Orthopedic Surgery Board Review: 100 High-Yield MCQs

Question 1

A 72-year-old female presents with recurrent posterior dislocations following primary total hip arthroplasty. Surgical exploration reveals an irreparably deficient abductor mechanism. The acetabular component is well-fixed and correctly positioned. What is the most appropriate management?

Explanation

Constrained liners are specifically indicated for recurrent instability in the setting of severe abductor deficiency or severe cognitive impairment. Dual mobility is preferred for patients with intact abductors to prevent impingement.

Question 2

A 6-year-old boy sustains a completely displaced extension-type supracondylar humerus fracture. Which associated nerve deficit is most characteristic of this specific injury pattern?

Explanation

The anterior interosseous nerve (AIN) is the most commonly injured nerve in extension-type supracondylar humerus fractures. Injury to the AIN manifests as motor weakness in the flexor pollicis longus and the flexor digitorum profundus to the index finger.

Question 3

A 35-year-old male sustains a midfoot crush injury. Weight-bearing radiographs demonstrate a 3mm diastasis between the medial cuneiform and the base of the second metatarsal. The primary stabilizing ligament of this joint originates from the plantar aspect of which structure?

Explanation

The Lisfranc ligament connects the plantar aspect of the medial cuneiform to the base of the second metatarsal. It is critical for the stability of the tarsometatarsal joint complex, and its rupture leads to midfoot instability.

Question 4

Which primary malignant bone tumor is classically driven by a t(11;22)(q24;q12) chromosomal translocation, resulting in the EWS-FLI1 fusion gene?

Explanation

Ewing sarcoma is characterized by the t(11;22) translocation, which creates the EWS-FLI1 fusion gene. This acts as an aberrant transcription factor that drives neoplastic proliferation in the medullary cavity of long bones.

Question 5

A 24-year-old elite soccer player is scheduled for anterior cruciate ligament (ACL) reconstruction. When counseling the patient on using a bone-patellar tendon-bone (BTB) autograft versus a hamstring autograft, which complication is significantly more common with the BTB graft?

Explanation

Bone-patellar tendon-bone (BTB) autografts are highly associated with donor site morbidity, particularly anterior knee pain, patellar tendinitis, and a small risk of patellar fracture. Hamstring grafts carry a higher risk of saphenous nerve irritation and hamstring weakness.

Question 6

A 65-year-old male presents with deteriorating handwriting, frequent dropping of objects, and a broad-based, unsteady gait. Physical examination reveals bilateral hyperreflexia, a positive Hoffmann sign, and inverted radial reflex. What is the most likely diagnosis?

Explanation

Cervical spondylotic myelopathy classically presents with upper extremity clumsiness, gait instability, and upper motor neuron signs. It is the most common cause of acquired spastic paresis in adults over the age of 55.

Question 7

A 40-year-old diabetic male presents with an exquisitely tender, swollen index finger held in slight flexion. Passive extension of the digit elicits extreme pain extending into the palm. What is the most appropriate next step in management?

Explanation

This presentation describes Kanavel's cardinal signs of acute pyogenic flexor tenosynovitis. This is an orthopedic surgical emergency requiring prompt incision, irrigation, drainage, and broad-spectrum IV antibiotics to prevent tendon necrosis.

Question 8

During the process of secondary fracture healing, which type of collagen is predominantly synthesized by chondrocytes during the soft callus phase?

Explanation

During the soft callus (cartilaginous) phase of secondary bone healing, chondrocytes primarily synthesize Type II collagen. As the cartilage calcifies and is replaced by bone in the hard callus phase, Type I collagen becomes predominant.

Question 9

A 12-year-old obese male presents with a limp and right anterior thigh pain for three weeks. Examination reveals an obligate external rotation of the right hip during passive flexion. What is the most appropriate definitive management for his right hip?

Explanation

The clinical picture is classic for a Slipped Capital Femoral Epiphysis (SCFE). The gold standard for definitive management of a stable SCFE is in situ percutaneous pinning using a single large cannulated screw to prevent further slip.

Question 10

A 60-year-old male develops a culture-positive periprosthetic joint infection (Staphylococcus aureus) 3 weeks after an uncomplicated primary total knee arthroplasty. The implants are well-fixed on radiographs. What is the most appropriate surgical intervention?

Explanation

For acute postoperative periprosthetic joint infections (typically within 4 weeks of the index surgery) with well-fixed components, DAIR (Debridement, Antibiotics, and Implant Retention) is the standard of care. This procedure must include the exchange of modular components, such as the polyethylene insert.

Question 11

An 18-year-old male complains of severe, unrelenting leg pain out of proportion to the injury after sustaining a closed tibial shaft fracture. Which pressure parameter is the most reliable threshold for diagnosing acute compartment syndrome?

Explanation

A delta pressure (diastolic blood pressure minus intra-compartmental pressure) of less than 30 mmHg is the most reliable and widely accepted indicator for acute compartment syndrome. Relying on delta pressure prevents unnecessary fasciotomies in hypotensive patients compared to absolute pressure limits.

Question 12

A 25-year-old falls on an outstretched hand, sustaining a minimally displaced scaphoid proximal pole fracture. Which artery provides the primary blood supply to this specific region of the scaphoid?

Explanation

The primary blood supply to the scaphoid is derived from the dorsal carpal branch of the radial artery, which enters the bone distally and flows in a retrograde fashion. This unique vascular anatomy places proximal pole fractures at extremely high risk for avascular necrosis and nonunion.

