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Free Orthopedics Review | Dr Hutaif General Orthopedics -...

23 Apr 2026 124 min read 126 Views
Orthopedic MCQS

Key Takeaway

This topic focuses on FREE Orthopedics MCQS 2022 1401-1450, Enchondroma is the most common primary bone tumor in the hand, often affecting the phalanges and metacarpals. This can involve joints like the metacarpophalangeal (MCP) joint and distal interphalangeal (DIP) joints. Additionally, ganglions frequently arise at DIP joints, termed mucous cysts. These represent prevalent pathologies within the hand's complex joint structures.

Free Orthopedics Review | Dr Hutaif General Orthopedics -...

Comprehensive 100-Question Exam


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Question 1

According to Perren's strain theory, what is the maximum tissue strain tolerated by lamellar bone formation during fracture healing?





Explanation

Perren's strain theory postulates that specific tissues tolerate specific maximum strain levels before failing. For lamellar bone to form, the strain must be less than 2%. This is the principle behind primary bone healing, which requires absolute stability. Woven bone can tolerate up to 10% strain, cartilage up to 30%, and granulation tissue can tolerate up to 100% strain.

Question 2

Which of the following physiologic parameters is the primary indication for initiating damage control orthopedics (DCO) rather than early total care (ETC) in a polytrauma patient with bilateral femur fractures?





Explanation

Indications for Damage Control Orthopedics (DCO) over Early Total Care (ETC) in a polytrauma patient include evidence of the 'lethal triad' or profound shock. Specific parameters prompting DCO include acidosis (pH < 7.24), hypothermia (Temp < 35°C), coagulopathy, severe prolonged hypotension, requirement of multiple blood transfusions (>10 units), and elevated serum lactate (> 2.5 mmol/L) or base deficit (> 6.0 mmol/L).

Question 3

A 6-week-old infant with developmental dysplasia of the hip (DDH) is being treated with a Pavlik harness. At the 1-week follow-up, the mother notes the infant has stopped kicking the affected leg. On examination, there is an absent patellar reflex on the affected side. What is the most appropriate next step in management?





Explanation

The clinical presentation is classic for a femoral nerve palsy, a known complication of Pavlik harness treatment due to excessive hyperflexion of the hip. The immediate and most appropriate treatment is to discontinue the harness until motor function returns, after which an alternative bracing strategy or a modified harness application may be considered.

Question 4

In a patient undergoing total hip arthroplasty, the use of a large-diameter cobalt-chromium femoral head on a titanium alloy femoral stem most significantly increases the risk of which of the following complications?





Explanation

The combination of a cobalt-chromium head on a titanium stem, particularly with large diameter heads that increase torque at the modular junction, predisposes the implant to mechanically assisted crevice corrosion (trunnionosis). This galvanic and mechanical wear process can lead to the release of metal ions and subsequent adverse local tissue reactions (ALTR).

Question 5

Which of the following structures is considered the primary static stabilizer to external tibial rotation at 30 degrees of knee flexion?





Explanation

The popliteofibular ligament (PFL), along with the popliteus tendon and the lateral collateral ligament (LCL), forms the primary components of the posterolateral corner (PLC) of the knee. The PFL and popliteus tendon are the primary stabilizers to external rotation, particularly evaluated at 30 degrees of flexion, whereas the LCL is the primary restraint to varus stress.

Question 6

During an extensive tenolysis of the flexor digitorum profundus in zone 2 of the hand, which of the following annular pulleys are considered biomechanically crucial to preserve to prevent bowstringing of the tendon?





Explanation

The A2 pulley (located over the proximal phalanx) and the A4 pulley (located over the middle phalanx) are the most critical annular pulleys biomechanically. Preserving or reconstructing them is essential to prevent bowstringing of the flexor tendons and maintain the functional moment arm for digit flexion.

Question 7

A 28-year-old male presents with a slow-growing, painful soft tissue mass near his knee joint. MRI shows an extra-articular mass with focal calcifications. A biopsy is performed. Which of the following chromosomal translocations is most characteristic of the likely diagnosis?





Explanation

The clinical picture describes a synovial sarcoma, which classically presents in young adults as a slow-growing soft tissue mass near joints (though rarely intra-articular) and may contain calcifications. The characteristic chromosomal translocation is t(X;18)(p11;q11), leading to the SYT-SSX fusion gene. t(11;22) is seen in Ewing sarcoma; t(9;22) in myxoid chondrosarcoma; t(12;16) in myxoid liposarcoma; and t(2;13) in alveolar rhabdomyosarcoma.

Question 8

Which of the following vessels provides the major blood supply to the body of the talus, placing it at high risk for avascular necrosis following a displaced talar neck fracture?





Explanation

The artery of the tarsal canal, a branch of the posterior tibial artery, provides the major blood supply to the body of the talus. Displaced talar neck fractures often disrupt this antegrade intraosseous supply, leading to a high rate of avascular necrosis. The deltoid artery supplies the medial aspect of the body and is often the only remaining supply after a displaced neck fracture.

Question 9

A 45-year-old male is involved in a motor vehicle collision resulting in a spinal cord injury. Neurological examination reveals preserved motor function below the neurological level of injury, and more than half of the key muscles below the neurological level have a muscle grade of 3 or greater. Sensory function is preserved. Which ASIA Impairment Scale (AIS) grade does this represent?





Explanation

The ASIA Impairment Scale (AIS) D is defined as motor incomplete, with motor function preserved below the neurological level, and at least half of the key muscles below the neurological level of injury having a muscle grade of 3 or greater. AIS C has less than half with grade 3 or greater. AIS B is sensory incomplete (no motor function), and AIS A is complete (no motor or sensory in S4-S5).

Question 10

What specific element is added to 316L stainless steel orthopedic implants to increase resistance to pitting corrosion and crevice corrosion in the chloride-rich environment of the human body?





Explanation

Molybdenum (usually 2-3%) is added to 316L stainless steel specifically to enhance resistance to pitting and crevice corrosion. Chromium is added to provide a passivating surface oxide layer. Nickel is used to stabilize the austenitic crystal structure at room temperature.

Question 11

A 32-year-old farmer sustains a highly contaminated open tibial shaft fracture (Gustilo-Anderson Type IIIA) after being pinned under a tractor. According to the most recent evidence-based guidelines, what is the most appropriate initial prophylactic antibiotic regimen?





Explanation

For Gustilo-Anderson Type III open fractures, standard prophylaxis includes a first-generation cephalosporin (for Gram-positive coverage) and an aminoglycoside (for Gram-negative coverage). In farm-related injuries with gross soil contamination, high-dose penicillin is added to provide coverage against anaerobic organisms, specifically Clostridium perfringens, to prevent gas gangrene.

Question 12

When performing in situ pinning for a severe Slipped Capital Femoral Epiphysis (SCFE), an unrecognized pin penetration into the anterosuperior quadrant of the joint space significantly increases the risk of which of the following complications?





Explanation

Unrecognized pin penetration into the joint space during SCFE pinning is a primary and highly morbid cause of chondrolysis. Approaching the screw from the anterior femoral neck to the posterior epiphysis increases this risk. The 'approach-withdraw' technique under live fluoroscopy while ranging the hip helps prevent it.

