Arab Orthopaedic Board MCQs - Part 24

During in situ pinning of a slipped capital femoral epiphysis (SCFE), unrecognized pin penetration into the hip joint space is most directly associated with which of the following postoperative complications?

A 25-year-old male sustains a vertically oriented (Pauwels Type III) intracapsular femoral neck fracture. To maximize biomechanical stability and minimize shear forces across the fracture site during internal fixation, which of the following constructs is most appropriate?

Which of the following bearing surface combinations in total hip arthroplasty exhibits the lowest volumetric wear rate, but carries the highest risk of catastrophic failure due to fracture?

A 72-year-old male falls from standing and sustains a Type II odontoid fracture with 5 mm of posterior displacement. If this patient is treated non-operatively with a rigid cervical collar, which of the following factors most strongly predicts the development of a nonunion?

A 32-year-old manual laborer presents with progressive dorsal wrist pain. Radiographs demonstrate sclerosis of the lunate, normal carpal height, and negative ulnar variance. MRI confirms osteonecrosis of the lunate without coronal fractures. According to the Lichtman classification, what is the most appropriate surgical intervention?

In the ultrasonographic evaluation of developmental dysplasia of the hip (DDH) using the Graf method, the alpha angle is used to assess acetabular development. Which of the following anatomical landmarks are used to measure the alpha angle?

Articular cartilage is organized into multiple histological zones, each with specific biomechanical properties. Which zone is characterized by the largest diameter collagen fibrils oriented perpendicular to the articular surface, the highest concentration of proteoglycans, and the lowest water content?

A 65-year-old male presents with a pathologic fracture of the proximal humerus. Workup reveals hypercalcemia, renal insufficiency, normocytic anemia, and a monoclonal protein spike on serum electrophoresis. Histological examination of the fracture site is most likely to show which of the following?

During the operative fixation of a primarily ligamentous Lisfranc injury involving the entire tarsometatarsal joint complex, which of the following represents the correct anatomical order and trajectory for the primary 'Lisfranc screw'?

The anterior cruciate ligament (ACL) is composed of two primary bundles, the anteromedial (AM) and posterolateral (PL) bundles. During physiologic knee range of motion, how do the tension patterns of these distinct bundles behave?

A 55-year-old female undergoes volar locking plate fixation for a displaced distal radius fracture. Six months postoperatively, she presents with a sudden inability to actively flex the interphalangeal joint of her thumb. Which of the following plate placement errors most likely contributed to this specific complication?

During a posterior-stabilized total knee arthroplasty, the surgeon performs gap balancing using tensioners. The knee is noted to be symmetric and well-balanced in full extension, but significantly tight in 90 degrees of flexion. Which of the following is the most appropriate intraoperative adjustment to achieve a balanced gap?

A 68-year-old male complains of bilateral leg pain and cramping that worsens after walking two blocks. Which of the following clinical findings most reliably differentiates neurogenic claudication (due to spinal stenosis) from vascular claudication?

A 6-year-old boy sustains a completely displaced (Gartland Type III) supracondylar humerus fracture. On initial presentation in the emergency department, his hand is warm and well-perfused (pink), but the radial pulse is absent on palpation and Doppler ultrasound. What is the most appropriate next step in management?

According to the modified Verdan classification of flexor tendon zones in the hand, which zone is historically referred to as 'no man's land' due to the high propensity for adhesion formation and poor surgical outcomes?

A 24-year-old professional baseball pitcher undergoes shoulder arthroscopy. A Type II SLAP (Superior Labrum Anterior to Posterior) lesion is identified. Which of the following best describes the pathomechanics of a Type II SLAP lesion?

In the initial ATLS resuscitation of a hemodynamically unstable patient with an Anteroposterior Compression Type III (APC-III) pelvic ring injury, what is the most appropriate anatomical landmark for the application of a non-invasive pelvic circumferential compression device (pelvic binder)?

A 14-year-old male presents with a painful mass in the diaphysis of the left femur. Radiographs show a permeative, destructive lesion with an 'onion-skin' periosteal reaction. A core needle biopsy is performed. Which of the following chromosomal translocations is most pathognomonic for this tumor?

