In a patient with a C5-6 herniation, the most likely sensory deficit will be in the

radial forearm, thumb, and index finger.

A 16-year-old football player is participating in the second session of two-a-day preseason practices. He complains of dizziness and fatigue. He is brought to the sideline by the athletic trainer where examinationdemonstrates confusion and disorienta

Rapid cooling via ice bath, cold water and fans

A 56-year-old mechanic has had pain in the hypothenar region of his dominant right hand for the past 6 months. He reports weakness in his grip and pain is worse with activity. Which of the following examination findings is most suggestive of a cervic

Relief of symptoms with shoulder abduction (placing hand over the head)

You are counseling a 55-year-old woman for a right carpal tunnel release. What can you tell her about the treatment benefit (grip strength and paresthesia relief) 1 year after surgery compared with continued splinting, NSAID use, physical therapy, an

Increase in grip strength and decrease in paresthesias

Figures 21a and 21b show a transverse MRI scan at L4/5 and a lateral radiograph of a 75-year-old man with a 2-year history of worsening low back and bilateral leg pain that occurs with ambulation beyond approximately a half a block. Management consis

Laminectomy and posterior spinal fusion of L4/5

At the level of tibial bone resection in total knee arthroplasty, where does the common peroneal nerve lie?

Superficial to the lateral head of the gastrocnemius

Free Orthopedics Review: Practice MCQs with Dr. Hutaif

Question 1

A 45-year-old male undergoes revision internal fixation for a femoral shaft nonunion. The surgeon plans to use a stainless steel plate with the retained titanium screws from the index procedure. Which of the following best describes the primary type of corrosion that is likely to occur?

Explanation

Galvanic corrosion occurs when two dissimilar metals (e.g., titanium and stainless steel) are placed in contact within a conductive fluid environment (body fluid). The less noble metal undergoes accelerated corrosion due to electrochemical differences.

Question 2

A 30-year-old male presents after a motorcycle collision with a hemodynamically unstable anteroposterior compression (APC) type III pelvic ring injury. After a pelvic binder is placed, he remains hypotensive despite aggressive fluid resuscitation. FAST exam is negative. What is the most appropriate next step in acute management?

Explanation

In a hemodynamically unstable patient with a pelvic ring injury despite binder application and adequate resuscitation (and a negative FAST exam), preperitoneal pelvic packing or pelvic angiography with embolization is indicated. Packing directly addresses the most common source of bleeding (venous plexus). A C-clamp is contraindicated in APC injuries.

Question 3

Which of the following is the strongest clinical indication for prophylactic in situ pinning of the contralateral hip in a 12-year-old male presenting with a unilateral slipped capital femoral epiphysis (SCFE)?

Explanation

Patients with underlying endocrine disorders (such as hypothyroidism, panhypopituitarism, or renal osteodystrophy) or prior radiation therapy have a significantly higher risk of bilateral SCFE. In these atypical presentations, prophylactic pinning of the contralateral hip is highly recommended.

Question 4

During the physical examination of a 22-year-old athlete, the Dial test demonstrates 15 degrees of increased external rotation at 30 degrees of knee flexion compared to the contralateral side, but symmetric external rotation at 90 degrees. Which structure is most likely injured?

Explanation

The Dial test evaluates external rotation of the tibia. Increased external rotation (>10 degrees compared to the normal side) at 30 degrees only indicates an isolated posterolateral corner (PLC) injury. Increased external rotation at both 30 and 90 degrees indicates injury to both the PLC and the PCL.

Question 5

Which of the following factors is most strongly associated with increased volumetric wear of highly cross-linked polyethylene in total hip arthroplasty?

Explanation

Increased femoral head size increases the sliding distance per step, which inherently increases volumetric wear of the polyethylene liner, although it decreases the risk of dislocation. While highly cross-linked polyethylene mitigates wear compared to conventional polyethylene, the physical relationship with head size remains.

Question 6

A 65-year-old male presents with deteriorating handwriting, frequent falls, and hyperreflexia in the bilateral lower extremities. MRI of the cervical spine shows severe stenosis at C5-C6. Which of the following physical exam findings is most specific for cervical myelopathy at this level?

Explanation

The inverted radial reflex (or inverted supinator reflex) is highly specific for cervical myelopathy localized to the C5-C6 level. It is elicited by tapping the brachioradialis tendon, resulting in paradoxical finger flexion. Hoffmann's sign is sensitive for upper motor neuron lesions but less specific.

Question 7

A 40-year-old female presents with aching pain in her proximal forearm and paresthesias in the radial three-and-a-half digits. Symptoms are not exacerbated by wrist flexion but worsen with resisted forearm pronation. Which of the following physical exam findings best differentiates this condition from carpal tunnel syndrome?

Explanation

The palmar cutaneous branch of the median nerve branches off proximal to the carpal tunnel and supplies sensation to the thenar eminence. In Pronator Syndrome (proximal median nerve compression), sensation over the thenar eminence is decreased. In Carpal Tunnel Syndrome, this branch is spared, and thenar sensation is normal.

Question 8

A 24-year-old professional soccer player sustains an acute fracture at the metaphyseal-diaphyseal junction of the fifth metatarsal. He wishes to return to play as soon as possible. What is the most appropriate management?

Explanation

A fracture at the metaphyseal-diaphyseal junction of the fifth metatarsal is a Jones fracture, which occurs in a vascular watershed area prone to nonunion. In elite athletes, early intramedullary screw fixation is the standard of care to reduce the risk of nonunion and allow a predictable, rapid return to play.

