Biology, Genetics & Bone Healing MCQs

Bone morphogenetic proteins (BMPs) initiate intracellular signaling pathways critical for osteoblast differentiation. Upon binding to their transmembrane serine/threonine kinase receptors, which intracellular proteins are directly phosphorylated to translocate to the nucleus?

According to Perren's strain theory of fracture healing, what type of tissue will form in a fracture gap if the local interfragmentary strain is maintained between 2% and 10%?

Which recombinant bone morphogenetic protein is FDA-approved for use as an alternative to autograft in acute, open tibial shaft fractures treated with an intramedullary nail?

While continuous high-dose Parathyroid Hormone (PTH) causes net bone resorption, intermittent low-dose PTH administration drives net bone formation. The anabolic effect of intermittent PTH is primarily mediated by upregulating which pathway?

A 68-year-old female with an 8-year history of alendronate therapy complains of dull right thigh pain. Radiographs reveal lateral cortical thickening and a transverse radiolucent line in the subtrochanteric region of the right femur, but no complete fracture. What is the most appropriate management?

A 40-year-old male presents with persistent pain 8 months after a midshaft tibial fracture treated in a cast. Radiographs show a prominent 'elephant foot' callus formation but a persistent radiolucent line across the fracture gap. The site is mobile on exam. What is the primary underlying cause, and the treatment of choice?

Bone morphogenetic proteins (BMPs) are utilized in orthopedic trauma to promote fracture healing. Through which of the following mechanisms do BMP-2 and BMP-7 primarily exert their osteoinductive effects?

Nine months after operative fixation of a midshaft femur fracture, a patient presents with persistent thigh pain. Radiographs demonstrate an atrophic nonunion with a 'pencil-point' appearance of the bone ends and no bridging callus. What principle dictates the surgical management of this condition?

Intravenous bisphosphonates are a mainstay of medical management for children with moderate to severe Osteogenesis Imperfecta (OI). What is the primary molecular target of nitrogen-containing bisphosphonates?

A 5-year-old boy with a history of multiple low-energy fractures, blue sclerae, and dentinogenesis imperfecta is treated with intravenous bisphosphonates. What is the primary mechanism of action of this medication in treating his condition?

A 60-year-old female presents with atraumatic thigh pain. Radiographs reveal a transverse fracture of the lateral cortex of the subtrochanteric femur with focal cortical thickening. She has been on alendronate for 7 years. Following intramedullary nailing, what is the best medical management?

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?

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?

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?