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Biology, Genetics & Bone Healing MCQs

Practice Set 2 of 212

This practice set contains high-yield board review questions covering key concepts in Biology, Genetics & Bone Healing. Each clinical scenario is designed to test your diagnostic and management skills relevant to this subspecialty.

Question 21

Topic: Biology, Genetics & Bone Healing

A 30-year-old female presents with a sacral mass causing bowel dysfunction. Biopsy reveals multinucleated giant cells and mononuclear stromal cells. If surgical resection carries unacceptable morbidity, which targeted medical therapy is most appropriate?

. Imatinib
. Zoledronic acid
. Rituximab
. Denosumab
. Methotrexate

Correct Answer & Explanation

. Denosumab

Explanation

Denosumab is a monoclonal antibody against RANKL, which is heavily expressed by the neoplastic mononuclear stromal cells in giant cell tumors. It prevents the activation of osteoclast-like giant cells and is FDA-approved for unresectable GCTs.

Question 22

Topic: Biology, Genetics & Bone Healing

Which of the following targeted treatments is correctly paired with its mechanism of action for managing unresectable giant cell tumors of bone?

. Denosumab: binds to RANKL, preventing osteoclast activation
. Imatinib: inhibits tyrosine kinase activity
. Bevacizumab: inhibits vascular endothelial growth factor (VEGF)
. Bisphosphonates: directly induces apoptosis of mononuclear neoplastic cells
. Methotrexate: competitively inhibits dihydrofolate reductase

Correct Answer & Explanation

. Denosumab: binds to RANKL, preventing osteoclast activation

Explanation

Denosumab binds to RANKL, preventing it from binding to RANK on the surface of osteoclast precursors. This inhibits the formation and activity of the osteoclast-like giant cells responsible for the severe osteolysis in GCT.

Question 23

Topic: Biology, Genetics & Bone Healing

A 65-year-old woman with known osteoporosis sustains an acute L1 compression fracture after lifting a box. She is neurologically intact, and her pain is adequately managed with oral analgesics. What is the most appropriate initial treatment?

. Posterior spinal fusion
. Anterior corpectomy and fusion
. Kyphoplasty
. Vertebroplasty
. Observation with early mobilization and pain control

Correct Answer & Explanation

. Observation with early mobilization and pain control

Explanation

The standard of care for neurologically intact, stable osteoporotic compression fractures is non-operative management. Early mobilization, pain control, and treatment of the underlying osteoporosis are recommended over immediate surgical intervention.

Question 24

Topic: Biology, Genetics & Bone Healing

A 28-year-old woman presents with severe sacral pain. Imaging shows a large, eccentric, purely lytic 'soap-bubble' lesion destroying the S1 and S2 vertebral bodies. Biopsy reveals multinucleated giant cells interspersed with mononuclear stromal cells. Which systemic medication targets the primary pathophysiology of this tumor?

. Imatinib
. Methotrexate
. Denosumab
. Doxorubicin
. Bevacizumab

Correct Answer & Explanation

. Denosumab

Explanation

Giant cell tumors of the bone express RANKL by the neoplastic stromal cells, which recruits osteoclast-like giant cells. Denosumab, a monoclonal antibody against RANKL, is an effective targeted therapy to shrink these tumors.

Question 25

Topic: Biology, Genetics & Bone Healing

A 40-year-old male presents with mechanical back pain and is found to have an expansile, osteolytic lesion isolated to the posterior elements of L4. Biopsy shows blood-filled spaces separated by septa containing giant cells and woven bone. During surgical treatment (curettage), massive bleeding is encountered. The most effective non-surgical adjunct to reduce recurrence of this specific lesion is:

. Postoperative local radiation therapy
. Preoperative selective arterial embolization
. Systemic administration of bisphosphonates
. Intravenous administration of denosumab
. Chemotherapy with ifosfamide and doxorubicin

Correct Answer & Explanation

. Preoperative selective arterial embolization

Explanation

The diagnosis is an aneurysmal bone cyst (ABC). Due to its highly vascular nature and risk of significant intraoperative blood loss, preoperative selective arterial embolization is a crucial adjunct that also helps decrease local recurrence rates.

