Arthrology and Infections Practice Questions

Q: Which of the following is not a component of Kocher's criteria when diagnosing septic arthritis of the hip?

C-reactive protein (CRP) > 20 mg/L.. **Explanation:** Kocher’s criteria is a high-yield clinical prediction tool used to differentiate **Septic Arthritis** from Transient Synovitis in a child with a painful hip. The diagnosis is critical because septic arthritis is a surgical emergency. **Why Option D is the correct answer:** While C-reactive protein (CRP) is a highly sensitive marker for inflammation and is often used in clinical practice to monitor treatment response, it was **not** part of the original four criteria described by Kocher et al. Later studies (Cady et al.) suggested adding CRP >20 mg/L as a fifth independent predictor, but it remains excluded from the classic "Kocher’s Criteria." **Analysis of Incorrect Options (The 4 Original Criteria):** 1. **Non-weight-bearing (Option A):** Inability to bear weight on the affected side is a primary clinical indicator. 2. **ESR > 40 mm/hr (Option B):** An elevated Erythrocyte Sedimentation Rate indicates systemic inflammation. 3. **WBC Count > 12,000/mm³ (Option C):** Peripheral leukocytosis is the third laboratory component. 4. **Fever > 38.5°C (101.3°F):** (Not listed in options but is the 4th criterion). **Clinical Pearls for NEET-PG:** * **Probability of Septic Arthritis:** * 1/4 criteria: 3% * 2/4 criteria: 40% * 3/4 criteria: 93% * 4/4 criteria: **99%** * **Gold Standard Diagnosis:** Joint aspiration (Arthrocentesis) showing a synovial WBC count >50,000/mm³ (predominantly neutrophils). * **Most Common Organism:** *Staphylococcus aureus*. * **Management:** Emergency incision and drainage (Arthrotomy) + intravenous antibiotics.

Q: What is the investigation of choice for acute osteomyelitis?

MRI. **Explanation:** **Investigation of Choice: MRI** MRI is the investigation of choice for acute osteomyelitis because it is the most sensitive (90-100%) and specific imaging modality for early detection. It can identify bone marrow edema—the earliest sign of infection—within **24 to 48 hours** of symptom onset. MRI provides superior soft-tissue contrast, allowing for the visualization of associated subperiosteal abscesses and soft tissue extensions, which is crucial for surgical planning. **Analysis of Incorrect Options:** * **CT Scan:** While excellent for visualizing cortical bone destruction and "sequestrum" in chronic osteomyelitis, it lacks the sensitivity to detect early marrow changes in the acute phase. * **Bone Scan (Technetium-99m):** Historically used for its high sensitivity, it is now a second-line option. It can detect changes within 48–72 hours but lacks specificity, as it shows increased uptake in any condition with high bone turnover (fractures, tumors). It remains useful if MRI is contraindicated or unavailable. * **PET Scan:** While highly sensitive, it is expensive, involves radiation, and is not the standard first-line clinical protocol for acute bone infections. **High-Yield Clinical Pearls for NEET-PG:** * **Earliest Investigation:** X-ray is usually the first test performed, but it remains negative for **10–14 days** until 30-50% of bone mineral is lost. * **Earliest Sign on X-ray:** Soft tissue swelling and obliteration of fat planes. * **Gold Standard:** Bone biopsy and culture remain the gold standard for definitive diagnosis and identifying the causative organism (most commonly *Staphylococcus aureus*). * **CRP/ESR:** These are sensitive markers for monitoring treatment response; CRP levels drop rapidly following successful therapy.

Q: Tietze syndrome involves swelling of which costochondral joint?

