Arthrology and Infections — MCQs

Arthrology and Infections Indian Medical PG Practice Questions and MCQs

Question 171: Baker's cyst is a swelling which occurs in:

A. Popliteal fossa (Correct Answer)
B. Cubital fossa
C. Lateral malleolus
D. Medial malleolus

Explanation: **Explanation:** **Baker’s Cyst (Popliteal Cyst)** is a fluid-filled distension of the gastrocnemio-semimembranosus bursa. It occurs in the **popliteal fossa** (the posterior aspect of the knee), typically communicating with the knee joint through a slit-like opening in the joint capsule. * **Why Option A is correct:** In adults, Baker’s cysts are usually secondary to intra-articular pathologies such as **Osteoarthritis** or **Rheumatoid Arthritis**. Increased synovial fluid production (effusion) leads to a "one-way valve" effect, forcing fluid into the bursa located between the medial head of the gastrocnemius and the semimembranosus tendon. * **Why Options B, C, and D are incorrect:** The **cubital fossa** is located at the elbow; common swellings here include olecranon bursitis or brachial artery aneurysms. The **malleoli** (lateral and medial) are landmarks of the ankle; swellings here are typically associated with ankle sprains, pott's fractures, or localized tenosynovitis, not synovial cysts of the knee. **High-Yield Clinical Pearls for NEET-PG:** 1. **Foucher’s Sign:** A Baker’s cyst becomes firm on knee extension and soft on knee flexion (due to compression by the muscles). This helps differentiate it from a popliteal artery aneurysm. 2. **Rupture:** A ruptured Baker’s cyst can mimic **Deep Vein Thrombosis (DVT)**, presenting with sudden calf pain, swelling, and a positive "crescent sign" (ecchymosis below the malleolus). 3. **Treatment:** In adults, the focus is on treating the underlying intra-articular cause (e.g., managing arthritis). In children, these cysts are often primary and frequently resolve spontaneously.

Question 172: What is not true about pseudogout?

A. Periarticular calcification
B. Calcium pyrophosphate deposition
C. Associated with hypothyroidism
D. Associated with hypoparathyroidism (Correct Answer)

Explanation: **Explanation:** Pseudogout, also known as **Calcium Pyrophosphate Deposition Disease (CPPD)**, is a crystal-induced arthropathy characterized by the deposition of calcium pyrophosphate dihydrate crystals in joint tissues. **Why Option D is the Correct Answer:** Pseudogout is classically associated with **Hyperparathyroidism**, not hypoparathyroidism. In hyperparathyroidism, elevated levels of parathyroid hormone (PTH) lead to hypercalcemia, which promotes the formation and deposition of calcium pyrophosphate crystals in the cartilage (chondrocalcinosis). **Analysis of Other Options:** * **Option A (Periarticular calcification):** This is a hallmark radiographic feature of CPPD. It often manifests as **chondrocalcinosis** (linear calcification of articular cartilage or fibrocartilage, commonly seen in the knee menisci or triangular fibrocartilage of the wrist). * **Option B (Calcium pyrophosphate deposition):** This is the fundamental pathophysiology of the disease. Unlike gout (monosodium urate), pseudogout involves CPPD crystals. * **Option C (Associated with hypothyroidism):** Hypothyroidism is a well-recognized metabolic association with CPPD. Other key associations include **hemochromatosis, hypomagnesemia, and Wilson’s disease.** **NEET-PG High-Yield Pearls:** * **Crystal Morphology:** CPPD crystals are **rhomboid-shaped** and show **weak positive birefringence** under polarized light (Gout crystals are needle-shaped and strongly negative birefringent). * **Most Common Joint:** The **Knee** is the most frequently affected joint in pseudogout. * **The "4 H's" of Pseudogout Associations:** **H**yperparathyroidism, **H**emochromatosis, **H**ypomagnesemia, and **H**ypothyroidism. * **Radiology:** Look for the "white line" of chondrocalcinosis parallel to the subchondral bone.

Question 173: What is the investigation of choice for acute osteomyelitis?

A. CT Scan
B. MRI (Correct Answer)
C. Bone Scan
D. PET

Explanation: **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.

Question 174: What is the pathognomonic finding in pseudogout?