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

A 60-year-old active male underwent a total hip arthroplasty using a ceramic-on-ceramic bearing surface two years ago. He now presents complaining of a high-pitched 'squeaking' sound emanating from the hip during walking, bending, and stair climbing. Which of the following component malpositions is most strongly associated with this phenomenon?

A 14-year-old boy with an acute-on-chronic Slipped Capital Femoral Epiphysis (SCFE) is treated with in-situ single screw fixation. Six months later, he presents with severe hip stiffness, pain, and loss of all hip motion. Radiographs demonstrate uniform narrowing of the joint space to less than 3 mm. Which of the following is the most established primary risk factor for this specific complication?

A 32-year-old female with a recurrent Giant Cell Tumor (GCT) of the distal femur is started on neoadjuvant medical therapy to facilitate joint-salvage surgery. She is given Denosumab, a human monoclonal antibody. What is the exact cellular target and mechanism of action of this medication in the context of GCT?

A 45-year-old manual laborer presents with chronic right wrist pain. Radiographs reveal severe joint space narrowing at the radioscaphoid and capitolunate joints. The radiolunate joint is completely preserved. Given this specific pattern of arthritis, which of the following surgical procedures is considered contraindicated?

During the acute trauma bay management of a hemodynamically unstable patient with an anteroposterior compression (APC) type III pelvic ring injury, a circumferential pelvic binder is applied. To achieve the maximal mechanical advantage for reducing pelvic volume, the binder must be centered exactly over which anatomical landmark?

In total hip arthroplasty, periprosthetic osteolysis is primarily driven by a macrophage response to ultra-high-molecular-weight polyethylene (UHMWPE) wear particles. Which mechanism of wear is most responsible for generating the billions of submicron particles (0.1-1.0 micrometers) typically seen in a well-functioning metal-on-polyethylene articulation?

A 65-year-old male sustains a Type II odontoid fracture following a fall. Which of the following factors represents the strongest clinical predictor for nonunion if this injury is treated non-operatively with a halo vest?

A 25-year-old athlete sustains a hyperplantarflexion injury to his midfoot. Weight-bearing radiographs demonstrate a 2 mm widening between the first and second metatarsal bases along with a subtle 'fleck sign'. The fleck sign represents a bony avulsion of the Lisfranc ligament from which specific anatomical structure?

During an Anterior Cruciate Ligament (ACL) reconstruction, the surgeon tensions the quadrupled hamstring graft to a specific length and secures it. Over the next several minutes, the tension (force) required by the fixation device to maintain that exact length decreases. This physical phenomenon is characteristic of viscoelastic materials and is known as:

When evaluating graft choices for primary Anterior Cruciate Ligament (ACL) reconstruction, biomechanical studies demonstrate varying properties of ultimate tensile load. Which of the following graft constructs possesses the highest ultimate tensile load (strength) compared to the native ACL (~2160 N)?

A 6-year-old boy presents with a Gartland Type III extension-type supracondylar humerus fracture. On initial exam, the hand is pink but lacks a palpable radial pulse. Following emergent closed reduction and percutaneous pinning in the operating room, the hand remains pink and pulseless, but capillary refill is brisk (<2 seconds). What is the most appropriate next step in management?

In the modern treatment protocol for high-grade, non-metastatic intramedullary osteosarcoma, surgical resection is typically preceded by neoadjuvant chemotherapy. Following surgical resection, which of the following histological parameters is the most important prognostic factor for the patient's long-term overall survival?

A 60-year-old male with a metal-on-metal total hip arthroplasty presents 5 years post-operatively with worsening groin pain and a palpable anterior soft tissue mass. Aspiration yields sterile, turbid fluid. Revision surgery is planned. Histological analysis of the pseudotumor (periprosthetic tissue) is most likely to demonstrate:

During a primary Zone II flexor tendon repair, a surgeon considers the biomechanical trade-offs of different suture configurations. Increasing the number of core suture strands crossing the repair site primarily improves which specific biomechanical property of the repaired tendon?

A 40-year-old female sustains a high-energy trauma and presents with an isolated coronal plane shear fracture of the distal femoral condyle. Regarding this specific injury (Hoffa fracture), which of the following statements is most accurate?