Question 9

A 35-year-old female presents with knee pain. Radiographs reveal an eccentric, lytic, epiphyseal lesion in the distal femur extending to the subchondral bone without a sclerotic rim. Biopsy shows multinucleated giant cells in a background of mononuclear stromal cells. Which of the following is the most appropriate targeted medical therapy?

Explanation

The clinical and histologic description is classic for a Giant Cell Tumor (GCT) of bone. Denosumab, a monoclonal antibody against RANKL, is specifically used to treat locally advanced or unresectable GCTs by inhibiting the RANK-RANKL interaction, thereby halting the osteoclast-like giant cells.

Question 10

A 55-year-old diabetic male presents with severe right leg pain, swelling, and erythema out of proportion to physical exam findings. Which of the following laboratory parameters is included in the Laboratory Risk Indicator for Necrotizing Fasciitis (LRINEC) score?

Explanation

The LRINEC score uses six routine laboratory parameters to risk-stratify for necrotizing fasciitis: C-reactive protein (CRP), total White Blood Cell (WBC) count, Hemoglobin, Serum sodium, Serum creatinine, and Serum glucose. Hyponatremia (< 135 mmol/L) scores 2 points.

Question 11

During secondary fracture healing, what is the predominant collagen type synthesized during the soft callus (cartilaginous) phase?

Explanation

Secondary fracture healing relies heavily on endochondral ossification. During the soft callus phase, chondrocytes proliferate and predominantly produce Type II collagen (cartilage). This is later replaced by Type I collagen as the soft callus mineralizes into a hard callus (woven bone).

Question 12

A 28-year-old male sustains a Hawkins Type III fracture of the talar neck. Which of the following sources of blood supply to the talus is most likely to remain intact in this specific injury pattern?

Explanation

A Hawkins Type III fracture involves a talar neck fracture with dislocation of both the subtalar and tibiotalar (ankle) joints. This pattern severely disrupts all three major blood supplies (artery of the tarsal canal, sinus tarsi, and deltoid branch), leading to a near 100% rate of avascular necrosis. None remain consistently intact.

Question 13

A 4-week-old female is diagnosed with developmental dysplasia of the hip (DDH) and placed in a Pavlik harness. Two weeks later, the parents report she has an inability to actively extend her knee on the treated side. What is the most likely cause?

Explanation

An inability to extend the knee points to a femoral nerve palsy, a known complication of the Pavlik harness. It is caused by excessive hyperflexion of the hip, which stretches or compresses the femoral nerve. Excessive abduction in the harness, by contrast, is associated with avascular necrosis.

Question 14

A 22-year-old baseball pitcher presents with posterior shoulder pain during the late cocking phase of throwing. MRI arthrogram reveals a 'peel-back' lesion of the superior labrum. What is the primary pathophysiologic mechanism of internal impingement in this athlete?

Explanation

Internal impingement in overhead athletes occurs in extreme abduction and external rotation (late cocking phase). The undersurface of the posterior rotator cuff becomes impinged (pinched) between the greater tuberosity of the humeral head and the posterosuperior glenoid labrum, often causing SLAP lesions and partial articular-sided cuff tears.

Question 15

Which of the following bearing surface combinations in total hip arthroplasty is most commonly associated with the phenomenon of 'stripe wear'?

Explanation

Stripe wear is a linear pattern of wear unique to ceramic-on-ceramic articulations. It is caused by micro-separation of the femoral head from the acetabular liner during the swing phase of gait, leading to edge loading when the head re-engages the liner at heel strike.

Question 16

According to the Thoracolumbar Injury Classification and Severity Score (TLICS), which of the following morphologic injury patterns is assigned the highest point value?

Explanation

In the TLICS system for thoracolumbar trauma, points for morphology are assigned as follows: Compression fracture = 1 point; Burst fracture = 2 points; Translation/rotation = 3 points; Distraction = 4 points. Thus, distraction injuries are deemed the most unstable morphology.

Question 17

A 30-year-old carpenter lacerates his index finger over the middle phalanx, dividing both the flexor digitorum profundus (FDP) and flexor digitorum superficialis (FDS) tendons. Based on the Verdan flexor tendon zone classification, in which zone did this injury occur?

Explanation

Zone II extends from the proximal edge of the A1 pulley (distal palmar crease) to the insertion of the FDS on the middle phalanx. It contains both the FDS and FDP tendons within the tight fibro-osseous sheath. Historically known as 'no man's land', lacerations here require meticulous repair.

Question 18

A 52-year-old patient with poorly controlled diabetes presents with a swollen, warm, and erythematous right foot. Radiographs reveal fragmentation, periarticular debris, and joint subluxation at the tarsometatarsal joints. According to the Eichenholtz classification for Charcot neuroarthropathy, what stage does this represent?

Explanation

The Eichenholtz classification divides Charcot arthropathy into stages: Stage 0 (prodromal, normal x-rays), Stage I (development/fragmentation, characterized by debris, subluxation, and fragmentation), Stage II (coalescence, absorption of fine debris, early fusion), and Stage III (reconstruction, consolidation, remodeling).

Question 19

A 14-year-old male presents with a diaphysial lesion of the femur characterized by an 'onion skin' periosteal reaction. A biopsy confirms Ewing sarcoma. Which of the following chromosomal translocations is most commonly associated with this diagnosis?

