1. General Principles & Basic Science MCQs

During an ACL reconstruction, a hamstring autograft is tensioned to a constant length before fixation. Over the next several minutes, the tension registered within the graft gradually decreases. This time-dependent biomechanical property is termed:

A 68-year-old woman with severe osteoporosis is treated with denosumab. This biologic agent exerts its anti-resorptive effect by binding directly to which of the following molecular targets?

Bone morphogenetic proteins (BMPs), particularly BMP-2 and BMP-7, are utilized to augment fracture healing and spinal fusions. These osteoinductive proteins primarily exert their cellular effects by signaling through which of the following intracellular pathways?

A surgeon retrieves a failed modular total hip arthroplasty implant and notes severe degradation at the head-neck taper junction. Which of the following mechanisms best describes the galvanic corrosion contributing to this failure?

A 5-year-old boy presents with frequent falls, a positive Gowers' sign, and marked calf pseudohypertrophy. The genetic defect responsible for this condition completely eliminates a protein that normally anchors the actin cytoskeleton to which of the following cellular components?

During heavy weight-bearing activities, articular cartilage relies heavily on boundary lubrication to prevent surface wear. Which specific molecule in synovial fluid is primarily responsible for boundary lubrication under high-load conditions?

An 80-year-old female with severe osteoporosis is started on teriparatide therapy. This medication, administered as a daily subcutaneous injection, increases bone mineral density primarily through which of the following mechanisms?

A 7-year-old girl with homozygous sickle cell disease presents with high fever, localized bone pain, and erythema over her left proximal humerus. Blood cultures and a bone aspirate subsequently grow a Gram-negative bacillus. Which of the following is the most likely causative organism?

During biomechanical tensile testing of a normal human flexor tendon, the initial "toe region" of the load-elongation curve represents functional physiological stretching. This specific phase is structurally due to which of the following?

According to Perren's strain theory, what is the maximum amount of interfragmentary strain that allows for primary bone healing to occur without callus formation?

Which of the following orthopedic implant materials has a modulus of elasticity (Young's modulus) that most closely resembles that of cortical bone?

A 45-year-old woman with a history of Roux-en-Y gastric bypass presents with diffuse bone pain and proximal muscle weakness. Laboratory evaluation reveals low serum calcium, low phosphorus, elevated alkaline phosphatase, and elevated parathyroid hormone (PTH). What is the most likely diagnosis?

A 30-year-old woman is diagnosed with an expansive, eccentrically located, lytic lesion in the distal femur extending to the subchondral bone. Biopsy confirms a Giant Cell Tumor of bone. If medical therapy is considered, which molecular pathway is targeted to inhibit the progression of this tumor?

Which phase of biofilm formation on an orthopedic implant is characterized by the production of an extracellular polymeric substance (EPS) matrix that protects the bacteria from systemic antibiotics and host immune responses?

A 4-year-old girl is evaluated for recurrent fractures with minimal trauma. Examination reveals blue sclerae and mild hearing loss. A defect in which of the following processes is primarily responsible for her condition?

Following a complete peripheral nerve transection (neurotmesis), Wallerian degeneration occurs distal to the injury site. Which cell type is primarily responsible for clearing the myelin debris to create a permissive environment for axonal regeneration?

During a prolonged endurance event, such as a marathon, the athlete's skeletal muscles predominantly rely on muscle fibers characterized by which of the following physiological profiles?

In normal articular cartilage, the primary function of aggrecan is to provide compressive stiffness to the tissue. This mechanical property is achieved through which of the following mechanisms?