Question 13

A 30-year-old female is diagnosed with an eccentric, lytic lesion in the distal femoral epiphysis. Biopsy reveals neoplastic mononuclear cells expressing RANKL and reactive multinucleated giant cells. Which targeted systemic therapy is indicated if the tumor is deemed surgically unresectable?

Explanation

Giant cell tumor of bone relies on the RANK/RANKL pathway for the recruitment of osteoclast-like giant cells by neoplastic mononuclear cells. Denosumab, a monoclonal antibody that inhibits RANKL, is utilized for advanced, recurrent, or surgically unresectable cases.

Question 14

A 45-year-old male sustains an acute, complete avulsion of the proximal hamstring origin (all three tendons) with 4 cm of retraction. If this is treated non-operatively, which long-term complication is he at highest risk for developing?

Explanation

Complete, retracted proximal hamstring avulsions treated without surgical repair frequently result in persistent weakness, cramping, and loss of power. Additionally, scarring of the retracted stump around the sciatic nerve can cause chronic neuropathic pain.

Question 15

When utilizing the Ponseti method for the conservative management of idiopathic clubfoot, what is the anatomically correct sequence for correcting the components of the deformity?

Explanation

The Ponseti method dictates a strict sequential correction of the clubfoot deformities, easily remembered by the acronym CAVE: Cavus (by supinating the forefoot), Adductus, Varus, and finally Equinus (usually requiring a percutaneous Achilles tenotomy).

Question 16

In the context of bone metabolism and molecular biology, which of the following accurately describes the primary function of sclerostin?

Explanation

Sclerostin is a glycoprotein secreted primarily by osteocytes that acts as a potent negative regulator of bone formation. It accomplishes this by binding to LRP5/6 receptors, thereby inhibiting the canonical Wnt/beta-catenin signaling pathway in osteoblasts.

Question 17

In the emergency management of a hemodynamically unstable patient with an anteroposterior compression (APC-III) pelvic ring injury, over which exact anatomical landmarks should a pelvic binder be centered?

Explanation

To effectively reduce pelvic volume, close the pelvic ring, and provide tamponade effect, a pelvic binder must be centered directly over the greater trochanters. Misplacement over the iliac crests is common but incorrect, as it can worsen the deformity in certain fracture patterns.

Question 18

According to the Denis three-column classification of spinal fractures, a typical thoracolumbar burst fracture involves biomechanical failure of which columns?

Explanation

In the Denis classification, a burst fracture requires structural failure of both the anterior and middle columns under axial compression. This is the crucial distinction from a simple compression fracture, which involves isolated failure of the anterior column.

Question 19

A 50-year-old female undergoes surgical repair of an acute Achilles tendon rupture. To optimize early healing and prevent permanent tendon elongation, evidence-based post-operative rehabilitation protocols most strongly support which strategy?

Explanation

Modern evidence-based management of Achilles tendon ruptures heavily emphasizes early functional rehabilitation and protected weight-bearing. Compared to prolonged strict immobilization, this approach yields similar re-rupture rates but significantly reduces deep vein thrombosis, muscle atrophy, and tendon elongation.

Question 20

A 35-year-old male sustains a comminuted fracture of the femoral shaft in a motor vehicle accident. Approximately 36 hours post-injury, he acutely develops hypoxia, a petechial rash on his chest and axillae, and acute confusion. Which pathophysiological phenomenon best explains his clinical deterioration?

Explanation

The classic triad of progressive hypoxia, an upper-body petechial rash, and neurologic abnormalities developing 24-72 hours after a long bone fracture is highly diagnostic for fat embolism syndrome. Early stabilization of long bone fractures is the single most effective preventative measure.

Question 21

A 5-year-old child sustains a Gartland type III supracondylar humerus fracture. On presentation, the hand is pink but pulseless. Following closed reduction and percutaneous pinning, the hand remains pink and pulseless. What is the most appropriate next step in management?

Explanation

In a pink, pulseless hand following adequate reduction and pinning of a supracondylar fracture, observation is recommended as collateral circulation is sufficient. Vascular exploration is indicated only if the hand becomes pale or ischemic.

Question 22

A 13-year-old boy undergoes in situ single-screw pinning for a stable Slipped Capital Femoral Epiphysis (SCFE). Six months later, he develops progressive loss of hip motion, severe pain, and marked joint space narrowing on radiographs. What is the most likely diagnosis?

Explanation

Chondrolysis is a severe complication of SCFE characterized by acute cartilage necrosis and profound joint space narrowing. It is strongly associated with unrecognized pin penetration into the hip joint during fixation.

Question 23

A 32-year-old female presents with symptomatic developmental dysplasia of the hip. Radiographs demonstrate an open triradiate cartilage, a lateral center-edge angle of 15 degrees, and minimal osteoarthritis (Toennis grade 1). Which pelvic osteotomy is most appropriate?

Explanation

The Bernese Periacetabular Osteotomy (PAO) is the treatment of choice for symptomatic adult DDH with closed triradiate cartilage and minimal osteoarthritis. It allows extensive multiplanar correction while preserving the posterior column.

Question 24

A 65-year-old male is 2 weeks post-Total Hip Arthroplasty (THA) via a posterior approach and experiences recurrent posterior dislocations. Radiographs show the acetabular component in 40 degrees of abduction and 0 degrees of version. What is the most appropriate surgical intervention?

Explanation

The acetabular component is neutral/retroverted (normal target is 15-20 degrees of anteversion). Revision of the cup to increase anteversion is required to correct the underlying mechanical cause of the recurrent posterior instability.