A 55-year-old patient with long-standing poorly controlled diabetes presents with a unilaterally swollen, erythematous, and warm foot without skin ulceration. Radiographs demonstrate extensive periarticular debris, bony fragmentation, and early subluxation of the tarsometatarsal joints. According to the Eichenholtz classification of Charcot arthropathy, this presentation corresponds to:

A 68-year-old man presents with bilateral leg heaviness, cramping, and pain that severely limits his walking distance. Which of the following historical features or clinical tests most reliably differentiates neurogenic claudication (due to lumbar spinal stenosis) from vascular claudication?

A 28-year-old football player is evaluated for acute knee instability. The tibial dial test is performed in the supine position. The examiner notes >10 degrees of increased external rotation on the injured side compared to the normal side when the knee is flexed at 30 degrees. However, when the knee is flexed to 90 degrees, the external rotation is symmetric bilaterally. This specific pattern confirms injury to which structure(s)?

Bone Morphogenetic Proteins (BMPs), specifically BMP-2 and BMP-7, are utilized clinically for their potent osteoinductive capabilities. Upon binding to their respective cell surface receptors, which specific intracellular signaling pathway is primarily activated to upregulate osteogenic gene transcription?

The Ponseti method relies on a precise, sequential manipulation and casting technique to treat idiopathic congenital talipes equinovarus (clubfoot). Which of the following represents the correct anatomical order of deformity correction dictated by this method?

A surgeon is templating for a primary Total Hip Arthroplasty (THA) and wishes to maximize the primary arc of motion to delay mechanical impingement of the components, thereby reducing dislocation risk. Which of the following geometric modifications to the implant will most effectively achieve this goal?

A 52-year-old mechanic presents with chronic, progressive wrist pain. Radiographs demonstrate scapholunate advanced collapse (SLAC) with severe narrowing of the radioscaphoid and capitolunate joints, while the radiolunate joint is preserved. A proximal row carpectomy (PRC) is being considered. Which of the following radiographic findings in this patient is an absolute contraindication to performing a PRC?

A 2-week-old infant with idiopathic clubfoot is undergoing correction via the Ponseti method. The treating physician applies the first cast. According to Ponseti principles, what is the primary goal of the very first cast application?

A 26-year-old male is brought to the emergency department after a motorcycle collision. Pelvic radiographs reveal an anteroposterior compression (APC) injury. Which of the following findings defines an APC III pelvic ring injury according to the Young-Burgess classification?

During medial patellofemoral ligament (MPFL) reconstruction for recurrent patellar instability, accurate femoral tunnel placement is critical to avoid graft mal-tensioning. Radiographically, 'Schöttle/'s point' is used to identify the anatomic femoral footprint. Anatomically, where is this point located?

A 58-year-old female with a history of a metal-on-metal total hip arthroplasty presents with groin pain and a palpable anterior mass. Aspiration yields sterile fluid, and revision surgery is performed. Histopathological examination of the periprosthetic tissue is most likely to reveal which of the following?

Biomechanical testing of a human anterior cruciate ligament graft is performed. When a constant load (stress) is applied to the ligament over an extended period, the ligament undergoes a gradual increase in length (strain). This viscoelastic property is best defined as:

A 15-year-old male presents with painful thoracolumbar scoliosis. Imaging reveals a 7 mm radiolucent nidus with surrounding sclerosis in the pedicle of T11 on the concave side of the curve. The lesion is situated 2 mm from the traversing nerve root. What is the most appropriate definitive management?

A 68-year-old male presents with progressive clumsiness in his hands and difficulty buttoning his shirts. Physical examination raises suspicion for cervical spondylotic myelopathy. The examiner tests for a Hoffmann sign. A positive response is indicated by which of the following movements when the nail of the patient/'s middle finger is briskly flicked downward?

A 45-year-old male sustains a high-energy varus directed force to his knee, resulting in a Schatzker IV tibial plateau fracture. CT scanning demonstrates a displaced coronal shear fracture of the posteromedial tibial plateau. Which surgical approach provides the most optimal visualization and biomechanical advantage for buttress plating of this specific fragment?