Question 13

During a posterior-stabilized total knee arthroplasty, the surgeon notes that the knee is tight in flexion but symmetric and balanced in extension. Which of the following is the most appropriate surgical step to balance the knee?





Explanation

A knee that is tight in flexion but balanced in extension has an isolated tight flexion gap. Downsizing the femoral component (using a smaller AP size) and shifting the component anteriorly effectively increases the flexion gap without altering the extension gap. Resecting more tibia would open both gaps equally. Releasing the PCL is not relevant here as it is already sacrificed in a posterior-stabilized TKA.

Question 14

The 'horn blower's sign' (Patte's test) is used during a physical examination to evaluate the integrity of which of the following rotator cuff muscles?





Explanation

The horn blower's sign evaluates the teres minor. It is positive when the patient is unable to hold the arm in external rotation with the shoulder abducted to 90 degrees and the elbow flexed to 90 degrees. A positive sign indicates a massive rotator cuff tear involving the teres minor.

Question 15

Which of the following clinical findings best differentiates Pronator Syndrome from Carpal Tunnel Syndrome on physical examination?





Explanation

The palmar cutaneous branch of the median nerve arises approximately 5 cm proximal to the wrist crease and travels superficial to the carpal tunnel to supply sensation to the thenar eminence. Therefore, numbness over the thenar eminence occurs in proximal median nerve compression (such as Pronator syndrome) but is spared in Carpal Tunnel Syndrome.

Question 16

Which of the following theories best explains the neurovascular pathophysiology underlying the active phase of Charcot arthropathy in patients with diabetes mellitus?





Explanation

The neurovascular theory of Charcot arthropathy postulates that autonomic neuropathy leads to a loss of sympathetic vascular tone, causing continuous arteriovenous shunting and hyperemia. This hyperemia increases osteoclastic bone resorption. The weakened, osteopenic bone, combined with loss of protective sensation (neurotraumatic theory), leads to repetitive microtrauma, fracture, and severe joint destruction.

Question 17

Which of the following orthopedic implant materials has a Young's modulus most closely matching that of cortical bone?





Explanation

Cortical bone has a Young's modulus of approximately 15-20 GPa. Polyetheretherketone (PEEK) has a modulus of around 3-4 GPa, and carbon-fiber-reinforced PEEK can be tailored to ~18 GPa, making it nearly isoelastic with cortical bone. This minimizes stress shielding compared to Titanium (~110 GPa), Stainless steel (~200 GPa), and CoCr (~240 GPa).

Question 18

During an anterior intrapelvic (modified Stoppa) approach for an acetabular fracture, significant arterial hemorrhage occurs near the superior pubic ramus. This is most likely due to an iatrogenic injury of an anastomosis between which two vascular systems?





Explanation

The 'corona mortis' is a critical vascular anastomosis between the obturator vessels (internal iliac system) and external iliac (or inferior epigastric) vessels. It traverses the posterior aspect of the superior pubic ramus at an average distance of 5-6 cm from the pubic symphysis and is at high risk of iatrogenic injury during anterior pelvic approaches.

Question 19

A 2-year-old child presents with a limp, low-grade fever, and refusal to bear weight. Laboratory studies show mild elevation of ESR and CRP. Blood cultures are negative at 48 hours. Joint aspiration yields synovial fluid with 45,000 WBCs/mm3. If special culture techniques or PCR were utilized, what is the most likely pathogen to be identified?





Explanation

Kingella kingae is now recognized as the most common cause of septic arthritis and osteomyelitis in children aged 6 months to 4 years. It often presents with milder systemic symptoms compared to S. aureus. It is a fastidious Gram-negative organism that is notoriously difficult to culture on standard solid media, often requiring inoculation into liquid blood culture vials or molecular detection via PCR.

Question 20

A 15-year-old male presents with dull, aching pain in his right anterior thigh that is significantly worse at night and dramatically relieved by taking ibuprofen. Radiographs show a distinct area of cortical thickening with a small (<1.5 cm) radiolucent nidus. Which of the following is the most appropriate initial management?





Explanation

The clinical and radiographic presentation is classic for an osteoid osteoma. Excessive prostaglandin production by the nidus causes the characteristic night pain that is relieved by NSAIDs. The first line of treatment is typically a trial of medical management (Observation with NSAIDs), as a significant proportion will spontaneously 'burn out' and resolve over several years. If medical management fails or is poorly tolerated, radiofrequency ablation (RFA) is the definitive treatment of choice.

Question 21

A 45-year-old patient undergoes open reduction and internal fixation of a distal radius fracture using a titanium plate and stainless steel screws. Which of the following forms of corrosion is most likely to occur at the implant interface?





Explanation

Galvanic corrosion occurs when two dissimilar metals are in contact within a conductive fluid (such as serum or interstitial fluid), creating an electrochemical cell. This leads to the accelerated corrosion of the less noble metal (in this case, stainless steel). Mixing metals like titanium and stainless steel should generally be avoided in orthopedics to prevent this phenomenon.

Question 22

In normal articular cartilage, which zone possesses the highest concentration of proteoglycans and the largest diameter collagen fibrils oriented perpendicular to the joint surface?





Explanation

The deep (radial) zone of articular cartilage is characterized by the highest concentration of proteoglycans and the largest diameter type II collagen fibrils, which are oriented radially (perpendicular) to the joint surface. This structure provides maximal resistance to compressive forces.

Question 23

A 52-year-old woman presents with diffuse bone pain and muscle weakness. Radiographs demonstrate bilateral symmetric radiolucent lines perpendicular to the cortex in her femoral necks. Laboratory evaluation reveals low serum calcium, low phosphorus, elevated alkaline phosphatase, and low 25-hydroxyvitamin D. What is the primary underlying defect in this condition?





Explanation

The clinical picture, lab profile, and radiographic findings (Looser zones/pseudofractures) are classic for osteomalacia. Osteomalacia is defined by defective mineralization of newly formed osteoid, most commonly due to severe vitamin D deficiency in adults.

Question 24

A 7-year-old boy presents with localized back pain. Radiographs demonstrate a flattened vertebra (vertebra plana) with no associated soft tissue mass. He has no systemic symptoms. A biopsy reveals histiocytes with folded nuclei, and electron microscopy shows Birbeck granules. What is the most likely diagnosis?





Explanation

Langerhans cell histiocytosis (LCH), particularly the solitary form historically known as eosinophilic granuloma, classically presents as vertebra plana in children. The diagnosis is confirmed histologically by the presence of Birbeck granules (tennis racket-shaped organelles) on electron microscopy.

Question 25

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





Explanation

Tranexamic acid is an antifibrinolytic agent that acts by competitively binding to the lysine receptor sites on plasminogen. This prevents plasminogen from binding to fibrin and being activated into plasmin, thereby inhibiting fibrinolysis and stabilizing clots.

Question 26

Prosthetic joint infections are characterized by bacterial formation of a protective biofilm. The extracellular polymeric substance (EPS) that comprises the bulk of this biofilm and shields bacteria from both the host immune system and antimicrobial agents is primarily composed of:





Explanation

The biofilm extracellular polymeric substance (EPS) is primarily composed of polysaccharides, along with proteins, extracellular DNA, and lipids. This complex matrix physically shields the bacteria embedded within it, requiring significantly higher minimum inhibitory concentrations of antibiotics to eradicate.

