad 1, 5, and 8, which then form a complex with Smad 4 and translocate into the nucleus to regulate transcription of osteogenic genes.

Question 23

A 12-year-old boy presents with a unilateral slipped capital femoral epiphysis (SCFE). Prophylactic pinning of the contralateral asymptomatic hip is most strongly indicated if the patient has a history of which of the following concomitant conditions?





Explanation

Patients with endocrine disorders, particularly hypothyroidism, panhypopituitarism, and renal osteodystrophy, have a significantly higher risk of developing bilateral SCFE. In these patients, prophylactic pinning of the contralateral hip is strongly recommended.

Question 24

A 65-year-old male presents with progressive clumsiness in his hands and broad-based gait instability. MRI confirms severe cervical spondylotic myelopathy. When classifying the severity of his myelopathy using the Nurick grading system, which of the following clinical factors is the primary determinant of his grade?





Explanation

The Nurick classification for cervical spondylotic myelopathy is based exclusively on the patient's gait dysfunction and ambulatory status (e.g., Grade 1: signs of cord involvement but normal gait; Grade 5: wheelchair-bound or bedridden).

Question 25

An 80-year-old female sustains a periprosthetic femur fracture around her cemented total hip arthroplasty stem after a fall. Radiographs demonstrate a fracture around the tip of the stem. The stem appears subsided and loose, but there is excellent diaphyseal bone stock remaining. According to the Vancouver classification, what is the most appropriate definitive management?





Explanation

This is a Vancouver B2 periprosthetic fracture (fracture around the stem, loose stem, good bone stock). The standard of care for a Vancouver B2 fracture is revision of the loose component to a long cementless stem that bypasses the fracture site by at least two cortical diameters.

Question 26

During a Zone II flexor tendon repair, a surgeon decides to place an epitendinous suture around the primary core suture repair. Which of the following is the primary biomechanical benefit of adding the epitendinous suture?





Explanation

The addition of a running epitendinous suture increases the tensile strength of the repair by 10% to 50%, improves resistance to gap formation, and decreases gliding resistance by smoothing out the bulky core suture knots.

Question 27

A 16-year-old high school female soccer player undergoes primary anterior cruciate ligament (ACL) reconstruction. Which of the following graft choices carries the highest risk of post-operative graft rupture in this specific demographic?





Explanation

Numerous studies and registries have demonstrated that the use of allograft tissue in young, highly active patients (typically < 25 years old) has a significantly higher failure rate (up to 3-4 times higher) compared to autograft tissue.

Question 28

A 55-year-old patient with poorly controlled type 2 diabetes presents with a red, hot, swollen right foot. Radiographs reveal fragmentation, periarticular debris, and subluxation of the tarsometatarsal joints. There are no open wounds or signs of systemic infection. According to the Eichenholtz classification, what is the best initial management for this stage of Charcot arthropathy?





Explanation

The patient is presenting with Eichenholtz Stage I (Developmental/Fragmentation stage) Charcot arthropathy. The gold standard for initial management is immobilization with a total contact cast (TCC) and strict non-weight bearing to halt the progression of deformity and allow progression to the coalescence stage.

Question 29

The biomechanical properties of articular cartilage are determined by its extracellular matrix components. Which of the following best describes the primary collagen type in articular cartilage and its primary mechanical function?





Explanation

Articular cartilage is composed primarily of Type II collagen (90-95% of the collagen content), which is responsible for the tissue's tensile strength and stiffness. Proteoglycans, primarily aggrecan, attract water and provide the tissue's resistance to compressive forces.

Question 30

A 30-year-old male is brought to the trauma bay after a motorcycle accident with an anteroposterior compression type III (APC-III) pelvic ring injury. He is hemodynamically unstable. In this type of injury, what is the most common anatomic source of massive venous hemorrhage?





Explanation

In pelvic ring injuries with posterior disruption (such as APC-III and vertical shear injuries), the presacral venous plexus and the prevesical venous plexus are the most common sources of major venous bleeding. Venous bleeding accounts for 80-90% of pelvic hemorrhage.

Question 31

A 2-week-old infant is undergoing serial casting for a severe idiopathic clubfoot using the Ponseti method. According to the principles of this technique, which component of the deformity is corrected last and typically requires a percutaneous tenotomy?





Explanation

The Ponseti method addresses clubfoot deformities in the order of the CAVE acronym: Cavus, Adductus, Varus, and finally Equinus. The cavus is corrected first by elevating the first ray (supinating the forefoot). Equinus is corrected last, and an Achilles tenotomy is required in approximately 80-90% of cases to achieve adequate dorsiflexion.

Question 32

A 45-year-old manual laborer presents with progressive wrist pain. Radiographs show lunate sclerosis and fragmentation, but normal carpal height. Ulnar variance is measured at minus 3 mm. According to the Lichtman classification, this is Stage IIIA Kienböck's disease. What is the most appropriate surgical treatment?





Explanation

In Lichtman Stage IIIA Kienböck's disease (lunate fragmentation without fixed carpal collapse), joint-leveling procedures are indicated if there is ulnar negative variance. A radial shortening osteotomy unloads the lunate and halts disease progression. Salvage procedures (PRC, 4-corner fusion) are reserved for Stage IIIB or IV.