Explanation

Ewing sarcoma is classically driven by the t(11;22)(q24;q12) translocation in ~85% of cases, resulting in the EWS-FLI1 fusion gene. t(9;22) is seen in myxoid chondrosarcoma; t(12;16) in myxoid liposarcoma; t(X;18) in synovial sarcoma; and t(2;13) in alveolar rhabdomyosarcoma.

Question 20

Which zone of articular cartilage is characterized by the highest concentration of proteoglycans, the lowest concentration of water, and collagen fibers arranged perpendicular to the joint surface?

Explanation

The deep (radial) zone of articular cartilage provides the greatest resistance to compressive loads. It has the highest concentration of proteoglycans, the lowest water content, and collagen fibers oriented perpendicular to the joint line. The superficial zone has the highest water content and parallel collagen fibers.

Question 21

A 4-year-old boy presents with frequent fractures and cranial nerve palsies. Radiographs demonstrate diffusely dense bones with a 'bone-within-bone' appearance. A mutation affecting which of the following is most likely responsible for this condition?

Explanation

This patient has osteopetrosis, a condition caused by osteoclast dysfunction leading to impaired bone resorption. A common autosomal recessive form is caused by a mutation in carbonic anhydrase II (CA II), resulting in an inability to secrete protons and acidify Howship's lacunae, which is required to dissolve bone mineral.

Question 22

A 14-year-old boy presents with thigh pain and fever. Radiographs show a permeative diaphyseal lesion in the femur with a prominent 'onion-skin' periosteal reaction. Biopsy reveals sheets of small round blue cells. Cytogenetic analysis is most likely to show which of the following translocations?

Explanation

Ewing sarcoma is characterized histologically by small round blue cells that are CD99 positive. It classically exhibits the t(11;22) translocation, which fuses the EWS gene to the FLI1 gene. The other translocations correspond to chondrosarcoma/CML (9;22), myxoid liposarcoma (12;16), synovial sarcoma (X;18), and alveolar rhabdomyosarcoma (2;13).

Question 23

During the application of a halo vest, the pins are initially torqued to 8 in-lbs. After 48 hours, the torque on the pins is measured and found to have decreased, despite the pins not visibly moving. Which of the following viscoelastic properties best explains this phenomenon?

Explanation

Stress relaxation is a viscoelastic property defined as a decrease in stress (or torque) over time when a material is held at a constant strain (or deformation). Creep, conversely, is the progressive deformation (strain) of a material over time under a constant load.

Question 24

Bone morphogenetic proteins (BMPs) play a crucial role in osteoinduction during fracture healing. Which of the following intracellular signaling molecules is directly phosphorylated following the binding of a BMP to its cell surface serine/threonine kinase receptor?

Explanation

BMPs belong to the TGF-beta superfamily. When they bind to their specific membrane receptors, the receptors phosphorylate intracellular proteins known as receptor-regulated Smads (specifically Smad 1, 5, and 8). These then form a complex with the co-Smad (Smad 4) and translocate to the nucleus to induce transcription of osteogenic genes.

Question 25

A new rapid diagnostic test for periprosthetic joint infection is implemented in a clinic. If the prevalence of periprosthetic joint infection in the clinic's patient population suddenly doubles while the sensitivity and specificity of the test remain unchanged, which of the following statistical values will increase?

Explanation

Positive predictive value (PPV) is highly dependent on disease prevalence. As the prevalence of a disease increases in a population, the PPV increases, while the negative predictive value (NPV) decreases. Sensitivity, specificity, and likelihood ratios are intrinsic properties of the test itself and do not fluctuate with disease prevalence.

Question 26

A 45-year-old man with a history of severe alcohol use disorder presents with swollen bleeding gums, petechiae, and joint pain. Radiographs of his knees show osteopenia and a dense provisional zone of calcification. The underlying nutritional deficiency in this patient primarily impairs which of the following steps of collagen synthesis?

Explanation

The patient has scurvy caused by Vitamin C (ascorbic acid) deficiency. Vitamin C is a required cofactor for the enzymes prolyl hydroxylase and lysyl hydroxylase. These enzymes are responsible for the hydroxylation of proline and lysine residues in procollagen, a critical step that allows for stable hydrogen bonding and subsequent triple helix formation.

Question 27

A patient sustains a closed midshaft humerus fracture and presents with a dense radial nerve palsy. After 3 weeks of observation, an electromyography (EMG) study is performed. Which of the following EMG findings is most indicative of active axonal denervation?

Explanation

Fibrillation potentials and positive sharp waves appearing roughly 2 to 4 weeks after an injury are the classic EMG signs of active denervation, indicating that muscle fibers have lost their nerve supply and are firing spontaneously. Polyphasic potentials indicate early reinnervation, while high-amplitude, long-duration potentials represent chronic reinnervation (giant motor units).

Question 28

Which of the following describes the primary cellular defect in the physis of a patient with an activating mutation in the Fibroblast Growth Factor Receptor 3 (FGFR3) gene?

Explanation

Achondroplasia is caused by an activating (gain-of-function) mutation in the FGFR3 gene. In normal enchondral ossification, FGFR3 negatively regulates chondrocyte proliferation. The activating mutation leads to an exaggerated inhibitory signal, which severely diminishes chondrocyte proliferation in the proliferative zone of the physis, resulting in rhizomelic short stature.