2nd or 3rd Costochondral joint. **Explanation:** **Tietze Syndrome** is a rare inflammatory disorder characterized by chest pain and **palpable swelling** of the costochondral, costosternal, or sternoclavicular joints. 1. **Why Option B is correct:** The condition most commonly affects the **2nd or 3rd costochondral joints** (occurring in over 70% of cases). It is usually unilateral and involves a single joint. The hallmark that distinguishes it from simple costochondritis is the presence of **visible, firm, non-fluctuant swelling** and localized tenderness. 2. **Why other options are wrong:** While inflammation can technically occur at any level, the 1st, 4th, 5th, 6th, and 7th joints are significantly less common sites for the specific clinical presentation of Tietze Syndrome. Lower rib involvement (Options C and D) is more frequently associated with "Slipping Rib Syndrome" rather than Tietze. **High-Yield Clinical Pearls for NEET-PG:** * **Tietze vs. Costochondritis:** This is a frequent exam trap. **Costochondritis** is common, involves multiple joints (usually 2nd to 5th), and has **no swelling**. **Tietze Syndrome** is rare, usually involves a single joint (2nd or 3rd), and **must have swelling**. * **Demographics:** Typically affects young adults (under 40). * **Etiology:** Often follows viral respiratory infections or physical strain (chronic coughing/heavy lifting). * **Management:** It is a self-limiting benign condition. Treatment is symptomatic with NSAIDs and rest. * **Radiology:** X-rays are usually normal, but MRI may show thickening of the cartilage and bone marrow edema in the subchondral bone.

Q: Sectoral sign is positive in which of the following conditions?

Avascular necrosis of femur head. ### Explanation **Sectoral Sign** is a classic radiological feature seen in the early stages of **Avascular Necrosis (AVN) of the femoral head**. **1. Why Avascular Necrosis is Correct:** The sectoral sign refers to a **wedge-shaped or sector-shaped area of radiolucency or sclerosis** (demarcated by a reactive line) typically located in the anterosuperior weight-bearing portion of the femoral head. This occurs because the blood supply to the femoral head (primarily via the medial circumflex femoral artery) is compromised in a specific distribution, leading to localized bone death. On a lateral X-ray or MRI, this "sector" of involvement is clearly visible before the entire head collapses. **2. Why Other Options are Incorrect:** * **Osteoarthritis of the hip:** Characterized by joint space narrowing, subchondral cysts, and osteophytes. It involves the entire joint surface rather than a specific "sector" of the femoral head. * **Protrusio acetabuli:** This is a deformity where the femoral head projects medially into the pelvic cavity beyond the ilioischial (Kohler’s) line. It is a structural displacement, not a localized necrotic sector. * **Slipped Capital Femoral Epiphysis (SCFE):** This involves the displacement of the epiphysis through the growth plate (physis). Key signs include **Trethowan’s sign** (Klein’s line) and the **Steel’s blanch sign**, but not the sectoral sign. **Clinical Pearls for NEET-PG:** * **Earliest Sign of AVN on X-ray:** Increased density (sclerosis). * **Most Sensitive Investigation:** MRI (shows the "Double Line Sign"). * **Crescent Sign:** Indicates subchondral fracture (Stage II/III), signifying impending collapse. * **Commonest Site:** Anterosuperior quadrant of the femoral head. * **Commonest Cause:** Trauma (fracture neck of femur); Non-traumatic causes include steroids and alcohol.

Q: Tom Smith's arthritis is due to what?

Pyogenic infection in infancy. ***Pyogenic infection in infancy*** - Tom Smith's arthritis is a specific type of **septic arthritis** occurring in infants, caused by **pyogenic bacteria** like *Staphylococcus aureus*. - It leads to **destruction of the femoral head** and **pathological dislocation of the hip** due to osteomyelitis spreading from the metaphysis. *Tuberculosis* - TB arthritis typically has a **chronic, insidious onset** over months to years, unlike the acute presentation in infancy. - It commonly affects **weight-bearing joints** in older children and adults, not specifically causing the characteristic hip destruction seen in Tom Smith's arthritis. *Rheumatoid arthritis* - RA is extremely **rare in infancy** and typically presents after 6 months of age with **systemic symptoms**. - It causes **symmetrical polyarticular involvement** rather than the specific hip pathology seen in Tom Smith's arthritis. *Osteoarthritis* - OA is a **degenerative joint disease** that occurs in older adults due to wear and tear, not in infants. - It involves **cartilage breakdown** and **osteophyte formation**, which are completely different from the infectious etiology of Tom Smith's arthritis.