A. Calcium pyrophosphate dihydrate (CPPD) crystals under microscope (Correct Answer)
B. Polyarthritis with urinary sediment
C. Juxta-articular osteopenia
D. Bone spurs

Explanation: **Explanation:** **Pseudogout**, clinically known as Calcium Pyrophosphate Deposition (CPPD) disease, is a crystal-induced arthropathy. The **pathognomonic finding** is the identification of **Calcium Pyrophosphate Dihydrate (CPPD) crystals** in the synovial fluid. Under polarized light microscopy, these crystals are characterized by their **rhomboid shape** and **weak positive birefringence** (appearing blue when parallel to the compensator axis), distinguishing them from the needle-shaped, negatively birefringent urate crystals of gout. **Analysis of Incorrect Options:** * **B. Polyarthritis with urinary sediment:** This is more characteristic of systemic conditions like Systemic Lupus Erythematosus (SLE) or vasculitis involving the kidneys. * **C. Juxta-articular osteopenia:** This is an early radiological hallmark of **Rheumatoid Arthritis**, caused by local inflammatory cytokines. In contrast, CPPD often shows subchondral cysts and sclerosis. * **D. Bone spurs (Osteophytes):** These are the hallmark of **Osteoarthritis**. While CPPD can coexist with osteoarthritis (often termed "pseudo-osteoarthritis"), bone spurs are not specific to it. **NEET-PG High-Yield Pearls:** * **Radiology:** Look for **Chondrocalcinosis** (linear calcification of articular cartilage or fibrocartilage, most commonly in the knee menisci, triangular fibrocartilage of the wrist, and symphysis pubis). * **Common Site:** The **knee** is the most frequently affected joint (unlike the 1st MTP joint in gout). * **Associations:** Always screen for "The 3 H’s": **Hyperparathyroidism, Hemochromatosis, and Hypomagnesemia**, as these metabolic conditions predispose patients to CPPD.

Question 175: What is the term for tuberculosis affecting the bones and joints of the hand?

A. Spina ventosa (Correct Answer)
B. Caries sicca
C. Pott's disease
D. None of the above

Explanation: **Explanation:** **Spina Ventosa** is the correct term for tuberculous dactylitis, which involves the short tubular bones (metacarpals, metatarsals, and phalanges) of the hands and feet. The term is derived from Latin: *Spina* (thorn) and *Ventosa* (inflated with air). Pathologically, the infection starts in the marrow cavity, leading to bone destruction and simultaneous subperiosteal new bone formation. This causes the bone to appear "expanded" or "ballooned" on X-ray, with a thin cortex and a hollowed-out center, mimicking a bone filled with air. It is most commonly seen in children. **Analysis of Incorrect Options:** * **Caries Sicca:** This refers specifically to tuberculosis of the **shoulder joint**. It is characterized by a "dry" form of destruction (sicca = dry) where there is significant bone wasting and restricted movement without the formation of an abscess or "cold" swelling. * **Pott’s Disease:** This is the eponymous name for **tuberculosis of the spine**. It typically affects the disco-vertebral junction and can lead to complications like kyphosis (gibbus deformity) and paraplegia (Pott’s paraplegia). **High-Yield Clinical Pearls for NEET-PG:** * **Radiological Sign:** The "ballooning" or expansion of the phalanx in Spina Ventosa is a classic MCQ favorite. * **Most Common Site for Skeletal TB:** The Spine (Pott's Disease), followed by the Hip and Knee. * **Cold Abscess:** A hallmark of skeletal TB, characterized by a collection of liquefactive necrosis (caseation) that lacks the typical signs of acute inflammation (heat, redness, pain).

Question 176: Septic arthritis can be caused by which of the following microorganisms?

A. Neisseria gonorrhoeae
B. Escherichia coli
C. Mycobacterium tuberculosis
D. All of the above (Correct Answer)

Explanation: **Explanation:** Septic arthritis is an emergency condition characterized by the invasion of the synovial space by microorganisms, leading to rapid joint destruction. While **Staphylococcus aureus** is the most common causative agent overall, a wide spectrum of pathogens can cause the infection depending on the patient's age, risk factors, and immune status. * **Neisseria gonorrhoeae (Option A):** This is the most common cause of septic arthritis in **young, sexually active adults**. It often presents as a triad of tenosynovitis, dermatitis, and polyarthralgia before localizing to a single joint. * **Escherichia coli (Option B):** Gram-negative bacilli like *E. coli* are frequent culprits in neonates, the elderly, intravenous drug users, and immunocompromised individuals. * **Mycobacterium tuberculosis (Option C):** While typically chronic, *M. tuberculosis* causes "Tuberculous Arthritis," a form of granulomatous septic arthritis usually affecting weight-bearing joints (hip and knee). Since all the listed organisms are documented causes of joint infection, **Option D** is the correct answer. **High-Yield NEET-PG Pearls:** 1. **Most common overall cause:** *Staphylococcus aureus*. 2. **Most common cause in Sickle Cell Disease:** *Salmonella* (though *S. aureus* remains frequent). 3. **Most common cause in neonates:** Group B Streptococcus and *S. aureus*. 4. **Gold Standard Diagnosis:** Arthrocentesis (Joint fluid analysis) showing a WBC count >50,000/mm³ with >75% polymorphonuclear cells. 5. **Kocher’s Criteria:** Used to differentiate septic arthritis from transient synovitis in children (Non-weight bearing, Fever >38.5°C, ESR >40 mm/hr, WBC >12,000/mm³).

