Questions - MCQs | FRCS Section 1 Prep | Comprehensive Medical Guide

Question 1

A 28-year-old male undergoes intramedullary nailing for a closed tibial shaft fracture. Twelve hours postoperatively, he complains of severe leg pain out of proportion to the injury, requiring escalating doses of opioids. Pain is exacerbated by passive dorsiflexion of the toes. His diastolic blood pressure is 75 mmHg and intracompartmental pressure of the anterior compartment is measured at 48 mmHg. What is the most appropriate management?

Explanation

This patient has acute compartment syndrome, indicated by pain out of proportion, pain on passive stretch, and a delta pressure (diastolic BP minus compartment pressure) of less than 30 mmHg (75 - 48 = 27 mmHg). Immediate four-compartment fasciotomy is the definitive treatment.

Question 2

A 65-year-old active female undergoes total hip arthroplasty with a highly cross-linked polyethylene (HXLPE) liner. Which of the following describes a biomechanical trade-off resulting from the irradiation and remelting process used to create HXLPE compared to conventional polyethylene?

Explanation

Irradiation creates free radicals that cross-link the polymer, drastically reducing wear. However, the subsequent remelting process used to eliminate remaining free radicals decreases the material's crystallinity, thereby reducing its ultimate tensile strength, yield strength, and fatigue resistance.

Question 3

A 6-month-old infant is diagnosed with developmental dysplasia of the hip (DDH) after failing conservative management in a Pavlik harness. The orthopaedic surgeon plans a closed reduction and spica casting. An arthrogram performed intraoperatively shows a medial dye pool of 7 mm. Which of the following structures is LEAST likely to block concentric reduction in this patient?

Explanation

Obstacles to concentric reduction in DDH include an inverted limbus, hypertrophied pulvinar, elongated ligamentum teres, constricted transverse acetabular ligament, and a tight psoas tendon. The iliacus muscle is not a recognized mechanical block to reduction in DDH.

Question 4

A 55-year-old man presents with chronic wrist pain. Radiographs show a scaphoid nonunion with degenerative changes involving the entire radioscaphoid joint and the capitolunate joint. The radiolunate articulation is completely spared. What is the most appropriate surgical management for this stage of Scaphoid Nonunion Advanced Collapse (SNAC)?

Explanation

This represents Stage III SNAC wrist, involving the radioscaphoid and capitolunate joints but sparing the radiolunate joint. Four-corner fusion with scaphoid excision is indicated. Proximal row carpectomy is contraindicated here due to existing capitolunate arthritis.

Question 5

A 25-year-old motorcyclist sustains a vertically unstable (Tile C) pelvic ring injury. Cranial migration of the hemipelvis is primarily driven by which muscle?

Explanation

Quadratus lumborum provides the primary deforming force causing vertical migration in unstable pelvic fractures. It originates on the iliac crest and pulls the hemipelvis proximally.

Question 6

Which of the following pediatric conditions is the strongest indication for prophylactic pinning of the contralateral, asymptomatic hip in Slipped Capital Femoral Epiphysis (SCFE)?

Explanation

Endocrine disorders, particularly hypothyroidism and renal osteodystrophy, highly predispose children to bilateral SCFE. Prophylactic pinning of the contralateral side is strongly recommended in these patients.

Question 7

The primary blood supply to the anterior cruciate ligament (ACL) is derived from which artery?

Explanation

The middle genicular artery, a branch of the popliteal artery, provides the primary vascular supply to the ACL. It pierces the posterior capsule to supply the cruciate ligaments.

Question 8

In a patient with aseptic loosening 15 years after a cemented total hip arthroplasty, what is the primary cell responsible for the periprosthetic osteolysis?

Explanation

Aseptic loosening is primarily driven by macrophage activation secondary to phagocytosis of particulate wear debris. This leads to the release of inflammatory cytokines that stimulate osteoclastic bone resorption.

Question 9

A 30-year-old man sustains a closed tibial shaft fracture. Which clinical finding is the most sensitive early indicator of acute compartment syndrome?

Explanation

Pain out of proportion to the injury and pain with passive stretching of the affected compartment's muscles are the earliest and most sensitive clinical signs. Pulselessness and pallor are late, unreliable signs of irreversible ischemia.

Question 10

A 60-year-old man presents with upper extremity weakness that is disproportionately greater than his lower extremity weakness following a hyperextension cervical spine injury. Which spinal cord syndrome is most likely?

Explanation

Central cord syndrome typically occurs after hyperextension injuries in patients with pre-existing cervical spondylosis. The centrally located cervical tracts supplying the upper extremities are more severely affected than the peripheral lower extremity tracts.

Question 11

A 15-year-old boy presents with a diaphyseal bone tumor. Biopsy reveals small round blue cells. Which specific chromosomal translocation is diagnostic for this malignancy?

Explanation

Ewing sarcoma is characterized by the t(11;22)(q24;q12) translocation, creating the EWS-FLI1 fusion protein. This cytogenetic marker is highly specific and used for molecular diagnosis.