Q: All of the following are associated with chronic osteomyelitis except?

Myositis ossificans. **Explanation:** Chronic osteomyelitis is a persistent infection of the bone characterized by low-grade inflammation, bone necrosis, and reactive bone formation. **Why Myositis Ossificans is the Correct Answer:** **Myositis Ossificans** is a condition where bone forms within muscle or soft tissue, usually following blunt trauma (hematoma). It is a **post-traumatic** complication, not an infectious one. It does not occur as a result of chronic bone infection, making it the "except" in this list. **Analysis of Incorrect Options:** * **Amyloidosis:** Chronic infections like osteomyelitis lead to the persistent production of Serum Amyloid A (SAA) protein. This can result in **Secondary (AA) Amyloidosis**, which often affects the kidneys. * **Sequestrum:** This is the hallmark of chronic osteomyelitis. It refers to a piece of **dead bone** that has become detached from its blood supply and is surrounded by infected tissue or pus. * **Metastatic Abnormality:** Chronic irritation of a long-standing sinus tract in osteomyelitis can lead to malignant transformation. The most common "metastatic" or malignant complication is **Squamous Cell Carcinoma** (Marjolin’s ulcer). **NEET-PG High-Yield Pearls:** 1. **Involucrum:** The layer of new, living bone formed around a sequestrum. 2. **Cloaca:** An opening in the involucrum through which pus and sequestra are discharged. 3. **Brodie’s Abscess:** A localized form of chronic osteomyelitis characterized by a radiolucent lesion with a sclerotic rim. 4. **Gold Standard Investigation:** MRI is highly sensitive, but for chronic cases, a **CT scan** is superior for visualizing the sequestrum and involucrum.

Q: What pathological process causes both destruction of bone and reduction of joint space?

Tuberculosis. ### Explanation The correct answer is **Tuberculosis (A)**. **Why Tuberculosis is Correct:** In musculoskeletal tuberculosis, the infection typically begins in the bone (metaphysis or epiphysis) or the synovium. As the disease progresses, the granulomatous process leads to the destruction of subchondral bone. Unlike pyogenic arthritis, where proteolytic enzymes destroy cartilage rapidly, TB causes a slow destruction of the articular cartilage through the formation of **pannus** and subchondral erosions. This dual involvement of the bone (osteolysis/caries) and the cartilage leads to the characteristic **reduction of joint space** seen on X-rays. In the spine (Pott’s disease), the destruction of the vertebral bodies and the intervening disc space is a classic hallmark. **Why Other Options are Incorrect:** * **B, C, and D (Metastasis, Multiple Myeloma, Lymphoma):** These are primarily neoplastic processes involving the bone marrow or cortex. While they cause significant **bone destruction** (lytic lesions), they characteristically **spare the joint space and the intervertebral discs**. Cartilage acts as a relative barrier to the spread of malignancy; therefore, a preserved joint space in the presence of extensive bone destruction is a key radiological feature distinguishing tumors from infections like TB. **High-Yield Clinical Pearls for NEET-PG:** * **Phemister’s Triad (Radiological features of TB Arthritis):** 1. Juxta-articular osteopenia, 2. Peripherally located osseous erosions, 3. Gradual narrowing of the joint space. * **Cold Abscess:** A hallmark of TB, where a collection of pus forms without the classic signs of inflammation (heat, redness). * **Spinal TB:** The most common site is the **thoracolumbar junction**. The disc is involved early in TB, whereas it is spared in malignancy.

Q: Epiphyseal enlargement occurs in which of the following conditions?