Question 27

When modifying the design of a cortical bone screw to maximize its pullout strength, which of the following geometric alterations would be most effective?





Explanation

Pullout strength of a screw is proportional to the outer diameter, the length of thread engagement, and inversely proportional to the thread pitch. Decreasing the thread pitch (meaning more threads per inch) increases the amount of thread contact with bone, thereby increasing pullout strength. Increasing the inner diameter or decreasing the outer diameter would decrease pullout strength.

Question 28

A 28-year-old athlete presents with shoulder weakness. Physical examination reveals prominent medial winging of the scapula when the patient pushes against a wall. Which of the following nerves is most likely injured?





Explanation

Medial winging of the scapula is caused by paralysis of the serratus anterior muscle, which is innervated by the long thoracic nerve. Lateral winging is caused by trapezius dysfunction, innervated by the spinal accessory nerve.

Question 29

Which of the following fixation constructs is most heavily reliant on cutting cone remodeling (primary bone healing) for the resolution of the fracture?





Explanation

Primary (direct) bone healing occurs under conditions of absolute stability without callus formation and relies on cutting cones of osteoclasts followed by osteoblasts bridging the fracture gap. Dynamic compression plating provides the absolute stability required for primary bone healing. The other options provide relative stability and heal via secondary bone healing (callus formation).

Question 30

A 19-year-old male complains of a dull, aching pain in his posterior spine that has progressively worsened over 6 months. The pain is not significantly relieved by NSAIDs. Radiographs show a 2.5 cm expansile radiolucent lesion in the posterior elements of L3. What is the most likely diagnosis?





Explanation

Osteoblastomas are benign bone-forming tumors that are histologically similar to osteoid osteomas but are distinguished by being larger (>2 cm), more locally aggressive, and having pain that is typically dull, aching, and not consistently relieved by NSAIDs. They frequently occur in the posterior elements of the spine.

Question 31

A newborn is diagnosed with achondroplasia. This condition is caused by a genetic mutation that primarily results in which of the following cellular events?





Explanation

Achondroplasia is caused by a gain-of-function mutation in the FGFR3 gene. FGFR3 normally functions to inhibit chondrocyte proliferation in the proliferative zone of the physis. The gain-of-function mutation constitutively activates this inhibition, leading to profoundly shortened long bones.

Question 32

In evaluating a diagnostic test for periprosthetic joint infection, which of the following statistical parameters will universally increase if the test is applied to a tertiary referral population with a significantly higher disease prevalence compared to the general population?





Explanation

Positive Predictive Value (PPV) is inherently dependent on the prevalence of the disease in the population being tested. As prevalence increases, PPV increases, and Negative Predictive Value (NPV) decreases. Sensitivity, specificity, and likelihood ratios are intrinsic properties of the test and do not change with disease prevalence.

Question 33

During prolonged standing, normal human articular cartilage relies primarily on which form of lubrication to prevent surface-to-surface wear under high-load, low-speed conditions?





Explanation

Boundary lubrication is driven by lubricin (PRG4) adhering to the articular surfaces, preventing direct contact. It is the primary lubrication mechanism under high-load and low-velocity conditions (such as standing). Elastohydrodynamic and weeping lubrication predominate during dynamic joint motion.

Question 34

In the pathogenesis of acute compartment syndrome following a tibia fracture, which of the following represents the initial physiologic derangement?





Explanation

Acute compartment syndrome begins when increasing intracompartmental tissue pressure eventually surpasses venous pressure, causing venous outflow obstruction. This leads to further fluid engorgement, escalating pressure that subsequently compromises the arteriolar-venous gradient, ultimately terminating capillary perfusion and causing tissue ischemia.

Question 35

Following a clean transection and meticulous microsurgical epineural repair of a peripheral nerve, axonal sprouting occurs. Once these regenerating sprouts cross the repair site and enter the distal endoneurial tubes, what is their approximate rate of growth?





Explanation

After Wallerian degeneration clears the distal nerve segment, regenerating axons grow down the endoneurial tubes at a rate of approximately 1 mm per day (or about 1 inch per month) under optimal conditions.

Question 36

A 12-year-old girl presents with an acute on chronic slipped capital femoral epiphysis (SCFE) of the left hip. Under which of the following circumstances is prophylactic in situ pinning of the contralateral right hip most strongly indicated?





Explanation

Prophylactic pinning of the contralateral hip in SCFE is highly controversial in idiopathic cases but is generally recommended for patients with underlying endocrine disorders (such as hypothyroidism or growth hormone deficiency) or metabolic bone disease, as these patients have a much higher rate of bilateral involvement (up to 100%).

Question 37

A 35-year-old carpenter sustains a zone II flexor tendon laceration and undergoes primary repair. At what time point post-operatively does the repaired tendon normally reach its lowest ultimate tensile strength?





Explanation

Following primary tendon repair, the strength of the repair decreases during the inflammatory phase due to collagenase activity and reaches its lowest point around 5 to 7 days (the transition from the inflammatory to the fibroblastic phase). Controlled passive motion protocols must carefully navigate this period of mechanical vulnerability.

Question 38

In modern total hip arthroplasty, highly cross-linked polyethylene (HXLPE) is routinely utilized. Increasing the radiation dose during the manufacturing of the polyethylene achieves which of the following biomechanical tradeoffs?





Explanation

Irradiating ultra-high molecular weight polyethylene (UHMWPE) creates free radicals that recombine to form cross-links between polymer chains. This drastically increases wear resistance (reducing osteolysis) but simultaneously decreases mechanical properties such as fatigue strength, ultimate tensile strength, and fracture toughness.

Question 39

A patient is prescribed rivaroxaban for deep vein thrombosis prophylaxis following a total knee arthroplasty. What is the specific mechanism of action of this medication?





Explanation

Rivaroxaban and apixaban are oral direct Factor Xa inhibitors. They act independently of antithrombin III to block the conversion of prothrombin to thrombin. Dabigatran is a direct thrombin inhibitor. Warfarin inhibits vitamin K epoxide reductase. Heparins function via antithrombin III.

Question 40

Which of the following best describes the classical sequence of incorporation for a structural cortical bone graft compared to a cancellous bone graft?





Explanation

Cortical bone grafts incorporate via creeping substitution, but unlike cancellous grafts (which undergo early osteoblastic bone apposition on existing trabeculae), cortical grafts first undergo osteoclastic resorption to widen Haversian canals. This makes cortical grafts transiently weaker than their initial state before osteoblasts deposit new bone.

Question 41

A 12-year-old obese male presents with a slipped capital femoral epiphysis (SCFE). The pathophysiology of this condition involves mechanical failure through which specific histologic zone of the physis?





Explanation

SCFE represents a type 1 Salter-Harris fracture where the epiphysis slips posteriorly and inferiorly. The mechanical failure occurs through the hypertrophic zone of the physis, which is structurally the weakest layer due to the large size of the chondrocytes and relatively sparse extracellular matrix.