Question 12

A 6-year-old boy sustains a completely displaced supracondylar humerus fracture. After closed reduction and percutaneous pinning, the hand remains pink with a capillary refill of 1.5 seconds, but the radial pulse is absent. What is the most appropriate next step in management?

Explanation

In a well-perfused, pink hand with brisk capillary refill but an absent pulse after reduction, collateral circulation is sufficient. Immediate surgical exploration is only indicated if the hand is dysvascular (pale and pulseless).

Question 13

During the soft callus phase of secondary fracture healing, the predominant collagen synthesized by chondrocytes is:

Explanation

During the soft callus stage, chondrocytes proliferate and predominantly secrete Type II collagen to form a cartilaginous template. This is later replaced by woven bone (Type I collagen) during hard callus formation.

Question 14

In the digital flexor sheath of the hand, Camper's chiasm refers to the bifurcation and decussation of which of the following tendons?

Explanation

Camper's chiasm is the bifurcation of the FDS tendon, allowing the FDP tendon to pass through and insert on the distal phalanx. This anatomical crossover occurs at the level of the proximal phalanx.

Question 15

During deep flexion of the normal knee joint, femoral rollback on the tibial plateau is primarily driven by the tension in which structure?

Explanation

The PCL is responsible for the posterior translation of the femur on the tibia (femoral rollback) during deep knee flexion. This mechanism optimizes the extensor mechanism's moment arm and prevents posterior impingement.

Question 16

A Schatzker IV (medial tibial plateau) fracture is notoriously associated with a high rate of which concomitant injury?

Explanation

Schatzker IV fractures involve the medial tibial plateau and represent high-energy trauma often associated with knee subluxation or dislocation. They carry a significantly high risk of popliteal artery injury.

Question 17

A 55-year-old diabetic patient presents with a swollen, erythematous, and painless foot. Radiographs show periarticular debris and fragmentation of the midfoot. What is the most appropriate initial management?

Explanation

In the acute inflammatory phase of Charcot arthropathy (Eichenholtz stage I), immediate immobilization and offloading are critical to prevent further structural collapse. A Total Contact Cast (TCC) is the gold standard initial treatment.

Question 18

A 45-year-old woman presents with neck pain radiating to her middle finger, weakness in elbow extension, and an absent triceps reflex. Which cervical nerve root is most likely compressed?

Explanation

C7 radiculopathy is characterized by weakness in elbow extension (triceps), wrist flexion, and finger extension, along with an absent triceps reflex. Sensory changes classically occur in the middle finger.

Question 19

When treating developmental dysplasia of the hip (DDH) with a Pavlik harness, excessive hyperflexion (greater than 120 degrees) increases the risk of which complication?

Explanation

Hyperflexion in a Pavlik harness can compress the femoral nerve against the rim of the pelvis, leading to a transient femoral nerve palsy. Excessive abduction, conversely, increases the risk of avascular necrosis.

Question 20

Denosumab is an effective pharmacological treatment for unresectable Giant Cell Tumors of bone. It exerts its effect by acting as a monoclonal antibody against:

Explanation

Denosumab is a monoclonal antibody that binds to RANKL, preventing its interaction with RANK on osteoclasts and giant cells. This effectively inhibits tumor-mediated osteolysis and giant cell formation.

Question 21

In a healthy human hip joint, which lubrication mechanism is dominant during the brief, high-load period of heel strike?

Explanation

Squeeze-film lubrication occurs when two joint surfaces move perpendicular to each other under high loads for a short duration, such as during heel strike. Synovial fluid is momentarily trapped, preventing surface-to-surface contact.

Question 22

During a two-incision fasciotomy of the lower leg for compartment syndrome, which compartment is most frequently inadequately decompressed?

Explanation

The deep posterior compartment is the most frequently missed compartment during fasciotomies because of its deep anatomic location surrounded by dense fascia. Inadequate decompression here can lead to severe ischemic contractures of the toe flexors.

Question 23

A patient presents with numbness in the radial 3.5 digits. Which physical examination finding would reliably differentiate Pronator Syndrome from Carpal Tunnel Syndrome?

Explanation

The palmar cutaneous branch of the median nerve arises proximal to the carpal tunnel and supplies sensation to the thenar eminence. Thus, thenar sensation is preserved in carpal tunnel syndrome but decreased in proximal compression like pronator syndrome.

Question 24

In orthopedic biomaterials, the addition of molybdenum to 316L stainless steel primarily serves to:

Explanation

The addition of 2-3% molybdenum to 316L stainless steel helps create a stable, protective passive oxide layer. This significantly enhances the metal's resistance to localized pitting and crevice corrosion in the chloride-rich physiological environment.

Question 25

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

Explanation

A pulseless, pink hand after reduction of a pediatric supracondylar fracture indicates adequate collateral perfusion. Observation is the standard of care, as the pulse typically returns within a few days once swelling subsides.

Question 26

A 35-year-old male is brought to the trauma bay with an Anteroposterior Compression (APC-III) pelvic ring injury. Despite application of a pelvic binder, 2L of crystalloid, and 2 units of uncrossmatched blood, his blood pressure remains 80/50 mmHg. A FAST exam is negative. What is the most appropriate next step?