Question 177: Clutton's joint is seen in?

A. Primary syphilis
B. Secondary syphilis
C. Tertiary syphilis
D. Congenital syphilis (Correct Answer)

Explanation: **Explanation:** **Clutton’s joint** is a classic musculoskeletal manifestation of **late congenital syphilis**, typically occurring in children and adolescents between the ages of 8 and 15 years. It is characterized by symmetrical, painless swelling (hydrarthrosis) of the large joints, most commonly the **knees**. The underlying pathology is a chronic synovitis with effusion that, despite the swelling, does not result in significant joint destruction or permanent disability. **Analysis of Options:** * **Congenital Syphilis (Correct):** It is part of the late stigmata of congenital syphilis. It often presents alongside other features like interstitial keratitis and Hutchinson’s teeth (Hutchinson’s triad). * **Primary Syphilis:** This stage is characterized by the painless chancre at the site of inoculation; joint involvement is not a feature. * **Secondary Syphilis:** This stage involves systemic dissemination, presenting with a maculopapular rash, lymphadenopathy, and condyloma lata. While arthralgia can occur, Clutton’s joint is specific to the congenital form. * **Tertiary Syphilis:** While tertiary syphilis involves the joints, it typically presents as **Charcot’s joint** (neuropathic arthropathy) secondary to Tabes Dorsalis, which is a destructive, painless joint process unlike the benign effusion of Clutton’s joint. **High-Yield Clinical Pearls for NEET-PG:** * **Hutchinson’s Triad:** Interstitial keratitis, sensorineural deafness (8th nerve), and Hutchinson’s teeth. * **Saber Shin:** Anterior bowing of the tibia due to periostitis in congenital syphilis. * **Wimberger’s Sign:** Focal erosion of the medial aspect of the proximal tibial metaphysis (seen in early congenital syphilis). * **Treatment:** Penicillin G remains the gold standard for all stages of syphilis.

Question 178: What is a Baker's cyst?

A. Gluteal abscess
B. Cyst on the posterior aspect of the thigh
C. Cyst over the popliteal fossa (Correct Answer)
D. Swelling of the bursa of semitendinosus and gracilis

Explanation: ### Explanation **Correct Answer: C. Cyst over the popliteal fossa** A **Baker’s cyst**, also known as a **popliteal cyst**, is a fluid-filled collection caused by the herniation of the synovial membrane or the distension of the bursa located between the **medial head of the gastrocnemius** and the **semimembranosus muscle**. It typically presents as a swelling in the popliteal fossa. In adults, it is usually secondary to intra-articular pathology, such as osteoarthritis or a meniscal tear, which causes chronic joint effusion that escapes into the bursa via a valve-like mechanism. **Analysis of Incorrect Options:** * **A. Gluteal abscess:** This is a collection of pus in the buttock region, usually following an infected injection or tuberculosis of the spine (cold abscess). It is unrelated to the knee joint. * **B. Cyst on the posterior aspect of the thigh:** While the popliteal fossa is posterior to the knee, a cyst specifically on the thigh would involve different anatomical structures (like the hamstring muscles) and is not termed a Baker’s cyst. * **D. Swelling of the bursa of semitendinosus and gracilis:** This refers to **Pes Anserine Bursitis**, which presents as pain and swelling on the **anteromedial** aspect of the proximal tibia, not the posterior popliteal fossa. **High-Yield Clinical Pearls for NEET-PG:** * **Foucher’s Sign:** The cyst becomes firm/prominent on knee extension and soft/disappears on knee flexion. * **Ruptured Baker’s Cyst:** Can mimic **Deep Vein Thrombosis (DVT)** due to sudden calf pain, swelling, and a positive Homan’s sign (Pseudothrombophlebitis syndrome). * **Primary vs. Secondary:** In children, these are often primary (no joint disease); in adults, always look for underlying **Osteoarthritis** or **Rheumatoid Arthritis**. * **Treatment:** Address the underlying intra-articular pathology; aspiration or excision is rarely needed unless symptomatic.

Question 179: Apparent lengthening is seen in which stage of Tuberculosis of the Hip?