Hemophilia. **Explanation:** **Correct Answer: D. Hemophilia** In Hemophilia, recurrent intra-articular bleeding (hemarthrosis) leads to chronic synovitis. The inflamed synovium becomes hypervascular, causing **increased blood flow (hyperemia)** to the adjacent epiphyses. In a growing child, this chronic hyperemia stimulates the epiphyseal growth plate, leading to accelerated maturation and **epiphyseal enlargement** (overgrowth). This is classically seen in the knee (enlarged femoral condyles) and the elbow (enlarged radial head). **Analysis of Incorrect Options:** * **A. Paget’s Disease:** This is a disorder of bone remodeling characterized by excessive bone resorption followed by disorganized bone formation. While it causes cortical thickening and bone enlargement, it typically affects the entire bone (diaphysis and epiphysis) in adults, rather than isolated epiphyseal enlargement in a pediatric context. * **B. Scheuermann’s Disease:** This is a developmental disorder of the spine causing thoracic kyphosis. It involves anterior wedging of vertebral bodies and Schmorl’s nodes, not peripheral epiphyseal enlargement. * **C. Epiphyseal Dysplasia:** Conditions like Multiple Epiphyseal Dysplasia (MED) typically result in **small, irregular, or fragmented** epiphyses, leading to short stature and early-onset osteoarthritis, rather than enlargement. **High-Yield Clinical Pearls for NEET-PG:** * **Jordan’s Sign:** A radiographic feature in Hemophilia where the intercondylar notch of the femur appears widened due to pressure from the hypertrophied synovium and cruciate ligament bleeding. * **Squaring of the Patella:** Another classic radiological sign of hemophilic arthropathy. * **Differential Diagnosis for Epiphyseal Enlargement:** Apart from Hemophilia, consider **Juvenile Idiopathic Arthritis (JIA)**, which also causes hyperemia-induced overgrowth. * **Earliest Sign of Hemophilic Arthropathy:** Soft tissue swelling.

Q: Which joint is commonly involved in osteochondritis dissecans?

Knee joint. **Explanation:** **Osteochondritis Dissecans (OCD)** is a joint condition where bone underneath the cartilage of a joint dies due to lack of blood flow (avascular necrosis). This bone and cartilage can then break loose, causing pain and joint instability. **Why the Knee Joint is Correct:** The **knee joint** is the most common site for OCD, accounting for approximately 75% of all clinical cases. Specifically, the **lateral aspect of the medial femoral condyle** is the most frequent site of involvement (often remembered by the mnemonic **LAME**: Lateral Aspect of Medial Eminence/Condyle). It typically affects adolescents and young adults, often linked to repetitive microtrauma. **Analysis of Incorrect Options:** * **Ankle Joint:** While the talus is the second most common site for OCD, it occurs much less frequently than in the knee. * **Elbow Joint:** OCD can occur here (specifically the capitellum), usually in young athletes like pitchers or gymnasts, but it is less common than knee involvement. * **Wrist Joint:** This is a very rare site for OCD. Conditions like Kienböck's disease (lunate necrosis) are more common in the wrist but are pathologically distinct from classic OCD. **Clinical Pearls for NEET-PG:** * **Classic Site:** Lateral surface of the Medial Femoral Condyle (70-80% of knee cases). * **Wilson’s Sign:** A clinical test for OCD of the knee where internal rotation of the tibia during extension causes pain, which is relieved by external rotation. * **Imaging:** X-ray may show a "joint mouse" (loose body). MRI is the gold standard for assessing the stability of the fragment. * **Etiology:** Most commonly attributed to repetitive microtrauma and ischemia.

Q: All are true about acute osteomyelitis except?