Question 26

Topic: Biology, Genetics & Bone Healing

A 30-year-old female presents with sacral pain. Imaging shows a lytic, expansile mass in the S1-S2 vertebral bodies. Biopsy demonstrates mononuclear cells and multinucleated giant cells. Which of the following targeted medical therapies is often used preoperatively to facilitate surgical resection by inducing an osteosclerotic shell?

. Imatinib
. Denosumab
. Zoledronic acid
. Rituximab
. Bevacizumab

Correct Answer & Explanation

. Denosumab

Explanation

Denosumab is a monoclonal antibody against RANKL used in giant cell tumors of bone. It inhibits osteoclast-like giant cells, arresting tumor growth and forming a peripheral sclerotic rim that facilitates intralesional curettage or en bloc resection.

Question 27

Topic: Biology, Genetics & Bone Healing

A 35-year-old man presents with back pain and a large expansile lytic lesion in the L4 vertebral body extending into the pedicle. Biopsy reveals multinucleated giant cells in a stroma of mononuclear cells. If the tumor is deemed unresectable due to neurovascular involvement, the best pharmacologic treatment is:

. Imatinib
. Zoledronic acid
. Denosumab
. Doxorubicin
. Methotrexate

Correct Answer & Explanation

. Denosumab

Explanation

This patient has a giant cell tumor (GCT) of the spine. Denosumab, a RANKL inhibitor, is highly effective for unresectable GCTs by inhibiting osteoclast-like giant cells and causing tumor ossification.

Question 28

Topic: Biology, Genetics & Bone Healing

Which of the following populations is most at risk for compression fractures of the spine:

. Middle-aged black women
. Elderly caucasian men
. Menopausal females of Inuit (Alaskan native) descent
. Elderly fair-skinned women of northern European descent
. Heavy laborers

Correct Answer & Explanation

. Elderly fair-skinned women of northern European descent

Explanation

Osteoporosis is an age-related decrease in bone mass usually associated with a loss of estrogen in postmenopausal women. Sedentary, thin white women of northern European descent are most severely affected. In addition, smoking, heavy drinking, and certain pharmacological agents, such as phenytoin, increase the severity of the disease. Women who breastfed their infants or those with low vitamin D or calcium diets are also at increased risk.

Question 29

Topic: Biology, Genetics & Bone Healing

Following an osteoporotic compression fracture, the risk of sustaining another compression fracture at a different level is increased by:

. 2 times
. 5 times
. 8 times
. 10 times
. 15 times

Correct Answer & Explanation

. 5 times

Explanation

Osteoporosis is a systemic disease affecting more than 24 million Americans. Osteoporosis results in progressive bone mineral loss and concurrent changes in bony architecture, which leave the spinal column vulnerable to compression fractures, often after minimal or no trauma. There are an estimated 700,000 osteoporotic vertebral compression fractures (VC Fs) in the United States each year, of which more than one third become chronically painful. Approximately 85% of VC Fs are due to primary osteoporosis and the remainder due to secondary osteoporosis or malignancies. These VC Fs lead to progressive sagittal spine deformity and changes in spinal biomechanics and are believed to contribute to a fivefold increased risk of further fracture by virtue of force transmission to weak vertebrae above or below. Whether the fracture is painful or not, the spinal deformity caused by two or more fractures dramatically impacts health, daily living, and medical costs through loss of lung capacity, loss of appetite, reduced mobility, chronic pain, and/or clinical depression.

Question 30

Topic: Biology, Genetics & Bone Healing

Teriparatide therapy reduces the risk of future vertebral compression fractures primarily through which mechanism of action?

