Biology, Genetics & Bone Healing MCQs

Bone Morphogenetic Proteins (BMPs) play a crucial role in osteoinduction during fracture healing. Following binding to their transmembrane receptors, which intracellular proteins are directly phosphorylated to translocate to the nucleus and regulate gene expression?

A 4-year-old child presents with frequent fractures, cranial nerve palsies, and diffuse osteosclerosis on radiographs. A defect in which of the following is the most likely underlying pathophysiological cause?

Alendronate is prescribed for a 70-year-old female with a fragility fracture of the distal radius. What is the precise intracellular target of this medication within the osteoclast?

According to Perren's strain theory of fracture healing, what is the maximum strain tolerated by lamellar bone before it fails?

A 4-year-old girl is evaluated for short stature and dense, brittle bones demonstrating an Erlenmeyer flask deformity on radiographs. Laboratory analysis reveals absent function of carbonic anhydrase II. Which cellular process is directly impaired in this condition?

Which of the following members of the Transforming Growth Factor-beta (TGF-b) superfamily is FDA approved for use in acute, open tibial shaft fractures treated with an intramedullary nail?

Parathyroid hormone (PTH) regulates serum calcium by exerting effects on bone. Intermittent, low-dose administration of synthetic PTH (e.g., Teriparatide) has what primary cellular effect?

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?

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?

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?

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?

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?

A 38-year-old male on long-term systemic corticosteroids for lupus presents with atraumatic hip pain. MRI confirms osteonecrosis of the femoral head. What is the primary cellular pathophysiology underlying corticosteroid-induced osteonecrosis?

In the process of bone remodeling, the activation of osteoclasts requires the binding of Receptor Activator of Nuclear Factor Kappa-B Ligand (RANKL) to RANK on osteoclast precursors. Which of the following cell types is the primary source of RANKL expression in bone?

A 65-year-old man presents with progressive bone pain, increasing hat size, and unilateral hearing loss. Laboratory investigations reveal an isolated, marked elevation of serum alkaline phosphatase, with normal serum calcium and phosphorus levels. The initial pathophysiological phase of this disorder is primarily driven by an abnormality in which of the following?

A transverse diaphyseal fracture of the radius is surgically treated with anatomic reduction and rigid fixation using a dynamic compression plate (absolute stability). Under these specific biomechanical conditions, the fracture will predominantly heal via primary bone healing (contact healing). This process is mediated directly by which of the following?

A 72-year-old female is prescribed oral alendronate for the treatment of postmenopausal osteoporosis following a low-energy distal radius fracture. Nitrogen-containing bisphosphonates, such as alendronate, reduce bone turnover primarily by inhibiting which of the following intracellular targets within the osteoclast?

A 32-year-old woman presents with persistent knee pain. Radiographs demonstrate an eccentric, completely lytic epiphyseal lesion extending into the metaphysis of the proximal tibia, lacking a sclerotic rim. Biopsy confirms a Giant Cell Tumor of bone (GCT). In cases where the tumor is deemed un-resectable or causes severe morbidity upon resection, which of the following targeted systemic therapies is FDA-approved for treatment?

A surgeon opts to use demineralized bone matrix (DBM) to supplement a posterolateral lumbar fusion. DBM is derived from allograft bone processed with an acid bath to remove the mineral component. Consequently, which of the following precise combinations of biologic bone grafting properties does DBM possess?