Arthrology and Infections Practice Questions

Q: Fibrous ankylosis is caused by which of the following?

TB arthritis. **Explanation:** The type of ankylosis (joint stiffness/fusion) depends on the nature of the inflammatory process and the extent of articular cartilage destruction. **1. Why TB Arthritis is correct:** Tuberculosis of the joint typically results in **Fibrous Ankylosis**. In TB arthritis, the formation of "cold abscesses" and the lack of proteolytic enzymes in the tuberculous exudate lead to the preservation of some cartilage or the formation of dense fibrous tissue between the joint surfaces. Because the bone ends are not completely denuded and fused by bone, the result is a stiff joint held by fibrous bands. **2. Analysis of Incorrect Options:** * **Septic Arthritis:** This typically leads to **Bony Ankylosis**. Pyogenic organisms (like *Staphylococcus aureus*) produce proteolytic enzymes that rapidly destroy the articular cartilage, exposing the subchondral bone. This leads to the fusion of bone to bone. * **Behcet’s Disease:** This is a multi-system inflammatory disorder. While it can cause recurrent synovitis, it rarely leads to permanent joint destruction or ankylosis. * **Psoriatic Arthritis:** This is a seronegative spondyloarthropathy. While it can cause joint fusion in advanced stages (especially in the DIP joints or spine), it is more classically associated with **Bony Ankylosis** (similar to Ankylosing Spondylitis). **Clinical Pearls for NEET-PG:** * **Bony Ankylosis:** Seen in Septic arthritis, Ankylosing spondylitis, and Rheumatoid arthritis (specifically in the carpal/tarsal bones). * **Fibrous Ankylosis:** Classically seen in Tuberculous arthritis. * **Triple Deformity of Knee:** A common outcome of TB of the knee, consisting of flexion, posterior subluxation, and external rotation. * **Phemister’s Triad (Radiology of TB Joint):** Juxta-articular osteopenia, peripheral osseous erosions, and gradual narrowing of the joint space.

Q: What is the radiographic appearance of dead bone on an X-ray?

More radiopaque. **Explanation:** The radiographic appearance of dead bone (known as a **Sequestrum**) is characterized by increased density, making it appear **more radiopaque** (whiter) than the surrounding living bone. **Why the correct answer is right:** The increased radiopacity of dead bone is primarily a **relative phenomenon**. In conditions like chronic osteomyelitis, the surrounding living bone undergoes hyperemia (increased blood flow), leading to inflammatory osteoporosis and bone resorption (decalcification). Since the dead bone (sequestrum) has no blood supply, it cannot undergo resorption and retains its original calcium content. Additionally, new bone formation (involucrum) around the dead bone and the possible deposition of calcium salts from pus onto the dead fragment further enhance its opaque appearance. **Why the incorrect options are wrong:** * **B. More radiolucent:** Radiolucency indicates bone loss or decreased density. Dead bone does not lose its mineral content because it lacks the vascularity required for osteoclastic activity. * **C. Same as normal bone:** While the absolute density may initially be similar, the surrounding bone becomes osteopenic, making the dead bone stand out as denser. * **D. Variable:** While the shape and size vary, the hallmark radiographic feature of a sequestrum is consistently increased opacity. **High-Yield NEET-PG Pearls:** * **Sequestrum:** A piece of dead bone separated from the living bone. * **Involucrum:** A layer of new living bone formed around the sequestrum. * **Cloaca:** An opening in the involucrum through which pus and sequestra may emerge. * **Gold Standard for Sequestrum:** While X-rays show opacity, **CT scan** is the most sensitive imaging modality to identify a sequestrum in chronic osteomyelitis.