. Directly stimulating osteoblast formation and action
. Inhibiting osteoclast-mediated bone resorption
. Binding to and neutralizing RANK ligand
. Inhibiting the secretion of sclerostin
. Binding to hydroxyapatite crystals to directly increase density

Correct Answer & Explanation

. Directly stimulating osteoblast formation and action

Explanation

Teriparatide is a recombinant parathyroid hormone (PTH 1-34) that acts as a potent anabolic agent when given intermittently. It directly stimulates osteoblast activity, leading to new bone formation and improved trabecular microarchitecture.

Question 31

Topic: Biology, Genetics & Bone Healing

Which of the following conditions represents an absolute medical contraindication to initiating oral bisphosphonate therapy in a patient with an osteoporotic compression fracture?

. History of deep vein thrombosis
. Severe renal impairment (Creatinine Clearance < 30 mL/min)
. Well-controlled gastroesophageal reflux disease (GERD)
. Previous history of breast cancer
. Mild asymptomatic hypercalcemia

Correct Answer & Explanation

. Severe renal impairment (Creatinine Clearance < 30 mL/min)

Explanation

Bisphosphonates are excreted unchanged via the kidneys and can accumulate, causing toxicity. They are absolutely contraindicated in patients with severe renal impairment, typically defined as a creatinine clearance of less than 30 to 35 mL/min.

Question 32

Topic: Biology, Genetics & Bone Healing

An 80-year-old female with known osteoporosis presents with severe back pain and an acute L2 compression fracture. Under what specific circumstance would open operative decompression and stabilization be indicated over percutaneous cement augmentation?

. 15% loss of anterior vertebral body height
. Failure of conservative treatment after 4 weeks
. Presence of severe axial back pain upon weight-bearing
. Progressive neurologic deficit secondary to retropulsed bone
. Presence of an intravertebral vacuum cleft on extension views

Correct Answer & Explanation

. Progressive neurologic deficit secondary to retropulsed bone

Explanation

A progressive neurologic deficit caused by canal compromise from retropulsed bone fragments is a clear indication for surgical decompression. Cement augmentation alone cannot decompress the neural elements and carries a risk of exacerbating the stenosis.

Question 33

Topic: Biology, Genetics & Bone Healing
According to the World Health Organization (WHO) criteria, severe (or established) osteoporosis is defined by a fragility fracture and a Dual-energy X-ray absorptiometry (DEXA) T-score of:
. > -1.0
. Between -1.0 and -2.5
. ≤ -2.5
. Between 0 and -1.0
. ≤ -1.5 without a fracture

Correct Answer & Explanation

. ≤ -2.5

Explanation

The WHO defines osteoporosis as a DEXA T-score of -2.5 or lower. The designation of "severe" or "established" osteoporosis is applied when a patient has a T-score of ≤ -2.5 combined with one or more fragility fractures.

Question 34

Topic: Biology, Genetics & Bone Healing

Denosumab is highly effective for patients with severe osteoporosis and recurrent vertebral fractures. What is its precise mechanism of action?

. Inhibition of the Wnt signaling pathway via sclerostin binding
. Activation of osteoprotegerin production by osteoblasts
. Stimulation of the parathyroid hormone receptor on osteoblasts
. Binding and inhibition of RANK Ligand (RANKL)
. Inhibition of cathepsin K to prevent matrix degradation

Correct Answer & Explanation

. Binding and inhibition of RANK Ligand (RANKL)

Explanation

Denosumab is a fully human monoclonal antibody that specifically binds to and inhibits RANK Ligand (RANKL). This prevents RANKL from activating the RANK receptor on osteoclast precursors, thereby profoundly inhibiting osteoclast formation, function, and survival.

Question 35

Topic: Biology, Genetics & Bone Healing

Which medication provides the most rapid, specific analgesic effect for acute osteoporotic vertebral compression fractures within the first few weeks of injury?