Question 33

During a total knee arthroplasty using a measured resection and anterior referencing technique, the surgeon evaluates the gaps and finds that the extension gap is perfectly balanced, but the flexion gap is unacceptably tight. Which of the following adjustments is the best step to balance the knee?





Explanation

When using an anterior referencing system, decreasing the size of the femoral component (downsizing) will result in more posterior femoral condyle bone being resected. This opens up (increases) the flexion gap without affecting the extension gap, correcting the tight flexion gap.

Question 34

A 68-year-old male presents with bilateral leg and buttock pain that worsens with walking. You are attempting to distinguish between neurogenic claudication due to lumbar spinal stenosis and vascular claudication. Which of the following historical features is the hallmark of neurogenic claudication?





Explanation

Neurogenic claudication is highly posture-dependent. Lumbar flexion (e.g., sitting, leaning forward on a shopping cart, or walking uphill) increases the cross-sectional area of the spinal canal and neural foramina, providing pain relief. Vascular claudication is relieved by resting (standing still) regardless of posture, and is worsened by walking uphill due to increased metabolic demand.

Question 35

A 24-year-old female presents with a deep, slow-growing, painful mass in her popliteal fossa. Biopsy reveals a biphasic tumor with both epithelial and spindle cell components. Molecular testing is ordered. Which of the following chromosomal translocations is pathognomonic for this diagnosis?





Explanation

The clinical picture and biphasic histology describe a synovial sarcoma. The characteristic cytogenetic abnormality found in >90% of synovial sarcomas is the t(X;18)(p11;q11) translocation, which results in the SYT-SSX fusion gene.

Question 36

A 32-year-old male falls from a height and sustains a vertical fracture through the neck of the talus. Radiographs demonstrate that the talar body is subluxated from the subtalar joint, but remains anatomically aligned within the ankle mortise. According to the Hawkins classification, this fracture is categorized as:





Explanation

Hawkins Type II talar neck fractures involve a displaced fracture of the talar neck with subluxation or dislocation of the subtalar joint, while the tibiotalar (ankle) joint remains intact. Type III involves both subtalar and tibiotalar dislocation. Type IV involves subtalar, tibiotalar, and talonavicular dislocation.

Question 37

A 40-year-old female presents with a painful bunion. Weight-bearing radiographs show a Hallux Valgus Angle (HVA) of 38 degrees and an Intermetatarsal Angle (IMA) of 16 degrees. Clinical examination reveals gross hypermobility of the first tarsometatarsal (TMT) joint. Which of the following surgical procedures is most appropriate?





Explanation

The Lapidus procedure (arthrodesis of the first TMT joint) is the treatment of choice for moderate to severe hallux valgus (IMA > 13 degrees) complicated by hypermobility of the first TMT joint. It corrects the deformity at the apex of the instability.

Question 38

During fracture healing and normal bone development, osteogenesis occurs via two distinct pathways. Intramembranous ossification differs from endochondral ossification fundamentally by the absence of which of the following during the process?





Explanation

Intramembranous ossification (seen in flat bones like the clavicle, skull, and during distraction osteogenesis) involves the direct differentiation of mesenchymal cells into osteoblasts without a preceding cartilaginous anlage (template). Endochondral ossification (long bone fracture callus) requires a cartilage intermediate that is subsequently mineralized and replaced by bone.

Question 39

A 22-year-old soccer player sustains a knee injury and an MRI demonstrates a tear of the medial meniscus. When determining the indication for meniscal repair versus meniscectomy, healing potential relies heavily on vascularity. Which zone of the meniscus has the highest healing potential due to robust blood supply?





Explanation

The vascular supply to the menisci originates from the perimeniscal capillary plexus, which is supplied by the medial and lateral geniculate arteries. This blood supply only penetrates the peripheral 10% to 30% of the meniscus (the red-red zone), giving this region the highest potential for healing after surgical repair.

Question 40

A 6-year-old boy is diagnosed with Legg-Calvé-Perthes disease. The presence of certain radiographic signs, termed 'head-at-risk' signs by Catterall, suggests a higher likelihood of poor outcomes and extrusion of the femoral head. Which of the following is one of these classic Catterall 'head-at-risk' signs?





Explanation

Catterall described five 'head-at-risk' clinical and radiographic signs in Perthes disease that predict extrusion and a poor outcome. These include: Gage's sign (a V-shaped radiolucency in the lateral portion of the epiphysis and metaphysis), calcification lateral to the epiphysis, lateral subluxation of the femoral head, a horizontal growth plate, and metaphyseal cysts.

Question 41

In the biomechanical design of a Grammont-style reverse total shoulder arthroplasty, how is the center of rotation altered compared to the native glenohumeral joint?





Explanation

The Grammont design medializes and distalizes (inferiorizes) the center of rotation. This alteration increases the deltoid lever arm, recruits more deltoid fibers, and improves resting tension, compensating for the absent rotator cuff.

Question 42

A 14-year-old boy presents with a diaphyseal femur lesion showing an 'onion skin' periosteal reaction. A biopsy confirms a small round blue cell tumor. Which of the following cytogenetic abnormalities is most diagnostic of this condition?





Explanation

Ewing sarcoma is characterized by the t(11;22)(q24;q12) translocation resulting in the EWS-FLI1 fusion protein. t(X;18) is associated with Synovial Sarcoma; t(12;16) with Myxoid Liposarcoma; and MDM2 amplification with Parosteal/Low-grade central osteosarcoma.

