+967-774203774 [email protected]
العربية
Part of the Master Guide

Arab Board Orthopedic B Review | Dr Hutaif General Orth -...

Arab Orthopaedic Board MCQs - Part 15

27 Apr 2026 76 min read 78 Views
Arab Ortho Board MCQs - Part 14

Key Takeaway

For anyone wondering about Arab Orthopaedic Board MCQs - Part 15, Practice Arab Orthopaedic Board MCQs Part 15. Review orthopedic surgery questions 701 to 750 for your board exam preparation.

Arab Orthopaedic Board MCQs - Part 15

Comprehensive 100-Question Exam


00:00

Start Quiz

Question 1

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





Explanation

Prophylactic pinning of the contralateral hip in SCFE is highly recommended in patients with endocrine disorders (e.g., hypothyroidism, growth hormone deficiency, renal osteodystrophy) due to the high risk of bilateral involvement (up to 100% in some endocrine conditions). Other risk factors include age <10 years (or open triradiate cartilage) and prior radiation therapy.

Question 2

According to the Young-Burgess classification, a lateral compression type II (LC-II) pelvic ring injury is characterized by an anterior ring fracture combined with which of the following posterior injuries?





Explanation

An LC-II injury in the Young-Burgess classification is characterized by an anterior ring injury (rami fractures) and an ipsilateral posterior ilium fracture (often a 'crescent' fracture) due to internal rotation force pivoting on the strong posterior sacroiliac ligaments. LC-I involves an ipsilateral sacral compression fracture. LC-III is an LC-I or LC-II with a contralateral anteroposterior compression (APC) injury (windswept pelvis).

Question 3

A 24-year-old football player sustains a high-energy knee injury. Clinical examination reveals a grade 3 positive dial test at 30 degrees of flexion, which reduces to a grade 1 at 90 degrees. He also exhibits an abnormal varus thrust during gait. Which structure is most likely disrupted?





Explanation

An isolated posterolateral corner (PLC) injury is characterized by increased external rotation (positive dial test) at 30 degrees of flexion, but not at 90 degrees. If the dial test is positive at both 30 and 90 degrees, it suggests a combined PCL and PLC injury. A varus thrust during gait is a classic dynamic clinical finding for PLC deficiency.

Question 4

In healthy articular cartilage, which zone is characterized by the highest concentration of proteoglycans, the lowest concentration of water, and chondrocytes aligned in vertical columns?





Explanation

The deep (radial) zone of articular cartilage contains the highest concentration of proteoglycans and the lowest water content. The chondrocytes in this layer are arranged in vertical columns parallel to the collagen fibers, which orient perpendicular to the joint surface to effectively resist and distribute compressive forces.

Question 5

A 35-year-old man presents following a motor vehicle accident. Radiographs reveal a traumatic spondylolisthesis of the axis (Hangman's fracture) with severe angulation and >5mm of translation of C2 on C3. The C2-C3 facet joints are dislocated. According to the Levine-Edwards classification, what is the grade and typical mechanism of this injury?





Explanation

Levine-Edwards Type III Hangman's fracture involves a fracture of the pars interarticularis with accompanying bilateral C2-C3 facet dislocations. The mechanism is flexion and distraction. Severe angulation and translation with facet dislocation characterize a Type III injury, which is highly unstable and typically requires open reduction and internal fixation.

Question 6

A 30-year-old male sustains a purely ligamentous Lisfranc injury involving the first, second, and third tarsometatarsal joints. Based on prospective randomized trials, what is the major clinical advantage of primary arthrodesis compared to Open Reduction and Internal Fixation (ORIF) for this specific injury pattern?





Explanation

Prospective randomized trials (e.g., Ly and Coetzee, JBJS 2006) have shown that for purely ligamentous Lisfranc injuries, primary arthrodesis leads to superior short- to medium-term outcomes and a significantly lower rate of secondary surgeries (such as hardware removal or salvage arthrodesis for post-traumatic arthritis) compared to ORIF.

Question 7

The major blood supply to the scaphoid enters through the dorsal ridge and supplies the proximal pole in a retrograde fashion. Which artery provides this primary vascular supply?





Explanation

The scaphoid receives 70-80% of its blood supply from the dorsal carpal branch of the radial artery, which enters at the dorsal ridge and flows retrogradely to supply the proximal pole. This delicate retrograde blood supply explains the high rate of avascular necrosis and nonunion seen in proximal pole scaphoid fractures.