Question 42

A 25-year-old male presents with a slow-growing, calcified mass near his right knee. A biopsy demonstrates a biphasic pattern consisting of both epithelial and spindle cells. Which of the following chromosomal translocations is diagnostic for this tumor?





Explanation

The clinical and histologic description is classic for synovial sarcoma, which frequently presents as a calcified periarticular mass in young adults. It is characterized by the t(X;18)(p11;q11) translocation, resulting in the SYT-SSX fusion gene.

Question 43

In the pathogenesis of cervical spondylotic myelopathy, anterior cord compression leads to ischemia primarily due to the mechanical obstruction of which of the following vascular structures?





Explanation

Cervical spondylotic myelopathy causes direct mechanical compression of the spinal cord and secondary ischemic changes due to compression of the anterior spinal artery. This primarily affects the anterior horn cells and the corticospinal tracts.

Question 44

During an anterior cruciate ligament (ACL) reconstruction, the surgeon elects to drill the femoral tunnel independently through an anteromedial (AM) portal rather than using a transtibial technique. Which of the following is the primary biomechanical advantage of the AM portal technique?





Explanation

Drilling the femoral tunnel through an anteromedial portal allows for anatomic placement of the femoral footprint (lower and further posterior in the notch with the knee in hyperflexion). This creates a more oblique graft orientation, which is biomechanically proven to better restore rotational stability compared to the vertical graft orientation typically resulting from a transtibial approach.

Question 45

A 30-year-old male sustains a Galeazzi fracture-dislocation. Following rigid internal fixation of the radial shaft, the distal radioulnar joint (DRUJ) remains unstable in neutral rotation. In which position is the DRUJ typically most stable and thus recommended for postoperative immobilization?





Explanation

A Galeazzi fracture involves the distal third of the radius with disruption of the DRUJ. Following internal fixation of the radius, the DRUJ is evaluated. It is typically most stable in supination because the palmar radioulnar ligament (the primary stabilizer in supination) and the intact interosseous membrane are tensioned, reducing the ulnar head into the sigmoid notch.

Question 46

Recombinant human bone morphogenetic protein-2 (rhBMP-2) is utilized in spine and trauma surgery for its osteoinductive properties. Once rhBMP-2 binds to its target cell surface receptor, which intracellular signaling pathway is primarily activated to upregulate osteoblast differentiation?





Explanation

BMPs belong to the TGF-beta superfamily. When osteoinductive BMPs (like BMP-2 and BMP-7) bind to their serine/threonine kinase receptors, they trigger the phosphorylation of receptor-regulated SMADs 1, 5, and 8. These complex with SMAD 4, enter the nucleus, and upregulate the transcription factor Runx2, driving osteoblast differentiation. SMAD 2/3 is associated with the TGF-beta/Activin pathway.

Question 47

In total hip arthroplasty, utilizing a femoral component with an increased lateral offset will have which of the following primary biomechanical effects?





Explanation

Increasing the femoral offset increases the distance from the center of rotation of the femoral head to the anatomical axis of the femur. This effectively increases the abductor moment arm, which subsequently reduces the amount of abductor muscle force required to stabilize the pelvis, thereby decreasing the resultant joint reaction force across the hip.

Question 48

The structural integrity of the midfoot is highly dependent on the Lisfranc ligament complex. The primary interosseous component of the Lisfranc ligament connects which two osseous structures?





Explanation

The Lisfranc ligament is an interosseous ligament that runs obliquely from the lateral aspect of the medial cuneiform to the medial aspect of the base of the second metatarsal. It is the primary stabilizer of the second tarsometatarsal joint.

Question 49

A 22-year-old male sustains a proximal pole scaphoid fracture. The high risk of avascular necrosis in this fracture pattern is directly related to the retrograde blood supply of the scaphoid. This blood supply primarily arises from which of the following vessels?





Explanation

The primary blood supply to the scaphoid (supplying the proximal 70-80% of the bone) comes from the dorsal carpal branch of the radial artery, which enters at the dorsal ridge near the scaphoid waist and flows in a retrograde fashion toward the proximal pole.

Question 50

An ultrasound of the hips is performed on a 6-week-old female infant. The Graf classification yields a Type IIa hip, characterized by an alpha angle of 55 degrees. What is the most appropriate management for this infant?





Explanation

A Graf Type IIa hip (alpha angle 50-59 degrees) in an infant under 3 months of age is considered physiologically immature rather than frankly dysplastic. The standard of care is observation and a repeat ultrasound at 10 to 12 weeks of age, as over 90% will normalize spontaneously.

Question 51

The Mirels scoring system is used to predict the risk of pathologic fracture in patients with metastatic bone lesions and guide the decision for prophylactic fixation. Which of the following parameters assigns the maximum of 3 points in this scoring system?





Explanation

The Mirels scoring system assigns points (1 to 3) across four categories: Site (Upper limb=1, Lower limb=2, Peritrochanteric=3), Pain (Mild=1, Moderate=2, Functional=3), Lesion character (Blastic=1, Mixed=2, Lytic=3), and Size (<1/3=1, 1/3-2/3=2, >2/3=3). A lytic lesion is assigned 3 points.

Question 52

According to the Young-Burgess classification for pelvic ring injuries, what specific anatomical disruption differentiates an Anteroposterior Compression Type III (APC III) injury from an APC II injury?





Explanation

In the Young-Burgess classification, APC II injuries involve symphyseal diastasis with disruption of the anterior sacroiliac, sacrotuberous, and sacrospinous ligaments, but the strong posterior sacroiliac ligaments remain intact (opening book). APC III injuries involve complete disruption of the anterior AND posterior sacroiliac ligaments, leading to complete hemipelvic instability.

Question 53

A 24-year-old overhead athlete undergoes surgical stabilization for recurrent anterior shoulder instability. The surgeon performs a 'Remplissage' procedure to address a large, engaging Hill-Sachs defect. This procedure involves the capsulotenodesis of which structure into the humeral defect?





Explanation

The Remplissage procedure (French for 'filling') addresses an off-track or engaging Hill-Sachs lesion by suturing the posterior joint capsule and the infraspinatus tendon into the humeral head defect, preventing the defect from engaging the anterior glenoid rim during external rotation and abduction.

Question 54

A 35-year-old male sustains an L1 burst fracture. He is neurologically intact. MRI reveals an indeterminate status of the posterior ligamentous complex (PLC). Using the Thoracolumbar Injury Classification and Severity (TLICS) score, what is the patient's calculated score, and what is the corresponding treatment recommendation?





Explanation

The TLICS score is calculated as follows: Morphology - Burst fracture = 2 points; Neurological status - Intact = 0 points; PLC status - Indeterminate = 2 points. Total = 4 points. A TLICS score of less than 4 recommends non-operative treatment, greater than 4 recommends operative treatment, and exactly 4 represents an equivocal case where either operative or non-operative management is acceptable based on surgeon preference.

Question 55

Articular cartilage relies on a highly organized extracellular matrix to withstand various mechanical loads. Which zone of articular cartilage is characterized by collagen fibrils oriented parallel to the joint surface, providing the highest resistance to shear forces?