Q: Brodie's abscess is the terminology for:

Chronic osteomyelitis. **Explanation:** **Brodie’s abscess** is a localized form of **Chronic Osteomyelitis**. It represents a subacute or chronic pyogenic infection of the bone where the body’s immune response has successfully contained the pathogen (most commonly *Staphylococcus aureus*) within a fibrous or granulation tissue wall. * **Why Option B is correct:** It is characterized by a well-circumscribed, intraosseous abscess, typically located in the **metaphysis** of long bones (most commonly the proximal or distal tibia). On X-ray, it appears as a radiolucent nidus surrounded by a rim of reactive sclerosis. Unlike acute osteomyelitis, systemic symptoms like fever are often absent. * **Why other options are incorrect:** * **Option A (Subungual infection):** This refers to infections under the nail bed, such as a subungual abscess or paronychia, which involve soft tissue rather than deep bone. * **Option C (Web space infection):** This is a soft tissue infection (cellulitis or abscess) located in the spaces between fingers or toes, often seen in the hand (Collar-button abscess). * **Option D (Infected hematoma):** While a hematoma can become infected (leading to an abscess), it is a soft tissue or intramuscular collection and does not define the specific bone pathology of Brodie’s abscess. **High-Yield Clinical Pearls for NEET-PG:** * **Most common site:** Metaphysis of the Tibia. * **Most common organism:** *Staphylococcus aureus*. * **Classic X-ray finding:** A radiolucent area with a **sclerotic rim**. * **Differential Diagnosis:** Osteoid Osteoma (distinguished by the fact that pain in Osteoid Osteoma is characteristically relieved by Aspirin). * **Treatment:** Surgical curettage and evacuation under antibiotic cover.

Q: What is the earliest site of bone involvement in hematogenous osteomyelitis?

Metaphysis. **Explanation:** The **metaphysis** is the earliest and most common site of involvement in acute hematogenous osteomyelitis, particularly in children. This is due to the unique vascular anatomy of the region: 1. **Hairpin Loops:** The nutrient artery ends in non-anastomotic, sharp "hairpin" capillary loops at the growth plate. These loops lead into large venous sinusoids. 2. **Sluggish Blood Flow:** The transition from narrow capillaries to wide sinusoids causes blood flow to slow down significantly, allowing circulating bacteria (most commonly *Staphylococcus aureus*) to settle and proliferate. 3. **Deficient Phagocytosis:** The capillary loops lack an effective lining of phagocytic cells (reticuloendothelial system), making the area an ideal "nidus" for infection. **Analysis of Incorrect Options:** * **Diaphysis:** While infection can spread to the diaphysis via the medullary canal or subperiosteal space, it is rarely the primary site (except in specific cases like *Salmonella* osteomyelitis in Sickle Cell disease). * **Epiphysis:** In children, the physis (growth plate) acts as a mechanical barrier, protecting the epiphysis. Epiphyseal involvement usually occurs only in infants (where trans-physeal vessels exist) or via secondary spread into the joint. * **Point of entry of the nutrient artery:** While the nutrient artery carries the bacteria, the high velocity of flow at the entry point prevents bacterial seeding; colonization only occurs where the flow slows down (the metaphysis). **High-Yield NEET-PG Pearls:** * **Most common organism:** *Staphylococcus aureus* (overall). * **Sickle Cell Anemia:** High association with *Salmonella*. * **Earliest Sign on X-ray:** Soft tissue swelling (bone destruction takes 7–14 days to appear). * **Investigation of Choice:** MRI (most sensitive for early detection). * **In infants (<1 year):** Infection can cross the physis, leading to frequent **septic arthritis**.

Q: Charcot's joint is another name for a joint affected by which condition?

