1. General Principles & Basic Science MCQs

A 45-year-old active male with a ceramic-on-ceramic (CoC) THA reports a loud squeaking noise with walking that is socially embarrassing. Which factor is most strongly associated with the etiology of this phenomenon?

During a complex revision Total Hip Arthroplasty for a well-fixed extensively porous-coated stem, an extended trochanteric osteotomy (ETO) is planned. Which of the following is true regarding the ETO technique?

Tranexamic acid (TXA) is routinely used to reduce blood loss in total joint arthroplasty. What is the precise mechanism of action of TXA?

A direct anterior approach to the hip utilizes an internervous and intermuscular plane. Which of the following accurately describes this superficial interval?

A surgeon is performing a total hip arthroplasty via the direct anterior (Smith-Petersen) approach. This approach exploits the internervous plane between which two muscle groups?

A 28-year-old male has an expansile, multiloculated radiolucent lesion in the body of the mandible. Histology shows interlacing fascicles of uniform, bland spindle cells with abundant collagen production and no cytologic atypia or mitotic figures. The lesion is locally aggressive. Mutations in which of the following signaling pathways are most commonly implicated in this tumor?

A 72-year-old male with a long history of bone pain, increasing head size, and progressive hearing loss suddenly develops severe pain and swelling in his right thigh. Radiographs reveal a highly destructive diaphyseal lesion with cortical breakthrough and a wide zone of transition. His alkaline phosphatase is markedly elevated. The underlying disease process that predisposed him to this malignancy primarily begins with the dysfunction of which cell type?

A 34-year-old female presents with an expansile, eccentric lytic lesion in the distal radius that extends to the subchondral bone plate. A biopsy confirms Giant Cell Tumor (GCT) of bone. Regarding the cellular constituents of this tumor, which of the following statements is most accurate regarding its pathogenesis and targeted medical treatment?

An 18-year-old male presents with persistent night pain in his thigh that is dramatically relieved by aspirin. Radiographs show a 1 cm radiolucent nidus surrounded by dense reactive cortical sclerosis in the proximal femoral diaphysis. The profound pain experienced by the patient is primarily due to local production of which of the following mediators?

A 70-year-old man presents with increasing head size, hearing loss, and anterior bowing of the tibiae. Laboratory testing reveals a markedly elevated serum alkaline phosphatase with normal calcium and phosphorus levels. A biopsy of the tibia would most likely show a mosaic pattern of lamellar bone. Mutations in which gene are most strongly implicated in the familial form of this condition?

A 12-year-old girl is evaluated for a leg length discrepancy and a 'shepherd's crook' deformity of her proximal femur. Radiographs show an expansile, ground-glass intramedullary lesion. Histological analysis demonstrates irregular trabeculae of woven bone lacking prominent osteoblastic rimming, set in a fibrous stroma. This condition is driven by an activating mutation in a gene encoding which of the following?

A 68-year-old woman presents with severe back pain. Radiographs reveal multiple 'punched-out' lytic lesions in her skull and spine. Bone marrow biopsy shows sheets of eccentric cells with abundant basophilic cytoplasm, a perinuclear halo (hof), and clock-face chromatin. Which cytokine is primarily responsible for the osteoclast activation and subsequent lytic bone destruction in this disease?

A 19-year-old male complains of severe, throbbing pain in his proximal tibia that is worse at night and dramatically relieved by ibuprofen. Imaging shows a cortical lucency measuring 8 mm, surrounded by dense reactive sclerosis. The intense pain associated with this lesion is primarily mediated by which of the following mechanisms?

A 68-year-old man presents with progressively increasing hat size, hearing loss, and bowing of his tibiae. Radiographs show thickened cortices and a coarse trabecular pattern. Bone biopsy reveals a mosaic pattern of lamellar bone with prominent cement lines. Which of the following gene mutations is most strongly associated with the familial form of this condition?

A 12-year-old boy is evaluated for multiple painless, bony bumps around his knees and shoulders. Radiographs show multiple pedunculated excrescences pointing away from the joint line. Genetic testing reveals a loss-of-function mutation in EXT1. The normal product of this gene is essential for which of the following cellular processes?

A 29-year-old recreational tennis player presents with vague, poorly localized shoulder pain and paresthesias over the lateral deltoid. MRI reveals isolated denervation atrophy of the teres minor. Which vascular structure is most likely compressed along with the involved nerve in this syndrome?

A 28-year-old competitive weightlifter feels a sudden "pop" in his anterior axilla while performing a heavy bench press. Examination reveals loss of the anterior axillary fold and weakness in internal rotation and adduction. Which of the following describes the most common anatomic location of this injury?

A 26-year-old professional baseball pitcher presents with vague posterior shoulder pain and numbness over the lateral deltoid. MRI reveals isolated atrophy of the teres minor. Compression of the involved nerve is most likely occurring in a space bounded medially by which of the following structures?

A 28-year-old competitive weightlifter feels a pop in his anterior axilla while performing a heavy bench press. Examination reveals ecchymosis and loss of the anterior axillary fold. MRI confirms a complete rupture of the pectoralis major tendon at its insertion. In surgical repair, what is the normal anatomical relationship of the pectoralis major insertion footprint?

A 29-year-old male competitive tennis player complains of vague posterior shoulder pain and numbness over the lateral deltoid after overhead activities. MRI of the shoulder reveals isolated fatty atrophy of the teres minor muscle. Which of the following structures are most likely being compressed?