Basic Science in Orthopaedics Practice Questions

Q: Who coined the term orthopaedics?

Nicholas Andry. **Explanation:** **Correct Answer: C. Nicholas Andry** The term "Orthopaedics" was coined by **Nicholas Andry** in **1741**. He was a French physician who published a famous book titled *Orthopaedia: or the Art of Correcting and Preventing Deformities in Children*. The word is derived from the Greek roots **"Orthos"** (meaning straight) and **"Paidios"** (meaning child). Andry believed that many adult skeletal deformities originated during childhood and could be prevented or corrected through exercise and posture. **Analysis of Incorrect Options:** * **A. Louis Pasteur:** Known as the father of microbiology; he developed the germ theory of disease and vaccines for rabies and anthrax. * **B. Edward Jenner:** Known as the father of immunology; he pioneered the concept of vaccines and created the first smallpox vaccine. * **C. Kuntscher (Gerhard Kuntscher):** A pioneer in modern trauma surgery who introduced the **Kuntscher nail (K-nail)** for the intramedullary nailing of long bone fractures (specifically the femur) during WWII. **High-Yield Clinical Pearls for NEET-PG:** * **The Symbol of Orthopaedics:** Nicholas Andry is also responsible for the **"Tree of Andry"** (a crooked sapling tied to a straight stake), which remains the universal symbol for orthopaedic surgery. * **Father of Orthopaedics:** While Andry coined the term, **Jean-André Venel** is often considered the "Father of Orthopaedics" for establishing the first true orthopaedic institute. * **Father of Modern Orthopaedics (UK):** Sir Hugh Owen Thomas. * **Father of Indian Orthopaedics:** Dr. Mukhopadhaya.

Q: All are true regarding bone remodeling, EXCEPT:

It involves the replacement of lamellar bone by woven bone.. **Explanation:** Bone remodeling is a lifelong physiological process where mature bone tissue is removed (resorption) and new bone tissue is formed (ossification). **1. Why Option A is the Correct Answer (The Exception):** In bone remodeling, the goal is to maintain structural integrity. Therefore, **woven bone (immature, disorganized bone) is replaced by lamellar bone (mature, organized bone)**, not the other way around. Woven bone is typically seen during rapid growth, initial fracture healing (callus), or pathological states (e.g., Paget’s disease). Remodeling converts this weak woven bone into strong, load-bearing lamellar bone. **2. Analysis of Other Options:** * **Option B:** Resorption is the first stage of the remodeling cycle (ARF: Activation-Resorption-Formation). This is carried out by **osteoclasts**, which create Howship’s lacunae. * **Option C:** Both cortical and cancellous bones undergo remodeling via **Basic Multicellular Units (BMUs)**, which consist of a coordinated team of osteoclasts (cutting cone in cortical bone) and osteoblasts (closing cone). * **Option D:** Once osteoblasts finish secreting the bone matrix (osteoid), some become trapped within the matrix and differentiate into **osteocytes**, which act as mechanosensors. **High-Yield NEET-PG Pearls:** * **Woven Bone:** Characterized by random collagen arrangement; it is always pathological in adults except during fracture healing. * **Lamellar Bone:** Characterized by parallel collagen layers; it is the hallmark of healthy mature bone. * **Wolff’s Law:** Bone remodels in response to the mechanical stresses placed upon it. * **RANKL/OPG Pathway:** The primary regulator of osteoclast differentiation and activity during remodeling.

Q: Myositis ossificans is differentiated from other reactive fibroblastic proliferations by the presence of?

Metaplastic bone. **Explanation:** **Myositis Ossificans (MO)** is a benign, non-neoplastic condition characterized by the formation of heterotopic bone within soft tissues, typically following trauma. **Why Metaplastic Bone is Correct:** The hallmark of Myositis Ossificans is **metaplasia**. In this process, primitive mesenchymal cells in the soft tissue differentiate into osteoblasts, which then lay down organized bone where it does not normally exist. Histologically, MO exhibits a characteristic **"Zonal Phenomenon"**: 1. **Central zone:** Proliferating undifferentiated fibroblasts. 2. **Intermediate zone:** Osteoblasts laying down unmineralized osteoid. 3. **Peripheral zone:** Mature, mineralized **metaplastic lamellar bone**. The presence of this well-organized metaplastic bone at the periphery helps differentiate it from malignant lesions like osteosarcoma (where the center is more mature). **Why Other Options are Incorrect:** * **Dysplastic bone:** Refers to abnormal, disorganized growth (often seen in fibrous dysplasia). MO is a reactive, not a dysplastic, process. * **Dystrophic bone:** This term is usually associated with *dystrophic calcification* (calcium deposits in dead/degenerate tissue without bone formation). MO involves true bone formation (ossification), not just calcification. * **Hypertrophic bone:** Refers to an increase in the size of existing bone (e.g., in response to stress). MO involves the formation of *new* bone in a new location. **NEET-PG High-Yield Pearls:** * **Common Site:** Brachialis (elbow) and Quadriceps (thigh). * **Clinical Sign:** Pain and a palpable mass following trauma; "Stiff joint" if near an articulation. * **Radiology:** "Egg-shell calcification" (peripheral mineralization). * **Management:** Conservative initially (Rest, NSAIDs). **Surgery is contraindicated** in the early stages as it leads to high recurrence; excision should only be done once the bone is "mature" (usually 6–12 months).

