Basic Science in Orthopaedics Indian Medical PG Practice Questions and MCQs
Practice Indian Medical PG questions for Basic Science in Orthopaedics. These multiple choice questions (MCQs) cover important concepts and help you prepare for your exams.
Basic Science in Orthopaedics Indian Medical PG Question 1: Bone mass is reduced in all of the following conditions EXCEPT:
- A. Osteoporosis
- B. Osteopetrosis (Correct Answer)
- C. Hyperparathyroidism
- D. Osteomalacia
Basic Science in Orthopaedics Explanation: **Osteopetrosis**
- **Osteopetrosis**, also known as **marble bone disease**, is a rare genetic disorder characterized by **increased bone density** due to defective osteoclast function.
- In this condition, osteoclasts are unable to resorb bone, leading to an excessive accumulation of bone tissue, resulting in **densified but brittle bones**.
*Osteoporosis*
- **Osteoporosis** is characterized by significantly **reduced bone mass** and microarchitectural deterioration of bone tissue [1].
- This leads to increased bone fragility and a higher risk of fractures, as the bone becomes porous and weak [2].
*Hyperparathyroidism*
- **Hyperparathyroidism** causes **increased bone resorption** due to excessive parathyroid hormone (PTH) secretion.
- PTH mobilizes calcium from the bones, leading to a **decrease in bone density** and potential bone cysts (**osteitis fibrosa cystica**) [3].
*Osteomalacia*
- **Osteomalacia** is a condition where there is **defective mineralization of bone osteoid**, leading to softer bones [4].
- While the bone mass might appear structurally normal, the **mineral content is reduced**, making the bone weak and susceptible to bowing and fractures.
**References:**
[1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Bones, Joints, and Soft Tissue Tumors, pp. 1189-1191.
[2] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Osteoarticular And Connective Tissue Disease, pp. 665-666.
[3] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Bones, Joints, and Soft Tissue Tumors, p. 1194.
[4] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Bones, Joints, and Soft Tissue Tumors, pp. 1194-1195.
Basic Science in Orthopaedics Indian Medical PG Question 2: Functional matrix theory suggests that the primary determinants of growth of skeletal tissues reside in:
- A. Cartilages
- B. Sutures
- C. Skeletal
- D. Non-skeletal tissues (Correct Answer)
Basic Science in Orthopaedics Explanation: ***Non-skeletal tissues***
- The **functional matrix theory** posits that the growth and development of skeletal tissues, particularly in the craniofacial region, are primarily determined by the surrounding soft tissues and their functions. [1]
- These **non-skeletal tissues**, such as muscles, nerves, blood vessels, and fat, exert forces and provide stimuli that dictate the growth and remodeling of adjacent bones.
*Cartilages*
- While **cartilage** (e.g., condylar cartilage of the mandible) is a significant growth center, the functional matrix theory suggests its growth is still influenced by surrounding functional demands, not solely intrinsic factors.
- Cartilage growth alone does not entirely explain the comprehensive craniofacial growth patterns according to this theory.
*Sutures*
- **Sutures** are important growth sites in the cranium and maxilla, contributing to bone apposition and separation. [1]
- However, the functional matrix theory views sutural growth as a secondary event, responding to the expansive forces generated by the growth of underlying soft tissues and functional spaces.
*Skeletal*
- The functional matrix theory explicitly argues against the idea that **skeletal tissues** themselves (bones and cartilage) are the primary determinants of their own growth.
- Instead, it emphasizes that skeletal growth is adaptive and reactive to the influences of the associated non-skeletal tissues and their functions.
Basic Science in Orthopaedics Indian Medical PG Question 3: The bone matrix has the following crystals -
- A. Calcium pyrophosphate
- B. Calcium hydroxyapatite (Correct Answer)
- C. Calcium phosphate
- D. Calcium sulphate
Basic Science in Orthopaedics Explanation: ***Calcium hydroxyapatite***
- The primary mineral component of bone matrix is **calcium hydroxyapatite**, which gives bone its rigidity and strength [1].
- These crystals are formed from **calcium and phosphate ions** arranged in a specific crystalline structure within the collagen fibers [1].
*Calcium pyrophosphate*
- **Calcium pyrophosphate dihydrate (CPPD)** crystals are associated with **pseudogout**, a condition causing joint inflammation, not the normal bone matrix [1].
- They are found in articular cartilage and synovial fluid, not as a structural component of healthy bone.
*Calcium phosphate*
- While hydroxyapatite is a form of **calcium phosphate**, simply "calcium phosphate" is too general and does not specify the exact crystalline structure found in bone [1].
- Many calcium phosphate compounds exist, but **hydroxyapatite** is the specific and most abundant one in bone [1].
*Calcium sulphate*
- **Calcium sulfate** is not a naturally occurring mineral component of the bone matrix in vertebrates.
- It is sometimes used in medical applications as a **bone graft substitute** or a drug delivery system, but not as an endogenous component.
Basic Science in Orthopaedics Indian Medical PG Question 4: Which of the following fractures of the neck of femur are associated with maximal compromise in blood supply ?
- A. Basicervical fracture
- B. Trans cervical fracture
- C. Sub Capital fractures (Correct Answer)
- D. Intertrochanteric fractures
Basic Science in Orthopaedics Explanation: ***Sub Capital fractures***
- These fractures occur at the anatomical **neck of the femur**, very close to the femoral head.
- Due to their location, they disrupt the main blood supply to the femoral head, primarily from the **retinacular arteries**, leading to a high risk of **avascular necrosis**.
*Trans cervical fracture*
- This fracture occurs through the **midneck of the femur**, which is still within the intracapsular region.
- While it has a significant risk of **ischemia**, the compromise is generally less severe than in subcapital fractures.
*Intertrochanteric fractures*
- These are **extracapsular fractures** occurring between the greater and lesser trochanters.
- They tend to have an **excellent blood supply** and thus a low risk of avascular necrosis, but are associated with more significant blood loss and malunion issues.
*Basicervical fracture*
- This is an **intracapsular fracture** that occurs at the base of the femoral neck, near the junction with the trochanters.
- Although intracapsular, its position is slightly more proximal than subcapital fractures, potentially leaving more of the **retinacular vessels** intact, resulting in a somewhat lower risk of avascular necrosis compared to subcapital fractures.
Basic Science in Orthopaedics Indian Medical PG Question 5: Not seen in osteogenesis imperfecta
- A. Thick cortical bone (Correct Answer)
- B. Wormian bones
- C. Coxa vara
- D. Saber shin
Basic Science in Orthopaedics Explanation: ***Thick cortical bone***
- Osteogenesis imperfecta (OI) is characterized by **fragile bones** due to defects in **Type I collagen** synthesis, leading to abnormally **thin cortical bone**.
- **Thick cortical bone** would indicate increased bone density or strength, which is the opposite of the fundamental pathology in OI.
*Wormian bones*
- **Wormian bones** (intrasutural bones) are frequently seen in individuals with **osteogenesis imperfecta**, particularly in types I and III.
- They are small, irregular bones that develop within the **cranial sutures**.
*Coxa vara*
- **Coxa vara**, a deformity where the angle between the femoral neck and shaft is decreased, is a common orthopedic complication of **osteogenesis imperfecta**.
- This deformity is primarily due to the **bone fragility** and remodeling issues inherent to the condition.
*Saber shin*
- **Saber shin** refers to an anterior bowing of the tibia, which is a classic orthopedic manifestation in patients with **osteogenesis imperfecta**.
- This bowing results from repeated microfractures and **abnormal bone remodeling** characteristic of the disease.
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