Question 29

A 62-year-old woman with a history of breast cancer presents with a newly identified lytic lesion in her right proximal femur (peritrochanteric region). The lesion involves 2/3 of the cortical diameter and is highly painful with weight-bearing. According to Mirels' criteria, what is the most appropriate management for this lesion?

Explanation

Mirels' criteria predict the risk of pathologic fracture. The four categories are Site (Upper extremity=1, Lower extremity=2, Peritrochanteric=3), Pain (Mild=1, Moderate=2, Functional=3), Lesion type (Blastic=1, Mixed=2, Lytic=3), and Size (<1/3=1, 1/3-2/3=2, >2/3=3). This patient's score is Peritrochanteric (3) + Functional pain (3) + Lytic (3) + Size >=2/3 (2 or 3) = 11 or 12. A score of 9 or greater carries a high risk of fracture, making prophylactic internal fixation the standard of care.

Question 30

In normal articular cartilage, the highest concentration of proteoglycans and the thickest collagen fibrils oriented perpendicular to the joint surface are found in which of the following zones?

Explanation

The deep (radial) zone of articular cartilage contains the highest concentration of proteoglycans and the lowest concentration of water. The thick Type II collagen fibrils in this zone are oriented strictly perpendicular to the joint surface to effectively resist compressive loads.

Question 31

Tranexamic acid (TXA) is frequently used in orthopedic surgery to reduce perioperative blood loss. Which of the following best describes its primary mechanism of action?

Explanation

Tranexamic acid is a synthetic analog of the amino acid lysine. It exerts its antifibrinolytic effect by competitively binding to the lysine receptor sites on plasminogen, which prevents plasminogen from binding to fibrin and activating into plasmin. This stabilizes existing blood clots.

Question 32

When comparing freeze-dried (lyophilized) cortical allograft to fresh-frozen cortical allograft, which of the following statements is true regarding the freeze-dried allograft?

Explanation

Freeze-drying (lyophilization) depletes major histocompatibility complex (MHC) antigens, significantly decreasing the immunogenicity of the allograft. However, this process alters the physical properties of the bone, markedly reducing its structural and biomechanical strength compared to fresh-frozen allografts. Neither graft contains viable osteoprogenitor cells.

Question 33

Which of the following orthopedic implant materials possesses a modulus of elasticity that most closely matches that of normal human cortical bone, thereby minimizing stress shielding?

Explanation

The modulus of elasticity (stiffness) of cortical bone is roughly 15-20 GPa. Titanium alloys (approx. 110 GPa) are closer to this value than 316L stainless steel (~200 GPa) or Cobalt-chromium (~220 GPa). This relative flexibility helps reduce stress shielding of the adjacent bone compared to stiffer metals. PMMA has a much lower modulus (~3 GPa).

Question 34

A 55-year-old woman presents with bone pain and a radiolucent lesion in her left proximal tibia. Laboratory tests reveal elevated serum calcium, decreased serum phosphate, and elevated alkaline phosphatase. A biopsy of the lesion reveals clusters of multinucleated giant cells within a highly vascularized, fibrous stroma containing abundant hemosiderin deposits. Which of the following is the most likely diagnosis?

Explanation

The patient's laboratory values (hypercalcemia and hypophosphatemia) are pathognomonic for primary hyperparathyroidism. The histologic findings of multinucleated giant cells in a fibrovascular stroma with hemosiderin (which imparts a brown color macroscopically) represent a Brown tumor, which is the hallmark focal lesion of osteitis fibrosa cystica resulting from severe hyperparathyroidism.

Question 35

Which of the following laboratory parameters is assigned the highest point value (4 points) in the Laboratory Risk Indicator for Necrotizing Fasciitis (LRINEC) score if its value exceeds a specific threshold?

Explanation

The LRINEC score is a clinical tool used to distinguish necrotizing fasciitis from other soft tissue infections. The variables are CRP, WBC count, hemoglobin, serum sodium, creatinine, and glucose. A CRP level >= 150 mg/L is assigned the highest individual weight (4 points).

Question 36

A 25-year-old man sustains a severe closed tibial plateau fracture. He is complaining of out-of-proportion pain that is exacerbated by passive stretch of the hallux. His blood pressure is 110/70 mmHg. Compartment pressures are measured using a slit catheter. Which of the following thresholds is widely accepted as an absolute indication for an emergency four-compartment fasciotomy?

Explanation

Acute compartment syndrome is diagnosed when tissue pressure exceeds perfusion pressure. A Delta P (Diastolic Blood Pressure minus absolute Compartment Pressure) of 30 mmHg or less is the widely accepted standard indication for emergent fasciotomy, as it accounts for the patient's systemic perfusion pressure rather than relying strictly on an absolute pressure number.

Question 37

During active bone resorption, osteoclasts attach to the bone matrix to create an isolated microenvironment known as the sealing zone. Which of the following integrin receptors mediates this firm attachment to osteopontin and bone sialoprotein?

Explanation

The alpha-v beta-3 (αvβ3) integrin is highly expressed on the ruffled border and sealing zone of osteoclasts. It is the primary receptor responsible for binding to the RGD (Arg-Gly-Asp) amino acid sequences found in bone matrix proteins like osteopontin and bone sialoprotein, anchoring the osteoclast to the bone surface.

Question 38

A 65-year-old man is scheduled for a total hip arthroplasty. He has a documented severe, IgE-mediated anaphylactic allergy to penicillin. Which of the following is the most appropriate preoperative prophylactic antibiotic regimen?