Explanation

In a hemodynamically unstable patient with a pelvic ring injury and a negative FAST exam, retroperitoneal venous or arterial bleeding is the primary culprit. Preperitoneal pelvic packing or angiography is the most appropriate next step to achieve hemostasis.

Question 27

During a Zone II flexor tendon repair, which of the following technical factors is most important for minimizing tendon gliding resistance and allowing for early active mobilization?

Explanation

The addition of a running epitendinous suture significantly decreases gliding resistance by smoothing the repair site. It also increases the overall tensile strength of the repair by up to 30%.

Question 28

A 65-year-old female with a conventional ultra-high-molecular-weight polyethylene (UHMWPE) total hip arthroplasty placed 15 years ago presents with massive asymmetric head penetration on radiographs and severe osteolysis. The polyethylene was sterilized via gamma irradiation in air. What is the primary mechanism of this catastrophic failure?

Explanation

Historically, gamma irradiation of UHMWPE in air led to free radical formation. Over time, these free radicals reacted with oxygen, causing oxidative degradation, chain scission, embrittlement, and subsequent catastrophic wear.

Question 29

A 72-year-old right-hand-dominant female presents with a severely displaced Neer 4-part proximal humerus fracture. Which of the following is the strongest indication to perform a Reverse Total Shoulder Arthroplasty (RTSA) rather than a Hemiarthroplasty?

Explanation

RTSA provides more predictable functional outcomes in the elderly with 4-part fractures because its function does not depend on tuberosity healing. Hemiarthroplasty outcomes are historically poor if the greater tuberosity fails to heal or malunions.

Question 30

According to Perren's strain theory of bone healing, what is the maximum amount of interfragmentary strain that can be tolerated for primary lamellar bone formation to occur?

Explanation

According to Perren's strain theory, lamellar bone can only form in stable environments with less than 2% interfragmentary strain. Fibrocartilage can tolerate up to 10% strain, and granulation tissue can tolerate up to 100% strain.

Question 31

In the surgical management of the 'terrible triad' of the elbow (elbow dislocation, radial head fracture, and coronoid fracture), standard treatment algorithms suggest addressing structures from deep to superficial. Which structure is typically repaired last, and only if residual instability persists?

Explanation

The standard sequence is fixing the coronoid, then addressing the radial head, followed by the LUCL. The MCL is typically only repaired if the elbow remains grossly unstable in extension after the anterior and lateral structures are stabilized.

Question 32

During a total knee arthroplasty for a patient with a severe, fixed valgus deformity, standard sequential lateral release is often required. Utilizing an outside-in technique (pie-crusting), which structure is typically released first?

Explanation

In a fixed valgus knee, the iliotibial band (ITB) is typically the most contracted structure in extension and is released first. Further releases may involve the LCL or popliteus depending on flexion and extension gap balancing.

Question 33

A 12-year-old boy presents with a unilateral Slipped Capital Femoral Epiphysis (SCFE). Which of the following is an absolute indication for prophylactic in-situ pinning of the contralateral, asymptomatic hip?

Explanation

Patients with underlying endocrine disorders (such as hypothyroidism or renal osteodystrophy) have a highly elevated risk of bilateral SCFE, often approaching 100%. Prophylactic fixation of the contralateral hip is universally recommended in these specific metabolic cases.

Question 34

A 25-year-old male with a closed tibia fracture treated with intramedullary nailing develops severe, disproportionate leg pain. Which intracompartmental pressure measurement is the most reliable threshold for performing a four-compartment fasciotomy?

Explanation

A delta pressure (diastolic blood pressure minus intra-compartmental pressure) of less than 30 mmHg is the most reliable clinical indicator for acute compartment syndrome. Absolute pressures alone can be misleading, especially in hypotensive trauma patients.

Question 35

A 22-year-old falls onto an outstretched hand with tenderness in the anatomical snuffbox. Initial radiographs are entirely normal. If imaging is to be performed at 24 hours to definitively rule out a fracture, which modality is the most sensitive?

Explanation

MRI is the most sensitive and specific modality for detecting occult scaphoid fractures within the first 24 to 48 hours. It can effectively visualize trabecular bone marrow edema and microscopic fracture lines missed by CT and early radiographs.

Question 36

A 30-year-old female presents with knee pain. Radiographs reveal an eccentric, purely lytic lesion in the distal femoral epiphysis extending to the subchondral bone. Biopsy shows mononuclear cells and multinucleated giant cells. The neoplastic cells express RANKL. What is the diagnosis?

Explanation

Giant cell tumors typically present as eccentric, lytic epiphyseal lesions in skeletally mature young adults. The neoplastic mononuclear stromal cells express RANKL, which recruits the reactive multinucleated osteoclast-like giant cells.

Question 37

Denosumab is an effective medical treatment for advanced or unresectable Giant Cell Tumor of bone. What is its exact mechanism of action?

Explanation

Denosumab is a fully human monoclonal antibody that binds specifically to the RANK Ligand (RANKL). By neutralizing RANKL, it prevents the activation of the RANK receptor on osteoclasts, halting bone destruction and tumor progression.