Explanation

The superficial (tangential) zone of articular cartilage contains densely packed, fine collagen fibrils (primarily Type II) oriented parallel to the articular surface. This specialized structure provides high tensile stiffness and represents the primary defense against shear stresses applied to the joint.

Question 56

A patient presents with a chronic high radial nerve palsy following a humerus fracture and elects to undergo tendon transfer surgery to restore wrist and finger extension. Which of the following is the most widely accepted standard tendon transfer to restore wrist extension in this scenario?





Explanation

In the standard set of tendon transfers for a high radial nerve palsy, the pronator teres (PT) is transferred to the extensor carpi radialis brevis (ECRB) to restore wrist extension. The ECRB is preferred over the ECRL because it inserts centrally at the base of the third metacarpal, providing pure wrist extension without the radial deviation seen when transferring to the ECRL.

Question 57

In diagnosing acute compartment syndrome of the lower extremity, measuring intra-compartmental pressure is the gold standard when clinical signs are ambiguous. Which of the following pressure parameters is considered the most reliable threshold indicative of compartment syndrome necessitating fasciotomy?





Explanation

The delta pressure (ΔP) is the difference between the patient's diastolic blood pressure and the measured compartment pressure. A delta pressure of less than or equal to 30 mmHg is considered the most reliable indicator of tissue ischemia and acute compartment syndrome, warranting emergent fasciotomy.

Question 58

When utilizing the Ponseti method for the serial casting of idiopathic clubfoot (talipes equinovarus), correction of the deformities follows a strict sequential order (CAVE). What is the critical first step in the manipulation and casting process?





Explanation

The CAVE acronym outlines the order of correction: Cavus, Adductus, Varus, Equinus. The very first step is to supinate the forefoot by elevating the first ray, which aligns the forefoot with the hindfoot and corrects the cavus. Pronating the forefoot is a common error that actually worsens the cavus deformity.

Question 59

During a primary total knee arthroplasty, trial components are inserted. The surgeon notes that the joint space is perfectly balanced in full extension but is excessively tight in 90 degrees of flexion. Which of the following isolated maneuvers is the most appropriate next step to correct this specific mismatch?





Explanation

A knee that is tight in flexion but balanced in extension requires an increase in the flexion gap without altering the extension gap. Downsizing the femoral component (using standard posterior referencing) reduces the posterior condylar offset, thereby increasing the flexion gap exclusively. Recutting the tibia or changing the poly thickness would affect both gaps.

Question 60

A 55-year-old male with poorly controlled diabetes mellitus presents with a swollen, erythematous, and warm unilateral foot. Radiographs demonstrate periarticular bony debris, fragmentation, and subluxation at the tarsometatarsal joints. According to the Eichenholtz classification, what stage is this patient in, and what is the gold standard initial treatment?





Explanation

The patient is presenting with acute Charcot neuroarthropathy. Radiographs showing fragmentation, debris, and subluxation represent Eichenholtz Stage I (Development/Fragmentation). The gold standard initial management in the acute phase is strict immobilization and offloading, most effectively achieved with a total contact cast (TCC).

Question 61

A 2-month-old infant is evaluated for bilateral developmental dysplasia of the hip. Examination reveals bilateral knee extension contractures, clubfeet, and a flattened facial profile. What is the most likely underlying diagnosis and the expected response to Pavlik harness treatment?





Explanation

Teratologic DDH is often seen in neuromuscular or syndromic conditions such as arthrogryposis multiplex congenita or myelomeningocele. These dislocations occur early in utero, are typically rigid, and are notoriously resistant to conservative management like the Pavlik harness, almost always requiring open surgical reduction.

Question 62

A 32-year-old female presents with knee pain. Radiographs reveal an eccentric, lytic, epiphyseal lesion of the distal femur without sclerotic margins. A biopsy confirms Giant Cell Tumor (GCT). If treated with Denosumab prior to surgical intervention, what is its primary mechanism of action?





Explanation

Denosumab is a monoclonal antibody that binds to RANKL. In GCT, the neoplastic stromal cells overexpress RANKL, which recruits and activates the reactive, bone-resorbing multinucleated giant cells. By inhibiting RANKL, denosumab reduces the giant cell population, decreasing tumor-associated osteolysis and facilitating intralesional curettage.

Question 63

Following a posterior-stabilized total knee arthroplasty, a patient experiences recurrent knee instability, specifically feeling a 'clunk' when extending the knee from a flexed position. Exam reveals catching in the patellofemoral joint. What is the primary cause and the most appropriate management?





Explanation

Patellar clunk syndrome is a known complication specific to posterior-stabilized TKA. It is caused by a fibrotic nodule forming at the superior pole of the patella that catches in the intercondylar box of the femoral component during extension from a flexed position. Treatment consists of arthroscopic or open excision of the fibrotic nodule.

Question 64

A 14-year-old female gymnast presents with progressive low back pain. Radiographs show a Grade 2 L5-S1 spondylolisthesis. MRI demonstrates an intact pars interarticularis but elongated pars and pedicles. According to the Wiltse classification, what type of spondylolisthesis does she have?





Explanation

Wiltse Type I (Dysplastic) spondylolisthesis is due to congenital abnormalities of the upper sacrum or L5 arch leading to facet incompetence. The pars is often elongated but remains intact. Type II (Isthmic) involves a lytic defect or stress fracture of the pars interarticularis, which is more common in gymnasts, but the MRI specifically noted an intact pars in this scenario.

Question 65

A 45-year-old manual laborer presents with chronic radial-sided wrist pain. Radiographs show a scaphoid nonunion with arthritic changes exclusively between the distal scaphoid fragment and the radial styloid. The midcarpal joint and radiolunate joint are preserved. This represents SNAC stage I. What is the most appropriate surgical intervention?





Explanation

Scaphoid Nonunion Advanced Collapse (SNAC) stage I involves isolated arthritis between the distal scaphoid pole and the radial styloid. Treatment typically consists of a radial styloidectomy to address the localized arthritis, combined with scaphoid ORIF and bone grafting to heal the nonunion. PRC or 4-corner fusion are salvage procedures reserved for Stages II and III.

Question 66

During anterior cruciate ligament (ACL) reconstruction using a bone-patellar tendon-bone (BTB) autograft, the bone plugs heal to the host bone tunnels via which of the following primary biologic mechanisms?





Explanation

Bone-to-bone healing in a BTB graft occurs via creeping substitution, a process where osteoclasts resorb the graft bone and osteoblasts lay down new woven bone. This leads to earlier rigid fixation at approximately 6 weeks, compared to soft tissue grafts (e.g., hamstrings) which heal to the bone tunnel via a slower fibrovascular interface (Sharpey fibers) taking 8-12 weeks.

Question 67

A 25-year-old male is brought to the ED after a motorcycle collision. Pelvic radiographs show a symphysis pubis diastasis of 3.5 cm and widening of the anterior sacroiliac joints bilaterally. The posterior sacroiliac ligaments are intact. According to the Young-Burgess classification, what is this injury?





Explanation

APC II injuries are characterized by symphysis diastasis > 2.5 cm and widening of the anterior SI joints, indicating disruption of the anterior SI ligaments, as well as the sacrotuberous and sacrospinous ligaments. The posterior SI ligaments remain intact, maintaining vertical stability. APC III involves disruption of both anterior and posterior SI ligaments, causing complete spinopelvic instability.