Explanation

In patients with a severe, IgE-mediated allergy (e.g., anaphylaxis, bronchospasm, hives) to penicillins, first- and second-generation cephalosporins (like cefazolin and cefuroxime) are generally contraindicated due to the risk of cross-reactivity. Vancomycin or Clindamycin are the standard evidence-based alternative prophylactic agents for joint arthroplasty in this scenario.

Question 39

When a stainless steel plate is fixed with titanium screws in an orthopedic construct, accelerated localized corrosion may occur at the screw-plate interface over time. Which specific type of corrosion is primarily responsible for this degradation?

Explanation

Galvanic corrosion occurs when two electrochemically dissimilar metals (e.g., stainless steel and titanium) are placed in direct physical contact within a conductive fluid environment (body fluids). An electrochemical cell is created where the less noble metal acts as the anode and undergoes accelerated corrosion.

Question 40

A 30-year-old female presents with a slow-growing, painful mass near her knee joint. Imaging reveals a calcified soft-tissue mass adjacent to but not involving the articular cavity. A biopsy reveals a biphasic spindle cell and epithelial cell morphology. Which cytogenetic abnormality is diagnostic for this tumor?

Explanation

The clinical presentation (young adult, painful juxta-articular mass with calcifications) and biphasic histology (epithelial and spindle cells) are classic for synovial sarcoma. This tumor is definitively characterized by the t(X;18)(p11;q11) chromosomal translocation, which results in the SYT-SSX fusion gene.

Question 41

Which bone morphogenetic protein (BMP) is FDA-approved and primarily used as an adjunct for the treatment of acute, open tibial shaft fractures treated with an intramedullary nail?

Explanation

Recombinant human BMP-2 (rhBMP-2) is FDA-approved for acute, open tibial shaft fractures treated with an intramedullary nail. BMP-7 (rhBMP-7) is typically utilized as an alternative to autograft for recalcitrant long bone nonunions.

Question 42

A 14-year-old male presents with distal femur pain. Imaging shows a sunburst periosteal reaction. Biopsy reveals malignant spindle cells producing osteoid. What is the most significant prognostic factor for long-term survival in this patient?

Explanation

The most significant prognostic factor in conventional osteosarcoma is the histologic response to neoadjuvant chemotherapy, defined by the percentage of tumor necrosis. Greater than 90% necrosis portends a significantly better overall prognosis.

Question 43

A 32-year-old male sustains a closed tibial shaft fracture. Two hours later, he develops severe pain out of proportion to the injury. Which of the following is the earliest and most sensitive physical exam finding in acute compartment syndrome?

Explanation

Pain with passive stretch of the muscles in the involved compartment is classically the most sensitive and earliest clinical sign of acute compartment syndrome. Pulselessness and paralysis are late, often irreversible findings.

Question 44

A 6-year-old girl sustains a widely displaced extension-type supracondylar humerus fracture. Upon reduction and pinning, she is unable to flex her thumb interphalangeal joint or index finger distal interphalangeal joint. Which nerve is most likely injured?

Explanation

The anterior interosseous nerve (AIN) is the most commonly injured nerve in extension-type supracondylar humerus fractures. It classically presents with the inability to form an "OK" sign due to weakness of the FPL and FDP to the index finger.

Question 45

According to the 2018 International Consensus Meeting (ICM) criteria, which of the following is considered a major criterion for definitively diagnosing a periprosthetic joint infection (PJI)?

Explanation

The two major criteria for PJI are the presence of a sinus tract communicating with the joint and two positive periprosthetic cultures with phenotypically identical organisms. Purulence alone is no longer considered a major definitive criterion.

Question 46

A 65-year-old male presents with deteriorating handwriting, frequent tripping, and hyperreflexia in all extremities. The Hoffmann sign is positive bilaterally. Which surgical approach is most appropriate for a patient with 4-level cervical spondylotic myelopathy, neutral sagittal alignment, and no significant neck pain?

Explanation

Posterior cervical laminoplasty is ideal for multi-level cervical spondylotic myelopathy in the setting of neutral or lordotic sagittal alignment with minimal axial neck pain. It preserves motion and avoids the morbidity of multi-level anterior surgery or posterior fusion.

Question 47

During an anterior cruciate ligament (ACL) reconstruction using a bone-patellar tendon-bone autograft, the surgeon inadvertently places the femoral tunnel too anteriorly. What is the most likely clinical consequence of this technical error?

Explanation

An anteriorly placed femoral tunnel creates a graft that is loose in extension and tight in flexion. This typically results in a severe restriction of knee flexion, or graft rupture if forced flexion is attempted.

Question 48

A 28-year-old male sustains a volar laceration to his proximal phalanx (Zone II) requiring primary flexor tendon repair. Which of the following rehabilitation protocols best promotes intrinsic tendon healing while minimizing adhesion formation?

Explanation

Early active extension and passive flexion (e.g., modified Duran or Kleinert protocol) minimizes peritendinous adhesions while protecting the newly repaired tendon. Modern protocols rely on controlled tendon glides rather than strict immobilization.

Question 49

A 42-year-old female sustains a lateral compression type II (LC-2) pelvic ring injury. According to the Young-Burgess classification, which of the following specifically defines an LC-2 fracture pattern?