Neuropathy. **Explanation:** **Charcot’s Joint**, also known as **Neuropathic Arthropathy**, is a progressive degenerative condition characterized by joint destruction, pathological fractures, and joint instability. It occurs due to a loss of protective sensation (pain and proprioception) in the joint. 1. **Why Neuropathy is Correct:** The underlying mechanism involves repetitive microtrauma to a joint that cannot sense pain. This leads to inflammatory bone resorption and structural collapse. Common causes include **Diabetes Mellitus** (most common, typically affecting the foot/ankle), **Syringomyelia** (typically affecting the shoulder), and **Tabes Dorsalis** (historically affecting the knee). 2. **Why Incorrect Options are Wrong:** * **Osteoarthritis:** This is a primary "wear and tear" degenerative disease of the articular cartilage, not primarily driven by sensory loss. * **Rheumatoid Arthritis:** This is an autoimmune, inflammatory systemic disease primarily affecting the synovium. * **Ankylosing Spondylitis:** This is a seronegative spondyloarthropathy characterized by enthesitis and joint fusion (ankylosis), rather than the "bag of bones" destruction seen in Charcot’s. **High-Yield Clinical Pearls for NEET-PG:** * **The 6 D’s of Charcot’s Joint:** Distension, Density (increased), Debris, Dislocation, Disorganization, and Destruction. * **Clinical Paradox:** The joint often appears severely deformed and swollen (the "bag of bones" appearance) but is remarkably **painless** or much less painful than the X-ray suggests. * **French Theory:** Suggests a neurovascular component where autonomic dysfunction leads to hyperemic bone resorption. * **Differential Diagnosis:** It is often confused with Osteomyelitis; however, Charcot’s typically presents with a rapid onset of deformity without significant systemic signs of infection.

Q: Monoarticular joint involvement is seen in which of the following?

Tubercular arthritis. **Explanation:** The pattern of joint involvement is a critical diagnostic clue in orthopaedics. **Tubercular arthritis** is the correct answer because it typically presents as a **chronic, progressive monoarthritis**. In India, the hip and knee are the most common peripheral joints affected. The pathology involves a slow, granulomatous destruction of a single joint, often characterized by the "Phemister triad" (juxta-articular osteopenia, peripheral erosions, and gradual joint space narrowing). **Analysis of Incorrect Options:** * **Primary Osteoarthritis (OA):** This is a degenerative condition that is typically **polyarticular and bilateral**, commonly affecting weight-bearing joints (knees, hips) and the small joints of the hands (Heberden’s and Bouchard’s nodes). * **Rheumatoid Arthritis (RA):** This is a classic **symmetrical inflammatory polyarthritis**. It predominantly involves small joints of the hands and feet (MCP, PIP joints) and spares the DIP joints. * **Seronegative Spondyloarthritis (SpA):** This group (e.g., Ankylosing Spondylitis, Psoriatic Arthritis) typically presents as an **asymmetrical oligoarthritis** (affecting 2–4 joints) or involves the axial skeleton (sacroiliitis). **High-Yield Clinical Pearls for NEET-PG:** * **Monoarthritis Differential:** Always rule out **Septic arthritis** (acute) and **Tubercular arthritis** (chronic) in cases of single joint involvement. * **TB Spine (Pott’s Disease):** The most common site of skeletal TB is the spine (thoracolumbar junction). * **Night Starts:** A characteristic feature of joint TB where pain occurs at night when the protective muscle splinting relaxes, allowing the inflamed articular surfaces to rub together. * **Cold Abscess:** A hallmark of TB, where a collection of pus forms without the typical signs of inflammation (heat, redness).

Q: Which of the following statements is FALSE regarding the given lesion?

Tibia is more commonly involved than mandible.. ***Tibia is more commonly involved than mandible.*** - This statement is **FALSE** - **Garré's sclerosing osteomyelitis** classically affects the **mandible**, particularly in children and adolescents. - The **mandible** is the most common site, not the tibia, making this the correct answer to identify as false. *It is a type of chronic osteomyelitis.* - This is **TRUE** - Garré's osteomyelitis is a form of **chronic non-suppurative sclerosing osteomyelitis**. - It represents a **low-grade chronic infection** with characteristic sclerotic bone changes rather than suppuration. *Long segments of bone are involved.* - This is **TRUE** - Garré's osteomyelitis typically involves **extensive segments** of the affected bone. - The infection spreads along the **medullary cavity**, causing diffuse sclerotic changes over long bone segments. *Associated with excessive bone formation.* - This is **TRUE** - The condition is characterized by **excessive sclerotic bone formation** and **periosteal reaction**. - Radiologically shows **onion-skin layering** and **cortical thickening** due to reactive bone formation.

