Biology, Genetics & Bone Healing MCQs

In the context of fracture healing, which biomechanical environment is most conducive to promoting primary (direct) bone healing without the formation of a visible callus?

A 32-year-old female presents with knee pain. Radiographs show an eccentric, lytic lesion in the distal femoral epiphysis extending to the articular surface. Biopsy reveals multinucleated giant cells in a background of mononuclear cells. Which medication targets the underlying pathophysiology of this tumor?

An 8-year-old boy sustains a minor fall and presents with arm pain. X-rays show a centrally located, completely lytic metaphyseal lesion in the proximal humerus with a "fallen leaf" sign. What is the accepted pathophysiology of this lesion?

A 32-year-old female presents with wrist pain. Radiographs reveal an eccentric, lytic, expansile lesion in the epiphysis of the distal radius extending to the subchondral bone, without a sclerotic rim. Biopsy confirms multinucleated giant cells. If the patient is treated with a targeted pharmacological agent prior to surgery, what is the mechanism of action of this drug?

A 32-year-old female presents with a large, lytic lesion in the distal femur extending to the subchondral bone. Biopsy confirms Giant Cell Tumor of bone. She is treated with denosumab pre-operatively. What is the specific mechanism of action of denosumab?

A 28-year-old female presents with a destructive, eccentric lytic lesion in the distal femur. Biopsy reveals numerous multinucleated giant cells in a stroma of mononuclear cells. Preoperative treatment with denosumab is planned to facilitate joint-salvage surgery. What is the mechanism of action of this medication?

An asymptomatic 12-year-old boy undergoes a radiograph for minor knee trauma, revealing a 2 cm eccentric, bubbly, cortically based metaphyseal radiolucency in the distal femur. If a biopsy were to be performed, which of the following histological patterns would be expected?

Which of the following histologic features is most characteristic of a non-ossifying fibroma (NOF)?

When reviewing the shoulder X-ray of an 84-year-old female, which radiographic finding is most indicative of severe osteoporosis, beyond just fracture presence?

Which of the following proteoglycan and structural changes is most characteristic of intervertebral disc degeneration contributing to age-related herniation?

Perren's strain theory dictates the type of bone healing that will occur based on the amount of deformation at the fracture site. What is the maximum interfragmentary strain tolerance for the formation of solid lamellar bone?

A rigid construct is applied to a transverse femoral shaft fracture, leaving a 1 mm gap. According to Perren's strain theory, what happens at the fracture site if the interfragmentary strain exceeds 10% but remains below the threshold for catastrophic failure?

A 22-year-old active male undergoes hardware removal (plates and screws) 18 months after successful ORIF of a both bones forearm fracture. To minimize the risk of refracture through previous screw holes, what is the most important post-operative instruction?

For highly comminuted mid-diaphyseal fractures of both the radius and ulna, bridge plating is selected instead of absolute rigid fixation. Which of the following biomechanical environments is created by bridge plating, and what is the primary mode of bone healing expected?

A 42-year-old male sustains highly comminuted midshaft fractures of both the radius and ulna. The surgeon utilizes 3.5 mm limited contact dynamic compression plates (LC-DCP) using a bridge plating technique over the comminuted segments. Which of the following best describes the biomechanical goal and expected bone healing mechanism of this construct?

A 72-year-old patient with severe osteoporosis undergoes open reduction and internal fixation of a proximal tibia fracture. The surgeon is particularly concerned about screw pull-out. Which of the following intraoperative strategies would provide the greatest cumulative benefit in maximizing screw pull-out strength in this patient?

According to Perren's strain theory, what level of interfragmentary strain at the fracture site is required to allow for primary (osteonal) bone healing?

According to Perren's strain theory, fracture healing is dictated by the amount of mechanical strain at the fracture gap. For primary (direct) bone healing to occur without the formation of a provisional callus, the interfragmentary strain must be kept below what threshold?

A surgeon is performing bridge plating on a comminuted midshaft humerus fracture. To decrease the stiffness of the construct and promote callus formation via relative stability, what modification should be made to the screw configuration?