Question 43

A 65-year-old female sustains a lateral compression type 1 (LC-1) pelvic ring injury following a ground-level fall. Her pain is well-controlled, and she is hemodynamically stable. What is the most appropriate initial management?





Explanation

LC-1 pelvic ring injuries (Denis zone 1 or 2 sacral fracture with ipsilateral rami fractures) are typically mechanically stable. The initial management is nonoperative with pain control and mobilization, allowing weight-bearing as tolerated.

Question 44

A 45-year-old man presents with chronic wrist pain and a known scaphoid nonunion. Radiographs reveal narrowing of the radioscaphoid joint and capitolunate joint, but the radiolunate joint is spared. What is the SNAC stage and most appropriate surgical treatment?





Explanation

SNAC Stage III involves arthritis of the radioscaphoid and midcarpal (capitolunate) joints, while the radiolunate joint is characteristically spared. Four-corner fusion (capitate, hamate, lunate, triquetrum) with scaphoid excision is the standard treatment when the capitate is involved, precluding a proximal row carpectomy.

Question 45

When evaluating a patient for total hip arthroplasty (THA), a pre-operative seated to standing lateral radiograph series reveals a change in pelvic tilt (PT) of less than 10 degrees. This finding indicates:





Explanation

A change in pelvic tilt of <10 degrees from standing to sitting indicates a stiff spinopelvic junction. Because the pelvis fails to retrovert normally when sitting, the acetabular component does not open anteriorly, leading to anterior impingement and an increased risk of posterior dislocation during sitting.

Question 46

A 9-year-old boy presents with right knee pain and a limp. Examination reveals obligate external rotation with hip flexion. Radiographs confirm a slipped capital femoral epiphysis (SCFE). Considering his age, which of the following laboratory tests is most critical?





Explanation

Atypical SCFE occurs in patients <10 years or >16 years old, or those with bilateral involvement, low weight, or short stature. Hypothyroidism is the most common endocrine disorder associated with atypical SCFE. Evaluation with TSH and Free T4 is mandatory.

Question 47

Bone morphogenetic proteins (BMPs) initiate intracellular signaling leading to osteoblast differentiation. Which of the following best describes the specific intracellular mediators that translocate to the nucleus upon BMP receptor activation?





Explanation

BMPs bind to serine/threonine kinase receptors on the cell surface, which phosphorylate receptor-regulated Smad 1, 5, and 8. These form a complex with the co-Smad (Smad 4) and translocate to the nucleus to regulate transcription of osteogenic genes like Runx2. Smad 2/3 are activated by TGF-beta.

Question 48

A 55-year-old woman presents with medial ankle pain and a progressively flattening arch. On examination, she has a flexible flatfoot deformity and cannot perform a single-limb heel rise on the affected side. According to the Johnson and Strom classification, what is her stage and optimal treatment?





Explanation

The patient has a flexible flatfoot (Stage II PTTD) with an inability to perform a single-leg heel rise. Stage I has pain without deformity. Stage III is a rigid deformity requiring arthrodesis. Stage II is typically treated with an FDL transfer to the navicular and a medializing calcaneal osteotomy.

Question 49

During a medial patellofemoral ligament (MPFL) reconstruction, the femoral tunnel must be placed accurately to ensure isometry. The Schöttle point is a radiographic landmark for this attachment. Which of the following accurately describes its location on a true lateral radiograph?





Explanation

The Schöttle point is a reliable radiographic landmark for the femoral origin of the MPFL. It is located 1 mm anterior to the posterior cortex extension line, 2.5 mm distal to the posterior border of Blumensaat line, and proximal to the posterior origin of the medial femoral condyle.

Question 50

A 40-year-old male sustains a high-energy Schatzker VI tibial plateau fracture. He presents with massive soft tissue swelling and fracture blisters over the proximal tibia. Compartment pressures are normal. What is the most appropriate initial management?





Explanation

In high-energy Schatzker VI fractures with significant soft tissue compromise (swelling, fracture blisters), the standard of care is temporary spanning external fixation (damage control orthopedics) to allow soft tissues to recover before definitive open reduction and internal fixation.

Question 51

A 32-year-old heavy laborer presents with chronic dorsal wrist pain. Radiographs reveal sclerosis and fragmentation of the lunate with proximal migration of the capitate and a measured radioscaphoid angle of 65 degrees. He has ulnar neutral variance. What is the most appropriate surgical intervention?





Explanation

The patient has Lichtman Stage IIIB Kienböck's disease (fragmentation of lunate, carpal collapse with fixed scaphoid rotation >60 deg). In the presence of carpal collapse and neutral ulnar variance, salvage procedures such as proximal row carpectomy or scaphoid excision and four-corner fusion are indicated. Radial shortening is reserved for earlier stages with ulnar minus variance.

Question 52

A 3-year-old girl is newly diagnosed with unilateral developmental dysplasia of the hip (DDH). The hip is dislocated and reducible. What is the most appropriate primary treatment?





Explanation

In a child older than 18-24 months of age, closed reduction is usually unsuccessful due to soft tissue contractures and adaptive bony changes. The standard of care for a 3-year-old with DDH is open reduction, often combined with a pelvic osteotomy and/or a femoral shortening osteotomy to relieve tension and provide stability.