A 55-year-old patient with poorly controlled type 2 diabetes presents with a unilaterally swollen, erythematous, and warm foot without open ulcerations. Radiographs show periarticular fragmentation, subluxation, and bony debris at the tarsometatarsal joints. According to the Eichenholtz classification, what is the stage of this disease process and the standard initial management?

A 23-year-old elite collegiate gymnast presents with vague anterior shoulder pain and a catching sensation. MRI arthrogram demonstrates a detachment of the superior labrum and the origin of the long head of the biceps tendon from the glenoid, without extension into the anterior or posterior labrum. What is the classification of this injury and the historically accepted gold standard surgical treatment for a young athletic patient?

An 8-week-old female infant is undergoing treatment for developmental dysplasia of the hip (DDH) with a Pavlik harness. During a routine clinical check, the orthopedic surgeon notes that the infant has decreased active extension of the knee on the affected side, and the patellar reflex is diminished. What is the most likely cause of this finding and the appropriate harness adjustment?

In the context of fracture healing and bone grafting, various Bone Morphogenetic Proteins (BMPs) have been extensively studied. Which specific recombinant human BMP is currently FDA-approved for use as an adjunct in the treatment of acute, open tibial shaft fractures treated with an intramedullary nail?

A 6-year-old boy presents to the emergency department after falling off monkey bars. Radiographs demonstrate a fracture of the ulnar diaphysis with an associated anterior dislocation of the radial head. According to the Bado classification of Monteggia fracture-dislocations, what type of injury is this, and what is its relative frequency in the pediatric population?

A 60-year-old male is evaluated for a medial unicompartmental knee arthroplasty (UKA) due to isolated medial compartment osteoarthritis. Which of the following is considered an absolute contraindication to proceeding with a medial UKA?

In the anatomic classification of flexor tendon injuries of the hand, Zone II (historically termed 'no man/'s land' due to poor surgical outcomes in the past) presents significant challenges for repair. What are the proximal and distal anatomic boundaries that define Zone II?

A 34-year-old construction worker falls 10 feet, sustaining a T12 burst fracture. He is neurologically intact. CT and MRI scans reveal a burst morphology with 25% canal compromise and an intact posterior ligamentous complex (PLC). Using the Thoracolumbar Injury Classification and Severity (TLICS) score, what is his total score and the most appropriate treatment recommendation?

A 12-year-old girl presents with deep, achy leg pain. Radiographs demonstrate a permeative, lytic lesion in the diaphysis of the femur with an 'onion skin' periosteal reaction. Biopsy confirms Ewing sarcoma. Which of the following chromosomal translocations is the genetic hallmark of this malignancy?

Recent high-level evidence and meta-analyses comparing operative versus non-operative management of acute Achilles tendon ruptures highlight specific complication profiles. When modern functional rehabilitation protocols (early weight-bearing and motion) are utilized for both groups, which of the following is true?

Historical anatomical teachings suggested that the anterior circumflex humeral artery was the primary blood supply to the humeral head. However, recent quantitative anatomical studies utilizing gadolinium enhancement have redefined this vascularity. Which vessel has been definitively shown to supply the vast majority (over 60%) of the blood flow to the humeral head?

A 12-year-old obese male presents with a left-sided Slipped Capital Femoral Epiphysis (SCFE). In which of the following scenarios is prophylactic in situ pinning of the contralateral asymptomatic right hip most strongly indicated?

A 60-year-old male undergoes a total hip arthroplasty using a ceramic-on-ceramic bearing. Two years postoperatively, he complains of an audible squeaking sound from the hip during walking, but denies pain. Which of the following factors is most strongly mechanically associated with squeaking in ceramic-on-ceramic THA?

A 45-year-old man presents with severe right anterior thigh pain and weakness. MRI reveals a far lateral (extraforaminal) disc herniation at the L3-L4 level on the right side. Which nerve root is most likely compressed, and what is the typical motor deficit?

In an anteroposterior compression type II (APC II) pelvic ring injury, which of the following ligamentous structures is primarily disrupted to allow widening of the pubic symphysis greater than 2.5 cm, while vertical stability is maintained?

Which of the following flexor tendon pulleys is the most critical to preserve during hand surgery to prevent bowstringing of the flexor tendons in the digits?