Question 38

A 28-year-old athlete sustains an acute mid-substance Achilles tendon rupture. Compared to functional bracing and early mobilization (non-operative management), surgical repair is associated with a higher incidence of which complication?

Explanation

While operative repair historically lowered the re-rupture rate slightly, it carries a significantly higher risk of iatrogenic complications. These include wound breakdown, deep infection, and sural nerve injury.

Question 39

A 70-year-old male is being evaluated for cervical spondylotic myelopathy. Which of the following physical examination findings is an upper motor neuron sign highly specific to cervical cord compression?

Explanation

An inverted brachioradialis reflex (spontaneous finger flexion upon striking the brachioradialis tendon) is a classic upper motor neuron sign. It indicates cord compression at the C5-C6 level with simultaneous lower motor neuron loss at C6 and upper motor neuron hyperreflexia below that level.

Question 40

In Legg-Calvé-Perthes disease, the lateral pillar (Herring) classification is the most reliable predictor of long-term outcome. At what stage of the disease should this classification be applied to ensure accuracy?

Explanation

The lateral pillar classification assesses the height of the lateral aspect of the femoral head to predict outcomes. It is most accurately and reliably applied during the late fragmentation stage, when the maximum extent of epiphyseal collapse is visible.

Question 41

A 13-year-old obese male presents with left groin pain and obligatory external rotation of the hip during flexion. Imaging confirms a severe slipped upper femoral epiphysis (SUFE). Anatomically, what is the primary mechanism of deformity in this condition?

Explanation

In SUFE, the epiphysis remains relatively secured in the acetabulum by the ligamentum teres. The deformity is actually caused by the femoral neck (metaphysis) displacing anteriorly and superiorly relative to the epiphysis.

Question 42

During the ilioinguinal approach for an anterior column acetabular fracture, severe hemorrhage is encountered near the superior pubic ramus. This is most likely due to an iatrogenic injury to the corona mortis, which represents an anastomosis between which two vascular systems?

Explanation

The corona mortis is an anatomical vascular variant connecting the external iliac system (usually via the inferior epigastric vessels) to the obturator system (internal iliac). Injury during pelvic approaches can cause massive, difficult-to-control hemorrhage.

Question 43

A 25-year-old rugby player sustains an acute knee injury. Radiographs reveal a small elliptical avulsion fracture of the lateral tibial plateau just distal to the articular surface (Segond fracture). Which capsuloligamentous structure is most commonly associated with this specific avulsion?

Explanation

The Segond fracture is a pathognomonic radiographic sign for an anterior cruciate ligament (ACL) tear. It represents an avulsion of the anterolateral capsule, specifically implicating the anterolateral ligament (ALL).

Question 44

A 45-year-old male is evaluated for acute cauda equina syndrome secondary to a massive L4-L5 disc herniation. Which of the following preoperative clinical findings is the most reliable predictor of postoperative urinary bladder function recovery?

Explanation

The severity of the neurological deficit at presentation, particularly the degree of saddle anesthesia and preoperative bladder dysfunction, is the strongest prognostic indicator for long-term urologic recovery.

Question 45

A 65-year-old female undergoes a total hip arthroplasty utilizing a ceramic-on-ceramic bearing surface. At her 1-year follow-up, she complains of an audible squeaking sound during ambulation. What is the most likely biomechanical etiology for this phenomenon?

Explanation

Squeaking in ceramic-on-ceramic THA is heavily associated with edge loading, often due to cup malpositioning (such as excessive steepness). This leads to localized stripe wear on the ceramic head, altering fluid film lubrication and generating noise.

Question 46

In flexor tendon repairs within Zone II of the hand, the preservation of the A2 and A4 pulleys is considered biomechanically critical. What is the primary functional consequence of completely resecting these specific pulleys?

Explanation

The A2 and A4 pulleys keep the flexor tendons closely apposed to the phalanges. Their loss results in bowstringing, which increases the moment arm but significantly reduces tendon excursion efficiency, leading to an increased work of flexion and loss of terminal active flexion.

Question 47

A 15-year-old male is diagnosed with classic high-grade osteosarcoma of the distal femur. Upon initial staging, what is the single most important prognostic factor for long-term survival?

Explanation

The presence of detectable metastases (most commonly pulmonary) at the time of initial diagnosis is the most significant negative prognostic factor in osteosarcoma. Non-metastatic disease has a significantly higher 5-year survival rate.

Question 48

A 55-year-old diabetic patient presents with a swollen, erythematous, and warm foot. There are no systemic signs of infection and no skin ulcerations. Radiographs show periarticular debris, fragmentation, and subluxation at the tarsometatarsal joints. What is the most appropriate initial management?

Explanation

The patient has acute Eichenholtz Stage 1 (developmental/fragmentation phase) Charcot arthropathy. The gold standard for initial treatment is immobilization and offloading using a total contact cast to halt progressive deformity.

Question 49

A 32-year-old male sustains a closed fracture of the distal third of the humeral shaft (Holstein-Lewis fracture). On initial presentation, his radial nerve function is completely intact. Following closed reduction and splinting in the emergency department, he immediately develops a dense radial nerve palsy. What is the most appropriate next step in management?