Question 53

A 55-year-old man undergoes resection of a large cartilaginous tumor of the proximal femur. Histopathology reveals abundant hyaline cartilage with hypercellularity, binucleate cells, and myxoid changes without osteoid matrix production. Which genetic mutation is most frequently associated with this primary bone malignancy?





Explanation

The histopathology describes a primary chondrosarcoma. Mutations in IDH1 and IDH2 (Isocitrate Dehydrogenase) are found in up to 50-60% of central chondrosarcomas. EXT1/EXT2 are associated with osteochondromas.

Question 54

A 65-year-old man presents with progressive clumsiness in his hands and difficulty with balance. Examination demonstrates hyperreflexia, a positive Hoffmann sign, and a positive inverted radial reflex. According to the Nurick classification, a patient whose gait abnormality prevents employment but who walks unassisted is classified as:





Explanation

Nurick Grade 3 describes a patient with a gait abnormality that prevents employment, but who can still walk unassisted. Grade 1: Signs of cord involvement but normal gait. Grade 2: Mild gait involvement, fully employed. Grade 4: Ambulates only with assistance (walker/cane). Grade 5: Chair-bound or bedridden.

Question 55

A 50-year-old male with a metal-on-metal total hip arthroplasty placed 8 years ago presents with new-onset groin pain. Radiographs show a well-fixed implant without loosening. Aspiration yields sterile fluid with a predominance of lymphocytes. What type of hypersensitivity reaction is primarily responsible for this adverse local tissue reaction (ALTR)?





Explanation

Adverse local tissue reactions (ALTR) or ALVAL (aseptic lymphocytic vasculitis-associated lesions) in metal-on-metal implants are characterized by a Type IV (delayed, cell-mediated) hypersensitivity reaction, leading to characteristic perivascular lymphocytic infiltration.

Question 56

During physical examination for shoulder pain, a patient has a positive 'bear hug' test and a positive 'belly press' test, but a negative 'lift-off' test. This combination of clinical findings most strongly suggests a tear involving which portion of the subscapularis tendon?





Explanation

The 'bear hug' and 'belly press' tests are highly sensitive for upper (superior) subscapularis tears. The 'lift-off' test primarily isolates the inferior portion of the subscapularis. A positive belly press and negative lift-off typically indicate a partial tear involving the superior subscapularis tendon.

Question 57

Boundary lubrication in native articular cartilage is primarily mediated by a superficial layer of molecules that reduce friction under high-load conditions. Which specific glycoprotein is the main contributor to this mechanism?





Explanation

Lubricin (proteoglycan 4 or PRG4) is synthesized by superficial zone chondrocytes and synoviocytes. It binds to the articular surface and provides boundary lubrication, critical for reducing friction under high loads. Hyaluronic acid primarily contributes to fluid-film (hydrodynamic) lubrication.

Question 58

A 25-year-old man sustains a closed diaphyseal tibia fracture. He reports out-of-proportion leg pain. His blood pressure is 110/70 mmHg. Compartment pressures are measured. What is the generally accepted threshold (delta p) for diagnosing acute compartment syndrome and indicating fasciotomy?





Explanation

The delta p (Δp) threshold for fasciotomy in acute compartment syndrome is defined as the diastolic blood pressure minus the intra-compartmental pressure. A Δp < 30 mmHg is highly indicative of compartment syndrome and requires emergent fasciotomy.

Question 59

A patient presents with intrinsic muscle wasting of the hand, numbness in the small finger, and a positive Froment's sign. Which muscle is compensating for the weakened adductor pollicis during the Froment's sign maneuver?





Explanation

Froment's sign occurs when the patient attempts to pinch a piece of paper between the thumb and index finger. Weakness of the adductor pollicis (ulnar nerve) causes the patient to hyperflex the thumb interphalangeal joint using the flexor pollicis longus (innervated by the anterior interosseous nerve/median nerve) to compensate.

Question 60

The anterior cruciate ligament (ACL) is composed of two primary bundles. In full knee extension, what is the relative tension and orientation of the anteromedial (AM) and posterolateral (PL) bundles?





Explanation

The ACL consists of the AM and PL bundles. In full extension, the posterolateral (PL) bundle is tight and provides essential rotational stability, while the anteromedial (AM) bundle is relatively lax. In flexion, the AM bundle tightens to control anterior translation, and the PL bundle becomes lax.

Question 61

During the manufacturing of highly cross-linked polyethylene (HXLPE) for total hip arthroplasty, what is the primary purpose of thermal treatment (remelting or annealing) after gamma irradiation?





Explanation

Gamma irradiation induces cross-linking in the polyethylene but leaves residual free radicals. Post-irradiation thermal treatment (either remelting above the melting temperature or annealing below it) is performed specifically to extinguish these free radicals, thereby preventing in vivo oxidative degradation.

Question 62

Which of the following arterial structures is most commonly injured and causes significant hemorrhage in a patient with a lateral compression (LC) pelvic ring injury with a displaced sacral fracture?





Explanation

The superior gluteal artery exits the pelvis through the greater sciatic foramen in close proximity to the posterior sacroiliac complex and sacrum. It is the most commonly injured artery in posterior pelvic ring disruptions, particularly lateral compression injuries with displaced sacral fractures.

Question 63

Mutations in the IDH1 and IDH2 genes are most characteristic of which of the following primary bone tumors?





Explanation

Isocitrate dehydrogenase (IDH) 1 and 2 mutations are found in a high percentage of central enchondromas and conventional central chondrosarcomas. These mutations result in the production of the oncometabolite D-2-hydroxyglutarate.