Explanation

A Lateral Compression type II (LC-2) fracture is characterized by an anterior ring injury combined with an ipsilateral crescent fracture of the posterior ilium. An LC-1 involves a sacral compression fracture instead of an iliac wing fracture.

Question 50

Secondary bone healing (callus formation) after a fracture is driven predominantly by which physiologic process?

Explanation

Secondary bone healing involves the formation of a cartilaginous callus that is subsequently mineralized and replaced by bone, a process known as endochondral ossification. Intramembranous ossification bypasses the cartilage phase and occurs in primary bone healing.

Question 51

A 68-year-old female undergoes a primary total hip arthroplasty via a posterior approach. Postoperatively, she experiences recurrent posterior dislocations. Which of the following component malpositioning errors most frequently contributes to this specific instability pattern?

Explanation

Acetabular retroversion (or insufficient anteversion) strongly predisposes the hip to posterior dislocation, particularly during hip flexion and internal rotation. Proper acetabular anteversion (usually 15-20 degrees) is critical for posterior stability.

Question 52

A 4-month-old female with developmental dysplasia of the hip (DDH) is being treated with a Pavlik harness. Three weeks later, her mother notes the infant has decreased active extension of the left knee. What is the most likely iatrogenic cause?

Explanation

Femoral nerve palsy is a known complication of the Pavlik harness, typically caused by excessive hyperflexion of the hips. It presents with decreased active quadriceps function and usually resolves with temporary adjustment or removal of the harness.

Question 53

A 30-year-old male sustains a displaced Hawkins type III talar neck fracture. Which of the following best describes the anatomical disruption associated with this specific classification?

Explanation

A Hawkins type III fracture is a displaced talar neck fracture accompanied by dislocation of both the subtalar and tibiotalar joints. This pattern carries an exceptionally high risk of avascular necrosis of the talar body.

Question 54

A 35-year-old female presents with a giant cell tumor extending into the metaphysis of the proximal tibia. Which targeted pharmacotherapy acts as an effective adjuvant treatment for aggressive or unresectable disease?

Explanation

Denosumab, a monoclonal antibody against RANKL, is highly effective in treating Giant Cell Tumor of Bone (GCTB). It inhibits the RANK-RANKL interaction, effectively suppressing the activation of the osteoclast-like giant cells.

Question 55

A 22-year-old football player with recurrent anterior shoulder dislocations is found to have 25% bipolar bone loss (glenoid and Hill-Sachs lesion). Which of the following is the most appropriate surgical intervention?

Explanation

The Latarjet procedure (coracoid transfer) is indicated for anterior shoulder instability in the setting of critical glenoid bone loss (typically >20-25%). Arthroscopic soft tissue stabilization alone has an unacceptably high failure rate in this scenario.

Question 56

A 25-year-old male injures his midfoot. Weight-bearing radiographs show widening between the first and second metatarsal bases. The primary stabilizing Lisfranc ligament connects which two osseous structures?

Explanation

The true Lisfranc ligament is an oblique intra-articular ligament that connects the lateral aspect of the medial cuneiform to the base of the second metatarsal. It is the keystone stabilizer of the midfoot arch.

Question 57

Ultra-high-molecular-weight polyethylene (UHMWPE) wear debris in total joint arthroplasty primarily leads to osteolysis through the initial activation of which cell type?

Explanation

Macrophages phagocytose particulate UHMWPE wear debris, triggering an inflammatory cascade. They release cytokines (such as TNF-alpha, IL-1, and IL-6) that subsequently recruit and activate osteoclasts, leading to periprosthetic osteolysis.

Question 58

During an open carpal tunnel release, the surgeon must identify and protect the recurrent motor branch of the median nerve. What is the most common anatomic variation of this motor branch?

Explanation

The extraligamentous type with a recurrent course is the most common anatomical variation (approximately 50-80%) of the recurrent motor branch. Transligamentous and subligamentous variants carry a much higher risk of iatrogenic transection.

Question 59

A 24-year-old male has a displaced fracture of the proximal pole of the scaphoid. What anatomical characteristic is the primary reason this specific fracture pattern carries a high rate of nonunion and avascular necrosis?

Explanation

The major blood supply to the scaphoid enters distally and flows proximally, creating a retrograde intraosseous blood supply. Fractures of the proximal pole mechanically isolate this segment from its blood supply, predisposing it to ischemia.

Question 60

A 70-year-old male undergoes a lumbar decompressive laminectomy. During the procedure, the dura is inadvertently torn, resulting in a cerebrospinal fluid (CSF) leak which is primarily repaired. What is the best immediate postoperative management?

Explanation

Following a primary repair of an incidental durotomy, keeping the patient flat for 24-48 hours decreases hydrostatic pressure on the dural repair, minimizing the risk of a persistent CSF leak. Lumbar drains are typically reserved for refractory or unrepairable leaks.

Question 61

A 65-year-old patient presents with osteolysis 10 years after a total hip arthroplasty using a highly cross-linked polyethylene liner. What is the primary mechanism by which highly cross-linked polyethylene reduces wear compared to conventional polyethylene?

Explanation

Cross-linking introduces covalent bonds between adjacent polyethylene chains, significantly reducing adhesive and abrasive wear. Post-irradiation melting or annealing eliminates free radicals to prevent oxidation, but the cross-linking itself primarily reduces wear.