Explanation

A secondary radial nerve palsy that develops immediately following closed reduction manipulation of a humeral shaft fracture is an absolute indication for surgical exploration, as the nerve may be entrapped within the fracture site.

Question 50

According to Perren's strain theory of bone healing, the type of tissue that forms in a fracture gap is dictated by the interfragmentary strain. What level of strain is specifically required to promote the formation of cartilage in secondary bone healing?

Explanation

Perren's theory dictates that primary bone healing (lamellar bone) occurs with <2% strain. Cartilage tolerates and forms under 2% to 10% strain, whereas granulation tissue forms when strain is between 10% and 100%.

Question 51

A reverse total shoulder arthroplasty (RTSA) is performed for a 75-year-old patient with severe rotator cuff tear arthropathy. How does the biomechanical design of the RTSA primarily restore active forward elevation?

Explanation

The RTSA design medializes and distalizes the glenohumeral joint's center of rotation. This recruits more deltoid muscle fibers and significantly increases the deltoid's moment arm, allowing it to substitute for the deficient supraspinatus.

Question 52

A 25-year-old male sustains a high-energy tibial plateau fracture and is suspected of developing acute compartment syndrome. According to the Whitesides concept (Delta P), what is the critical pressure threshold used to confirm the diagnosis and indicate fasciotomy?

Explanation

The Delta P concept defines compartment syndrome as occurring when the compartment pressure approaches systemic perfusion pressure. A Delta P (Diastolic BP - compartment pressure) of less than 30 mmHg is considered the threshold for cellular ischemia and mandates fasciotomy.

Question 53

A 6-week-old infant is undergoing treatment with a Pavlik harness for developmental dysplasia of the hip (DDH). During a follow-up visit, it is noted that the anterior straps are overly tightened, placing the hip in excessive flexion. What is the most likely iatrogenic complication of this specific malpositioning?

Explanation

In Pavlik harness treatment, excessive hip flexion (over-tightened anterior straps) stretches the femoral nerve against the inguinal ligament, causing a femoral nerve palsy. Conversely, excessive abduction (over-tightened posterior straps) increases the risk of avascular necrosis.

Question 54

A 40-year-old male presents with a vertical shear femoral neck fracture classified as Pauwels type III (fracture angle > 50 degrees). Biomechanically, what is the primary deforming force acting on this fracture pattern that complicates stable internal fixation?

Explanation

The Pauwels classification is based on the angle of the fracture line relative to the horizontal. Type III fractures are highly vertical, converting the physiological weight-bearing loads across the hip joint into extreme shear forces, leading to a high rate of fixation failure.

Question 55

A 30-year-old female presents with a recurrent giant cell tumor (GCT) of the distal radius. She is treated preoperatively with Denosumab to consolidate the tumor margin. What is the specific molecular mechanism of action of this pharmacological agent?

Explanation

Denosumab is a fully human monoclonal antibody that binds to Receptor Activator of Nuclear factor Kappa-B Ligand (RANKL). By neutralizing RANKL, it prevents the interaction with RANK receptors on osteoclast precursors, dramatically reducing osteoclast-like giant cell formation.

Question 56

Aseptic loosening secondary to particulate wear debris remains a primary cause of late failure in total hip arthroplasty. Which specific cell type is primarily responsible for the phagocytosis of polyethylene particles and the subsequent initiation of the osteolytic cytokine cascade?

Explanation

Macrophages phagocytose submicron wear particles (0.1 to 10 micrometers) but cannot digest them. This results in the release of pro-inflammatory cytokines (IL-1, IL-6, TNF-alpha) that stimulate osteoclastic bone resorption, leading to osteolysis.

Question 57

During a surgical debridement for insertional Achilles tendinopathy and excision of a prominent Haglund's deformity, it is necessary to detach a portion of the Achilles tendon. What is the generally accepted maximum percentage of the tendon insertion that can be detached before a formal tendon augmentation (e.g., FHL transfer) is strictly required?

Explanation

Biomechanical and clinical studies demonstrate that up to 50% of the Achilles tendon insertion can be detached and resected without critically compromising its strength. Resections exceeding 50% generally mandate reconstruction, often utilizing a flexor hallucis longus (FHL) transfer.

Question 58

A 65-year-old male with progressive gait deterioration presents for evaluation. On examination, a rapid flicking of the distal phalanx of the middle finger results in spontaneous flexion of the thumb and index finger (positive Hoffmann's sign). This physical finding typically indicates an upper motor neuron lesion above which specific spinal cord level?

Explanation

A positive Hoffmann's sign is indicative of an upper motor neuron (UMN) lesion in the cervical spine. It specifically points to cord compression or dysfunction at or above the C5/C6 level.

Question 59

A 35-year-old motorcyclist sustains a highly comminuted open tibial shaft fracture. The wound is 5 cm long, severely contaminated, and there is extensive periosteal stripping. Following radical debridement, the bone cannot be covered with local soft tissues and requires a free latissimus dorsi flap. According to the Gustilo-Anderson classification, this is a:

Explanation

Type IIIB fractures are high-energy injuries with extensive soft tissue loss, periosteal stripping, and bone exposure that require a flap (local or free) for coverage. Type IIIC would additionally require a vascular repair to salvage the limb.