Question 25

During a primary Total Knee Arthroplasty (TKA), trial components are inserted. The surgeon notes a tight flexion gap and a perfectly balanced extension gap. Which surgical maneuver correctly addresses this mismatch?

Explanation

A tight flexion gap with a balanced extension gap requires increasing only the flexion space. This can be achieved by downsizing the femoral component (which removes more posterior condylar bone) or increasing the posterior tibial slope.

Question 26

A 45-year-old male with a tibial shaft fracture treated with a reamed intramedullary nail presents 9 months post-op with continued pain. Radiographs reveal a hypertrophic nonunion (elephant shoe appearance). What is the best treatment?

Explanation

Hypertrophic nonunions have excellent biological healing potential but lack mechanical stability. Exchange nailing with a larger diameter reamed nail provides the necessary biomechanical stability to induce fracture consolidation.

Question 27

A 28-year-old male sustains a traumatic knee dislocation. Following closed reduction, his Ankle-Brachial Index (ABI) is measured at 0.8. What is the most appropriate next step in management?

Explanation

An Ankle-Brachial Index (ABI) less than 0.9 following a knee dislocation strongly suggests a popliteal artery injury. A CT angiogram is the gold standard next step to anatomically define the injury prior to operative intervention.

Question 28

A 25-year-old male sustains an isolated, vertically oriented medial malleolus fracture. According to the Lauge-Hansen classification, what is the most likely mechanism of injury?

Explanation

A vertically oriented medial malleolus fracture is characteristic of a Supination-Adduction (SAD) injury. It is typically treated with anti-glide plating to counteract the vertical shear forces.

Question 29

A 22-year-old athlete presents with chronic anterior knee pain and catching. MRI reveals an osteochondritis dissecans (OCD) lesion. What is the most common anatomical location for this pathology in the knee?

Explanation

The most common location for an OCD lesion in the knee is the lateral aspect of the medial femoral condyle. This classic location accounts for approximately 70% of all knee OCD lesions.

Question 30

A 15-year-old presents with a high-grade osteosarcoma of the distal femur. What is the classic genetic mutation associated with the pathogenesis of this tumor in familial syndromes?

Explanation

Osteosarcoma is frequently associated with mutations in tumor suppressor genes such as RB1 (hereditary retinoblastoma) and TP53 (Li-Fraumeni syndrome). In contrast, t(11;22) is characteristic of Ewing sarcoma.

Question 31

A patient with severe rheumatoid arthritis presents with progressive cervical myelopathy. Flexion-extension radiographs show 9 mm of atlantoaxial subluxation (AAS). Which radiographic parameter is the most critical predictor of postoperative neurological recovery?

Explanation

The Posterior Atlantodens Interval (PADI), which represents the space available for the spinal cord, is the most reliable predictor of neurologic recovery in RA patients with AAS. A PADI of less than 14 mm is an indication for surgical stabilization.

Question 32

A 30-year-old male is diagnosed with an L1 burst fracture after a fall. He is neurologically intact, and MRI confirms an intact posterior ligamentous complex. His TLICS score is 2. What is the most appropriate management?

Explanation

A Thoracolumbar Injury Classification and Severity (TLICS) score of 3 or less indicates non-operative management. For an isolated burst fracture with intact neurology and posterior ligaments, a TLSO brace is the standard of care.

Question 33

A 35-year-old male sustains a displaced fracture of the scaphoid waist. Which of the following blood vessels provides the primary retrograde blood supply to the proximal pole of the scaphoid?

Explanation

The dorsal carpal branch of the radial artery enters the scaphoid at the distal pole and provides retrograde blood flow to the proximal pole. This retrograde supply explains the high rate of avascular necrosis seen in proximal scaphoid fractures.

Question 34

In the context of flexor tendon repairs in 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 to the insertion of the FDS tendon. It is known as "No Man's Land" because both the FDS and FDP tendons run tightly within a single fibro-osseous sheath, making repairs highly prone to restrictive adhesions.

Question 35

During a standard deltopectoral approach for total shoulder arthroplasty, an inferior capsular release is performed to mobilize the proximal humerus. Which nerve is at greatest risk of iatrogenic injury during this specific step?

Explanation

The axillary nerve passes just inferior to the shoulder capsule (closest at the 6 o'clock position). It is highly vulnerable during inferior capsular release if the surgeon strays too far from the glenoid rim or humeral neck.

Question 36

A 40-year-old male is brought to the trauma bay with an open-book pelvic fracture (APC-II) after a motorcycle collision. He is hemodynamically unstable despite massive transfusion protocol initiation. What is the most appropriate immediate intervention?

Explanation

In a hemodynamically unstable patient with an open-book pelvic ring injury, the immediate first step is to reduce pelvic volume. This is best achieved rapidly by applying a pelvic binder centered over the greater trochanters to provide tamponade.

Question 37

A 12-year-old boy with Legg-Calve-Perthes disease presents in the fragmentation stage. Radiographs reveal >50% collapse of the lateral pillar (Herring Lateral Pillar Type C). What is the expected outcome and recommended treatment approach?

Explanation

Lateral Pillar Type C (>50% collapse) in an older child (>8 years of age) carries a poor prognosis. Studies have shown that surgical containment in this specific high-risk group yields little clinical or radiographic improvement compared to non-operative treatment.

Question 38

Which of the following osteoinductive agents is currently FDA-approved for use in acute, open tibial shaft fractures treated with intramedullary nailing?

Explanation

Recombinant human BMP-2 (rhBMP-2) is specifically FDA-approved for acute, open tibial shaft fractures stabilized with an intramedullary nail. It is also approved for use in anterior lumbar interbody fusions (ALIF).