Question 8

A 45-year-old active male undergoes a total hip arthroplasty with a ceramic-on-ceramic bearing. Which of the following is a recognized unique complication associated specifically with this type of bearing surface?





Explanation

Squeaking is a well-documented and unique complication of ceramic-on-ceramic (CoC) bearing surfaces in total hip arthroplasty, occurring in up to 10% of cases. Risk factors include component malposition (e.g., edge loading, microseparation), younger age, and high BMI. While stripe wear also occurs in CoC, squeaking is the most distinct clinical complication reported by patients.

Question 9

An 8-week-old female infant is treated with a Pavlik harness for Developmental Dysplasia of the Hip (DDH). During a follow-up visit, the mother notes that the infant is no longer kicking her leg on the affected side. Examination reveals an absent patellar reflex and inability to actively extend the knee. What positioning error in the Pavlik harness most likely caused this complication?





Explanation

The clinical picture describes a femoral nerve palsy, a known complication of the Pavlik harness. It is typically caused by excessive hip flexion (often >120 degrees), which compresses the femoral nerve against the inguinal ligament. Excessive hip abduction, conversely, places the patient at a higher risk for avascular necrosis (AVN) of the femoral head.

Question 10

A 55-year-old woman falls on an outstretched hand and sustains a distal radius fracture. Radiographs show a fracture of the volar rim of the distal radius with volar subluxation of the carpus. The dorsal cortex remains intact. What is the correct eponymous term for this fracture pattern?





Explanation

A volar Barton's fracture is an intra-articular shear fracture of the volar rim of the distal radius with associated volar subluxation or dislocation of the radiocarpal joint. Colles' is a dorsal angulated extra-articular fracture; Smith's is a volar angulated extra-articular fracture; Chauffeur's is a radial styloid fracture; Die-punch involves a depressed lunate fossa.

Question 11

A 14-year-old boy presents with a painful mass in the diaphysis of his left femur. Radiographs reveal a permeative, destructive lesion with an onion-skin periosteal reaction. A biopsy is performed, and molecular pathology identifies a specific chromosomal translocation. Which translocation is most diagnostic for this neoplasm?





Explanation

The clinical and radiographic presentation is classic for Ewing sarcoma. The t(11;22)(q24;q12) translocation is present in approximately 85% of Ewing sarcomas, resulting in the EWS-FLI1 fusion gene. t(X;18) is associated with synovial sarcoma; t(12;16) with myxoid liposarcoma; t(2;13) with alveolar rhabdomyosarcoma; and t(9;22) is the Philadelphia chromosome (CML).

Question 12

According to the 2018 International Consensus Meeting (ICM) criteria for periprosthetic joint infection (PJI), which of the following carries the highest diagnostic weight (major criterion) when confirming PJI?





Explanation

According to the MSIS and 2018 ICM criteria, the two major criteria (either of which alone is diagnostic for PJI) are: 1) Two positive periprosthetic cultures with phenotypically identical organisms, and 2) A sinus tract communicating with the joint. Alpha-defensin, leukocyte esterase, PMN%, and synovial CRP are minor criteria in the scoring system.

Question 13

A 28-year-old male sustains a closed tibial shaft fracture. Two hours post-admission, he complains of severe pain out of proportion to the injury, unrelieved by opioids. Compartment pressure monitoring is performed. Which of the following pressure measurements is generally accepted as the threshold indicating the need for emergent fasciotomy?





Explanation

The delta pressure (Diastolic Blood Pressure minus Intracompartmental Pressure) is the most reliable indicator for acute compartment syndrome. A delta pressure of less than 30 mmHg (some sources say <=30 mmHg) strongly indicates the need for emergent fasciotomy, as absolute pressures can be misleading depending on the patient's systemic blood pressure.

Question 14

During a flexor tendon repair in the hand, preserving the pulley system is crucial to prevent bowstringing and ensure efficient digit flexion. Which two annular pulleys are considered the most biomechanically essential and must be preserved or reconstructed?





Explanation

The A2 (arising from the proximal phalanx) and A4 (arising from the middle phalanx) are the major pulleys required to prevent bowstringing of the flexor tendons and maintain mechanical advantage. They are biomechanically the most important. A1, A3, and A5 arise from the volar plates of the MP, PIP, and DIP joints, respectively.