Question 62

A 25-year-old male sustains a closed tibial shaft fracture. Within 12 hours, he develops severe pain out of proportion to the injury. Intracompartmental pressure measurements reveal a pressure of 45 mmHg with a diastolic blood pressure of 60 mmHg. Which of the following is the most appropriate management?

Explanation

The patient has acute compartment syndrome indicated by a delta pressure less than 30 mmHg (60 - 45 = 15 mmHg). A two-incision, four-compartment fasciotomy is the gold standard surgical treatment to adequately decompress the leg.

Question 63

A 14-year-old boy presents with progressive knee pain. Radiographs show a mixed lytic and sclerotic lesion in the distal femoral metaphysis with a Codman triangle. Biopsy confirms high-grade osteosarcoma. What is the most significant prognostic factor for long-term survival in this patient?

Explanation

The degree of tumor necrosis after neoadjuvant chemotherapy is the most reliable prognostic indicator for overall survival in high-grade osteosarcoma. A necrosis rate of 90 percent or greater is considered a good response.

Question 64

A 40-year-old male undergoes open reduction and internal fixation of a radius fracture with a dynamic compression plate. Which type of bone healing is expected to primarily occur at the fracture site?

Explanation

Rigid internal fixation with absolute stability, such as dynamic compression plating, suppresses callus formation and promotes primary (Haversian) bone healing. This process relies on osteoclast cutting cones crossing the fracture site followed by osteoblast bone deposition.

Question 65

A 70-year-old female presents with acute onset of knee pain and swelling 3 years after a total knee arthroplasty. Joint aspiration yields 60,000 WBCs/uL with 95% neutrophils. Which of the following is the most appropriate initial surgical management?

Explanation

For a late, acute hematogenous prosthetic joint infection (or chronic PJI), a two-stage revision with an antibiotic spacer is the gold standard. DAIR is generally reserved for early postoperative infections within 4 weeks of surgery or acute symptom duration less than 3 weeks.

Question 66

A 65-year-old man presents with an enlarging hat size and progressively worsening right thigh pain. Radiographs of the femur show cortical thickening, coarse trabeculae, and bowing. Laboratory tests reveal an isolated, significantly elevated alkaline phosphatase. Which of the following is the primary cellular defect in this condition?

Explanation

The patient has Paget disease of bone, characterized by an initial phase of excessive osteoclast activity followed by a compensatory, but disorganized, osteoblast response. This results in structurally weak woven bone that is prone to deformity and fracture.

Question 67

A 35-year-old male sustains a midshaft humeral fracture and immediately presents with an inability to extend his wrist or fingers. He undergoes closed management in a Sarmiento brace. At 12 weeks, there is no clinical or electromyographic (EMG) evidence of nerve recovery. What is the most appropriate next step?

Explanation

Most radial nerve palsies associated with closed humeral shaft fractures resolve spontaneously. However, if there is no clinical or EMG evidence of recovery by 3 to 4 months, surgical exploration of the nerve is indicated.

Question 68

A 60-year-old woman presents with severe back pain. Radiographs reveal a compression fracture of L2 and multiple punched-out lytic lesions in her skull. Serum protein electrophoresis shows a monoclonal spike. Which of the following is the most likely mechanism of osteolysis in this patient?

Explanation

Multiple myeloma causes osteolytic lesions primarily through the secretion of factors like RANKL, IL-6, and MIP-1 alpha by myeloma cells. These factors potently stimulate osteoclastogenesis while inhibiting osteoblast function.

Question 69

Articular cartilage has a limited capacity for repair following injury. Which of the following zones of articular cartilage contains the highest concentration of proteoglycans and the lowest concentration of water?

Explanation

The deep (radial) zone of articular cartilage has the highest proteoglycan content and the lowest water content. Conversely, the superficial zone has the highest water content and collagen concentration but the lowest proteoglycan content.

Question 70

A 45-year-old farmer sustains an open tibia fracture highly contaminated with soil. He is given broad-spectrum antibiotics and undergoes emergent irrigation and debridement. Which specific antibiotic should be added to his regimen to cover the most likely atypical pathogen associated with this environment?

Explanation

Farm injuries or fractures heavily contaminated with soil are at high risk for Clostridium perfringens infection. High-dose penicillin is added to the standard broad-spectrum regimen to provide specific coverage against these anaerobic, spore-forming bacteria.

Question 71

When inserting a cortical screw for fracture fixation, which of the following modifications will most significantly increase the pull-out strength of the screw?

Explanation

Pull-out strength of a screw is most significantly influenced by the major (outer) diameter of the screw. Decreasing thread pitch also increases pull-out strength, but increasing the outer diameter has a much larger exponential effect.

Question 72

A 4-month-old female infant is diagnosed with developmental dysplasia of the hip (DDH). Ultrasound shows an alpha angle of 45 degrees. The infant is placed in a Pavlik harness. Which of the following positions is most likely to cause iatrogenic avascular necrosis (AVN) of the femoral head in this device?

Explanation

The primary risk factor for avascular necrosis of the femoral head during Pavlik harness treatment is excessive hip abduction. Conversely, excessive hip flexion primarily causes femoral nerve palsy.

Question 73

According to current AAOS and ACCP guidelines, which of the following is the recommended maximum duration of venous thromboembolism (VTE) prophylaxis following an elective total hip arthroplasty in a patient with standard risk?

Explanation

Current guidelines recommend extending VTE prophylaxis for up to 35 days following elective total hip and knee arthroplasty. The risk of thromboembolic events remains elevated during this extended postoperative period.