Question 60

A 45-year-old carpenter presents with a chronic, unretractable rupture of the extensor pollicis longus (EPL) tendon, which occurred 3 months following a non-operative distal radius fracture. The surgeon plans a tendon transfer to restore thumb extension. Which of the following is the most appropriate and commonly used donor tendon for this procedure?

Explanation

The Extensor Indicis Proprius (EIP) is the gold standard donor tendon for restoring EPL function. It has an appropriate line of pull, sufficient excursion, and its harvest leaves the index finger with independent extension via the intact EDC tendon.

Question 61

A 25-year-old male sustains a vertical, displaced basicervical femoral neck fracture (Pauwels III). Which fixation method offers the greatest biomechanical stability against shear forces?

Explanation

A sliding hip screw with a derotation screw provides the most biomechanically stable construct for highly vertical (Pauwels III) basicervical femoral neck fractures. It optimally resists the high shear forces present in this fracture pattern compared to isolated cancellous screws.

Question 62

A 12-year-old obese boy presents with a 2-week history of knee pain and an obligate external rotation of the hip during active flexion. An AP pelvis radiograph shows a widened physis. What is the most common long-term complication of the standard definitive surgical management?

Explanation

In-situ pinning is the standard treatment for a stable slipped capital femoral epiphysis (SCFE). Because the deformity is not acutely corrected, patients commonly develop cam-type femoroacetabular impingement due to the prominent anterolateral metaphysis.

Question 63

During the creeping substitution of a massive structural cortical bone allograft, which biological process is characteristically delayed or absent compared to cancellous autograft?

Explanation

Structural cortical allografts undergo slow and incomplete revascularization, which is often restricted to the periphery of the graft. This delayed creeping substitution makes them prone to late fatigue fractures due to the persistence of a necrotic core.

Question 64

A 30-year-old carpenter sustains a volar laceration to the index finger at the level of the proximal interphalangeal joint crease, resulting in isolated loss of active distal interphalangeal joint flexion. Which anatomical zone of the flexor tendon is injured?

Explanation

Zone I extends from the insertion of the flexor digitorum superficialis (FDS) to the insertion of the flexor digitorum profundus (FDP) at the distal phalanx base. An injury here results in an isolated loss of FDP function, preventing active DIP joint flexion.

Question 65

A 45-year-old female presents with acute onset of bilateral sciatica, saddle anesthesia, and urinary retention with overflow incontinence following a heavy lifting injury. An MRI confirms a massive L4-L5 disc herniation. What is the most critical prognostic factor for postoperative bladder function recovery?

Explanation

The most significant predictor of neurological recovery, particularly bladder and bowel function, in Cauda Equina Syndrome is the time to surgical decompression. Surgery should ideally be performed within 24 to 48 hours of symptom onset to maximize functional recovery.

Question 66

A 15-year-old boy presents with progressive night pain in his distal femur. Radiographs show a destructive metaphyseal lesion with a "sunburst" periosteal reaction and Codman's triangle. Histology reveals malignant spindle cells producing unmineralized osteoid. What is the most critical step in initial staging?

Explanation

The scenario describes classic osteosarcoma, which most commonly metastasizes hematogenously to the lungs. Therefore, a high-resolution CT scan of the chest is an essential and critical component of initial tumor staging.

Question 67

A 68-year-old woman is evaluated for a painful total hip arthroplasty 10 years post-surgery. Radiographs show eccentric wear of the polyethylene liner and substantial osteolysis in Gruen zones 1 and 7. What is the primary biological mediator responsible for this osteolysis?

Explanation

Periprosthetic osteolysis is primarily driven by a macrophage-mediated inflammatory response to particulate wear debris. Macrophages phagocytose the particles and release pro-inflammatory cytokines like TNF-alpha, IL-1, and IL-6, which stimulate osteoclastogenesis.

Question 68

When reconstructing the anterior cruciate ligament (ACL) with a bone-patellar tendon-bone autograft, placing the femoral tunnel too anteriorly (shallow) will result in which of the following postoperative clinical findings?

Explanation

A femoral tunnel placed too anteriorly creates a non-isometric graft where the distance between the tibial and femoral tunnels increases during knee flexion. This results in the graft becoming excessively tight in flexion and loose in extension, restricting normal knee flexion.

Question 69

A 55-year-old diabetic male presents with a swollen, erythematous, and warm left foot. Radiographs reveal fragmentation and subluxation of the tarsometatarsal joints. His pedal pulses are bounding. What is the most appropriate initial management?

Explanation

This patient is in the acute inflammatory (Eichenholtz stage I) phase of Charcot neuroarthropathy. The gold standard for initial management is strict immobilization and offloading, typically achieved with a total contact cast, to halt progression and prevent further deformity.

Question 70

A 4-month-old girl is diagnosed with developmental dysplasia of the hip (DDH). Ultrasound confirms a dislocated left hip that is reducible. Treatment with a Pavlik harness is initiated. Which complication is most likely if the hips are positioned in excessive hyperflexion (>120 degrees)?