Question 15

During arthroscopic evaluation of a shoulder, a surgeon identifies a SLAP (Superior Labrum Anterior to Posterior) lesion. Which type of SLAP lesion is defined by a bucket-handle tear of the superior labrum with the biceps anchor remaining intact?





Explanation

According to the Snyder classification of SLAP lesions: Type I is fraying of the superior labrum; Type II is detachment of the superior labrum and biceps anchor from the glenoid; Type III is a bucket-handle tear of the superior labrum with an intact biceps anchor; Type IV is a bucket-handle tear that extends into the biceps tendon.

Question 16

According to Perren's strain theory of bone healing, what is the maximum amount of interfragmentary strain that can be tolerated for primary (osteonal) bone healing to occur without the formation of a visible callus?





Explanation

Perren's strain theory states that primary (direct) bone healing via osteonal cutting cones requires absolute stability. This occurs only when interfragmentary strain is less than 2%. Strains between 2% and 10% result in secondary bone healing (callus formation). Strains >10% typically lead to nonunion, as the strain exceeds the tolerance of bone and cartilage formation.

Question 17

A 7-year-old boy is diagnosed with Legg-Calve-Perthes disease. According to the Herring Lateral Pillar Classification, which of the following describes a Group B hip, and what is its prognostic significance?





Explanation

The Herring Lateral Pillar Classification assesses the height of the lateral pillar of the femoral head on an AP radiograph during the fragmentation stage. Group A has no loss of height; Group B has >50% maintained (i.e., <50% loss of height); Group C has <50% of the height maintained. Group B hips generally have a good outcome in patients <8 years old but a less predictable/worse outcome in older patients.

Question 18

A 65-year-old man presents with progressive clumsiness in his hands and a broad-based gait. Physical examination reveals a positive Hoffmann's sign and a positive inverted radial reflex. What does a positive inverted radial reflex indicate in the context of cervical spondylotic myelopathy?





Explanation

The inverted brachioradialis (radial) reflex is elicited by tapping the brachioradialis tendon at the distal radius. A normal response is elbow flexion. An abnormal, 'inverted' response consists of absent elbow flexion but brisk finger flexion. This indicates a lower motor neuron lesion at C5/C6 (absent brachioradialis reflex) combined with an upper motor neuron lesion below that level (hyperreflexia of the C8-innervated finger flexors), strongly suggesting a spinal cord lesion at C5-C6.

Question 19

A 52-year-old diabetic patient with peripheral neuropathy presents with a warm, swollen, erythematous foot. Radiographs demonstrate periarticular debris, fragmentation of the navicular and cuneiforms, and subluxation of the midfoot. According to the Eichenholtz classification, what stage of Charcot arthropathy is this patient currently in?





Explanation

The Eichenholtz classification of Charcot arthropathy: Stage 0 (Inflammatory) shows clinical warmth/swelling with normal radiographs; Stage 1 (Development) shows bony fragmentation, periarticular debris, and joint subluxation/dislocation; Stage 2 (Coalescence) shows absorption of debris and early fusion/sclerosis; Stage 3 (Reconstruction) shows rounding of bone ends, consolidation, and decreased sclerosis.

Question 20

The Sanders classification system for intra-articular calcaneal fractures is heavily utilized to guide surgical management. This classification is primarily based on the number and location of fracture lines through which articular surface on coronal Computed Tomography (CT) scans?





Explanation

The Sanders classification is based on coronal CT images detailing the fracture lines through the posterior facet of the calcaneus. It dictates surgical decision-making. Type I fractures are nondisplaced regardless of the number of fracture lines. Type II are 2-part (1 fracture line in the posterior facet), Type III are 3-part (2 fracture lines), and Type IV are 4-part (highly comminuted).

Question 21

A surgeon uses a structural cortical allograft to reconstruct a massive diaphyseal defect following tumor resection. Which of the following best describes the initial phase of graft incorporation for this specific type of bone graft?





Explanation

Cortical bone grafts incorporate via creeping substitution, which initially involves osteoclastic resorption through cutting cones. This initial resorptive phase leads to a temporary decrease in the mechanical strength of the cortical graft. In contrast, cancellous bone grafts incorporate primarily through early osteoblastic apposition of new bone onto the existing dead trabecular framework without initial significant resorption.

Question 22

During the ilioinguinal approach to the acetabulum, severe bleeding is encountered while dissecting over the superior pubic ramus. This is likely due to injury to the 'corona mortis'. What is the correct anatomical description of this structure?