Q: Which of the following changes occurs during bone growth?

Increased osteocalcin. **Explanation:** Bone growth and remodeling are dynamic processes involving bone formation (osteoblastic activity) and bone resorption (osteoclastic activity). **Why Option D is Correct:** **Osteocalcin** is a non-collagenous protein hormone synthesized specifically by **mature osteoblasts**. It plays a crucial role in bone mineralization and calcium ion binding. Because its synthesis is directly linked to osteoblast activity, serum osteocalcin levels serve as a highly specific **biochemical marker of bone formation**. During periods of active bone growth (such as puberty or fracture healing), osteoblast activity increases, leading to elevated levels of osteocalcin. **Why Other Options are Incorrect:** * **A. Increased acid phosphatase:** Tartrate-resistant acid phosphatase (TRAP) is a marker of **bone resorption** (osteoclast activity), not bone formation. * **B. Increased urinary calcium:** Urinary calcium is typically a marker of bone resorption or metabolic derangements (like hyperparathyroidism). It does not specifically indicate physiological bone growth. * **C. Increased bone nucleotidase:** This is not a standard marker for bone growth. While 5'-nucleotidase is a liver enzyme, it has no specific diagnostic value in monitoring bone formation. **NEET-PG High-Yield Pearls:** * **Markers of Bone Formation:** Serum Alkaline Phosphatase (ALP) - *most commonly used*; Osteocalcin - *most specific*; Serum P1NP (Procollagen type 1 N-terminal propeptide). * **Markers of Bone Resorption:** Urinary Hydroxyproline; Serum/Urinary Pyridinoline and Deoxypyridinoline; Serum TRAP. * **Clinical Note:** Osteocalcin is Vitamin K and Vitamin D dependent; it also has an extra-skeletal role in glucose metabolism by increasing insulin secretion and sensitivity.

Q: All of the following cause osteonecrosis except?

None of the above. **Explanation:** Osteonecrosis, also known as **Avascular Necrosis (AVN)**, is a condition resulting from the temporary or permanent loss of blood supply to the bone, leading to cell death and eventual collapse of the bone structure. The correct answer is **"None of the above"** because all three listed conditions (A, B, and C) are well-established causes of osteonecrosis. * **Sickle Cell Anemia:** This is a classic cause of AVN. The sickled red blood cells cause "sludging" and vaso-occlusion in the microvasculature of the bone (especially the femoral head), leading to ischemia. * **Corticosteroid Use:** Steroids are the most common non-traumatic cause of AVN. They are thought to cause hypertrophy of fat cells in the bone marrow, increasing intraosseous pressure and reducing sinusoidal blood flow. * **Disseminated Intravascular Coagulation (DIC):** DIC leads to the formation of widespread microthrombi within the systemic circulation. When these thrombi occur in the terminal vessels supplying bone, they cause infarction and subsequent necrosis. **Clinical Pearls for NEET-PG:** * **Most Common Site:** The **Femoral Head** is the most common site for AVN due to its retrograde blood supply (primarily the medial circumflex femoral artery). * **Most Sensitive Investigation:** **MRI** is the gold standard for early diagnosis (shows the "double line sign"). * **X-ray Finding:** The **"Crescent Sign"** (subchondral lucency) indicates impending articular collapse. * **Mnemonic for Causes (PLASTIC RAGS):** **P**ancreatitis/Pregnancy, **L**upus (SLE), **A**lcohol, **S**teroids, **T**rauma, **I**diopathic/Infection, **C**aisson disease, **R**adiation, **A**myloidosis, **G**aucher disease, **S**ickle cell anemia.

Q: What type of joint is the inferior tibiofibular joint?

Syndesmosis. **Explanation:** The **inferior tibiofibular joint** is a classic example of a **Syndesmosis**. A syndesmosis is a type of fibrous joint where two adjacent bones are linked by a strong interosseous membrane or ligament, allowing for minimal movement but providing significant structural stability. At the ankle, this joint is formed by the rough surfaces of the distal tibia and fibula, held together by the anterior and posterior tibiofibular ligaments and the interosseous ligament. **Analysis of Options:** * **Gomphosis (A):** This is a specialized fibrous "peg-and-socket" joint, found exclusively where the roots of the **teeth** fit into the alveolar sockets of the mandible and maxilla. * **Condylar (B):** This is a type of synovial joint (e.g., the knee or metacarpophalangeal joints) where an ovoid articular surface fits into an elliptical cavity, allowing movement in two planes. * **Synchondrosis (D):** This is a primary cartilaginous joint where bones are joined by hyaline cartilage (e.g., the **epiphyseal plate** in growing bone or the first rib-sternum junction). These usually ossify with age. **Clinical Pearls for NEET-PG:** * **High-Yield Fact:** The inferior tibiofibular syndesmosis is crucial for the stability of the **ankle mortise**. * **Clinical Correlation:** A "High Ankle Sprain" refers to an injury of this syndesmosis. * **Radiology:** On an X-ray, an increase in the "tibiofibular clear space" (>6mm) indicates a syndesmotic injury, often requiring surgical stabilization with a syndesmotic screw. * **Other Syndesmoses:** The middle radio-ulnar joint is another example of a syndesmosis in the human body.

