Arthrology and Infections Practice Questions

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: 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.

Q: Tuberculous arthritis of a joint, in sites other than the spine, in advanced cases leads to which of the following?

Fibrous ankylosis. **Explanation:** The hallmark of healing in **Tuberculous (TB) arthritis** of peripheral joints is **Fibrous Ankylosis**. **Why Fibrous Ankylosis is correct:** In tuberculosis, the infection is characterized by chronic granulomatous inflammation. Unlike pyogenic (septic) arthritis, TB bacilli do not produce proteolytic enzymes (like elastase or hyaluronidase) that completely destroy the articular cartilage. Instead, the cartilage is slowly replaced by **pannus** (granulation tissue). When the infection heals, this granulation tissue matures into dense fibrous tissue, leading to a "fibrous ankylosis"—where the joint becomes stiff but not completely fused by bone. **Analysis of Incorrect Options:** * **A. Bony Ankylosis:** This is the characteristic outcome of **Pyogenic/Septic Arthritis**. Proteolytic enzymes in pus destroy the cartilage entirely, allowing raw bone ends to meet and fuse. *Exception:* In TB, bony ankylosis occurs only in the **Spine (Pott’s disease)** and occasionally the sacroiliac joint. * **C. Loose Joints:** TB arthritis typically leads to stiffness and contractures, not laxity. Joint destruction and fibrosis limit movement. * **D. Charcot’s Joints:** This refers to neuropathic arthropathy (painless destruction) caused by loss of proprioception and pain sensation, commonly seen in Diabetes Mellitus, Syphilis (Tabes dorsalis), or Syringomyelia. **High-Yield NEET-PG Pearls:** * **Triple Deformity:** Classic in TB Knee (Flexion, Posterior subluxation, and External rotation). * **Phemister’s Triad (Radiology):** Juxta-articular osteopenia, peripheral osseous erosions, and gradual narrowing of joint space. * **Cold Abscess:** A collection of pus/debris without signs of inflammation (heat/redness), typical of TB. * **Gold Standard Diagnosis:** Synovial biopsy showing caseating granulomas.

Q: What is the most common site of tuberculosis?

Spine. **Explanation:** Tuberculosis (TB) of the musculoskeletal system accounts for approximately 1–3% of all TB cases and about 10% of extrapulmonary TB cases. Among these, the **Spine (Pott’s disease)** is the most common site, representing roughly **50% of all osteoarticular tuberculosis** cases. **Why Spine is the Correct Answer:** The spine is highly susceptible due to the rich vascular supply of the vertebral bodies and the presence of the **Batson’s venous plexus**, which allows for the hematogenous spread of *Mycobacterium tuberculosis* from primary sites (usually the lungs or lymph nodes). The infection typically begins in the anterior part of the vertebral body near the disc space (paradiscal lesion). **Analysis of Incorrect Options:** * **Hip Joint (Option A):** This is the **second most common** site of osteoarticular TB (approx. 15%). It usually presents with a "wandering acetabulum" or pathological dislocation in advanced stages. * **Knee Joint (Option B):** This is the **third most common** site. It often presents with "triple deformity" (flexion, posterior subluxation, and external rotation of the tibia). * **Ankle Joint (Option D):** While TB can affect any joint, the ankle and foot are significantly less common than the spine, hip, or knee. **NEET-PG High-Yield Pearls:** * **Most common site in Spine:** Lower Thoracic and Upper Lumbar vertebrae. * **Earliest sign on X-ray:** Rarefaction/demineralization of the bone and narrowing of the disc space. * **Phemister’s Triad (Radiological features of TB joints):** 1. Juxta-articular osteoporosis, 2. Peripherally located osseous erosions, 3. Gradual narrowing of the joint space. * **Cold Abscess:** A hallmark of spinal TB, it occurs when the infection tracks along tissue planes (e.g., Psoas abscess) without the typical signs of acute inflammation (heat/redness).

Q: Brodie's abscess occurs in which type of bone?