Explanation

The corona mortis ('crown of death') is a vascular anastomosis between the obturator system (internal iliac system) and the external iliac or inferior epigastric system. It typically crosses the superior pubic ramus and is highly vulnerable to injury during anterior approaches to the pelvis (e.g., ilioinguinal approach) or during placement of superior pubic ramus screws.

Question 23

A 12-year-old boy presents with a left-sided severe slipped capital femoral epiphysis (SCFE). Which of the following factors provides the strongest indication for prophylactic pinning of the asymptomatic contralateral hip?





Explanation

Prophylactic pinning of the contralateral hip in SCFE is heavily debated, but there is broad consensus that patients with underlying endocrine disorders (e.g., hypothyroidism, growth hormone deficiency, renal osteodystrophy) or previous radiation therapy are at a remarkably high risk of developing a contralateral slip. Thus, prophylactic pinning is strongly indicated in these populations.

Question 24

Which of the following statements correctly describes the tensioning patterns of the two functional bundles of the anterior cruciate ligament (ACL) during knee range of motion?





Explanation

The ACL is composed of two main bundles: the anteromedial (AM) bundle and the posterolateral (PL) bundle. The AM bundle is primarily tight in flexion and provides the main restraint to anterior tibial translation at 90 degrees of flexion. The PL bundle is tight in extension and is the primary restraint to rotatory loads.

Question 25

A patient experiences posterior instability following a total hip arthroplasty. Intraoperatively, the surgeon wishes to increase the tension of the posterior soft tissues and abductor complex without significantly increasing the patient's leg length. Which of the following adjustments is most appropriate?





Explanation

Increasing the femoral offset shifts the femur laterally, which effectively increases the tension of the abductor musculature and posterior soft tissues, improving joint stability without significantly altering the leg length. In contrast, increasing the neck length (especially with a valgus neck) will increase both offset and leg length.

Question 26

A 35-year-old patient with a high radial nerve palsy secondary to a humerus fracture fails to show nerve recovery at 6 months. In a standard tendon transfer procedure to restore wrist extension, which of the following muscles is most commonly utilized as the motor unit?





Explanation

In standard radial nerve tendon transfers (e.g., Boyes, Jones, or modified Green transfers), the Pronator Teres (PT) is the most common muscle transferred to the Extensor Carpi Radialis Brevis (ECRB) to restore wrist extension. It is synergistic and provides excellent excursion and power.

Question 27

A 22-year-old male is evaluated for neck pain following an axial loading injury. Radiographs show a C1 burst fracture (Jefferson fracture). Which of the following findings on an open-mouth odontoid view is indicative of a complete rupture of the transverse atlantal ligament?





Explanation

According to the rule of Spence, a combined lateral mass overhang (displacement) of C1 on C2 of greater than 6.9 mm on an open-mouth AP radiograph indicates a rupture of the transverse atlantal ligament, rendering the C1 ring fracture unstable.

Question 28

A 14-year-old boy completes neoadjuvant chemotherapy and undergoes surgical resection for a non-metastatic osteosarcoma of the distal femur. What is the most important prognostic factor for his long-term survival?





Explanation

The most significant prognostic factor for long-term survival in patients with non-metastatic osteosarcoma is the histologic response to neoadjuvant chemotherapy, defined by the percentage of tumor necrosis in the resected specimen. Greater than 90% necrosis identifies 'good responders' and is associated with significantly better outcomes.

Question 29

A 30-year-old construction worker sustains a midfoot injury. Imaging reveals widening between the first and second metatarsals. The Lisfranc ligament, critical for midfoot stability, originates and inserts onto which of the following osseous structures?





Explanation

The Lisfranc ligament is a strong interosseous ligament that connects the medial cuneiform to the base of the second metatarsal. There is no direct ligamentous connection between the bases of the first and second metatarsals, making the Lisfranc ligament vital for transverse midfoot stability.

Question 30

According to Saunders et al., the determinants of normal human gait function to minimize the vertical and lateral displacement of the body's center of gravity. Which of the following movements is a primary determinant that specifically acts to reduce the peak of the vertical center of gravity trajectory?





Explanation

Saunders et al. described six determinants of gait. Knee flexion in the stance phase (typically around 15 degrees) serves to lower the peak of the vertical displacement of the center of gravity, thereby reducing the metabolic energy required for walking.