Question 39

A 60-year-old diabetic patient presents with a severely swollen, erythematous, but painless foot. Radiographs demonstrate marked osteopenia, bony fragmentation, and periarticular debris at the tarsometatarsal joints. According to the Eichenholtz classification, what stage is this?

Explanation

Eichenholtz Stage 1 (Developmental/Fragmentation) of Charcot arthropathy is characterized clinically by acute inflammation and radiographically by bone fragmentation, joint dislocation, and debris formation. Stage 2 involves early healing and absorption of fine debris.

Question 40

In the operative management of a displaced distal radius fracture using a volar Henry approach, the surgeon dissects through an internervous plane. This plane is located between which two structures?

Explanation

The classic volar Henry approach to the distal radius utilizes the internervous plane between the brachioradialis (innervated by the radial nerve) and the flexor carpi radialis (innervated by the median nerve).

Question 41

A 6-year-old boy presents with a Gartland type III supracondylar humerus fracture. His hand is pink but the radial pulse is absent. Following closed reduction and percutaneous pinning, the hand remains pink and pulseless. What is the most appropriate next step in management?

Explanation

A pink, pulseless hand after reduction and pinning of a supracondylar humerus fracture indicates it is well-perfused through collateral circulation. The standard of care is close observation, as the pulse often returns within 24 to 48 hours.

Question 42

During an anterior cruciate ligament (ACL) reconstruction, the femoral tunnel is inadvertently placed too far anteriorly. What is the most likely biomechanical consequence of this technical error?

Explanation

An anteriorly placed femoral tunnel in ACL reconstruction results in a graft that tightens excessively as the knee flexes. This restricts deep knee flexion and increases the risk of premature graft failure or rupture.

Question 43

A 4-month-old infant is being treated with a Pavlik harness for developmental dysplasia of the hip (DDH). At a follow-up visit, the mother notes that the child is no longer kicking the affected leg. Examination reveals an inability to actively extend the knee. Which of the following is the most likely cause?

Explanation

Hyperflexion of the hip in a Pavlik harness can lead to compression and temporary paralysis of the femoral nerve. This typically resolves spontaneously once the harness is adjusted to reduce the degree of hip flexion or temporarily removed.

Question 44

A 25-year-old athlete sustains a twisting injury to the knee. Physical examination demonstrates a positive Dial test with more than 10 degrees of increased external rotation at 30 degrees of knee flexion, but symmetrical external rotation at 90 degrees of knee flexion. What does this indicate?

Explanation

Increased external rotation isolated to 30 degrees of flexion with a normal assessment at 90 degrees indicates an isolated posterolateral corner (PLC) injury. If rotation is increased at both 30 and 90 degrees, it suggests a combined PCL and PLC injury.

Question 45

A 12-year-old boy presents with a painful, swollen thigh. Radiographs show a permeative diaphyseal lesion with an onion-skin periosteal reaction. Histology reveals small round blue cells. Which chromosomal translocation is most characteristically associated with this tumor?

Explanation

This presentation is classic for Ewing sarcoma, which is characterized by the t(11;22) chromosomal translocation. This specific genetic mutation results in the EWS-FLI1 fusion protein, an aberrant transcription factor.

Question 46

Recombinant human bone morphogenetic protein-2 (rhBMP-2) is utilized in anterior cervical discectomy and fusion (ACDF) to enhance arthrodesis rates. Which of the following is the most significant recognized complication associated with its use in the anterior cervical spine?

Explanation

The use of rhBMP-2 in the anterior cervical spine is highly associated with significant prevertebral soft tissue swelling. This can lead to severe dysphagia, airway compromise, and occasionally requires emergency intubation.

Question 47

A 35-year-old trauma patient presents with a hemodynamically unstable open-book pelvic fracture (APC type II). You decide to apply a non-invasive circumferential pelvic binder. To achieve maximal reduction of the symphysis pubis, over which anatomical landmark should the binder be centered?

Explanation

Circumferential pelvic binders are most effective at reducing pelvic volume when placed directly over the greater trochanters. Placement over the iliac crests is biomechanically less effective and can paradoxically widen the pelvic ring.

Question 48

A 55-year-old man who underwent a total hip arthroplasty 3 years ago presents with a loud, audible squeaking noise from his hip with movement. Radiographs show well-fixed components. Which bearing surface combination is most classically associated with this phenomenon?

Explanation

Squeaking is a specific and well-documented complication of ceramic-on-ceramic total hip arthroplasty. It is often related to component malposition, microseparation, or stripe wear.

Question 49

A 30-year-old man sustains a closed tibial shaft fracture. Two hours later, he develops severe pain out of proportion to the injury. Which of the following absolute criteria is most specific for diagnosing acute compartment syndrome and indicating fasciotomy?

Explanation

A delta pressure (diastolic blood pressure minus the measured compartment pressure) of less than 30 mmHg is considered the most reliable indicator for acute compartment syndrome. Relying purely on an absolute pressure threshold can lead to overtreatment or undertreatment depending on systemic hemodynamics.

Question 50

A 28-year-old overhead athlete presents with posterior shoulder pain and profound weakness in external rotation. Forward elevation strength is normal. Examination reveals isolated atrophy of the infraspinatus. An MRI shows a paralabral cyst. Where is the most likely location of the nerve compression?

Explanation

Isolated weakness and atrophy of the infraspinatus points to compression of the suprascapular nerve at the spinoglenoid notch. Compression at the suprascapular notch would typically involve denervation of both the supraspinatus and infraspinatus muscles.