Question 68

A 55-year-old diabetic male presents with a warm, swollen, erythematous foot. Radiographs show periarticular osteopenia, fragmentation, and subluxation at the tarsometatarsal joint. According to the Eichenholtz classification, what stage does this represent, and what is the most appropriate initial management?





Explanation

Eichenholtz Stage 1 (Developmental/Fragmentation) presents with an acutely inflamed foot, radiographic fragmentation, debris, and subluxation. The mainstay of initial treatment is offloading and immobilization via a total contact cast (TCC) to prevent further deformity until the acute inflammatory phase resolves (progression to coalescence).

Question 69

In normal adult articular cartilage, which zone is characterized by the highest concentration of proteoglycans, the lowest concentration of water, and chondrocytes arranged in distinct vertical columns?





Explanation

The deep (radial) zone of articular cartilage provides the greatest resistance to compressive forces. It has the highest proteoglycan content, the lowest water content, and features chondrocytes arranged in vertical columns (perpendicular to the joint surface). The superficial zone has the highest water content and collagen fibers oriented parallel to the joint surface to resist shear forces.

Question 70

A 12-year-old obese male presents with left groin pain and a limp for 3 weeks. Examination reveals obligatory external rotation of the hip upon passive flexion. Radiographs confirm a mild slipped capital femoral epiphysis (SCFE). During in situ pinning, where should the screw be positioned within the epiphysis to minimize complications?





Explanation

In SCFE pinning, the goal is to place a single screw in the center-center position of the epiphysis on both AP and lateral radiographs. This maximizes biomechanical stability and minimizes the risk of joint penetration (which can lead to chondrolysis) or damage to the vulnerable posterior-superior retinacular vessels (which can cause avascular necrosis).

Question 71

A 70-year-old female presents with chronic pseudoparalysis of the right shoulder due to massive rotator cuff tear arthropathy. Radiographs show superior migration of the humeral head with acetabularization of the acromion. She is scheduled for a Reverse Total Shoulder Arthroplasty (RTSA). The success of RTSA is most critically dependent on the function of which of the following nerves?





Explanation

An intact axillary nerve (which innervates the deltoid) is a strict prerequisite for Reverse Total Shoulder Arthroplasty. RTSA shifts the center of rotation medially and inferiorly, increasing the moment arm and resting tension of the deltoid. This allows the deltoid to effectively abduct and elevate the arm, compensating for the deficient rotator cuff.

Question 72

Which of the following clinical scenarios presents the highest statistical risk for developing acute compartment syndrome of the lower extremity?





Explanation

Acute compartment syndrome is most commonly associated with fractures of the tibia. The highest risk profile includes young male patients with high-energy, closed proximal-third tibia fractures, particularly those with a crush mechanism. While open fractures allow some pressure release, they do not eliminate the risk, but the proximal closed crush injury represents the classic highest-risk presentation.

Question 73

When selecting bearing surfaces for a total hip arthroplasty in a young, active patient, which of the following combinations demonstrates the lowest in vitro volumetric wear rate?





Explanation

Ceramic-on-ceramic (CoC) bearing surfaces exhibit the lowest volumetric wear rates of all currently used combinations, making them appealing for very young, active patients. However, they carry unique risks such as component fracture and audible squeaking. Highly cross-linked polyethylene drastically reduces wear compared to conventional polyethylene but still wears more than a CoC construct.

Question 74

A 28-year-old chef sustains a deep laceration to the volar aspect of his index finger at the level of the proximal phalanx, resulting in an inability to flex the PIP and DIP joints. This injury occurred in Flexor Tendon Zone II. What anatomical boundaries define this zone?





Explanation

Zone II (historically termed 'No Man/'s Land') of the flexor tendons extends from the proximal margin of the A1 pulley (roughly corresponding to the distal palmar crease) to the insertion of the flexor digitorum superficialis (FDS) at the middle phalanx. It is notorious for difficult repairs due to the tight fibro-osseous canal and risk of dense adhesions.

Question 75

A 15-year-old male presents with persistent distal femur pain. Radiographs reveal a sunburst periosteal reaction and a Codman's triangle. Biopsy confirms high-grade intramedullary osteosarcoma. What is the most critical prognostic factor for long-term survival in this patient?





Explanation

In the treatment of high-grade osteosarcoma, the histologic response to neoadjuvant chemotherapy (specifically, the percentage of tumor necrosis observed in the resected specimen) is the single most important prognostic indicator for long-term survival. Greater than 90% necrosis indicates a good response and significantly better overall prognosis.

Question 76

A 45-year-old male presents with right-sided neck pain radiating down his arm, accompanied by weakness in triceps extension and wrist flexion, as well as numbness in his middle finger. The triceps reflex is absent. Which cervical nerve root is most likely compressed?





Explanation

C7 radiculopathy is the most common cervical radiculopathy. Its classic clinical presentation includes pain/numbness radiating to the middle finger, weakness in elbow extension (triceps) and wrist flexion (flexor carpi radialis), and a diminished or absent triceps reflex. C6 typically affects the biceps reflex, wrist extension, and numbness in the thumb/index finger.

Question 77

Following a diaphyseal femur fracture treated with a relatively stable but not absolutely rigid construct (e.g., intramedullary nail), secondary fracture healing occurs. Which phase of this healing process is fundamentally characterized by the conversion of woven bone to lamellar bone according to Wolff's law?





Explanation

Secondary fracture healing consists of inflammation, soft callus (cartilage) formation, hard callus (woven bone) formation, and remodeling. The remodeling phase takes months to years and is driven by coupled osteoclast and osteoblast activity acting according to Wolff's law, where mechanically inferior woven bone is gradually replaced by mechanically robust lamellar bone along lines of stress.

Question 78

When evaluating a patient for suspected acute compartment syndrome, you decide to measure intra-compartmental pressures. Which pressure parameter is considered the most reliable indicator requiring emergent fasciotomy?





Explanation

The delta pressure (Diastolic Blood Pressure - Intra-compartmental Pressure) is the most reliable and widely accepted threshold for diagnosing acute compartment syndrome. A delta pressure (Δp) of less than 30 mmHg indicates inadequate capillary perfusion pressure to the tissue and is a strong, definitive indication for emergent fasciotomy.

Question 79

A 35-year-old avid cyclist complains of numbness in his ring and small fingers, and weakness with finger abduction. However, he has completely normal sensation over the dorso-ulnar aspect of his hand. Examination reveals a positive Froment's sign. Where is the most likely anatomic site of neural compression?





Explanation

The dorsal ulnar cutaneous nerve branches off the main ulnar nerve proximal to the wrist (roughly 5-8 cm proximal to the ulnar styloid). Preservation of dorso-ulnar sensation with concurrent ulnar motor (positive Froment's sign) and sensory deficits in the palmar digits indicates a distal lesion, classically at Guyon's canal ('cyclist/'s palsy'). Compression at the elbow (cubital tunnel) would typically affect the dorsal sensory branch.

Question 80

A 40-year-old male sustains an acute Achilles tendon rupture while playing basketball. He opts for non-operative management utilizing a strict functional rehabilitation protocol. Based on modern randomized controlled trials, how do the outcomes of this non-operative protocol compare to traditional open surgical repair?