Question 31

A 3-month-old female with developmental dysplasia of the hip (DDH) is being treated with a Pavlik harness. At follow-up, the mother reports the infant has stopped kicking her left leg. On examination, the infant lacks active knee extension, but passive knee range of motion is normal. Which nerve is most likely compressed, and what positioning error causes this complication?





Explanation

Femoral nerve palsy is a known complication of the Pavlik harness and presents with decreased active knee extension. It is typically caused by excessive flexion of the hip. The treatment is temporarily loosening the anterior straps or discontinuing the harness until nerve function returns.

Question 32

A 25-year-old male undergoes a dual-incision fasciotomy for acute compartment syndrome of the leg following a tibial shaft fracture. When releasing the deep posterior compartment, the surgeon must be mindful of the structures running within it. Which major nerve courses through the deep posterior compartment of the leg?





Explanation

The tibial nerve runs through the deep posterior compartment of the leg, along with the posterior tibial artery and the deep flexor muscles (tibialis posterior, flexor digitorum longus, and flexor hallucis longus). The deep peroneal nerve is in the anterior compartment, the superficial peroneal nerve is in the lateral compartment, and the sural and saphenous nerves are subcutaneous.

Question 33

A 28-year-old overhead athlete presents with mechanical shoulder pain. An MRI arthrogram demonstrates a bucket-handle tear of the superior labrum that extends into the long head of the biceps tendon. According to the Snyder classification, what type of SLAP tear is this?





Explanation

In the Snyder classification of SLAP tears: Type I is fraying of the superior labrum; Type II is detachment of the labrum and biceps anchor; Type III is a bucket-handle tear of the labrum with an intact biceps anchor; Type IV is a bucket-handle tear of the labrum that extends into the biceps tendon.

Question 34

During a flexor tendon repair in Zone II of the hand, the surgeon meticulously manages the flexor tendon sheath to prevent postoperative bowstringing. Which two annular pulleys are biomechanically the most critical to preserve or reconstruct?





Explanation

The A2 (located over the proximal phalanx) and A4 (located over the middle phalanx) pulleys are the most crucial for preventing bowstringing of the flexor tendons and maintaining the mechanical advantage of the flexor system in the digits. They should be preserved or reconstructed whenever possible.

Question 35

In total knee arthroplasty, the posterior cruciate ligament (PCL) is often sacrificed. In a posterior-stabilized (PS) design, which specific feature substitutes for the resected PCL to enforce femoral rollback and prevent paradoxical anterior translation of the femur during flexion?





Explanation

In a posterior-stabilized (PS) TKA, the cam on the femoral component engages the post on the tibial polyethylene insert during mid-to-deep flexion. This cam-post interaction substitutes for the function of the resected PCL, enforcing posterior femoral rollback and preventing paradoxical anterior femoral translation.

Question 36

A 15-year-old female gymnast presents with chronic low back pain. Radiographs reveal a grade II L5-S1 spondylolisthesis. Oblique radiographs demonstrate bilateral defects in the pars interarticularis. According to the Wiltse classification of spondylolisthesis, which type does this patient have?





Explanation

The Wiltse classification categorizes spondylolisthesis into five types. Type II is Isthmic, which involves a defect, elongation, or acute fracture of the pars interarticularis. It is the most common type seen in young athletes (e.g., gymnasts). Type I is dysplastic, Type III is degenerative, Type IV is traumatic (fracture other than pars), and Type V is pathologic.

Question 37

A 40-year-old male sustains an acute rupture of the Achilles tendon. The rupture occurs in the classic 'watershed' zone, which is relatively hypovascular and prone to degeneration. Where is this watershed zone typically located?





Explanation

The Achilles tendon has a relative hypovascular 'watershed' zone located approximately 2 to 6 cm proximal to its insertion on the calcaneus. This compromised blood supply makes this region particularly susceptible to tendinopathy and acute rupture.

Question 38

A 12-year-old presents with a diaphyseal bone lesion. Biopsy reveals sheets of small, round, blue cells with CD99 positivity. Cytogenetic analysis is ordered. Which of the following chromosomal translocations is most characteristic of this malignancy?





