Surgical Considerations in Metabolic Bone Diseases — MCQs
What is the gold standard for the diagnosis of osteoporosis?
All statements are true for osteomalacia except:
True about osteoporosis
Which is the drug of choice in Paget's disease?
A 70 year old male, known case of chronic renal failure suffers from a pathological fracture of Rt femur, the diagnosis is -
Select the type of bone disease which is most likely to be associated with genetically determined disorder in the structure or processing of type I collagen (SELECT 1 DISEASE)
Avascular necrosis of bone is LEAST likely to be associated with?
Osteonecrosis is seen in all except
A 70-year-old female has been on alendronate for 7 years for osteoporosis and now complains of pain in her right thigh. What is the next investigation to be performed?
Brittle bone disease is -
Surgical Considerations in Metabolic Bone Diseases Indian Medical PG Practice Questions and MCQs
Question 1: What is the gold standard for the diagnosis of osteoporosis?
- A. Dual energy X-ray absorptiometry (Correct Answer)
- B. Single energy X-ray absorptiometry
- C. Ultrasound
- D. Quantitative computed tomography
Explanation: ***Dual energy X-ray absorptiometry*** - **DXA** is the current **gold standard** for diagnosing osteoporosis and assessing fracture risk due to its high precision and accuracy in measuring **bone mineral density (BMD)**. - It measures BMD at clinically relevant sites such as the **lumbar spine** and **hip**, providing T-scores and Z-scores for comparison. *Single energy X-ray absorptiometry* - **SXA** measures BMD at peripheral sites but is **less accurate** and comprehensive than DXA for diagnosing osteoporosis. - It has **limited utility** as a diagnostic tool for osteoporosis at the hip or spine, which are critical sites for fracture risk. *Ultrasound* - **Quantitative ultrasound (QUS)** can assess bone quality but is primarily used for **screening** and is not accurate enough for definitive diagnosis or treatment monitoring of osteoporosis. - It does **not provide direct bone mineral density measurements** comparable to DXA for diagnostic purposes. *Quantitative computed tomography* - **QCT** can measure volumetric bone density and is useful for assessing **trabecular bone**, but involves higher radiation exposure than DXA. - It is **more expensive** and less readily available than DXA, making it a secondary option for osteoporosis diagnosis.
Question 2: All statements are true for osteomalacia except:
- A. Raised serum calcium (Correct Answer)
- B. Muscular weakness
- C. Loosers zone on X-ray
- D. Commoner in females
Explanation: ***Raised serum calcium*** - **Osteomalacia** is characterized by defective **bone mineralization**, predominantly due to **vitamin D deficiency** (or abnormal metabolism) or phosphate deficiency [1]. - This typically leads to **hypocalcemia** (low serum calcium), not elevated calcium, as vitamin D is essential for calcium absorption from the gut [1], [3]. *Muscular weakness* - **Proximal muscle weakness**, particularly in the thighs and pelvic girdle, is a common symptom of **osteomalacia** [1]. - This **myopathy** is thought to be directly related to **vitamin D deficiency** and the resulting metabolic disturbances affecting muscle function [1]. *Looser's zone on X-ray* - **Looser's zones**, also known as **pseudofractures**, are characteristic radiological findings in **osteomalacia** [2]. - These are areas of **unmineralized osteoid** that appear as radiolucent bands perpendicular to the bone cortex, often found in the femoral neck, pubic rami, or ribs [2]. *Commoner in females* - **Osteomalacia** is indeed more common in **females**, particularly in those of **childbearing age** or with **multiple pregnancies**, due to increased calcium and vitamin D demands. - **Postmenopausal women** are also at higher risk, often linked to reduced sun exposure, dietary deficiencies, or medication use.
Question 3: True about osteoporosis
- A. Normal serum phosphate levels
- B. Normal serum alkaline phosphatase level
- C. Normal serum calcium levels
- D. All of the options (Correct Answer)
Explanation: ***All of the options*** - In **primary osteoporosis**, serum levels of calcium, phosphate, and alkaline phosphatase are typically **normal**, distinguishing it from other metabolic bone diseases [1]. - The diagnosis of osteoporosis is based on **bone mineral density (BMD)** measurements, not on abnormalities in these serum markers [3]. *Normal serum phosphate levels* - While correct that serum phosphate is usually normal in osteoporosis, this option alone does not encompass the full biochemical picture [1]. - Osteoporosis is primarily a disorder of **bone quantity**, not systemic mineral metabolism, so levels of **calcium and phosphate remain homeostatically regulated** [1]. *Normal serum alkaline phosphatase level* - Similarly, a normal alkaline phosphatase level reflects the absence of significantly increased **osteoblast activity** or **bone turnover** that would be seen in conditions like osteomalacia or Paget's disease [2]. - This observation is a key biochemical finding, but it is not the only normal lab value. *Normal serum calcium levels* - Normal serum calcium is characteristic of osteoporosis, as **parathyroid hormone** and **vitamin D** regulation of calcium remains intact [4]. - Hypercalcemia or hypocalcemia would suggest alternative diagnoses or complications, such as **primary hyperparathyroidism** or **vitamin D deficiency** [4].