Explanation

Recent high-quality studies and meta-analyses have demonstrated that when non-operative management of acute Achilles tendon ruptures is paired with an early functional rehabilitation protocol (early weight-bearing and functional mobilization in an orthosis), the functional outcomes and re-rupture rates are statistically equivalent to operative repair, while successfully avoiding surgical complications such as wound breakdown or infection.

Question 81

A 16-year-old male presents with severe thigh pain and a rapidly expanding mass following minor trauma. Radiographs show a purely lytic, expansile lesion in the distal femoral metaphysis. MRI demonstrates multiple fluid-fluid levels. Biopsy reveals blood-filled spaces lined by anaplasia and malignant cells producing a lacelike matrix. Which of the following is the most critical feature differentiating this lesion from an aneurysmal bone cyst (ABC)?





Explanation

The clinical and radiographic presentation of telangiectatic osteosarcoma is remarkably similar to that of an aneurysmal bone cyst (ABC), as both can present as expansile lytic lesions with fluid-fluid levels on MRI. The definitive differentiating factor is histological: telangiectatic osteosarcoma features highly atypical, malignant cells that produce a malignant osteoid matrix (often lacelike) within the septa, whereas an ABC is benign and lacks malignant cytology and malignant osteoid.

Question 82

A 68-year-old female presents with groin pain and swelling three years after a primary metal-on-polyethylene total hip arthroplasty (THA). Serum cobalt and chromium levels are significantly elevated. Joint aspiration yields sterile, dark fluid. The components appear well-fixed on radiographs, but MRI shows a large cystic pseudotumor. What is the primary mechanism of failure in this scenario?





Explanation

The patient is experiencing an adverse local tissue reaction (ALTR) or metallosis (trunnionosis) in a metal-on-polyethylene THA. This is primarily caused by mechanically assisted crevice corrosion (fretting and corrosion) at the modular junction between the femoral head and the trunnion of the stem. This generates metal ions (cobalt and chromium) leading to a localized inflammatory response and pseudotumor formation.

Question 83

A 13-year-old obese male presents to the emergency department complaining of left hip and knee pain for 2 weeks. Today, after a minor slip, he is completely unable to bear weight on the left leg, even with the assistance of crutches. Radiographs confirm a slipped capital femoral epiphysis (SCFE). Based on the Loder classification, what is the most significant prognostic risk for this specific type of slip?





Explanation

The Loder classification defines a SCFE as 'unstable' if the patient is unable to bear weight, even with crutches. Unstable slips have a significantly higher risk of avascular necrosis (AVN) of the femoral head (approaching 20-50%) compared to stable slips, where the patient can bear weight and the AVN risk is nearly zero.

Question 84

A 45-year-old male sustains a severe crush injury to his lower extremity. The vascular surgeon restores perfusion after 7 hours of ischemia. To utilize the Mangled Extremity Severity Score (MESS) effectively for amputation decision-making, which of the following accurately describes how the ischemia scoring component is calculated in this patient?





Explanation

In the Mangled Extremity Severity Score (MESS), the variables include skeletal/soft-tissue injury, limb ischemia, shock, and age. For the limb ischemia component, the points are doubled if the ischemic time exceeds 6 hours. A total MESS score of 7 or higher historically correlates with a high likelihood of eventual amputation.

Question 85

A 22-year-old unrestrained driver is involved in a motor vehicle collision. Cervical spine imaging reveals a traumatic spondylolisthesis of the axis (Hangman's fracture) with severe angulation and minimal translation. The fracture line is oblique from anterior-inferior to posterior-superior. According to the Levine-Edwards classification (Type IIA), what is the most appropriate initial management, and what is its pathomechanism?





Explanation

A Levine-Edwards Type IIA Hangman's fracture features significant angulation with minimal translation and an oblique fracture line. The mechanism of injury is flexion and distraction. Traction is strictly contraindicated as it will exacerbate the translation and widen the disc space. The correct initial management involves gentle reduction with extension and compression, often maintained in a halo vest.

Question 86

A 28-year-old athlete sustains a high-energy multiligamentous knee injury (KD-III). On examination, the foot is warm, and dorsalis pedis and posterior tibial pulses are palpable and symmetrical to the contralateral limb. An ankle-brachial index (ABI) is measured at 0.85. What is the most appropriate next step in management regarding the patient's vascular status?





Explanation

In the assessment of knee dislocations, an ABI should be routinely performed. An ABI less than 0.9, even in the presence of palpable pulses, is highly suspicious for a vascular intimal injury of the popliteal artery and necessitates further advanced imaging, typically a CT angiogram (CTA). Immediate exploration is reserved for 'hard signs' of arterial injury (e.g., absent pulses, expanding hematoma).

Question 87

A 35-year-old male presents with progressive wrist pain years after an untreated scaphoid waist fracture. Radiographs show a scaphoid nonunion advanced collapse (SNAC). Imaging demonstrates arthritic changes at the radioscaphoid joint, and between the scaphoid, capitate, and lunate. Which joint typically remains spared in the late stages of SNAC wrist, making the patient a candidate for a four-corner fusion?





Explanation

In Scaphoid Nonunion Advanced Collapse (SNAC), the normal kinematics of the wrist are disrupted, leading to progressive arthritis. The arthritis typically starts at the radioscaphoid joint (Stage I), progresses to the scaphocapitate joint (Stage II), and then to the capitolunate joint (Stage III). The radiolunate joint is characteristically spared, because the lunate remains concentrically located in the lunate fossa of the radius. This preservation allows for a motion-preserving salvage procedure such as a proximal row carpectomy (PRC) or a four-corner fusion.

Question 88

A 55-year-old diabetic patient presents with a red, hot, swollen right foot. He is afebrile and his WBC count is normal. Radiographs reveal fragmentation of the tarsometatarsal joints, subchondral debris, and subluxation. Based on the Eichenholtz classification of Charcot arthropathy, which stage is this patient in, and what is the gold standard initial treatment?





Explanation

The patient is in Eichenholtz Stage 1 (Developmental/Fragmentation stage) of Charcot arthropathy, characterized clinically by a red, hot, swollen foot and radiographically by bone fragmentation, joint dislocation, and debris. The gold standard for initial management during this active phase is immobilization and offloading using a Total Contact Cast (TCC) to prevent further deformity until the active inflammatory phase subsides (transitioning to Stage 2 - Coalescence).

Question 89

In the pathogenesis of periprosthetic osteolysis following total joint arthroplasty, which of the following characteristics of ultra-high-molecular-weight polyethylene (UHMWPE) wear particles most aggressively stimulates the macrophage-mediated inflammatory cascade?





Explanation

The biological response to wear debris in arthroplasty is highly dependent on particle size. Macrophages are most actively stimulated to phagocytose polyethylene particles that are in the submicron to low-micron range, specifically 0.1 to 1.0 micrometers. Once phagocytosed, the macrophages release pro-inflammatory cytokines (TNF-alpha, IL-1, IL-6), leading to RANKL activation and subsequent osteoclastic bone resorption.