Question 51

A 60-year-old woman is treated non-operatively in a cast for a minimally displaced Colles fracture. Six weeks later, after cast removal, she suddenly loses the ability to actively extend her thumb interphalangeal joint. What is the most appropriate definitive management for this complication?

Explanation

Spontaneous rupture of the EPL tendon post-distal radius fracture is due to ischemia or attrition over Lister's tubercle. Because the tendon ends retract and degenerate, primary repair is usually impossible, making an EIP to EPL transfer the gold standard.

Question 52

A 22-year-old football player sustains a midfoot injury. Weight-bearing radiographs demonstrate widening of the space between the first and second metatarsals. The primary ligament injured in this condition connects which two anatomical structures?

Explanation

The Lisfranc ligament is a strong interosseous ligament that spans from the lateral aspect of the medial cuneiform to the medial aspect of the base of the second metatarsal. Its disruption causes midfoot instability and a classic diastasis on radiographs.

Question 53

A 45-year-old man presents to the emergency department with severe lower back pain, new-onset bilateral leg weakness, and urinary retention with overflow incontinence. MRI confirms a massive L4-L5 central disc herniation. To maximize the chance of complete neurological recovery, surgical decompression should ideally be performed within what timeframe from symptom onset?

Explanation

Cauda equina syndrome is an orthopedic and neurosurgical emergency. Current literature strongly supports that surgical decompression within 48 hours of symptom onset significantly improves the likelihood of a complete return of bowel and bladder function.

Question 54

An obese 13-year-old boy is diagnosed with a stable left slipped capital femoral epiphysis (SCFE). The surgeon is debating whether to prophylactically pin the contralateral, asymptomatic right hip. If prophylactic pinning is performed, which of the following is the most likely complication associated with this specific intervention?

Explanation

Prophylactic pinning of the contralateral hip in SCFE is controversial due to procedural risks. The most significant specific risk of the pinning itself, particularly if the start point is below the lesser trochanter, is creating a stress riser that leads to a subtrochanteric femur fracture.

Question 55

A 35-year-old construction worker presents with a swollen, painful index finger 3 days after a puncture wound. Which of the following represents the four classic Kanavel signs of pyogenic flexor tenosynovitis?

Explanation

Kanavel's four cardinal signs of flexor tenosynovitis are a flexed resting posture of the digit, fusiform (sausage-like) swelling, exquisite pain on passive extension, and tenderness along the entire course of the flexor tendon sheath.

Question 56

A 40-year-old male presents with an APC III pelvic ring injury and hemodynamic instability. Despite a correctly placed pelvic binder, he remains hypotensive. What is the most common anatomical source of the hemorrhage in this scenario?

Explanation

The presacral venous plexus and cancellous bone bleeding are the most common sources of hemorrhage in pelvic ring injuries. Arterial bleeding occurs in about 10-20% of cases, typically involving the superior gluteal or internal pudendal arteries.

Question 57

A 6-year-old boy sustains a completely displaced extension-type supracondylar humerus fracture. After closed reduction and percutaneous pinning, the hand remains pink and pulseless. What is the next best step in management?

Explanation

A pink, pulseless hand following adequate reduction and pinning of a supracondylar humerus fracture indicates sufficient collateral circulation. Observation for 24-48 hours is indicated as pulses often return; immediate exploration is reserved for a white, pulseless hand.

Question 58

A 30-year-old male sustains a vertical, high-shear femoral neck fracture (Pauwels Type III). Which of the following biomechanical constructs provides the greatest resistance to vertical shear forces and varus collapse?

Explanation

A sliding hip screw (SHS) combined with a derotation screw provides superior biomechanical resistance to vertical shear forces compared to multiple cancellous screws in high-angle fractures. This reduces the risk of varus collapse and nonunion in young adults.

Question 59

An 18-year-old male presents with deep knee pain. Radiographs show a lytic lesion in the distal femur with a "sunburst" periosteal reaction. Biopsy reveals malignant spindle cells producing osteoid. Which genetic mutations are most commonly associated with this pathology?

Explanation

The clinical and histologic picture describes conventional osteosarcoma. Mutations in tumor suppressor genes such as RB1 (retinoblastoma) and TP53 are highly associated with the development of osteosarcoma.

Question 60

A 25-year-old female sustains a closed middle-third humeral shaft fracture with a primary radial nerve palsy. A closed reduction and splinting are performed. Post-reduction, the radial nerve palsy persists. What is the most appropriate management of the nerve injury?

Explanation

Primary radial nerve palsy in the setting of a closed humeral shaft fracture is managed with observation, as spontaneous recovery occurs in over 90% of cases. Exploration is reserved for open fractures, penetrating injuries, or palsy developing secondary to reduction.

Question 61

A 55-year-old manual laborer presents with chronic wrist pain. Radiographs reveal advanced scapholunate advanced collapse (SLAC) with degenerative changes involving the radioscaphoid joint and the entire scaphoid facet of the radius, sparing the capitolunate joint. What SLAC stage does this represent?

Explanation

SLAC Stage II involves osteoarthritis of the entire radioscaphoid joint. Stage III involves the capitolunate joint, and Stage I is limited to the radial styloid-scaphoid articulation.

Question 62

In a 7-year-old boy diagnosed with Legg-Calve-Perthes disease, which of the following radiographic classifications is most prognostic for final hip outcome and guides surgical decision-making?

Explanation

The Herring Lateral Pillar classification assesses the height of the lateral aspect of the capital femoral epiphysis during the fragmentation stage. It is the most reliable prognostic indicator for long-term hip sphericity.