Q: The X-ray shows plating done for a fracture. How does this fracture heal?

Primary healing. **Primary healing** - **Plating of a fracture** aims to achieve **absolute stability** at the fracture site, which facilitates primary bone healing. - In primary healing, there is **direct bone formation** across the fracture gap without the formation of a significant callus. *Secondary healing* - Secondary healing involves the formation of a **callus** (fibrous tissue, cartilage, and immature bone) to bridge the fracture gap. - This type of healing occurs in situations with **relative stability** and some micromotion at the fracture site, such as with casting or intramedullary nailing. *Tertiary healing* - **Tertiary healing** is not a recognized term in the context of fracture healing. - Bone healing typically involves either primary or secondary mechanisms depending on the stability achieved. *Distraction histiogenesis* - **Distraction histiogenesis** is the process by which new bone is formed between bone surfaces that are gradually pulled apart using an external fixator (**distraction osteogenesis**). - This is used in procedures like **limb lengthening** and is distinct from the direct healing of a fracture fixed with a plate.

Q: If the outer sheath and nerve fibres are intact and the inner axon is damaged, it is known as

Axonotmesis. ***Axonotmesis*** - This type of nerve injury involves damage to the **axon** itself, while the connective tissue layers (**endoneurium, perineurium, epineurium**) remain intact. - While the axon is disrupted, the preservation of the nerve's outer sheath allows for potential, albeit slow, **regeneration** of the axon. *Axonapraxia* - This term is not a standard classification of nerve injury. The correct term for a transient block in nerve conduction is **neurapraxia**. *Neurotmesis* - **Neurotmesis** is the most severe type of nerve injury, involving complete severance of the **axon** and all supporting **connective tissue sheaths**. - This type of injury requires **surgical repair** for any chance of functional recovery. *Neurapraxia* - **Neurapraxia** is the mildest form of nerve injury, characterized by a temporary **conduction block** without axonal damage. - Recovery is typically complete within days to weeks, as the **myelin sheath** may be temporarily dysfunctional but the axon remains intact.

Question 1

Wolff's law states that:

Accepted Answer

If a bone is continuously subjected to a particular stress, it will adapt to become stronger to resist that loading.

Answer

Only the diaphysis allows longitudinal growth in childhood.

Answer

Any infection not showing periosteal reaction within 1 week of symptoms can be ruled out to be osteomyelitis.

Answer

Angular deformities will progress until the closure of the physis.

Question 2

Who coined the term orthopaedics?

Accepted Answer

Nicholas Andry

Answer

Louis Pasteur

Answer

Edward Jenner

Answer

Kuntscher

Question 3

What is the difference between neuropraxia and axonotmesis?

Accepted Answer

Electromyography (EMG) finding

Answer

Sensory loss

Answer

Motor loss

Answer

All of the above

Question 4

All are true regarding bone remodeling, EXCEPT:

Accepted Answer

It involves the replacement of lamellar bone by woven bone.

Answer

Osteoclastic activity at the resorption site.

Answer

Osteoclastic activity and osteoblastic activity are both needed for bone remodeling in cortical and cancellous bones.

Answer

Osteoblasts transform into osteocytes.

Question 5

Myositis ossificans is differentiated from other reactive fibroblastic proliferations by the presence of?

Accepted Answer

Metaplastic bone

Answer

Dysplastic bone

Answer

Dystrophic bone

Answer

Hypertrophic bone

Question 6

Which of the following changes occurs during bone growth?

Accepted Answer

Increased osteocalcin

Answer

Increased acid phosphatase

Answer

Increased urinary calcium

Answer

Increased bone nucleotidase

Question 7

All of the following cause osteonecrosis except?

Accepted Answer

None of the above

Answer

Sickle cell anemia

Answer

Corticosteroid use

Answer

Disseminated intravascular coagulation (DIC)

Question 8

What type of joint is the inferior tibiofibular joint?

Accepted Answer

Syndesmosis

Answer

Gomphosis

Answer

Condylar

Answer

Synchondrosis

Question 9

The X-ray shows plating done for a fracture. How does this fracture heal?

Accepted Answer

Primary healing

Answer

Secondary healing

Answer

Tertiary healing

Answer

Distraction histiogenesis

Question 10

If the outer sheath and nerve fibres are intact and the inner axon is damaged, it is known as

Accepted Answer

Axonotmesis

Answer

Axonapraxia

Answer

Neurotmesis

Answer

Neurapraxia

Basic Science in Orthopaedics — MCQs

Basic Science in Orthopaedics — MCQs

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