Explanation

The presentation is classic for Ewing Sarcoma. The hallmark cytogenetic abnormality for Ewing Sarcoma is the t(11;22)(q24;q12) translocation, which creates the EWS-FLI1 fusion gene. t(X;18) is seen in Synovial Sarcoma. t(2;13) is seen in Alveolar Rhabdomyosarcoma. t(12;16) is seen in Myxoid Liposarcoma. t(9;22) is the Philadelphia chromosome seen in CML.

Question 39

A 2-year-old child is being evaluated for bilateral tibia vara (bowlegs). The surgeon suspects infantile Blount's disease rather than physiologic bowing. Which of the following radiographic measurements strongly predicts the development of Blount's disease over physiologic bowing?





Explanation

The metaphyseal-diaphyseal angle (MDA) of Drennan is highly useful in distinguishing physiologic bowing from infantile Blount's disease. An MDA greater than 11 degrees is strongly predictive of progression to Blount's disease, whereas an angle less than 11 degrees usually resolves as physiologic bowing.

Question 40

A 24-year-old male sustains a proximal pole fracture of the scaphoid. This region is at high risk for avascular necrosis due to its retrograde blood supply. Which of the following arteries provides the primary blood supply to the proximal 80% of the scaphoid?





Explanation

The major blood supply to the scaphoid enters distally along the dorsal ridge via the dorsal carpal branch of the radial artery. It flows in a retrograde fashion to supply the proximal 80% of the bone, making proximal pole fractures particularly vulnerable to avascular necrosis.

Question 41

Which of the following modifications to ultra-high molecular weight polyethylene (UHMWPE) most effectively increases its wear resistance in total hip arthroplasty?





Explanation

Highly cross-linked polyethylene is produced by exposing UHMWPE to irradiation (gamma or electron beam), which creates free radicals that form cross-links. This significantly improves wear resistance. Subsequent remelting or annealing eliminates residual free radicals to prevent long-term in vivo oxidation.

Question 42

An 82-year-old male presents with neck pain after a low-energy fall. Radiographs and CT show a displaced Type II odontoid fracture. He has multiple medical comorbidities (ASA III). What is the most appropriate management?





Explanation

In elderly patients (especially >80 years) with significant comorbidities, the morbidity and mortality of halo vest immobilization or surgical intervention (like C1-C2 fusion) are prohibitively high. Evidence supports treating Type II odontoid fractures in this population with a rigid cervical collar, prioritizing life and comfort over fracture union, as nonunion is typically well-tolerated if fibrous stability is achieved.

Question 43

A 24-year-old rugby player undergoes revision surgery for recurrent anterior shoulder instability. Diagnostic arthroscopy reveals 25% anterior glenoid bone loss and a deep Hill-Sachs lesion that engages the anterior glenoid rim in abduction and external rotation. Which of the following is the most appropriate surgical intervention?





Explanation

For recurrent instability with significant anterior glenoid bone loss (>20-25%) and an engaging Hill-Sachs lesion (an 'off-track' lesion), an isolated soft tissue repair is insufficient. The Latarjet procedure (coracoid transfer) is the standard of care as it restores the glenoid arc and provides a sling effect to prevent engagement.

Question 44

A 12-year-old obese male presents with a left-sided slipped capital femoral epiphysis (SCFE). Which of the following is the strongest indication for prophylactic in situ pinning of the contralateral right hip?





Explanation

Endocrinopathies (such as hypothyroidism, panhypopituitarism, or renal osteodystrophy) are strong indications for prophylactic contralateral pinning in SCFE due to the very high risk (often >50%) of subsequent bilateral involvement. Age < 10 years or an open triradiate cartilage are also significant risk factors for bilaterality.

Question 45

A 14-year-old boy presents with a permeative lytic lesion in the diaphysis of the femur with an associated 'onion skin' periosteal reaction. A biopsy is performed. Which of the following chromosomal translocations is most characteristic of this tumor?





Explanation

The clinical and radiographic presentation is classic for Ewing sarcoma. Ewing sarcoma is characterized by the t(11;22)(q24;q12) translocation, resulting in the EWS-FLI1 fusion protein. Translocation t(X;18) is seen in synovial sarcoma; t(12;16) in myxoid liposarcoma; t(2;13) in alveolar rhabdomyosarcoma.

Question 46

A 45-year-old avid cyclist presents with intrinsic muscle weakness in his right hand. Sensation is decreased over the volar aspect of the little finger and the ulnar half of the ring finger, but normal over the dorsal ulnar aspect of the hand. Where is the most likely site of nerve compression?