Question 64

A 16-year-old female presents with low back pain and a grade II L5-S1 isthmic spondylolisthesis. Which of the following spinopelvic parameters is highly correlated with the risk of progression in isthmic spondylolisthesis and is a fixed morphological parameter that does not change with patient positioning?





Explanation

Pelvic incidence (PI) is a fixed anatomical parameter unique to each individual and does not change with posture (PI = Pelvic Tilt + Sacral Slope). A high pelvic incidence is strongly correlated with the development and progression of L5-S1 isthmic spondylolisthesis due to the resultant higher shear forces at the lumbosacral junction.

Question 65

Which of the following clinical scenarios is the strongest indication for prophylactic in situ pinning of the contralateral asymptomatic hip in a patient presenting with a unilateral slipped capital femoral epiphysis (SCFE)?





Explanation

Endocrine disorders (such as hypothyroidism, panhypopituitarism, and renal osteodystrophy) carry an exceptionally high risk of bilateral SCFE, sometimes approaching 100%. Prophylactic pinning of the contralateral hip is strongly indicated in patients with underlying endocrinopathies, history of pelvic radiation therapy, or those presenting at an unusually young age (<10 years).

Question 66

The vincula tendinum provide segmental blood supply to the flexor tendons within the digital sheath. Which of the following vessels provides the primary direct blood supply to the vinculum breve of the flexor digitorum profundus (FDP)?





Explanation

Within the flexor sheath, the flexor tendons receive nutrition via diffusion from synovial fluid and via direct vascular perfusion through the vincula. The vincula (longa and brevia) are supplied by transverse communicating branches arising directly from the proper digital arteries.

Question 67

During an anterior cruciate ligament (ACL) reconstruction, the femoral tunnel is inadvertently placed too anteriorly (shallow) in the intercondylar notch. What is the expected biomechanical consequence on the graft during knee range of motion?





Explanation

A femoral tunnel placed too anteriorly (shallow, non-isometric) results in the distance between the tibial and femoral tunnels increasing as the knee flexes. Consequently, the graft becomes inappropriately tight in flexion (causing loss of flexion/capture) and lax in extension (resulting in an extension lag or instability).

Question 68

A 55-year-old male with poorly controlled type 2 diabetes mellitus presents with a swollen, erythematous, and warm right foot. Radiographs show periarticular fragmentation, subluxation of the tarsometatarsal joints, and debris. Which Eichenholtz stage does this represent, and what is the most appropriate initial management?





Explanation

The patient is in Eichenholtz Stage 1 (Developmental/Fragmentation stage), characterized by erythema, swelling, warmth, joint laxity, subluxation, and radiographic evidence of osteopenia, fragmentation, and debris. The gold standard initial treatment is immobilization and off-loading with a total contact cast (TCC) to halt progression and prevent deformity.

Question 69

Which internervous plane is utilized superficially during the direct anterior (Smith-Petersen) approach to the hip?





Explanation

The direct anterior (Smith-Petersen) approach utilizes a true superficial internervous plane between the sartorius (innervated by the femoral nerve) and the tensor fasciae latae (innervated by the superior gluteal nerve). The deep plane is between the rectus femoris (femoral nerve) and gluteus medius (superior gluteal nerve).

Question 70

Bone morphogenetic proteins (BMPs) stimulate osteoblast differentiation. Upon binding to their cell surface serine/threonine kinase receptors, which family of intracellular signaling molecules is directly phosphorylated to translocate to the nucleus and regulate gene transcription?





Explanation

BMPs belong to the TGF-beta superfamily. When they bind to their specific serine/threonine kinase receptors, the activated receptor directly phosphorylates intracellular receptor-regulated Smad proteins (R-Smads, typically Smad1, 5, and 8). These form a complex with Co-Smad (Smad4), which translocates to the nucleus to induce transcription of osteogenic genes like Runx2.

Question 71

A 4-month-old infant with developmental dysplasia of the hip (DDH) is being treated with a Pavlik harness. The parents adjusted the harness themselves, placing the hips in extreme hyperflexion. Which of the following complications is the infant at the highest risk of developing?





Explanation

Improper use of the Pavlik harness can lead to significant complications. Extreme hyperflexion of the hips can compress the femoral nerve against the inguinal ligament, leading to a femoral nerve palsy, which manifests clinically as an absence of active knee extension. Avascular necrosis is typically associated with excessive forced abduction.

Question 72

A 40-year-old male sustains a Schatzker IV tibial plateau fracture. Imaging reveals a displaced posteromedial shear fragment. What is the most appropriate surgical approach to reduce and buttress this specific fragment?





Explanation

Schatzker IV fractures often involve a high-energy medially based shear fragment, frequently with a posteromedial component. An anteromedial approach is insufficient for posterior fragments. A posteromedial approach (interval between the medial head of the gastrocnemius and the pes anserinus) allows direct visualization, anatomical reduction, and placement of a posteromedial anti-glide/buttress plate to counteract the deforming shear forces.

Question 73

In a patient with cervical spondylotic myelopathy, the presence of an inverted supinator reflex localizes the primary compressive pathology to which cervical cord level?