Q: A patient has a history of similar symptoms at the same site two years ago, developing pain and swelling. X-ray shows the following features. What is the diagnosis?

Chronic osteomyelitis. ***Chronic osteomyelitis*** - History of **recurrent pain and swelling** at the same site over 2 years is pathognomonic for chronic osteomyelitis with periodic **exacerbations**. - X-ray features include **sequestrum** (dead bone), **involucrum** (new bone formation), **cortical sclerosis**, and **periosteal reaction**. *Osteogenic sarcoma* - Typically presents as a **primary malignancy** in adolescents/young adults without history of recurrent episodes at the same site. - X-ray shows characteristic **sunburst appearance** and **Codman's triangle**, not the mixed sclerotic-lytic pattern of chronic osteomyelitis. *Ewing's sarcoma* - Usually affects children and adolescents as an **aggressive primary bone tumor** without chronic recurrent history. - X-ray demonstrates **onion-skin periosteal reaction** and **permeative bone destruction**, distinct from chronic osteomyelitis findings. *Multiple myeloma* - Presents in **older adults** (>60 years) with systemic symptoms like bone pain, anemia, and hypercalcemia. - X-ray shows characteristic **punched-out lytic lesions** without sclerosis or periosteal reaction, unlike chronic osteomyelitis.

Question 1

Fibrous ankylosis is caused by which of the following?

Accepted Answer

TB arthritis

Answer

Septic arthritis

Answer

Behcet's disease

Answer

Psoriatic arthritis

Question 2

What is the radiographic appearance of dead bone on an X-ray?

Accepted Answer

More radiopaque

Answer

More radiolucent

Answer

Same as normal bone

Answer

Variable

Question 3

Brodie's abscess is the terminology for:

Accepted Answer

Chronic osteomyelitis

Answer

Subungual infection

Answer

Web space infection

Answer

Infected hematoma

Question 4

What is the earliest site of bone involvement in hematogenous osteomyelitis?

Accepted Answer

Metaphysis

Answer

Diaphysis

Answer

Epiphysis

Answer

Point of entry of the nutrient artery

Question 5

A child presents with a swollen, painful knee and high fever, with no history of trauma. Acute osteomyelitis is suspected. Which part of the bone is earliest involved in hematogenous osteomyelitis?

Accepted Answer

Metaphysis

Answer

Diaphysis

Answer

Epiphysis

Answer

Area around the nutrient artery

Question 6

Charcot's joint is another name for a joint affected by which condition?

Accepted Answer

Neuropathy

Answer

Osteoarthritis

Answer

Rheumatoid arthritis

Answer

Ankylosing spondylitis

Question 7

Monoarticular joint involvement is seen in which of the following?

Accepted Answer

Tubercular arthritis

Answer

Primary osteoarthritis

Answer

Rheumatoid arthritis

Answer

Seronegative spondyloarthritis

Question 8

Which of the following statements is FALSE regarding the given lesion?

Accepted Answer

Tibia is more commonly involved than mandible.

Answer

It is a type of chronic osteomyelitis.

Answer

Long segments of bone are involved.

Answer

Associated with excessive bone formation.

Question 9

A patient has a history of similar symptoms at the same site two years ago, developing pain and swelling. X-ray shows the following features. What is the diagnosis?

Accepted Answer

Chronic osteomyelitis

Answer

Osteogenic sarcoma

Answer

Ewing's sarcoma

Answer

Multiple myeloma

Question 10

A 30-year-old male who is positive for HIV and on antiretroviral therapy presents with pain in the right hip region. He has had a flexion, abduction, and external rotation deformity of the right hip for 2 months. What is the most likely diagnosis?

Accepted Answer

Tuberculous arthritis of the hip

Answer

Avascular necrosis

Answer

Transient synovitis

Answer

Septic arthritis

Arthrology and Infections — MCQs

Arthrology and Infections — MCQs

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