Arab Orthopaedic Board MCQs - Part 19

An 8-year-old girl is diagnosed with bilateral slipped capital femoral epiphysis (SCFE). On examination, her height and weight are both below the 5th percentile for her age. Which of the following is the most likely underlying etiology and the most appropriate screening test?

A 25-year-old man sustains a severe pelvic crush injury resulting in a U-shaped sacral fracture (spinopelvic dissociation). Which of the following neurological deficits is most characteristic of this specific injury pattern?

A trauma surgeon decides to ream a tibial shaft and change the planned solid intramedullary nail from a 10 mm diameter to a 12 mm diameter. By approximately what factor does this change increase the torsional rigidity of the implant?

During the trialing phase of a posterior-stabilized total knee arthroplasty, the knee is found to be symmetrically tight in flexion but well-balanced and stable in extension. Which of the following is the most appropriate next surgical step to balance the knee?

While soft tissue sarcomas generally metastasize hematogenously to the lungs, certain subtypes have a higher propensity for lymphatic spread to regional lymph nodes. Which of the following soft tissue sarcomas is most likely to exhibit lymphatic metastasis?

A 55-year-old man presents with bilateral hand clumsiness and a broad-based gait. On physical examination, tapping the distal brachioradialis tendon produces a diminished brachioradialis reflex but a brisk reflexive flexion of the fingers. This specific clinical sign indicates spinal cord and nerve root compression most likely at which of the following levels?

During physical examination of a knee with a suspected anterior cruciate ligament (ACL) injury, the pivot-shift test is performed. This test primarily isolates and evaluates which specific structural component of the ACL?

The monoclonal antibody Romosozumab is utilized in the treatment of severe osteoporosis. Its primary mechanism of action in increasing bone mineral density is by binding to and inhibiting which of the following molecules?

A 42-year-old carpenter presents with a 3-month history of aching pain in his proximal volar forearm and numbness involving the palmar aspect of his thumb, index, and middle fingers, as well as the thenar eminence. He has weakness in thumb opposition. A Tinel's sign is positive over the proximal anterior forearm but negative at the wrist. What is the most likely diagnosis?

The main blood supply to the adult femoral head is provided by the deep branch of the medial femoral circumflex artery (MFCA). Prior to perforating the joint capsule, this vessel courses superiorly between which two anatomic structures?

In the Graf ultrasound classification for developmental dysplasia of the hip (DDH) in an infant, the alpha angle is widely utilized to determine the severity of dysplasia. What anatomic feature does the alpha angle represent, and what is its generally accepted normal value?

A 45-year-old woman presents with severe bunion pain. Radiographs demonstrate a hallux valgus angle (HVA) of 45 degrees, an intermetatarsal angle (IMA) of 20 degrees, and clinical hypermobility of the first tarsometatarsal (TMT) joint. Which of the following surgical procedures is most appropriate to address her pathology?

A 60-year-old woman with metastatic breast cancer presents with a newly identified lytic lesion in her left peritrochanteric femur. The lesion involves 50% of the cortical diameter. She reports moderate, aching pain with weight-bearing. Using Mirels' criteria, what is her calculated score, and what is the recommendation?

A 40-year-old man presents to the emergency department with severe low back pain and bilateral radiculopathy following a heavy lifting injury. You suspect acute cauda equina syndrome. Based on recent literature, which of the following is considered the most sensitive and specific early clinical indicator of this condition?

In elite overhead throwing athletes, such as baseball pitchers, Type II Superior Labrum Anterior to Posterior (SLAP) tears are a common source of shoulder pain. Which of the following biomechanical mechanisms is most widely accepted as the primary cause of these SLAP lesions during the late cocking phase of throwing?

A 28-year-old man falls on an outstretched hand and sustains a Galeazzi fracture-dislocation. Radiographs show a fracture of the distal third of the radius with dislocation of the distal radioulnar joint (DRUJ). Which muscle is primarily responsible for the volar displacement and pronation of the distal radial fracture fragment?

Biofilm formation is a critical factor in the pathogenesis of periprosthetic joint infections, rendering bacteria highly resistant to systemic antibiotics. In Staphylococcus epidermidis infections, what is the primary extracellular polymeric substance responsible for intercellular adhesion and structural integrity of the biofilm?

A 35-year-old man presents with a permanent low radial nerve palsy after a humerus fracture. A standard Jones tendon transfer procedure is planned. To restore thumb extension, which of the following muscle-tendon transfers is classically utilized in this procedure?

A 2-year-old child presents with an acute monoarticular septic arthritis of the knee. Standard synovial fluid cultures are negative at 48 hours, but the ESR and CRP are significantly elevated. Which of the following organisms is most likely responsible and optimally requires inoculation into BACTEC blood culture bottles or PCR for detection?

When performing a cemented total hip arthroplasty using a collarless, polished, taper-slip femoral stem (e.g., the Exeter stem), which of the following biomechanical principles describes the primary mechanism by which the stem achieves long-term stability within the cement mantle?