A 25-year-old athlete sustains a purely ligamentous Lisfranc injury. Current evidence comparing primary arthrodesis versus open reduction and internal fixation (ORIF) for purely ligamentous Lisfranc injuries suggests which of the following regarding primary arthrodesis?

Following neoadjuvant chemotherapy for conventional high-grade osteosarcoma, surgical resection is performed. According to the Huvos grading system, what percentage of tumor necrosis is considered a 'good response' and is the most significant prognostic factor for long-term survival?

When performing an anterior cruciate ligament (ACL) reconstruction, drilling the femoral tunnel via an anteromedial (AM) portal instead of a transtibial technique is advantageous primarily because it allows for:

During the natural progression of tendon healing, the remodeling phase is characterized by the replacement of immature collagen with mature collagen. Which type of collagen transitions to which type during this phase?

In a pediatric patient with a lateral condyle fracture of the humerus, the Milch classification differentiates between two types based on the fracture anatomy. Where does the fracture line exit the articular surface in a Milch Type II fracture?

In a patient with a displaced proximal humerus fracture, which of the following Hertel criteria is the most reliable predictor for the development of avascular necrosis (AVN) of the humeral head?

Which of the following best describes the intended biomechanical advantage of femoral roll-back in a posterior stabilized (PS) total knee arthroplasty?

During an in situ ulnar nerve decompression at the elbow, the surgeon must divide several structures to fully release the cubital tunnel. Which of the following structures forms the roof of the cubital tunnel?

Superior capsular reconstruction (SCR) is a surgical option for massive, irreparable rotator cuff tears. The primary biomechanical goal of the graft in SCR is to:

A 55-year-old male with poorly controlled diabetes presents with a swollen, erythematous, and warm left foot. Radiographs reveal periarticular debris, fragmentation, and subluxation of the tarsometatarsal joints. According to the Eichenholtz classification, what is the appropriate stage and recommended initial treatment?

A 70-year-old male sustains a Type II odontoid fracture after a ground-level fall. Which of the following radiographic findings is most strongly associated with a high risk of non-union if treated conservatively with a rigid cervical collar?

A trauma surgeon is selecting an intramedullary nail for a tibial fracture. Comparing titanium alloy (Ti-6Al-4V) to 316L stainless steel, titanium alloy exhibits:

When treating congenital idiopathic clubfoot (talipes equinovarus) using the Ponseti method, what is the correct sequence of deformity correction during serial casting?

A 62-year-old female with breast cancer presents with right thigh pain. Radiographs reveal a lytic metastatic lesion in the peritrochanteric region of the right femur, involving greater than 2/3 of the cortical diameter. She describes moderate pain with weight-bearing. Using Mirels' criteria, what is her score and the recommended management regarding prophylactic fixation?

A patient sustains a complex bicondylar tibial plateau fracture with a large posteromedial fragment. To adequately reduce and buttress this specific fragment, which surgical approach is most appropriate?

A 45-year-old male presents with right arm pain and weakness. Physical examination reveals weakness in right elbow extension and wrist flexion. He has diminished pinprick sensation over the dorsal aspect of the middle finger. Which cervical nerve root is most likely compressed?

A 60-year-old male presents with a destructive radiolucent lesion in his proximal femur. Histological examination reveals two distinct morphological components: a well-differentiated hyaline cartilage tumor sharply juxtaposed against a high-grade, non-cartilaginous spindle cell sarcoma. What is the most likely diagnosis?

A 28-year-old male sustains a high-energy multiligamentous knee injury with complete ruptures of the ACL, PCL, and MCL (Schenck KD-III M). Upon closed reduction in the emergency department, his pedal pulses are palpable, but his ankle-brachial index (ABI) is 0.85. What is the most appropriate next step in management?

During surgical repair of a Zone II flexor tendon injury, maintaining the integrity of the A2 and A4 pulleys is crucial to prevent bowstringing. If the A2 pulley is inadvertently excised, what is the most significant biomechanical consequence regarding the function of the flexor tendon?