Explanation

Compression in Zone 1 of Guyon's canal (proximal to the bifurcation of the ulnar nerve) results in both motor (intrinsic weakness) and sensory (volar ulnar digits) deficits. The dorsal ulnar cutaneous nerve branches off proximal to the wrist; thus, dorsal sensation is spared, differentiating it from cubital tunnel syndrome. Zone 2 causes isolated motor deficits, and Zone 3 causes isolated sensory deficits.

Question 47

A 32-year-old male is brought to the emergency department after a motorcycle collision. He is hemodynamically unstable. Pelvic radiographs demonstrate an anteroposterior compression type III (APC III) pelvic ring injury. After application of a pelvic binder and initial fluid resuscitation, his blood pressure remains 70/40 mmHg. What is the most appropriate next step in management?





Explanation

In a hemodynamically unstable patient with a mechanically unstable pelvic ring injury who does not respond to initial resuscitation and pelvic binding, preperitoneal/retroperitoneal pelvic packing is the most rapid and effective intervention to control venous bleeding, which represents the source in 80-90% of pelvic hemorrhage. Angiography is indicated if arterial bleeding is confirmed (e.g., contrast blush on CT) or if instability persists after packing.

Question 48

According to the Sanders classification of intra-articular calcaneus fractures, which of the following best describes a Sanders Type III fracture?





Explanation

The Sanders classification is based on coronal CT images through the posterior facet of the calcaneus. Type I fractures are nondisplaced. Type II are two-part fractures (one fracture line). Type III are three-part fractures (two fracture lines). Type IV are four-part or highly comminuted fractures.

Question 49

A 65-year-old female presents with a painful catching sensation in her knee when extending from a flexed position, 1 year following a posterior-stabilized total knee arthroplasty. What is the underlying pathophysiology of this condition?





Explanation

Patellar clunk syndrome is a complication classically seen in posterior-stabilized TKA designs. It is caused by the formation of a fibrotic nodule on the undersurface of the quadriceps tendon just superior to the patella. During knee extension from a flexed position, this nodule catches in the intercondylar box of the femoral component, producing a painful 'clunk'.

Question 50

The primary blood supply to the body of the talus is derived from which of the following vessels?





Explanation

The artery of the tarsal canal, a branch of the posterior tibial artery, is the dominant blood supply to the body of the talus. It enters the talar neck and forms an anastomotic sling with the artery of the sinus tarsi (a branch of the dorsalis pedis and peroneal arteries), but the tarsal canal artery supplies the vast majority of the talar body.

Question 51

During an anatomical reconstruction of the posterolateral corner (PLC) of the knee, a fibular-based technique is utilized. Which three primary static stabilizing structures are being reconstructed?





Explanation

Anatomical reconstructions of the posterolateral corner of the knee focus on restoring the three primary static stabilizers: the fibular collateral ligament (FCL, also known as the LCL), the popliteus tendon (PLT), and the popliteofibular ligament (PFL). These structures primarily resist varus opening and external rotation.

Question 52

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





Explanation

The Ponseti method systematically corrects clubfoot deformities in a specific sequence, remembered by the acronym CAVE: Cavus, Adductus, Varus, and Equinus. The first cast supinates the forefoot to align it with the midfoot and hindfoot, correcting the cavus. Subsequent casts correct adductus and varus by abducting the supinated foot around the head of the talus. Equinus is corrected last, often requiring a percutaneous Achilles tenotomy.

Question 53

A 6-year-old girl falls on an outstretched hand and sustains a Bado Type III Monteggia equivalent lesion. Which of the following best describes the radiographic findings?





Explanation

The Bado classification describes Monteggia fracture-dislocations. Type I: Anterior dislocation of the radial head with anterior angulation of the ulnar fracture. Type II: Posterior dislocation with posterior angulation. Type III: Lateral or anterolateral dislocation of the radial head with a fracture of the ulnar metaphysis (most common in children). Type IV: Anterior dislocation of the radial head with fractures of both the radius and ulna shafts.

Question 54

A 55-year-old diabetic male presents with severe back pain, fever, progressive bilateral lower extremity weakness, and urinary retention over the past 24 hours. MRI confirms a large dorsal epidural abscess at T8-T10. What is the most appropriate definitive management?