Question 4: Which is the drug of choice in Paget's disease?
- A. Allopurinol
- B. Calcitonin
- C. Alendronate (Correct Answer)
- D. Steroids
Explanation: ***Alendronate*** - **Bisphosphonates** like alendronate are the **first-line treatment** for Paget's disease due to their potent antiresorptive inhibitory effect on **osteoclasts**. - They reduce bone turnover, bone pain, and the risk of complications such as **fractures** and **bone deformities**. *Allopurinol* - This drug is used to treat **gout** by inhibiting **xanthine oxidase** and reducing uric acid production. - It has no role in the management of Paget's disease, which is a disorder of abnormal bone remodeling. *Calcitonin* - Historically, calcitonin was used for Paget's disease, but its effectiveness is **less than bisphosphonates** and it is associated with more side effects. - It is now generally reserved for patients who **cannot tolerate bisphosphonates** or have severe renal impairment. *Steroids* - **Corticosteroids** are potent anti-inflammatory and immunosuppressive agents. - They are primarily used in conditions like **autoimmune disorders** or severe inflammatory diseases, and are **not indicated** for the treatment of Paget's disease.
Question 5: A 70 year old male, known case of chronic renal failure suffers from a pathological fracture of Rt femur, the diagnosis is -
- A. Scurvy
- B. Secondary Hyperparathyroidism (Correct Answer)
- C. Vitamin D Resistant rickets
- D. Primary Hyperparathyroidism
Explanation: ***Secondary Hyperparathyroidism*** - **Chronic renal failure** causes **hyperphosphatemia** and **decreased production of calcitriol (active vitamin D)**. - This leads to hypocalcemia, which stimulates the parathyroid glands to produce excessive **parathyroid hormone (PTH)**, resulting in bone demineralization and **pathological fractures** [2]. *Scurvy* - Caused by **vitamin C deficiency**, leading to impaired collagen synthesis and fragility of blood vessels. - While it can cause bone pain and potential for fractures in severe cases, it is not directly associated with **chronic renal failure** as a primary cause of pathological fracture. *Vitamin D Resistant rickets* - This is a genetic disorder (e.g., X-linked hypophosphatemia) characterized by impaired renal phosphate reabsorption and normal or elevated PTH levels. - While it causes bone demineralization, it is typically a **childhood-onset condition** [1] and not directly linked to **acquired chronic renal failure** in a 70-year-old male. *Primary Hyperparathyroidism* - Characterized by autonomous **overproduction of PTH** due to parathyroid gland adenoma or hyperplasia, leading to **hypercalcemia** and hypophosphatemia. - Unlike secondary hyperparathyroidism, which is a compensatory response to hypocalcemia in the context of renal failure, primary hyperparathyroidism is a direct parathyroid gland pathology.
Question 6: Select the type of bone disease which is most likely to be associated with genetically determined disorder in the structure or processing of type I collagen (SELECT 1 DISEASE)
- A. Osteogenesis imperfecta (Correct Answer)
- B. Osteopetrosis
- C. Osteomalacia
- D. Osteitis fibrosa cystica
Explanation: ***Osteogenesis imperfecta*** - This condition is primarily caused by **genetic defects** in the production of **type I collagen**, leading to fragile bones. - Due to these defects, bones are prone to **fractures** with minimal trauma. *Osteopetrosis* - Characterized by abnormally **dense bones** due to a defect in **osteoclast function**, not collagen structure [1]. - This leads to bones that are brittle and prone to fracture, but the underlying cause is different from collagen abnormalities [1]. *Osteomalacia* - This refers to the **softening of bones** due to impaired **mineralization**, most commonly from **vitamin D deficiency** or phosphate imbalance. - It does not involve a primary defect in the genetic structure or processing of type I collagen. *Osteitis fibrosa cystica* - This is a bone lesion caused by **severe hyperparathyroidism**, leading to excessive bone resorption and replacement by fibrous tissue and cysts. - It is an endocrine disorder affecting **calcium metabolism**, not a primary collagenopathy. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Bones, Joints, and Soft Tissue Tumors, p. 1188.
Question 7: Avascular necrosis of bone is LEAST likely to be associated with?