Explanation

The inverted supinator (brachioradialis) reflex is characterized by finger flexion (or wrist extension) when the brachioradialis tendon is tapped, without the normal elbow flexion. This indicates a lower motor neuron lesion at the C5-C6 level (absent brachioradialis reflex) and an upper motor neuron lesion below this level (hyperactive finger flexors, C8), effectively localizing the spinal cord compression to the C5-C6 level.

Question 74

The natural history of an untreated scaphoid nonunion progresses predictably to Scaphoid Nonunion Advanced Collapse (SNAC). Which specific joint articulation is initially spared in the early stages (SNAC Stage I and II) but eventually becomes involved in SNAC Stage III?





Explanation

SNAC wrist progresses in a predictable pattern. Stage I involves the radial styloid-scaphoid articulation. Stage II involves the entire radioscaphoid articulation. Stage III progresses to involve the midcarpal joint, specifically the capitolunate joint. The radiolunate joint is characteristically spared in both SLAC and SNAC wrists due to the spherical articulation and the protective short radiolunate ligament.

Question 75

During an arthroscopic stabilization for recurrent anterior shoulder instability, the surgeon identifies an anterior labral tear that has displaced medially and healed directly to the anterior glenoid neck beneath an intact periosteum. What is the specific eponym for this lesion?





Explanation

An ALPSA (Anterior Labroligamentous Periosteal Sleeve Avulsion) lesion occurs when the anterior inferior labrum is torn and displaced medially, healing in an abnormal position on the glenoid neck with an intact periosteal sleeve. Unlike a Perthes lesion (where the periosteum is intact but the labrum is not medially displaced) or a classic Bankart (where the periosteum is torn), an ALPSA must be systematically mobilized laterally before it can be anatomically repaired.

Question 76

During skeletal muscle contraction, action potentials travel down the T-tubules to trigger the release of calcium. Which specific receptor complex physically facilitates the release of calcium from the sarcoplasmic reticulum into the cytosol?





Explanation

Depolarization of the T-tubule membrane causes conformational changes in voltage-sensitive dihydropyridine (DHP) receptors. These are physically coupled to ryanodine receptors (RyR1) on the terminal cisternae of the sarcoplasmic reticulum. Activation of this DHP-RyR complex opens calcium channels, causing a massive efflux of Ca2+ into the sarcoplasm to initiate contraction.

Question 77

A 25-year-old male develops acute compartment syndrome in the right lower leg following a tibial shaft fracture. If the deep posterior compartment is left unreleased during fasciotomy, which of the following deficits is most likely to persist?





Explanation

The deep posterior compartment of the leg contains the flexor digitorum longus, flexor hallucis longus, tibialis posterior, and the tibial nerve. Failure to decompress this compartment will lead to ischemic necrosis of these muscles (loss of active toe flexion and ankle inversion) and ischemic injury to the tibial nerve (loss of sensation on the plantar surface of the foot).

Question 78

In total knee arthroplasty, accurately establishing the femoral component rotation is critical for patellofemoral tracking and flexion gap balancing. Which of the following axes is defined by a line connecting the deepest part of the trochlear groove to the center of the intercondylar notch?





Explanation

Whiteside's line (the anteroposterior axis) is a crucial anatomical landmark used to establish femoral component rotation in TKA. It is defined by drawing a line from the deepest part of the trochlear groove anteriorly to the center of the intercondylar notch posteriorly. The femoral component is typically rotated externally so its posterior condyles are perpendicular to this line.

Question 79

A 62-year-old female with breast cancer presents with a metastatic lesion in her femur. According to Mirels' criteria, which combination of factors yields the highest score, strongly indicating the need for prophylactic internal fixation?





Explanation

Mirels' scoring system evaluates the risk of pathologic fracture based on four criteria: Site (upper extremity=1, lower extremity=2, peritrochanteric=3), Pain (mild=1, moderate=2, severe=3), Lesion character (blastic=1, mixed=2, lytic=3), and Size (<1/3=1, 1/3-2/3=2, >2/3=3). Option D (Lower extremity [2], lytic [3], >2/3 [3], severe pain [3]) yields a score of 11. A score of 9 or greater strongly recommends prophylactic fixation.

Question 80

When comparing functional rehabilitation (early mobilization) protocols for non-operative management of acute Achilles tendon ruptures to surgical repair, large randomized controlled trials (such as the Willits trial) have demonstrated which of the following?





Explanation

High-quality randomized controlled trials (e.g., Willits et al., JBJS 2010) have shown that when acute Achilles tendon ruptures are treated with early functional rehabilitation protocols (early weight-bearing and early range of motion in a functional orthosis), there is no clinically important difference in re-rupture rates or long-term functional outcomes compared to operative repair, while avoiding surgical risks such as infection or sural nerve injury.

Question 81

A 35-year-old male presents with chronic shoulder pain. Radiographs reveal a lytic lesion in the proximal humeral epiphysis with a sclerotic margin. Biopsy shows large cells with abundant clear cytoplasm and central nuclei, interspersed among woven bone. What is the most appropriate management?





Explanation

Clear cell chondrosarcoma typically presents in the epiphysis of long bones (proximal humerus/femur) in young adults (20-50 yrs). Histology shows characteristic clear cells. It is a low-grade malignant bone tumor. Because intralesional curettage leads to high recurrence rates, and it is resistant to chemotherapy and radiation, wide surgical resection is the standard of care.

Question 82

A 2-year-old child presents with a painless lump over the right clavicle present since birth. Radiographs show a distinct gap in the middle third of the right clavicle with smooth, rounded bone ends. There is no history of trauma. Which of the following is true regarding this condition?





