1. General Principles & Basic Science MCQs

A 10-year-old boy presents with frequent fractures and cranial nerve palsies. Radiographs reveal generalized increased bone density with a 'bone-within-bone' appearance. Which of the following enzymes is most likely deficient in this patient's osteoclasts?

A patient with end-stage renal disease develops secondary hyperparathyroidism. Which of the following pathophysiological mechanisms is the primary driver of this condition?

A 55-year-old female is prescribed Alendronate for osteoporosis. This medication primarily causes osteoclast apoptosis by disrupting which of the following intracellular pathways?

During the primary healing of a transverse diaphyseal fracture treated with absolute stability, what is the maximum interfragmentary strain that allows for primary bone healing?

A surgeon uses a stainless steel screw to secure a titanium plate during an open reduction and internal fixation. Which of the following describes the most likely mechanism of failure if corrosion occurs?

Which of the following bone morphogenetic proteins (BMPs) has been approved by the FDA as an alternative to autogenous bone graft for acute, open tibial shaft fractures?

A 68-year-old male is undergoing treatment for a prosthetic joint infection caused by Staphylococcus epidermidis. The pathogenesis of this organism's persistence on the implant surface is most dependent on the production of:

Which of the following non-collagenous proteins is primarily responsible for initiating the mineralization process within the bone matrix by binding calcium and hydroxyapatite?

A patient undergoes testing of isolated muscle properties. Which of the following modes of muscle contraction typically generates the maximum intrinsic force?

A 72-year-old female presents with acute knee pain. Aspiration reveals negatively birefringent, needle-shaped crystals under polarized light microscopy. The inflammatory response triggered by these crystals is primarily mediated by the activation of which complex?

During an ACL reconstruction, a hamstring autograft is subjected to a constant tension load on a preparation board. Over the next 15 minutes, the graft gradually elongates. Which viscoelastic property does this phenomenon represent?

Recombinant human Bone Morphogenetic Protein-2 (rhBMP-2) is utilized as a potent osteoinductive agent in spinal fusion surgery. Upon binding to its surface receptors, through which primary intracellular signaling pathway does rhBMP-2 mediate its osteoinductive effect?

A 28-year-old male suffers a stab wound to the right side of his neck at the C6 level, resulting in a Brown-Sequard syndrome. Based on the anatomical pathways of the spinal cord, which of the following physical examination findings is expected?

Recombinant human Bone Morphogenetic Protein-2 (rhBMP-2) is utilized in spinal fusion surgery to enhance arthrodesis. At the cellular level, through which of the following intracellular signaling pathways does rhBMP-2 primarily exert its osteoinductive effect?

Which of the following thermal processing methods for highly cross-linked polyethylene (HXLPE) is associated with the lowest level of measurable free radicals, but also results in a reduction of the material's yield and fatigue strength?

A patient undergoes a primary THA via the direct anterior (Smith-Petersen) approach. Postoperatively, she reports a burning sensation and numbness over the anterolateral aspect of her thigh. Which nerve is most likely affected, and between which two muscles does it typically emerge in the proximal thigh?

A 72-year-old female on long-term bisphosphonate therapy for osteoporosis presents with thigh pain. Radiographs reveal a transverse fracture of the lateral femoral cortex with localized cortical thickening (beaking), extending halfway across the diaphysis. This fracture is located 2 cm distal to the tip of a well-fixed, uncemented standard-length THA stem inserted 8 years ago. What is the most appropriate management?