1. General Principles & Basic Science MCQs

A patient presents with an acute monoarticular swelling of the first metatarsophalangeal joint. Joint aspiration is performed. Under polarized light microscopy, the synovial fluid is expected to demonstrate:

A patient presents with a midshaft humerus fracture and a concomitant complete radial nerve palsy. The fracture is closed and treated nonoperatively in a functional brace. At 12 weeks, there is no clinical or electromyographic (EMG) evidence of radial nerve recovery, and the fracture is healing well. What is the most appropriate next step in management?

A 72-year-old female who has been taking a medication for osteoporosis for 8 years presents with a low-energy fracture of the femoral shaft.

What is the primary mechanism by which bisphosphonates increase the risk of these atypical femur fractures?

A 65-year-old male undergoes a primary total hip arthroplasty using a titanium alloy (Ti-6Al-4V) femoral stem and a cobalt-chromium (CoCr) alloy femoral head. Five years later, he presents with progressive groin pain and a large cystic mass on MRI, without evidence of infection. Revision surgery reveals black debris and damage at the head-neck taper junction. What is the primary pathophysiologic mechanism of this wear pattern?

A 45-year-old patient with a highly comminuted diaphyseal femur fracture is treated with a bridging locked intramedullary nail. The resulting mechanical construct provides relative stability. Which of the following predominantly characterizes the bone healing process in this mechanical environment?

A 32-year-old female presents with wrist pain. Radiographs demonstrate an expansile, eccentrically located lytic lesion in the distal radius epiphysis without a sclerotic rim. Biopsy confirms a giant cell tumor of bone.

Because the tumor involves the joint extensively, neoadjuvant medical therapy is planned to facilitate joint-sparing surgery. The primary medical treatment (denosumab) for this condition targets which of the following?

Articular cartilage is a highly specialized tissue designed to withstand repetitive compressive forces. When evaluating the structural and biochemical composition of articular cartilage across its depth, which zone is characterized by having the highest concentration of water, the lowest concentration of proteoglycans, and collagen fibrils aligned parallel to the joint surface?

A 32-year-old female presents with knee pain. Radiographs show a large, eccentric, purely lytic, expansile lesion in the distal femoral epiphysis extending to the subchondral bone. A biopsy reveals numerous multinucleated giant cells in a stroma of mononuclear cells. For advanced, unresectable cases, or as a neoadjuvant therapy to facilitate intralesional curettage, which of the following monoclonal antibodies is an FDA-approved targeted treatment?

A 35-year-old woman undergoes open reduction and internal fixation of a diaphyseal radial fracture using a dynamically compressed plate, achieving absolute fracture stability and anatomical reduction. Which of the following best describes the primary mechanism of bone healing expected in this specific environment?

A 32-year-old woman complains of left knee pain. Radiographs show an eccentric, purely lytic lesion in the distal femoral epiphysis extending to the subchondral bone, without a sclerotic margin. Biopsy reveals multinucleated giant cells interspersed among mononuclear stromal cells. For recurrent or surgically unsalvageable cases of this specific tumor, which of the following is the most appropriate targeted medical therapy?

Distraction osteogenesis, as pioneered by Ilizarov, is a powerful technique for limb lengthening and deformity correction. The formation of new bone across the distraction gap primarily relies on which biological process?

To avoid galvanic corrosion in orthopedic implants, dissimilar metals should generally not be in physical contact. However, combining a cobalt-chromium femoral head with a titanium alloy femoral stem is clinically common and highly successful. What is the primary electrochemical reason this specific modular combination is acceptable?

A 45-year-old woman requires open reduction and internal fixation for a volar Barton's fracture of the distal radius. The surgeon utilizes the standard volar Henry approach. Distally, this approach develops an internervous plane between which two structures?

A 6-year-old boy falls from monkey bars and sustains a completely displaced extension-type supracondylar humerus fracture. Radiographs show the distal fragment is displaced posterolaterally. Based on this displacement pattern, which neurovascular structure is at the greatest risk of injury?

Which of the following Bone Morphogenetic Proteins (BMPs) is an FDA-approved osteoinductive agent for the treatment of acute, open tibial shaft fractures?

A 35-year-old female presents with knee pain. Radiographs reveal an eccentric, lytic epiphyseal lesion extending to the subchondral bone of the distal femur. Biopsy confirms a Giant Cell Tumor (GCT) of bone.

Which cellular component of this tumor expresses RANKL, serving as the target for medical therapy?

According to Perren's strain theory of bone healing, the process of primary bone healing (direct remodeling by osteonal cutting cones without callus formation) depends heavily on the mechanical environment. For primary bone healing to occur, the interfragmentary strain must remain below which of the following thresholds?