Explanation

Hyperflexion of the hips in a Pavlik harness compresses the femoral nerve against the inguinal ligament, leading to transient femoral nerve palsy. Conversely, excessive abduction significantly increases the risk of avascular necrosis of the femoral head.

Question 71

A 30-year-old man sustains a closed tibial shaft fracture. Twelve hours later, he develops excruciating leg pain out of proportion to the injury, exacerbated by passive toe stretch. Which physiological mechanism best explains the underlying pathology?

Explanation

Acute compartment syndrome occurs when tissue pressure within a closed osteofascial space exceeds capillary perfusion pressure. This initially collapses low-pressure venous outflow, which further raises intracompartmental pressure and eventually compromises arterial inflow.

Question 72

A 45-year-old typist presents with numbness and tingling in her thumb, index, and long fingers. Examination reveals a positive Tinel's sign at the wrist and weakness in thumb abduction. Which electrodiagnostic finding most specifically confirms compression at the carpal tunnel?

Explanation

Prolonged median nerve distal sensory and motor latencies across the carpal tunnel are hallmark electrodiagnostic findings of Carpal Tunnel Syndrome. The flexor pollicis longus is innervated proximal to the carpal tunnel and would not show abnormalities in isolated CTS.

Question 73

Six weeks after a total knee arthroplasty, a patient presents with persistent wound drainage and erythema. Aseptic aspiration yields a synovial fluid white blood cell count of 45,000 cells/uL with 92% neutrophils. What is the most appropriate surgical intervention?

Explanation

For acute periprosthetic joint infections occurring within 4 weeks of surgery or within 3 weeks of acute symptom onset, DAIR with modular component exchange is indicated. The implants are well-fixed, and the biofilm is immature, making salvage possible.

Question 74

A 60-year-old man presents after a motor vehicle accident with neck pain. A lateral cervical spine radiograph shows a bilateral pars interarticularis fracture of C2 with 2 mm of anterior displacement of C2 on C3 and no angulation. What is the Levine-Edwards classification of this fracture?

Explanation

A Levine-Edwards Type I Hangman's fracture involves bilateral pars interarticularis fractures of C2 with less than 3 mm of displacement and no significant angulation. It is a highly stable injury typically treated conservatively with a rigid cervical collar.

Question 75

In the context of total hip arthroplasty, which of the following wear mechanisms is primarily responsible for the generation of submicron polyethylene particles when a roughened femoral head articulates with the liner?

Explanation

Abrasive wear occurs when a hard, rough surface (like a scratched metallic femoral head) ploughs through a softer material (polyethylene), shaving away micro-particles. This is a primary generator of the debris that leads to osteolysis.

Question 76

A hemodynamically unstable polytrauma patient arrives in the ER. Pelvic radiographs show an "open book" pelvic fracture with a widely displaced symphysis pubis. A pelvic binder is to be applied. What is the optimal anatomical landmark for the center of the binder to maximize fracture reduction?

Explanation

To effectively close an "open book" pelvic ring injury, the pelvic binder must be centered directly over the greater trochanters. Placement over the iliac crests is a common error that can inadvertently distract the pelvis or fail to provide adequate mechanical compression.

Question 77

A 13-year-old obese male presents with a 2-week history of worsening groin pain and a sudden inability to bear weight on the right leg after a minor slip. Radiographs confirm a severe slipped capital femoral epiphysis (SCFE). Which of the following factors is the most significant predictor for the development of avascular necrosis (AVN) in this patient?

Explanation

Instability, defined clinically as the inability to bear weight even with crutches, is the most significant risk factor for AVN in SCFE. The rate of AVN in unstable SCFE can approach 50%, compared to near zero in stable slips.

Question 78

During a total knee arthroplasty, trial reduction reveals that the knee is well-balanced in flexion but tight in extension. Which of the following is the most appropriate intraoperative step to address this mismatch?

Explanation

A knee that is tight in extension but balanced in flexion requires an increase in the extension gap without altering the flexion gap. This is achieved by resecting more distal femur or releasing the posterior capsule.

Question 79

A 35-year-old male is brought to the trauma bay following a high-speed motorcycle collision. He has a mechanically unstable APC-III pelvic ring injury. Despite application of a pelvic binder and initial fluid resuscitation, his blood pressure remains 70/40 mmHg. FAST scan is negative. What is the most appropriate next step in management?

Explanation

In a hemodynamically unstable patient with a pelvic ring injury and a negative FAST scan, the source of bleeding is likely retroperitoneal. Preperitoneal pelvic packing or pelvic angiography with embolization is indicated to control hemorrhage.

Question 80

A 45-year-old manual laborer presents with chronic wrist pain. Radiographs reveal a scaphoid nonunion with arthritic changes involving the radioscaphoid and midcarpal joints, while the radiolunate joint is spared. This corresponds to a Stage III SNAC wrist. Which of the following is the most appropriate surgical treatment?

Explanation

Stage III SNAC wrist involves arthritis of the radioscaphoid and midcarpal (capitolunate) joints. Proximal row carpectomy is contraindicated due to capitate articular compromise, making scaphoid excision and four-corner fusion the preferred motion-preserving option.