Question 90

A 60-year-old male undergoes wide resection of a proximal femur mass. Histologic examination reveals a distinct biphasic pattern consisting of islands of low-grade malignant hyaline cartilage sharply juxtaposed against a high-grade, non-cartilaginous spindle cell sarcoma, with no transitional zone between the two. What is the most accurate diagnosis?





Explanation

The pathognomonic histologic feature of dedifferentiated chondrosarcoma is a bimorphic (biphasic) pattern characterized by a well-differentiated (low-grade) cartilaginous tumor abruptly transitioning into a highly anaplastic, high-grade non-cartilaginous sarcoma (often osteosarcoma, fibrosarcoma, or undifferentiated pleomorphic sarcoma). The lack of a transitional zone is a hallmark.

Question 91

In the management of pelvic ring injuries, the volume of the true pelvis plays a critical role in hemodynamics. Which of the following injury patterns is associated with the greatest increase in pelvic volume, thereby accommodating the largest amount of retroperitoneal hemorrhage?





Explanation

Anteroposterior Compression Type III (APC-III) injuries involve complete disruption of the symphysis pubis and both the anterior and posterior sacroiliac ligaments. This 'open book' deformity significantly increases the internal volume of the pelvis, negating the tamponade effect and allowing for massive, life-threatening retroperitoneal venous and arterial hemorrhage. Lateral compression injuries generally decrease pelvic volume.

Question 92

A 45-year-old active male presents with medial compartment knee osteoarthritis and varus malalignment. He is being considered for a high tibial osteotomy (HTO). Which of the following preoperative clinical findings is generally considered an absolute contraindication for performing an HTO?





Explanation

High Tibial Osteotomy (HTO) relies on redistributing weight-bearing forces to the relatively preserved lateral compartment. Absolute contraindications typically include inflammatory arthritis, a flexion contracture greater than 15 degrees, knee flexion less than 90 degrees, severe patellofemoral arthritis, and significant instability (unless concurrently addressed). A 20-degree flexion contracture prevents normal gait biomechanics and results in poor outcomes post-HTO.

Question 93

According to the Ponseti method for the correction of idiopathic clubfoot, the sequence of deformity correction is critical. Which of the following best describes the very first manipulation and casting step?





Explanation

The Ponseti method follows the acronym CAVE (Cavus, Adductus, Varus, Equinus) for the sequence of correction. The first step addresses the Cavus. Because the cavus is caused by pronation of the forefoot relative to the hindfoot (a dropped first metatarsal), the correct initial maneuver is to elevate the first ray and supinate the forefoot, aligning it with the hindfoot. Subsequent casts abduct the foot around the fixed head of the talus.

Question 94

An 82-year-old female presents with a Type II odontoid fracture following a ground-level fall. She has multiple comorbidities but is neurologically intact. What is the preferred definitive treatment for this patient to minimize mortality and optimize union rates?





Explanation

Type II odontoid fractures in the elderly (>70-80 years old) are notoriously difficult to treat. Conservative management with a halo vest is associated with unacceptably high morbidity and mortality in the elderly population (up to 40%). Anterior odontoid screws have high failure rates due to osteopenia. Posterior C1-C2 arthrodesis is the most reliable treatment, offering the highest union rates and lower mortality compared to halo placement in this specific demographic.

Question 95

A 24-year-old rugby player undergoes evaluation for recurrent anterior shoulder instability. Advanced imaging reveals a large 'engaging' Hill-Sachs lesion and a glenoid bone loss measured at 28%. What is the most appropriate surgical intervention?





Explanation

Glenoid bone loss exceeding critical thresholds (traditionally cited as 20-25%, though some recent literature suggests >13.5-15% in high-risk athletes) is a contraindication to an isolated soft-tissue Bankart repair due to unacceptably high recurrence rates. A Latarjet procedure (transfer of the coracoid process with the attached conjoint tendon to the anterior glenoid neck) restores the osseous arc and provides a 'sling' effect, making it the procedure of choice for massive glenoid bone loss.

Question 96

During a primary repair of a Zone II flexor digitorum profundus (FDP) laceration, an epitenon (epitendinous) suture is placed circumferentially around the repair site in addition to a multistrand core suture. What is the primary biomechanical advantage of adding the epitenon suture?





Explanation

The addition of a running epitenon suture over a core suture provides two major benefits in flexor tendon repair: it smooths the surface to reduce gliding resistance (preventing snagging on the pulleys) and it significantly increases the overall tensile strength of the repair, often by 10% to 30%, which helps prevent gap formation during early active rehabilitation protocols.

Question 97

A 30-year-old male sustains a Hawkins Type II talar neck fracture. At the 8-week postoperative follow-up, an AP radiograph of the ankle demonstrates a subchondral radiolucent band in the dome of the talus (Hawkins sign). What does this radiographic finding indicate?





Explanation

The Hawkins sign is a subchondral radiolucent band seen in the dome of the talus on an AP or mortise radiograph, typically appearing 6 to 8 weeks post-injury. It represents subchondral bone resorption due to disuse osteopenia. Because osteopenia requires an intact blood supply to allow osteoclastic activity, a positive Hawkins sign is an excellent prognostic indicator that the talar body is vascularized and avascular necrosis (AVN) is unlikely.

Question 98

Articular cartilage is structurally divided into four distinct zones. Which of the following characteristics accurately describes the superficial (tangential) zone of normal adult articular cartilage?





Explanation

The superficial (tangential) zone of articular cartilage is the thinnest layer but is critical for resisting shear stress. It is characterized by having the highest water content, the lowest concentration of proteoglycans, and flattened chondrocytes. Most importantly, its Type II collagen fibrils are oriented parallel to the joint surface to withstand sheer forces. The deep zone features perpendicular collagen, highest proteoglycan content, and columnar chondrocytes.

Question 99

A 40-year-old construction worker falls from a height and sustains a Schatzker VI tibial plateau fracture. Which of the following best defines the anatomic hallmark of a Schatzker VI fracture?





Explanation

The Schatzker classification is used for tibial plateau fractures. Schatzker VI represents the most severe form, characterized by a transverse or oblique fracture through the metaphysis that separates the articular surfaces (condyles) from the diaphysis. This is known as metaphyseal-diaphyseal dissociation. It typically involves high-energy trauma and has a high risk of compartment syndrome.

Question 100

A 4-year-old child is brought to the ED refusing to walk on her right leg. She has a temperature of 38.8°C (101.8°F). Laboratory tests show an ESR of 45 mm/h, a WBC count of 13,000/mm^3, and a CRP of 3.5 mg/dL. According to the classic Kocher criteria and subsequent validated models (e.g., Caird), what is the approximate probability that this child has septic arthritis of the hip rather than transient synovitis?





Explanation

The classic Kocher criteria for differentiating septic arthritis from transient synovitis include: 1) Non-weight bearing, 2) ESR > 40 mm/hr, 3) Fever > 38.5°C, and 4) WBC > 12,000. Having 4 of 4 predictors yields a 99% probability of septic arthritis. Additionally, Caird et al. added CRP > 2.0 mg/dL as an independent predictor. Since this patient meets all 4 classic criteria plus the CRP criterion, the probability is > 90% (specifically, historically quoted as 99%).

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