- A. Osgood -Schlatter disease (Correct Answer)
- B. Long-term use of corticosteroids
- C. Sickle-cell disease
- D. Legg-Perthes disease
Explanation: ***Osgood-Schlatter disease*** - This condition is characterized by **inflammation of the patellar ligament** at its insertion into the tibial tuberosity, primarily due to repetitive stress in adolescents. - While it involves pain and swelling around the knee, it is a **traction apophysitis** and not a form of avascular necrosis. *Long-term use of corticosteroids* - **Corticosteroids** are a well-established risk factor for avascular necrosis, particularly in the femoral head, by affecting lipid metabolism and blood flow. - They can lead to **fat embolism** and increased intraosseous pressure, compromising blood supply to the bone. *Sickle-cell disease* - **Sickle cell disease** significantly increases the risk of avascular necrosis due to **vaso-occlusive crises**, where sickled red blood cells block small blood vessels. - This leads to **ischemia and infarction** in bone marrow, commonly affecting the femoral and humeral heads. *Legg-Perthes disease* - This is a specific type of **avascular necrosis of the femoral head** in children, causing a temporary interruption of blood supply to the epiphysis. - It results in the collapse of the femoral head and subsequent repair processes, consistent with the pathology of avascular necrosis.
Question 8: Osteonecrosis is seen in all except
- A. Fracture neck femur
- B. Paget's disease (Correct Answer)
- C. Perthe's disease
- D. Sickle cell anemia
Explanation: ***Paget's disease*** - **Paget's disease of bone (osteitis deformans)** is a localized disorder of bone remodeling, characterized by excessive and disorganized bone formation, leading to enlarged, softened, and misshapen bones, but not directly causing osteonecrosis. - While complications like **pathological fractures** and **osteosarcoma** can occur, primary osteonecrosis is not a typical feature of Paget's disease itself. *Fracture neck femur* - **Fractures of the femoral neck** can disrupt the blood supply to the femoral head, particularly the medial circumflex femoral artery, leading to **avascular necrosis** (osteonecrosis) of the femoral head. - This is a well-known and common complication, especially in displaced fractures. *Sickle cell anemia* - **Sickle cell anemia** causes sickling of red blood cells, leading to **vaso-occlusion** and impaired blood flow to bones, resulting in **bone infarcts** (osteonecrosis). - This can affect various bones, including the femoral head, humeral head, and vertebrae. *Perthe's disease* - **Perthe's disease** (Legg-Calvé-Perthes disease) is a childhood condition characterized by **idiopathic osteonecrosis** of the femoral head. - It involves the collapse and subsequent re-ossification of the femoral epiphysis due to an interruption of its blood supply.
Question 9: A 70-year-old female has been on alendronate for 7 years for osteoporosis and now complains of pain in her right thigh. What is the next investigation to be performed?
- A. DEXA scan
- B. Serum vitamin D levels
- C. Serum alkaline phosphate levels
- D. X-ray (Correct Answer)
Explanation: **X-ray** - Alendronate, a **bisphosphonate**, is associated with **atypical femoral fractures** after prolonged use, and an X-ray is the most appropriate initial investigation to visualize such a fracture. - Complaints of thigh pain in a patient on long-term bisphosphonate therapy should prompt imaging to rule out this serious complication. *DEXA scan* - A DEXA scan assesses **bone mineral density** but does not provide information about acute fractures or structural integrity in response to specific pain. - While it's used for osteoporosis diagnosis and monitoring, it won't directly identify an atypical femoral fracture. *Serum vitamin D levels* - Maintaining adequate **vitamin D levels** is important for bone health, but its measurement won't explain acute thigh pain or identify a fracture. - Low vitamin D levels can contribute to osteoporosis but are not the primary cause of pain suggestive of an atypical femoral fracture. *Serum alkaline phosphate levels* - **Alkaline phosphatase** levels can be elevated in conditions involving increased bone turnover, such as healing fractures or certain bone diseases. - However, it is not a direct diagnostic tool for identifying atypical femoral fractures and would not be the first line investigation.
Question 10: Brittle bone disease is -
- A. Osteoporosis
- B. Pagets disease
- C. Osteopetrosis
- D. Osteogenesis imperfecta (Correct Answer)
Explanation: ***Osteogenesis imperfecta*** - **Osteogenesis imperfecta** is an inherited disorder characterized by **brittle bones** that fracture easily, due to a defect in **collagen type I** synthesis. - Patients often present with **blue sclera**, **dentinogenesis imperfecta**, and **hearing loss**, in addition to frequent fractures. *Osteoporosis* - **Osteoporosis** is a condition of **decreased bone density**, making bones fragile and prone to fracture, but it is not typically referred to as "brittle bone disease" in the same congenital sense. - It is more common in older adults and is often related to **hormonal changes** (e.g., post-menopause) or lifestyle factors. *Paget's disease* - **Paget's disease of bone** involves abnormal bone remodeling with excessive bone resorption followed by disorganized and expanded bone formation, leading to **enlarged, weakened bones**. - It typically affects older individuals and can lead to bone pain, deformities, and fractures, but it's not the primary condition associated with "brittle bone disease." *Osteopetrosis* - **Osteopetrosis** is characterized by **abnormally dense bones** due to impaired osteoclast function, leading to a buildup of bone. - While bones are dense, they are also **brittle** and prone to fracture, and the condition is also known as "marble bone disease" rather than "brittle bone disease."
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