Question 63

A 45-year-old male is diagnosed with acute Cauda Equina Syndrome secondary to a massive L4-L5 disc herniation. Surgical decompression is most optimal to maximize the return of bladder and bowel function if performed within which time frame?

Explanation

Current literature suggests that surgical decompression within 24 to 48 hours of symptom onset significantly improves outcomes for bowel, bladder, and sexual function. Outcomes rapidly deteriorate if delayed beyond 48 hours.

Question 64

A 4-month-old infant is treated with a Pavlik harness for Developmental Dysplasia of the Hip (DDH). The mother notes that the child is no longer actively extending the knee on the treated side. What is the most likely cause?

Explanation

Femoral nerve palsy is a known complication of the Pavlik harness, typically caused by excessive hip flexion pressing the nerve against the inguinal ligament. The harness must be removed or adjusted immediately to allow nerve recovery.

Question 65

A 32-year-old athlete sustains an acute complete Achilles tendon rupture. He opts for non-operative management with an early functional rehabilitation protocol. Compared to open surgical repair, this non-operative approach is associated with:

Explanation

Functional rehabilitation protocols for non-operative Achilles ruptures yield similar re-rupture rates to surgical repair. The primary advantage of non-operative management is avoiding surgical soft-tissue complications and infections.

Question 66

A 25-year-old sustains an acute traumatic knee dislocation (KD III). The Ankle-Brachial Index (ABI) is 0.85 in the affected limb. What is the most appropriate next step in management?

Explanation

An ABI of less than 0.9 in the setting of a knee dislocation is highly suspicious for a vascular injury. A CT angiogram is the gold standard diagnostic step to evaluate the popliteal artery before proceeding to surgical intervention.

Question 67

A 65-year-old woman undergoes volar locked plating for a displaced distal radius fracture. Six months later, she is unable to actively flex the interphalangeal joint of her thumb. What is the most likely cause of this complication?

Explanation

Placement of a volar plate distal to the watershed line of the distal radius can cause attrition and subsequent rupture of the Flexor Pollicis Longus (FPL) tendon. This presents as a delayed inability to actively flex the thumb IP joint.

Question 68

Denosumab is effectively used in the treatment of recurrent or unresectable Giant Cell Tumor (GCT) of bone. What is its specific mechanism of action?

Explanation

Denosumab is a monoclonal antibody that targets and binds to RANKL, preventing it from activating RANK. In GCT, neoplastic stromal cells overexpress RANKL, and denosumab halts the resulting osteoclast-mediated osteolysis.

Question 69

A 12-year-old boy presents with a stable Slipped Capital Femoral Epiphysis (SCFE) of the left hip. Which of the following is an established indication for prophylactic pinning of the asymptomatic contralateral hip?

Explanation

Prophylactic pinning of the contralateral hip in SCFE is highly recommended for patients with endocrine disorders (e.g., hypothyroidism) or those presenting at a very young age (<10 years), as they have a significantly higher risk of bilateral involvement.

Question 70

A 68-year-old male is undergoing a total hip arthroplasty and asks about the specific risks of using a ceramic-on-ceramic bearing surface. Which of the following is a well-documented complication unique to this bearing combination?

Explanation

Ceramic-on-ceramic bearings offer ultra-low wear rates and no risk of metallosis. However, they are uniquely associated with audible squeaking during motion in a small percentage of patients, which can cause significant dissatisfaction.

Question 71

A 12-year-old boy with renal osteodystrophy presents with a limp and hip pain. Radiographs confirm a unilateral slipped capital femoral epiphysis (SCFE). Which of the following is the most appropriate management regarding the contralateral hip?

Explanation

Prophylactic pinning of the contralateral hip is highly recommended in patients with endocrine or metabolic disorders (e.g., renal osteodystrophy, hypothyroidism) due to the high risk of bilateral SCFE. Routine prophylactic pinning in idiopathic cases remains controversial.

Question 72

Which of the following histologic variants of osteosarcoma typically carries the most favorable prognosis?

Explanation

Parosteal osteosarcoma is a low-grade surface lesion that carries the best prognosis among osteosarcoma variants. Telangiectatic and classic intramedullary variants are high-grade and have a significantly poorer prognosis.

Question 73

A 35-year-old male sustains a vertically unstable (Denis Zone 3) sacral fracture following a fall from height. Which of the following neurologic deficits is most specifically associated with this injury pattern?

Explanation

Denis Zone 3 sacral fractures involve the central sacral canal and carry a high risk (up to 60%) of bowel, bladder, and sexual dysfunction due to injury to the sacral nerve roots (S2-S4). Zones 1 and 2 are more associated with unilateral lower extremity radiculopathies.

Question 74

During anterior cruciate ligament (ACL) reconstruction, understanding the anatomy of the native bundles is crucial. Which of the following accurately describes the primary function of the anteromedial (AM) bundle of the ACL?

Explanation

The anteromedial (AM) bundle of the ACL is the primary restraint to anterior tibial translation when the knee is flexed to 90 degrees. The posterolateral (PL) bundle is tight in extension and provides primary rotatory stability.

Question 75

A 65-year-old patient presents with thigh pain 12 years after a cementless total hip arthroplasty. Radiographs show eccentric polyethylene wear and significant periprosthetic radiolucent lines. What is the primary biological mediator initiating this osteolysis?

Explanation

Polyethylene wear debris undergoes phagocytosis by macrophages, leading to the release of inflammatory cytokines such as IL-1, IL-6, and TNF-alpha. These cytokines stimulate osteoclast-mediated bone resorption, resulting in aseptic loosening.