A 65-year-old male with a metal-on-polyethylene total hip arthroplasty (titanium stem, large-diameter cobalt-chromium head) performed 6 years ago presents with groin pain and a large hip effusion. Aspiration is negative for infection but reveals dark, blackish debris. Serum cobalt levels are significantly elevated, while serum chromium levels are normal. What is the most likely diagnosis?

An 8-year-old boy, who is in the 10th percentile for height and 90th percentile for weight, presents with an idiopathic unilateral slipped capital femoral epiphysis (SCFE). Given his young age, an underlying endocrinopathy is highly suspected. Which of the following laboratory profiles is most classically associated with the most common endocrine cause of SCFE in this age group?

The torsional rigidity of a solid cylindrical intramedullary nail is mathematically governed by its polar moment of inertia. Based on this formula, the torsional rigidity is proportional to which of the following regarding the radius of the nail?

A 55-year-old poorly controlled diabetic patient presents with a swollen, warm, and erythematous right foot. There is no open ulceration. Radiographs reveal focal osteopenia, joint subluxation, debris, and fragmentation around the tarsometatarsal joints. Which of the following corresponds to the correct Eichenholtz stage and the standard of care initial management?

In a patient presenting with hemorrhagic shock secondary to a severe anterior-posterior compression (APC-III) pelvic ring injury, what is the most common anatomical source of the massive retroperitoneal hemorrhage?

A 34-year-old female presents with numbness and tingling in the radial three-and-a-half digits of her right hand, along with volar forearm pain. Which of the following clinical findings most specifically distinguishes Pronator Syndrome from Carpal Tunnel Syndrome?

When planning corrective surgery for adult degenerative spinal deformity to optimize patient-reported outcomes and minimize the risk of adjacent segment breakdown, achieving appropriate sagittal balance is paramount. According to current biomechanical targets, the mismatch between Pelvic Incidence (PI) and Lumbar Lordosis (LL) should ideally be corrected to within:

The Ponseti method is the recognized gold standard for the conservative treatment of idiopathic clubfoot. According to this protocol, what is the very first component of the deformity that must be corrected during the initial casting phase?

During a posterior-stabilized total knee arthroplasty, the trial reduction reveals that the knee is well-balanced and symmetric in extension, but it is too tight in flexion, preventing adequate range of motion. Which of the following surgical modifications is the most appropriate next step to balance the knee?

Denosumab is an established targeted therapy used in the management of unresectable or recurrent Giant Cell Tumor of Bone (GCTB). What is its precise mechanism of action?

A 42-year-old recreational overhead athlete presents with persistent anterior shoulder pain and deep clicking. An MRI arthrogram demonstrates an isolated Type II SLAP tear. After 6 months of dedicated physical therapy, symptoms remain debilitating. Which of the following surgical interventions is most strongly supported by current literature for a patient of this age?

A 50-year-old female presents with a sudden inability to actively flex the interphalangeal joint of her thumb. Three years prior, she underwent volar plate fixation of a distal radius fracture. The spontaneous rupture of the flexor pollicis longus (FPL) tendon in this setting is most commonly associated with which of the following intraoperative technical errors?

According to Perren's strain theory regarding fracture healing, what mechanical strain condition within a fracture gap is required to achieve primary (direct) bone healing via Haversian remodeling, bypassing cartilaginous callus formation?

An 8-week-old infant with developmental dysplasia of the hip (DDH) is being treated with a Pavlik harness. During a routine follow-up, the parents note that the child is no longer actively kicking the leg on the affected side. Upon physical examination, there is an absent patellar reflex and decreased active knee extension. Which of the following errors in harness application is the most likely cause of this complication?

A 52-year-old female presents with medial ankle pain and a progressively flattening arch. Examination shows a flexible pes planovalgus, inability to perform a single-limb heel rise, and a positive "too many toes" sign. Radiographs show significant talonavicular uncoverage (>40%). Which of the following is the most appropriate surgical reconstruction for this specific stage of adult-acquired flatfoot deformity (Stage IIB)?

A 68-year-old male presents with bilateral lower extremity pain and cramping associated with walking. To differentiate between neurogenic claudication (due to lumbar spinal stenosis) and vascular claudication (due to peripheral arterial disease), which of the following historical features is most specific for neurogenic claudication?