Question 74

What is the primary biologic mechanism of osteolysis following total hip arthroplasty with ultra-high-molecular-weight polyethylene (UHMWPE) wear?

Explanation

Polyethylene wear debris in the size range of 0.1 to 1.0 micrometers is phagocytosed by macrophages. This triggers an inflammatory cascade releasing cytokines (IL-1, TNF-alpha) that activate osteoclasts, leading to periprosthetic osteolysis.

Question 75

A 32-year-old male sustains a closed tibial shaft fracture. His diastolic blood pressure is 80 mmHg. What absolute intracompartmental pressure or delta pressure threshold is the most accepted indication for a four-compartment fasciotomy?

Explanation

A delta pressure (diastolic blood pressure minus intracompartmental pressure) of less than 30 mmHg is the most widely accepted and reliable indication for fasciotomy. Absolute pressure thresholds are less accurate due to physiological variations in systemic perfusion pressure.

Question 76

A 4-week-old female is treated with a Pavlik harness for developmental dysplasia of the hip (DDH). At the two-week follow-up, she is noted to lack active knee extension on the affected side. What is the most likely cause?

Explanation

Hyperflexion of the hips in a Pavlik harness (>120 degrees) impinges the femoral nerve against the inguinal ligament, leading to an acute compressive neuropathy. It typically resolves with appropriate adjustment of the anterior straps.

Question 77

A 16-year-old male presents with distal femur pain and a periosteal "sunburst" reaction on plain radiographs. Biopsy confirms high-grade intramedullary osteosarcoma. What is the most significant prognostic factor for long-term survival in this patient?

Explanation

The histologic response to neoadjuvant chemotherapy, defined as the percentage of tumor necrosis, is the single most important prognostic factor for overall survival in patients with high-grade osteosarcoma. Greater than 90% necrosis indicates a good response.

Question 78

A 55-year-old active male undergoes total hip arthroplasty using a ceramic-on-ceramic bearing. Three years postoperatively, he complains of a reproducible squeaking noise during gait. Which of the following component position factors is most strongly associated with this phenomenon?

Explanation

Squeaking in ceramic-on-ceramic THA is heavily associated with edge loading of the bearing surfaces. This edge loading typically results from component malpositioning, such as excessive steepness or abnormal version of the acetabular cup.

Question 79

A 24-year-old male is involved in a motor vehicle accident and sustains a traumatic spondylolisthesis of the axis (Hangman's fracture). Imaging shows a fracture through the pars interarticularis with severe angular kyphosis but minimal translation. Traction exacerbates the deformity. What is the appropriate classification and treatment?

Explanation

Type IIA Hangman's fractures feature severe angulation with minimal translation. Traction is strictly contraindicated as it exacerbates the deformity; treatment requires gentle reduction in extension and compression followed by halo vest immobilization.

Question 80

Which of the following is an inherent biomechanical advantage of using a bone-patellar tendon-bone (BPTB) autograft over a quadruple-stranded hamstring autograft for anterior cruciate ligament (ACL) reconstruction?

Explanation

BPTB autografts allow for rigid osseous fixation and true bone-to-bone healing within the tunnels, which occurs reliably at about 6 weeks. Soft tissue grafts rely on slower Sharpey fiber incorporation, requiring more prolonged biological integration.

Question 81

A 35-year-old male sustains a spiral fracture of the distal third of the humerus. On presentation, he lacks active wrist and thumb extension. He undergoes closed reduction and splinting. At 12 weeks, there is no clinical or electromyographic (EMG) evidence of radial nerve recovery. What is the most appropriate next step in management?

Explanation

A radial nerve palsy associated with a closed humeral shaft fracture typically warrants observation for 3 months. If there is no clinical or EMG evidence of recovery by 12 weeks, surgical exploration of the nerve is definitively indicated.

Question 82

The Lisfranc ligament complex is critical for maintaining midfoot stability. Which of the following best describes the anatomic attachment of the primary and strongest band of the Lisfranc ligament?

Explanation

The true Lisfranc ligament spans from the lateral aspect of the medial cuneiform to the medial aspect of the base of the second metatarsal. Its plantar band is the thickest and biomechanically strongest component of the complex.

Question 83

According to the Ponseti method for the treatment of idiopathic clubfoot, what is the correct sequence of deformity correction?

Explanation

The Ponseti method corrects idiopathic clubfoot deformities sequentially based on the acronym CAVE: Cavus, Adductus, Varus, and finally Equinus. Equinus is corrected last, frequently requiring a percutaneous Achilles tenotomy.

Question 84

During secondary bone healing, which growth factor is most directly responsible for the induction of angiogenesis during the transition from a soft cartilaginous callus to a hard bony callus?

Explanation

Vascular Endothelial Growth Factor (VEGF) is critical for angiogenesis during the transition from a hypoxic cartilaginous soft callus to an ossified hard callus. Inhibition of VEGF halts endochondral ossification and impairs fracture healing.

Question 85

During a posterior-stabilized total knee arthroplasty, trial reduction reveals that the knee is equally tight in both flexion and extension. Overall limb alignment and component rotations are correct. What is the most appropriate next step to balance the knee?

Explanation

When a knee is symmetrically tight in both flexion and extension, equivalent resection of bone is required to increase both gaps globally. Recutting the proximal tibia effectively enlarges both the flexion and extension spaces by the same amount.

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