Question 76

A 25-year-old male is involved in a motor vehicle accident and sustains a unilateral cervical facet dislocation at C5-C6. What is the most common mechanism of injury for this specific pathology?

Explanation

Unilateral cervical facet dislocations typically result from a mechanism of flexion, distraction, and rotation. Bilateral facet dislocations generally result from a severe flexion-distraction injury without the rotational component.

Question 77

A 22-year-old snowboarder sustains a proximal pole scaphoid fracture. The high risk of avascular necrosis in this fracture pattern is primarily due to the anatomy of its blood supply, which is derived mostly from the:

Explanation

The proximal pole of the scaphoid is susceptible to avascular necrosis because its blood supply enters distally and flows retrogradely. This blood supply is primarily provided by the dorsal carpal branch of the radial artery.

Question 78

During secondary fracture healing, the soft callus transitions into a hard callus. Which type of collagen dominates the extracellular matrix during the hard callus phase?

Explanation

The hard callus phase of secondary bone healing is characterized by the replacement of woven bone and cartilage with lamellar bone. Lamellar bone is predominantly composed of Type I collagen, unlike the soft callus which is rich in Type II collagen.

Question 79

A 30-year-old male undergoes antegrade intramedullary nailing for a distal third femoral shaft fracture. Which of the following coronal and sagittal plane malalignments is most commonly seen post-operatively in this specific fracture pattern?

Explanation

Distal third femur fractures are prone to a valgus and apex anterior (procurvatum) deformity during intramedullary nailing. This is due to the pull of the gastrocnemius posteriorly and the adductor magnus medially.

Question 80

A 2-year-old girl is diagnosed with developmental dysplasia of the hip (DDH) after presenting with a painless limp. Which of the following is the most appropriate definitive management?

Explanation

In children aged 18 months to 3 years with late-diagnosed DDH, open reduction is usually required, often supplemented with a pelvic osteotomy (e.g., Salter) or femoral shortening osteotomy. The Pavlik harness is indicated for infants under 6 months.

Question 81

A 55-year-old female presents with a destructive lesion in her proximal femur featuring popcorn calcifications and endosteal scalloping > 2/3 of the cortical thickness. Biopsy confirms a grade II chondrosarcoma. What is the standard of care?

Explanation

Chondrosarcomas (grade II and III) are highly resistant to both chemotherapy and radiation. The standard treatment is wide surgical resection with negative margins.

Question 82

A 45-year-old man presents with severe right leg pain, weakness in ankle dorsiflexion, and numbness extending to the dorsum of his foot. MRI reveals a large posterolateral disc herniation at the L4-L5 level. Which nerve root is most likely affected?

Explanation

In the lumbar spine, a posterolateral disc herniation typically affects the traversing nerve root, which is the root of the lower segment. Thus, an L4-L5 herniation compresses the traversing L5 nerve root.

Question 83

A 35-year-old male sustains a high-energy Schatzker VI tibial plateau fracture. Severe soft tissue swelling and fracture blisters are present. What is the most appropriate clinical indicator that the soft tissues are ready for definitive open reduction and internal fixation?

Explanation

High-energy tibial plateau fractures often require delayed definitive fixation using a spanning external fixator. Definitive surgery should be delayed until the reappearance of skin wrinkles, indicating that swelling has subsided enough to allow safe surgical incisions.

Question 84

During a total knee arthroplasty (TKA), the surgeon inadvertently places the femoral component in excessive internal rotation. What is the most likely clinical consequence of this error?

Explanation

Internal rotation of the femoral component in a TKA shifts the trochlear groove medially relative to the extensor mechanism. This increases the Q-angle, leading to lateral patellar tilt, subluxation, and anterior knee pain.

Question 85

A 22-year-old collegiate baseball pitcher presents with a symptomatic Type II SLAP tear that has failed conservative management. Which surgical intervention is most appropriate?

Explanation

In young, active overhead throwing athletes, the preferred surgical treatment for a Type II SLAP tear is arthroscopic repair. Biceps tenodesis alters the anatomy and is generally reserved for older patients or those with recurrent tears.

Question 86

A patient presents with Anterior Interosseous Nerve (AIN) syndrome. On physical examination, they are unable to form an "OK" sign. Which of the following muscles is definitively spared in an isolated AIN palsy?

Explanation

The AIN innervates the flexor pollicis longus, pronator quadratus, and the flexor digitorum profundus to the index and middle fingers. The flexor digitorum superficialis is innervated by the main trunk of the median nerve and is completely spared.

Question 87

A 70-year-old male develops a prosthetic joint infection 3 weeks after a total hip arthroplasty. Which of the following organisms is most commonly responsible for acute, early post-operative infections?

Explanation

Early prosthetic joint infections (within 3 months) are typically caused by highly virulent organisms, most commonly Staphylococcus aureus. Delayed infections (3-24 months) are more often caused by low-virulence organisms like Staphylococcus epidermidis.

Question 88

A 4-year-old boy sustains an isolated, closed, length-stable spiral fracture of the femoral shaft. Which of the following is the optimal position for hip and knee immobilization in a spica cast?

Explanation

For pediatric femoral shaft fractures in young children, a spica cast is often applied with the hips and knees flexed to 90 degrees. This 90-90 position relaxes the deforming muscles, maintains fracture length, and prevents the child from pistoning within the cast.

Question 89

A 45-year-old male sustains an APC-III pelvic ring injury. After pelvic binder application and 2 liters of crystalloid, his systolic BP remains 75 mmHg. The FAST exam is negative. What is the most appropriate next step in management?