Question 81

According to Perren's strain theory, what is the maximum interfragmentary strain threshold compatible with primary bone healing (absolute stability)?

Explanation

Primary bone healing requires absolute stability, which corresponds to an interfragmentary strain of less than 2%. Strains between 2% and 10% promote secondary bone healing via callus formation.

Question 82

The vulnerability of the scaphoid proximal pole to avascular necrosis following fracture is primarily dictated by its blood supply. Which of the following vessels provides the dominant intraosseous blood supply to the scaphoid?

Explanation

The dorsal carpal branch of the radial artery supplies 70-80% of the scaphoid, entering at the distal ridge and flowing retrogradely to the proximal pole. This retrograde flow is responsible for the high rate of AVN in proximal fractures.

Question 83

A 65-year-old female presents with a painful popping sensation at the anterior aspect of her knee when extending from a flexed position, 12 months after a total knee arthroplasty. Which of the following implant designs is classically associated with this complication?

Explanation

Patellar clunk syndrome is typically associated with posterior-stabilized TKA designs. It occurs when a fibrous nodule forms at the superior pole of the patella and catches in the intercondylar box of the femoral component during extension.

Question 84

Denosumab is frequently used in the management of unresectable or metastatic giant cell tumor (GCT) of bone. What is the specific mechanism of action of this medication?

Explanation

Denosumab is a fully human monoclonal antibody that binds to RANKL, preventing its interaction with the RANK receptor on osteoclast precursors. This inhibits osteoclast-like giant cell formation and function, leading to massive tumor necrosis and ossification.

Question 85

Six months following volar locking plate fixation of a distal radius fracture, a patient reports a sudden inability to actively flex the interphalangeal joint of the thumb. Attritional rupture of the flexor pollicis longus (FPL) is suspected. Which surgical technical error is the most common cause of this complication?

Explanation

Attritional rupture of the FPL tendon is most commonly caused by placement of the volar plate at or distal to the watershed line. This prominence creates friction against the flexor tendons during wrist motion.

Question 86

A 42-year-old male undergoes surgery for a "terrible triad" injury of the elbow. The radial head is replaced, the coronoid fracture is fixed with a suture lasso, and the lateral ulnar collateral ligament (LUCL) is repaired. Intraoperative fluoroscopic testing reveals the elbow persistently subluxates when extended past 30 degrees of flexion. What is the most appropriate next step in management?

Explanation

The standard surgical sequence for a terrible triad injury is coronoid fixation, radial head repair or replacement, followed by LUCL repair. If the elbow remains unstable in extension after these steps, the next appropriate action is exploration and repair of the MCL. A hinged external fixator is reserved for persistent instability even after the MCL has been addressed.

Question 87

A 35-year-old female presents with a rapidly enlarging, painful mass in her distal femur. Biopsy confirms a Giant Cell Tumour (GCT) of bone. The multidisciplinary team recommends neoadjuvant treatment with Denosumab. What is the precise mechanism of action of this pharmacological agent?

Explanation

Denosumab is a human monoclonal antibody that binds directly to RANKL, preventing it from interacting with the RANK receptor on osteoclasts and their precursors. In GCT, neoplastic mononuclear stromal cells overexpress RANKL, which aggressively recruits and activates the destructive osteoclast-like giant cells.

Question 88

A 12-year-old obese boy presents with a 3-week history of left thigh pain and an antalgic gait. Radiographs confirm a slipped capital femoral epiphysis (SCFE). According to the modified Southwick classification, which of the following defines a "moderate" slip on a frog-leg lateral radiograph?

Explanation

The Southwick classification uses the difference in the epiphyseal-shaft angle between the affected and normal hips on a frog-leg lateral radiograph. A difference of less than 30 degrees is mild, 30-50 degrees is moderate, and greater than 50 degrees is severe. Translation percentages refer to the Wilson classification.

Question 89

A 72-year-old man undergoes a revision total hip arthroplasty for aseptic loosening. The femur exhibits a Paprosky Type IIIB defect, and the surgeon opts for a modular, fluted, tapered titanium stem. What is the primary biomechanical mechanism of diaphyseal fixation for this implant?

Explanation

In severe metaphyseal bone loss (Paprosky IIIB), modular fluted tapered stems bypass the proximal deficiency to achieve stable diaphyseal fixation. The longitudinal flutes (splines) cut into the cortical bone to provide rotational stability, while the tapered design engages the diaphysis to provide axial stability and prevent subsidence.

FRCS: Questions (MCQs)

Quick Medical Answer

FRCS: Questions (MCQs)

Detailed Chapters & Topics

FRCS: Hand and wrist

FRCS: Shoulder and elbow

FRCS: Spine

FRCS: Hip and pelvis

FRCS: Knee

FRCS: Foot and ankle

FRCS: Pathology

FRCS: Paediatric orthopaedics

FRCS: Trauma

FRCS: Basic science

FRCS EMQs: Paediatric orthopaedics

FRCS EMQs: Basic science

FRCS EMQs: Spine

FRCS EMQs: Knee

FRCS EMQs: Foot and ankle

Guide Overview