Explanation

Congenital pseudarthrosis of the clavicle (CPC) is a rare condition occurring almost exclusively on the right side. It occurs due to the failure of coalescence of the medial and lateral primary ossification centers of the clavicle. Unlike congenital pseudarthrosis of the tibia, it is not associated with Neurofibromatosis type 1 (NF-1). Surgery is generally considered for cosmetic prominence, pain, or functional limitation, usually around ages 3-5.

Question 83

In the surgical management of a 'terrible triad' injury of the elbow (elbow dislocation, radial head fracture, coronoid fracture), what is the generally recommended sequence of repair to restore elbow stability?





Explanation

The standard surgical algorithm for a terrible triad injury involves restoring structures from deep to superficial, moving from anterior/medial to lateral: 1) Repair or fix the coronoid (or anterior capsule) to restore the anterior buttress, 2) Replace or fix the radial head, 3) Repair the lateral collateral ligament (LCL) complex. MCL repair is only considered if the elbow remains grossly unstable after the first three steps.

Question 84

A 7-year-old boy presents with torticollis following an upper respiratory tract infection. Radiographs and CT show anterior displacement of the atlas on the axis of 4 mm, with one lateral mass acting as the pivot point. According to the Fielding and Hawkins classification, what type of atlantoaxial rotatory subluxation is this?





Explanation

Fielding and Hawkins Type II AARS involves anterior displacement of the atlas by 3-5 mm, with one lateral mass acting as the pivot point, indicating a deficiency of the transverse ligament. Type I has no anterior displacement (pivot on the dens). Type III has >5mm anterior displacement (deficiency of transverse and alar ligaments). Type IV involves posterior displacement.

Question 85

A patient with rheumatoid arthritis presents with a swan neck deformity of the ring finger. What is the primary pathophysiological event that typically initiates this specific deformity in the rheumatoid hand?





Explanation

In rheumatoid arthritis, the swan neck deformity typically initiates with synovitis at the proximal interphalangeal (PIP) joint, leading to stretching and attenuation of the volar plate. This causes PIP joint hyperextension, followed secondarily by dorsal subluxation of the lateral bands and compensatory flexion at the DIP joint. Central slip rupture causes a boutonniere deformity.

Question 86

When performing a posterolateral corner (PLC) reconstruction of the knee using an anatomic fibular-based technique (e.g., LaPrade technique), the graft is typically routed to reconstruct which three primary stabilizing structures?





Explanation

The primary static stabilizers of the posterolateral corner (PLC) of the knee are the fibular collateral ligament (FCL), the popliteus tendon (PT), and the popliteofibular ligament (PFL). Anatomic reconstructive techniques specifically aim to recreate these three crucial structures using an allograft or autograft to restore normal kinematics.

Question 87

During the process of creeping substitution in a structural cortical bone allograft, which of the following sequences best describes the biologic incorporation?





Explanation

Cortical bone grafts incorporate via creeping substitution, which is strictly initiated by osteoclastic resorption (cutting cones) of the necrotic graft bone, followed directly by osteoblastic deposition of new viable bone within the newly created vascular channels. This transient porosity weakens the graft before it reaches its final mechanical strength.

Question 88

A 45-year-old active male underwent a total hip arthroplasty using a ceramic-on-ceramic bearing surface. Two years postoperatively, he complains of a loud 'squeaking' noise from the hip with deep flexion. Which of the following is considered a significant risk factor for the development of squeaking in this bearing type?





Explanation

Squeaking is a specific complication of ceramic-on-ceramic (CoC) bearings. Significant risk factors include acetabular component malposition (such as excessive inclination or anteversion), which leads to edge loading. Edge loading results in the loss of fluid film lubrication, stripe wear, and micro-separation, mechanically producing the audible squeak.

Question 89

A 28-year-old motorcyclist sustains a distal femur fracture. CT imaging reveals a coronal plane fracture of the lateral femoral condyle. What is the standard classification and typical mechanism for this specific fracture pattern?





Explanation

A coronal plane fracture of the femoral condyle is known as a Hoffa fracture (AO/OTA 33-B3). It most commonly involves the lateral condyle. The typical mechanism of injury is a direct anterior-to-posterior force applied to the knee while in a flexed position, such as striking a dashboard during a motor vehicle collision.

Question 90

In a patient presenting with a unilateral Slipped Capital Femoral Epiphysis (SCFE), which of the following is the strongest indication for prophylactic in situ pinning of the contralateral asymptomatic hip?





Explanation

Prophylactic pinning of the contralateral hip in unilateral SCFE is highly recommended in patients with an underlying endocrine disorder (e.g., hypothyroidism, renal osteodystrophy) or a history of radiation therapy. These patients have a significantly elevated risk (>50%) of developing a bilateral slip. Younger age (<10 years) is also an indication.

Question 91

An 82-year-old male with multiple medical comorbidities sustains a Type II odontoid fracture after a ground-level fall. The fracture is displaced 2 mm anteriorly. His neurologic exam is completely intact. What is the most appropriate initial management considering his age and fracture pattern?