Involves the epiphyseal plate. ### Explanation **1. Why Option C is the Correct Answer (The "Except" Statement):** In acute hematogenous osteomyelitis (AHO), the **epiphyseal plate (growth plate) acts as a physical barrier** that prevents the spread of infection from the metaphysis to the epiphysis. This is because the metaphyseal nutrient arteries loop back sharply at the level of the growth plate and do not cross it in children. Therefore, the infection is typically confined to the metaphysis. * *Exception:* In infants (under 1 year), small trans-physeal vessels exist, allowing infection to cross into the epiphysis and joint. **2. Analysis of Incorrect Options:** * **A. Common in children:** This is true. AHO primarily affects the pediatric population due to the highly vascularized and growing nature of long bones. * **B. Severe pain:** This is true. The infection causes increased intraosseous pressure and subperiosteal abscess formation, leading to exquisite tenderness and "pseudoparalysis" (the child refuses to move the limb). * **D. Treatment involves 6 weeks of antibiotics:** This is true. Standard management requires a prolonged course (usually 4–6 weeks) of antibiotics to ensure complete eradication of the pathogen and prevent progression to chronic osteomyelitis. **3. Clinical Pearls for NEET-PG:** * **Most common site:** Metaphysis of long bones (due to sluggish blood flow in venous hair-pin bends, favoring bacterial seeding). * **Most common organism:** *Staphylococcus aureus* (overall). In Sickle Cell Anemia patients, look for *Salmonella*. * **Earliest X-ray sign:** Soft tissue swelling (Bone changes like periosteal reaction take 7–14 days to appear). * **Investigation of choice:** MRI is the most sensitive early diagnostic tool. * **Surgical Indication:** If there is no clinical improvement within 24–48 hours of starting antibiotics or if a fluctuant abscess is present.

Question 1

Which of the following is not a component of Kocher's criteria when diagnosing septic arthritis of the hip?

Accepted Answer

C-reactive protein (CRP) > 20 mg/L.

Answer

Non-weight-bearing on the affected side.

Answer

Erythrocyte sedimentation rate (ESR) greater than 40mm/hr.

Answer

White blood cell (WBC) count of >12000/mm³.

Question 2

What is the investigation of choice for acute osteomyelitis?

Accepted Answer

MRI

Answer

CT Scan

Answer

Bone Scan

Answer

PET

Question 3

Tietze syndrome involves swelling of which costochondral joint?

Accepted Answer

2nd or 3rd Costochondral joint

Answer

1st Costochondral joint

Answer

4th & 5th Costochondral joint

Answer

6th or 7th Costochondral joint

Question 4

Sectoral sign is positive in which of the following conditions?

Accepted Answer

Avascular necrosis of femur head

Answer

Osteoarthritis of hip

Answer

Protrusio acetabuli

Answer

Slipped capital femoral epiphyses

Question 5

Tom Smith's arthritis is due to what?

Accepted Answer

Pyogenic infection in infancy

Answer

Tuberculosis

Answer

Rheumatoid arthritis

Answer

Osteoarthritis

Question 6

All of the following are associated with chronic osteomyelitis except?

Accepted Answer

Myositis ossificans

Answer

Amyloidosis

Answer

Sequestrum

Answer

Metastatic abnormality

Question 7

What pathological process causes both destruction of bone and reduction of joint space?

Accepted Answer

Tuberculosis

Answer

Metastasis

Answer

Multiple myeloma

Answer

Lymphoma

Question 8

Epiphyseal enlargement occurs in which of the following conditions?

Accepted Answer

Hemophilia

Answer

Paget's disease

Answer

Scheuermann's disease

Answer

Epiphyseal dysplasia

Question 9

Which joint is commonly involved in osteochondritis dissecans?

Accepted Answer

Knee joint

Answer

Ankle joint

Answer

Wrist joint

Answer

Elbow joint

Question 10

All are true about acute osteomyelitis except?

Accepted Answer

Involves the epiphyseal plate

Answer

Common in children

Answer

Severe pain

Answer

Treatment involves 6 weeks of antibiotics

Arthrology and Infections — MCQs

Arthrology and Infections — MCQs

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