. Oral alendronate
. Intravenous zoledronic acid
. Subcutaneous teriparatide
. Intranasal calcitonin
. Subcutaneous denosumab

Correct Answer & Explanation

. Intranasal calcitonin

Explanation

Intranasal calcitonin has been shown to provide a significant, early analgesic effect in acute osteoporotic vertebral compression fractures. It is often prescribed early in the fracture course specifically for this symptom-modifying property.

Question 36

Topic: Biology, Genetics & Bone Healing

A 68-year-old woman with a T-score of -3.0 sustains a T11 compression fracture. She is started on a daily subcutaneous medication that acts as an anabolic agent to stimulate bone formation. What is the mechanism of action of this medication?

. Inhibition of osteoclast action via RANKL binding
. Direct apoptosis of osteoclasts via bisphosphonate accumulation
. Recombinant human parathyroid hormone (PTH) analog action
. Sclerostin inhibition
. Selective estrogen receptor agonism

Correct Answer & Explanation

. Recombinant human parathyroid hormone (PTH) analog action

Explanation

Teriparatide is a recombinant human PTH analog administered daily subcutaneously. It acts as an anabolic agent by stimulating osteoblast activity and directly forming new bone.

Question 37

Topic: Biology, Genetics & Bone Healing

A 78-year-old patient with severe osteoporosis presents with multiple wedge compression fractures.

According to the World Health Organization (WHO) definition, severe osteoporosis is diagnosed when a patient has a fragility fracture and a DEXA T-score of:

. -1.0 or less
. -1.5 or less
. -2.0 or less
. -2.5 or less
. -3.0 or less

Correct Answer & Explanation

. -2.5 or less

Explanation

The WHO defines osteoporosis as a DEXA T-score of -2.5 or lower. Severe (or established) osteoporosis is defined as a T-score of -2.5 or lower in the presence of one or more fragility fractures.

Question 38

Topic: Biology, Genetics & Bone Healing

When evaluating a patient's risk for future osteoporotic fractures using the FRAX tool, which of the following is NOT included as a primary variable in the calculation?

. Current smoking status
. Previous fragility fracture
. Serum Vitamin D level
. Use of systemic glucocorticoids
. Rheumatoid arthritis

Correct Answer & Explanation

. Serum Vitamin D level

Explanation

The FRAX (Fracture Risk Assessment Tool) algorithm evaluates 11 clinical risk factors including age, sex, BMI, prior fracture, parental hip fracture, current smoking, glucocorticoid use, rheumatoid arthritis, secondary osteoporosis, alcohol intake, and femoral neck BMD. Serum Vitamin D levels are not a variable.

Question 39

Topic: Biology, Genetics & Bone Healing

A patient with multiple osteoporotic compression fractures is evaluated for teriparatide therapy. This medication is strictly contraindicated in patients with a history of which of the following conditions?

. Peptic ulcer disease
. Deep vein thrombosis
. Paget disease of bone
. Rheumatoid arthritis
. Chronic kidney disease stage II

Correct Answer & Explanation

. Paget disease of bone

Explanation

Teriparatide is a recombinant parathyroid hormone analogue with an anabolic effect on bone. It carries a black box warning for osteosarcoma and is contraindicated in patients with Paget disease, prior skeletal radiation, or unexplained elevations of alkaline phosphatase.

Question 40

Topic: Biology, Genetics & Bone Healing

Which medical therapy has been shown to uniquely provide acute analgesic effects for osteoporotic vertebral compression fractures, in addition to its anti-resorptive properties?

. Oral alendronate
. Intranasal calcitonin
. Subcutaneous teriparatide
. Intravenous zoledronic acid
. Oral raloxifene

Correct Answer & Explanation

. Intranasal calcitonin

Explanation

Intranasal calcitonin is unique among pharmacological osteoporosis treatments for having a documented acute analgesic effect. This effect is believed to be mediated through the release of endogenous endorphins and is useful in the acute phase of fracture management.

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