Long bone. **Explanation:** **Brodie’s abscess** is a localized, chronic form of pyogenic osteomyelitis. It is characterized by a collection of pus surrounded by a wall of granulation tissue and reactive bone (sclerosis). **Why Long Bone is Correct:** Brodie’s abscess typically occurs in the **metaphysis of long bones**, with the **tibia** (distal or proximal) being the most common site, followed by the femur. The metaphysis is the preferred site because of its high vascularity and the presence of "hairpin" loops of capillary beds, which allow blood-borne bacteria (most commonly *Staphylococcus aureus*) to settle and form a localized infection. Because the patient’s immunity is relatively high or the organism’s virulence is low, the body walls off the infection rather than allowing it to spread. **Why Other Options are Incorrect:** * **Flat bones & Small bones:** While osteomyelitis can occur in these bones (e.g., pelvis or tarsals), they lack the specific metaphyseal anatomy and vascular patterns that typically lead to the formation of a classic Brodie’s abscess. * **Sesamoid bones:** These bones (like the patella) are embedded in tendons and have a limited blood supply; they are extremely rare sites for any form of primary osteomyelitis. **High-Yield Clinical Pearls for NEET-PG:** * **Most common organism:** *Staphylococcus aureus*. * **Classic X-ray finding:** A well-defined **radiolucent (lytic) lesion** in the metaphysis surrounded by a rim of **sclerotic bone**. * **Clinical presentation:** Chronic, intermittent pain (often worse at night) and localized tenderness, usually without systemic symptoms like fever. * **Differential Diagnosis:** Often confused with **Osteoid Osteoma**; however, the pain in Brodie’s abscess is not always relieved by aspirin, unlike Osteoid Osteoma. * **Treatment:** Surgical curettage and antibiotics.

Q: The joint commonly involved in psoriatic arthritis is?

Knee. **Explanation:** Psoriatic arthritis (PsA) is a chronic inflammatory spondyloarthropathy associated with psoriasis. While PsA is famous for involving the small joints of the hands (specifically the Distal Interphalangeal joints), when considering **large joints**, the **Knee** is the most commonly affected joint. 1. **Why Knee is Correct:** Psoriatic arthritis frequently presents as an asymmetrical oligoarthritis (affecting <5 joints). In this clinical subtype, the knee is the most frequent large joint involved. It often presents with significant effusion and inflammatory markers. 2. **Why other options are incorrect:** * **Hip and Shoulder:** While these proximal girdle joints can be involved in the symmetric polyarthritis or spondylitic subtypes of PsA, they are significantly less common than the knee. Hip involvement, in particular, is more characteristic of Ankylosing Spondylitis. * **Wrist:** Although the wrist is often involved in the symmetric polyarthritis subtype (which mimics Rheumatoid Arthritis), the knee remains statistically more prevalent across the various clinical presentations of PsA. **High-Yield Clinical Pearls for NEET-PG:** * **Classic Sign:** **DIP joint involvement** is a hallmark of PsA (unlike RA, which spares the DIP). * **Dactylitis:** "Sausage digit" (diffuse swelling of a finger or toe) is a pathognomonic feature. * **Radiology:** Look for the **"Pencil-in-cup" deformity** (erosion of the distal bone with expansion of the proximal base). * **Nail Changes:** Pitting of nails and onycholysis are strong clinical predictors of joint involvement. * **Mnemonic:** PsA is **Seronegative** (RF negative).

Question 1

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 2

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 3

Monoarticular joint involvement is seen in which of the following?

Accepted Answer

Tubercular arthritis

Answer

Primary osteoarthritis

Answer

Rheumatoid arthritis

Answer

Seronegative spondyloarthritis

Question 4

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 5

Tuberculous arthritis of a joint, in sites other than the spine, in advanced cases leads to which of the following?

Accepted Answer

Fibrous ankylosis

Answer

Bony ankylosis

Answer

Loose joints

Answer

Charcot's joints

Question 6

Acute osteomyelitis of long bones commonly affects which part?

Accepted Answer

Metaphysis

Answer

Epiphysis

Answer

Diaphysis

Answer

Articular surfaces

Question 7

All of the following findings are in favor of an inflammatory joint pathology except?

Accepted Answer

Non-uniform joint space loss

Answer

Juxta-articular osteoporosis

Answer

Bone erosions

Answer

Bilateral symmetric involvement

Question 8

What is the most common site of tuberculosis?

Accepted Answer

Spine

Answer

Hip joint

Answer

Knee joint

Answer

Ankle joint

Question 9

Brodie's abscess occurs in which type of bone?

Accepted Answer

Long bone

Answer

Flat bone

Answer

Small bone

Answer

Sesamoid bone

Question 10

The joint commonly involved in psoriatic arthritis is?

Accepted Answer

Knee

Answer

Hip

Answer

Shoulder

Answer

Wrist

Arthrology and Infections — MCQs

Arthrology and Infections — MCQs

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