Explanation

The patient has a spinal epidural abscess with progressive neurologic deficits (myelopathy). This is a surgical emergency. Emergent surgical decompression (posterior laminectomy for a dorsal abscess) and debridement is required to prevent irreversible neurologic damage. This is followed by culture-directed intravenous antibiotic therapy.

Question 55

In Scaphoid Nonunion Advanced Collapse (SNAC) of the wrist, which articulation is characteristically spared from degenerative changes, allowing for motion-preserving salvage procedures such as a four-corner fusion?





Explanation

In both SNAC and SLAC (Scapholunate Advanced Collapse) wrist arthritis patterns, the radiolunate joint is characteristically spared from osteoarthritis. This occurs because the lunate maintains a congruent and concentric articulation with the lunate fossa of the radius. This preservation allows for salvage procedures like a four-corner fusion or proximal row carpectomy.

Question 56

A 35-year-old active male requires a total hip arthroplasty for post-traumatic osteoarthritis. The surgeon decides to use a ceramic-on-ceramic bearing surface. Which of the following is a recognized unique complication associated specifically with this type of bearing?





Explanation

Squeaking is a unique complication associated with ceramic-on-ceramic bearing surfaces in total hip arthroplasty, occurring in 1-20% of patients. It is thought to be related to edge loading, micro-separation, or altered fluid film lubrication. Trunnionosis, metallosis, and galvanic corrosion are associated with metal-on-metal or modular metal heads on metal stems.

Question 57

A patient presents with recurrent fractures, anemia, and hepatosplenomegaly. Radiographs demonstrate diffuse osteosclerosis and a 'bone-within-a-bone' appearance. The primary defect in this disorder is related to the dysfunction of which of the following?





Explanation

The clinical and radiographic presentation is classic for osteopetrosis (Albers-Schönberg disease). It is caused by a genetic defect resulting in impaired osteoclast function (e.g., defective carbonic anhydrase II, TCIRG1 mutation, or CLCN7 mutation), leading to a failure of normal bone resorption, acidification, and remodeling.

Question 58

A 58-year-old male presents with painful, restricted dorsiflexion of his first metatarsophalangeal (MTP) joint. Radiographs show large dorsal osteophytes and complete joint space obliteration consistent with Grade 3 hallux rigidus. He has failed shoe modifications and NSAIDs. Which surgical procedure is considered the gold standard for durable pain relief in this patient?





Explanation

For advanced hallux rigidus (Coughlin and Shurnas Grade 3 or 4) with significant pain and loss of motion, first MTP joint arthrodesis is the gold standard surgical treatment, providing the most predictable, powerful, and durable pain relief. Cheilectomy is indicated for earlier stages (Grades 1 and 2) where the joint cartilage space is still relatively preserved.

Question 59

The blood supply to the humeral head is a critical factor in determining the risk of avascular necrosis following a proximal humerus fracture. According to Hertel's radiographic criteria, which of the following fracture patterns carries the highest risk of ischemia to the humeral head?





Explanation

Hertel identified several predictors of humeral head ischemia after proximal humerus fractures. The highest risk factors are an anatomic neck fracture pattern, a short calcar length (posteromedial metaphyseal head extension < 8 mm), and disruption of the medial hinge (> 2 mm displacement). An anatomic neck fracture intrinsically disrupts the primary blood supply (the ascending branch of the anterior circumflex humeral artery and intraosseous vessels).

Question 60

A 22-year-old male presents with dull, aching pain in his posterior thoracic spine that is not reliably relieved by NSAIDs. Radiographs and a CT scan reveal a 2.5 cm radiolucent nidus in the right lamina of T8 with surrounding sclerosis. What is the most likely diagnosis?





Explanation

Both osteoid osteoma and osteoblastoma have similar histologic appearances (woven bone, prominent osteoblasts), but they are differentiated primarily by size and clinical presentation. Osteoblastomas are typically > 2 cm (often > 1.5-2.0 cm threshold used), locate commonly in the posterior elements of the spine, and cause dull aching pain that is less likely to have dramatic relief with NSAIDs/aspirin compared to osteoid osteoma (which is < 1.5 cm and classically features severe nocturnal pain dramatically relieved by NSAIDs).

Previous ChapterArab Orthopaedic Board MCQs - Part 14 Next Chapter Arab Orthopaedic Board MCQs - Part 16
Clinic OS
Medically Verified Content by
Prof. Clinic OS
Consultant Orthopedic & Spine Surgeon
Chapter Index
    Back to Master Guide