Explanation

In elderly patients (>80 years) with multiple comorbidities, a rigid cervical collar is often the most appropriate management for a minimally displaced Type II odontoid fracture. Halo vest immobilization is poorly tolerated and associated with high mortality in the elderly. While surgical stabilization (posterior fusion) may increase union rates, the perioperative risk is high. A stable, fibrous nonunion treated in a collar is frequently asymptomatic and acceptable in this population.

Question 92

A 25-year-old male presents with chronic, dull pain in his anterior leg. Radiographs demonstrate a multiloculated, expansile, eccentric, mixed lytic-sclerotic lesion in the anterior cortex of the tibial diaphysis. Biopsy reveals islands of epithelial cells in a fibrous stroma. What is the best treatment for this lesion?





Explanation

The clinical, radiographic, and histologic presentation (epithelial cells in fibrous stroma) is classic for an adamantinoma. This is a rare, low-grade malignant bone tumor that almost exclusively occurs in the anterior tibial diaphysis. Because it is malignant and resistant to radiation and chemotherapy, the standard of care is wide surgical resection with limb-salvage reconstruction.

Question 93

A 12-year-old boy presents with a rigid flatfoot and recurrent ankle sprains. Radiographs show the 'anteater nose' sign on the lateral view. Which type of tarsal coalition is most likely present, and what is the best initial non-operative treatment?





Explanation

The 'anteater nose' sign on a lateral foot radiograph is pathognomonic for a calcaneonavicular coalition, representing the elongated anterior process of the calcaneus approaching the navicular. Initial non-operative management for a symptomatic, painful tarsal coalition typically involves a period of immobilization in a short leg cast (4-6 weeks) to decrease inflammation and joint irritability.

Question 94

In the classification of flexor tendon injuries of the hand, which zone is historically referred to as 'no man's land' due to the high risk of adhesion formation and historically poor surgical outcomes?





Explanation

Zone II extends from the proximal edge of the A1 pulley (distal palmar crease) to the insertion of the flexor digitorum superficialis (FDS) at the middle phalanx. It is called 'no man's land' because both the FDS and flexor digitorum profundus (FDP) tendons run tightly together in the fibro-osseous sheath, making repair challenging and prone to severe adhesion formation.

Question 95

During reconstruction of the ulnar collateral ligament (UCL) of the elbow in a throwing athlete, which bundle is the primary restraint to valgus stress and the primary anatomic target for reconstruction?





Explanation

The ulnar collateral ligament (UCL) complex consists of anterior, posterior, and transverse bundles. The anterior bundle is the primary restraint to valgus stress at the elbow between 30 and 120 degrees of flexion. Specifically, the anterior band of the anterior bundle is the most critical structure and is the primary target recreated during a 'Tommy John' reconstruction.

Question 96

A 40-year-old male is brought to the trauma bay after a severe crush injury. He has a hemodynamically unstable 'open book' pelvic fracture. A commercial pelvic binder is applied. To maximize mechanical advantage and safely reduce pelvic volume, over which anatomical landmarks should the binder be centered?





Explanation

A pelvic binder or circumferential sheet must be centered directly over the greater trochanters. This alignment effectively creates an internal rotation moment around the posterior pelvis, closing the open book (APC) injury and effectively reducing pelvic volume. Placing the binder too high (e.g., over the iliac crests) is less effective and can paradoxically widen the symphysis.

Question 97

When using a locked plate construct for a comminuted diaphyseal fracture, increasing the 'working length' of the plate achieves which of the following biomechanical effects?





Explanation

In locked plating of comminuted fractures, the goal is relative stability to promote secondary (callus) bone healing. The 'working length' is the longitudinal distance between the two innermost screws spanning the fracture. Increasing the working length increases the overall flexibility of the construct, which allows beneficial interfragmentary micromotion and stimulates robust callus formation.

Question 98

A patient with a metal-on-metal total hip arthroplasty presents with groin pain and a large cystic mass around the hip. A revision is performed, and tissue pathology reveals an aseptic lymphocyte-dominated vasculitis-associated lesion (ALVAL). This histological response is best characterized as which type of hypersensitivity reaction?





Explanation

ALVAL (Aseptic Lymphocyte-Dominated Vasculitis-Associated Lesion) is an adverse local tissue reaction associated predominantly with metal-on-metal implants. Histologically, it presents with a dense perivascular infiltrate of lymphocytes, characterizing it as a Type IV (delayed-type, cell-mediated) hypersensitivity reaction to metal ions (typically cobalt and chromium).

Question 99

A 6-year-old child sustains a completely displaced supracondylar humerus fracture and an ipsilateral displaced distal radius fracture ('floating elbow'). The hand is pink, but the radial pulse is absent before reduction. What is the most appropriate management sequence?





Explanation

In a pediatric 'floating elbow' with a pink but pulseless hand, the priority is reduction and stabilization of the supracondylar humerus fracture. The brachial artery is frequently kinked, compressed, or entrapped at the supracondylar fracture site. Closed reduction and percutaneous pinning (CRPP) of the humerus often restores the pulse. The distal radius fracture is managed subsequently.

Question 100

The Lisfranc ligament is a crucial primary stabilizer of the midfoot. Which of the following accurately describes its anatomic origin and insertion?





Explanation

The Lisfranc ligament is the strongest interosseous ligament in the tarsometatarsal joint complex. It originates from the lateral aspect of the medial cuneiform and courses obliquely to insert onto the medial aspect of the base of the second metatarsal. Notably, there is no direct intermetatarsal ligament connecting the bases of the first and second metatarsals.

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