Explanation

In a hemodynamically unstable patient with an unstable pelvic fracture and a negative FAST exam, hemorrhage is likely retroperitoneal. Preperitoneal pelvic packing (or angiography, depending on institutional protocol) is the treatment of choice for mechanical hemostasis.

Question 90

A 28-year-old male is 6 months status-post anterior cruciate ligament (ACL) reconstruction. He complains of an audible clunk and a painful block to terminal knee extension. MRI is likely to reveal a lesion consisting primarily of what tissue type?

Explanation

This patient has a Cyclops lesion, which is localized anterior arthrofibrosis consisting of a fibrovascular nodule. It typically causes a physical block to terminal knee extension and requires arthroscopic excision.

Question 91

A 22-year-old rugby player presents with an inability to flex the distal interphalangeal (DIP) joint of his ring finger. Ultrasound confirms the flexor digitorum profundus (FDP) tendon has retracted into the palm. What is the maximum recommended time frame for primary repair to avoid myotendinous contracture?

Explanation

This is a Type I Jersey finger (FDP avulsion retracted into the palm), which completely disrupts the vincula. It requires surgical repair within 7 to 10 days before the tendon becomes irreparably contracted and ischemic.

Question 92

A 55-year-old female presents with neck pain radiating to her right thumb. Examination reveals weakness in wrist extension and a diminished brachioradialis reflex. Which cervical disc level is most likely herniated?

Explanation

A C5-C6 disc herniation compresses the C6 nerve root. C6 radiculopathy typically presents with weakness in wrist extension and elbow flexion, numbness in the thumb, and a diminished brachioradialis reflex.

Question 93

An 18-year-old male undergoes neoadjuvant chemotherapy followed by wide local excision of a distal femur osteosarcoma. Which of the following histologic findings in the resected specimen is the most significant predictor of long-term survival?

Explanation

The percentage of tumor necrosis following neoadjuvant chemotherapy is the single most important prognostic factor in osteosarcoma. Greater than 90% necrosis indicates a good response to chemotherapy and correlates with improved survival.

Question 94

A 68-year-old female complains of a painful catch at 40 degrees of flexion when extending her knee, 1 year after a posterior-stabilized total knee arthroplasty (TKA). What is the underlying pathophysiology of her symptoms?

Explanation

Patellar clunk syndrome occurs primarily in posterior-stabilized TKA designs. It is caused by a fibrous nodule forming at the superior pole of the patella that catches within the intercondylar box during active extension.

Question 95

A 35-year-old male sustains a high-energy varus and axial load injury to his knee, resulting in a medial tibial plateau fracture with coronal extension. Which surgical approach and fixation strategy is most critical to prevent displacement of this fracture pattern?

Explanation

Medial tibial plateau fractures with a coronal split (posteromedial fragment) are highly unstable. They typically require a posterior or posteromedial approach with an antiglide buttress plate to counteract the deforming shear forces.

Question 96

The watershed area of the Achilles tendon is the most common site of spontaneous rupture. This region is located 2 to 6 cm proximal to the calcaneal insertion and is primarily supplied by the vascular watershed of which two arteries?

Explanation

The Achilles tendon receives its blood supply predominantly from branches of the peroneal and posterior tibial arteries. The watershed zone 2-6 cm proximal to the insertion represents an area of relative hypovascularity prone to rupture.

Question 97

During the process of endochondral ossification in fracture healing, which transcription factor is considered the master regulator for differentiating mesenchymal stem cells into the osteoblast lineage?

Explanation

Runx2 (CBFA1) is the primary transcription factor required for osteoblast differentiation. By contrast, SOX9 regulates chondrogenesis, and PPAR-gamma directs adipogenesis.

Question 98

A 12-year-old obese male presents with acute left groin pain and inability to bear weight after a minor fall. Radiographs demonstrate a slipped capital femoral epiphysis (SCFE). He is classified as having an unstable SCFE. What is the most common severe complication associated with this specific classification?

Explanation

By definition, an unstable SCFE is one in which the patient cannot bear weight even with crutches. This instability significantly increases the risk of disrupting the epiphyseal blood supply, leading to avascular necrosis rates as high as 50%.

Question 99

A 45-year-old female sustains a non-displaced fracture of the distal radius. Four weeks later, she presents with sudden inability to actively extend the interphalangeal joint of her thumb. Which of the following is the most likely cause of this complication?

Explanation

Extensor pollicis longus (EPL) tendon rupture is a known complication of non-displaced distal radius fractures. It typically occurs due to mechanical attrition over the fracture callus at Lister's tubercle or localized ischemia.

Question 100

A 65-year-old male with progressive adult spinal deformity presents for surgical planning. His pelvic incidence (PI) is 60 degrees. To achieve optimal sagittal balance and minimize the risk of adjacent segment disease, what should his target postoperative lumbar lordosis (LL) be?

Explanation

To maintain optimal sagittal balance in adult spinal deformity, the surgical goal is to match lumbar lordosis to pelvic incidence within 10 degrees (PI - LL = +/- 10 degrees). Therefore, a target of 60 degrees is ideal for this patient.

Orthopedic Board Review: Set 861 - 100 High-Yield MCQs

Orthopedic Surgery Board Review: 100 High-Yield MCQs | Mock Exam Set 849 | Dr. Mohammed Hutaif

Key Takeaway

Orthopedic Surgery Board Review: 100 High-Yield MCQs | Mock Exam Set 849 | Dr. Mohammed Hutaif

Chapter Index