A. Stage 1 (Correct Answer)
B. Stage 2
C. Stage 3
D. Stage 4

Explanation: In Tuberculosis (TB) of the hip, the clinical presentation is divided into three distinct stages based on the progression of the disease and the position of the limb. ### **1. Stage 1: Stage of Synovitis (Correct Answer)** In this early stage, there is inflammation of the synovium leading to joint effusion. To accommodate the increased intra-articular fluid and minimize pressure, the hip assumes the position of maximum capacity: **Flexion, Abduction, and External Rotation.** * **The Concept:** Because the limb is abducted, the pelvis tilts downwards on the affected side to keep the legs parallel for walking. This pelvic tilt results in **Apparent Lengthening**, although the actual bony length remains the same. ### **2. Why the other options are incorrect:** * **Stage 2 (Stage of Arthritis):** As the disease progresses to the cartilage, the joint becomes painful. To protect the joint, the powerful adductors and flexors go into spasm. The hip moves into **Flexion, Adduction, and Internal Rotation.** This causes the pelvis to tilt upwards on the affected side, leading to **Apparent Shortening.** * **Stage 3 (Stage of Erosion/Destruction):** There is significant destruction of the acetabulum and femoral head (Wandering Acetabulum) or pathological dislocation. The limb remains in **Flexion, Adduction, and Internal Rotation**, but now there is **True Shortening** due to bony destruction. * **Stage 4:** This is not a standard classification stage for TB Hip; however, late-stage neglected TB results in bony or fibrous ankylosis with permanent shortening. ### **High-Yield Clinical Pearls for NEET-PG:** * **Deformity Sequence:** FABER (Stage 1) $\rightarrow$ FADIR (Stage 2 & 3). * **Thomas Test:** Used to detect fixed flexion deformity. * **Night Cries:** Common in Stage 2 when muscle relaxation during sleep leads to painful rubbing of inflamed surfaces. * **Cold Abscess:** Most commonly presents in the gluteal region or Scarpa’s triangle.

Question 180: Triple deformity of the knee joint is seen in which of the following conditions?

A. Tuberculosis (Correct Answer)
B. Trauma
C. Malignant tumour
D. Sarcoidosis

Explanation: **Explanation:** The **Triple Deformity of the knee** is a classic clinical manifestation of advanced **Tuberculosis (TB) of the knee joint**. It occurs due to the progressive destruction of the joint surfaces and the weakening of the stabilizing ligaments (particularly the Cruciates), combined with the powerful pull of the hamstring muscles. The "Triple Deformity" consists of: 1. **Flexion:** Caused by the dominant action of the hamstring muscles. 2. **Posterior Subluxation of the Tibia:** Due to the destruction of the Anterior Cruciate Ligament (ACL). 3. **External Rotation of the Tibia:** Caused by the pull of the Biceps Femoris muscle. **Analysis of Options:** * **A. Tuberculosis (Correct):** Chronic synovial hypertrophy and "pannus" formation lead to the destruction of cartilage and ligaments, resulting in this characteristic malalignment. * **B. Trauma:** While trauma can cause dislocations or fractures, it typically results in acute instability or specific deformities (like genu valgum/varum) rather than this specific triad. * **C. Malignant Tumour:** Bone tumors (like Osteosarcoma) usually present with localized swelling, pathological fractures, or joint effusion, but do not characteristically produce a triple deformity. * **D. Sarcoidosis:** This is a multisystem granulomatous disease. While it can cause dactylitis or acute arthritis (Lofgren syndrome), it rarely causes the gross structural joint destruction seen in TB. **High-Yield Clinical Pearls for NEET-PG:** * **Stages of TB Knee:** Stage 1 (Synovitis), Stage 2 (Arthritis), Stage 3 (Erosion/Triple Deformity), Stage 4 (Ankylosis). * **Fibrous Ankylosis:** TB of the knee typically results in fibrous ankylosis (unlike Pyogenic arthritis, which leads to bony ankylosis). * **Radiology:** Look for **Phemister’s Triad** (Juxta-articular osteopenia, peripheral osseous erosions, and gradual narrowing of the joint space).

Practice by Chapter

Septic Arthritis

Practice Questions

Osteomyelitis

Practice Questions

Tuberculosis of Bones and Joints

Practice Questions

Fungal and Parasitic Infections

Practice Questions

Diabetic Foot Infections

Practice Questions

Prosthetic Joint Infections

Practice Questions

Reactive Arthritis

Practice Questions

Management of Joint Infections

Practice Questions

Prevention of Orthopaedic Infections

Practice Questions

Biofilms in Orthopaedic Infections

Practice Questions

Antibiotic Prophylaxis

Practice Questions

Implant-Related Infections

Practice Questions

Want unlimited practice?

Get full access to all questions, explanations, and performance tracking.

Start For Free