Arthrology and Infections Practice Questions

Q: What is the main diagnostic feature of chronic osteomyelitis?

Sequestrum. **Explanation:** Chronic osteomyelitis is characterized by persistent infection leading to bone necrosis and new bone formation. The **Sequestrum** is the hallmark diagnostic feature of this condition. 1. **Why Sequestrum is Correct:** A sequestrum is a piece of dead (necrotic) bone that has become separated from the surrounding living bone during the process of necrosis. It occurs because the pus in the medullary cavity and subperiosteal space strips the periosteum, compromising the blood supply. Because it is avascular, it appears **radiodense (whiter)** on X-rays compared to the surrounding osteoporotic bone and acts as a nidus for persistent infection. 2. **Analysis of Incorrect Options:** * **Bone Fracture:** While pathological fractures can occur in chronic osteomyelitis due to weakened bone structure, they are a complication rather than a diagnostic hallmark. * **Deformity:** Chronic infection can lead to growth plate disturbances or malunion, resulting in deformity, but this is a late sequela and not specific to the diagnosis of the infection itself. * **Brodie’s Abscess:** This is a localized form of **subacute osteomyelitis**, typically found in the metaphysis of long bones (most commonly the tibia). While it involves infection, it represents a contained, chronic-onset abscess rather than the generalized necrotic process of classic chronic osteomyelitis. **NEET-PG High-Yield Pearls:** * **Involucrum:** The layer of new living bone formed around the sequestrum. * **Cloaca:** An opening in the involucrum through which pus and sequestra are discharged. * **Marjolin’s Ulcer:** A rare but high-yield complication where squamous cell carcinoma develops in a long-standing sinus tract of chronic osteomyelitis. * **Gold Standard Investigation:** MRI is the most sensitive for early detection, but the presence of a sequestrum on X-ray is the classic diagnostic sign.

Q: Which of the following is NOT true about HIV-associated osteomyelitis?

Necrosis is absent. **Explanation:** HIV-associated osteomyelitis presents with unique pathological features compared to pyogenic osteomyelitis in immunocompetent individuals. **1. Why "Necrosis is absent" is the correct answer (False Statement):** In HIV-associated osteomyelitis, **necrosis is actually a hallmark feature.** The infection is often aggressive due to the compromised immune system, leading to extensive bone destruction and the formation of **sequestrum** (dead bone). The statement that necrosis is absent is incorrect, making it the right choice for this "NOT true" question. **2. Analysis of Incorrect Options:** * **B. It is often bilateral:** Unlike standard osteomyelitis, which is typically unifocal, HIV-associated bone infections frequently present with **multifocal or bilateral involvement** due to hematogenous spread and poor host containment. * **C. Periosteal new bone formation is present:** Despite the necrosis, the body attempts to stabilize the bone. Radiologically, this manifests as **involucrum** (periosteal new bone formation) surrounding the infected area. * **D. The most common cause is *Staphylococcus aureus*:** Even in HIV-positive patients, ***Staphylococcus aureus*** remains the most common causative organism. However, there is a higher-than-normal incidence of atypical pathogens like *Salmonella*, *Mycobacterium avium-intracellulare*, and fungi. **Clinical Pearls for NEET-PG:** * **Radiological triad:** Look for bone destruction (necrosis), sequestrum, and involucrum. * **Atypical Presentation:** In advanced AIDS, inflammatory markers (like ESR/CRP) may be lower than expected due to a blunted immune response. * **Differential:** Always consider **Bacillary Angiomatosis** (caused by *Bartonella*) in HIV patients presenting with lytic bone lesions and overlying skin nodules.

Q: A 36-year-old woman with sickle cell disease presents with increasing pain in her right hip. She has no fever, chills, back or other bone pain, and there is no history of any trauma. On examination, her temperature is 37.3°C, range of motion in the right hip is reduced, she walks with a limp, and the right leg is shorter than the left. Movements of the hip and walking on it are painful. X-rays of the hip are shown. Which of the following is the most likely diagnosis?

avascular necrosis (AVN) of the femoral head. ***Avascular necrosis (AVN) of the femoral head*** - **Sickle cell disease** predisposes to AVN due to **vascular occlusion** from sickling of red blood cells, leading to bone infarction and necrosis of the femoral head. - Clinical presentation of **reduced hip range of motion**, **leg length discrepancy**, and **painful walking** without fever are classic signs of AVN in sickle cell patients. *Osteomyelitis* - Typically presents with **systemic symptoms** including high fever, chills, and elevated inflammatory markers, which are absent in this case. - **Sickle cell patients** are prone to osteomyelitis, but the lack of fever and normal temperature make this diagnosis less likely. *Hip fracture* - Requires a **history of trauma** or significant force, which is explicitly absent in this patient's presentation. - **X-ray findings** would show clear fracture lines rather than the changes typical of avascular necrosis. *Septic arthritis* - Usually presents with **high fever**, **acute onset** of severe pain, and **systemic toxicity**, none of which are present here. - The **gradual onset** and **absence of fever** make septic arthritis unlikely despite the patient's underlying sickle cell disease.

Q: Multifocal non-suppurative osteomyelitis is seen in which of the following conditions?

SAPHO syndrome. **Explanation:** **SAPHO syndrome** is the correct answer because it is a rare inflammatory disorder characterized by **sterile (non-suppurative)** bone and joint inflammation. The acronym stands for **S**ynovitis, **A**cne, **P**ustulosis, **H**yperostosis, and **O**steitis. The hallmark pathological feature is chronic recurrent multifocal osteomyelitis (CRMO), which involves inflammatory bone lesions without the presence of pyogenic bacteria or pus formation. **Analysis of Incorrect Options:** * **Infantile cortical hyperostosis (Caffey’s Disease):** While it involves multifocal bone formation (hyperostosis) and subperiosteal new bone, it is characterized by sudden onset irritability and soft tissue swelling in infants, typically involving the mandible. It is a proliferative bone disease rather than a classic "osteomyelitis" pattern. * **Thalassemia:** This is a hematologic disorder. Bone changes (like the "crew-cut" appearance) occur due to **extramedullary hematopoiesis** and marrow expansion, not due to an inflammatory or non-suppurative osteomyelitic process. * **Salmonella infections:** This causes **suppurative** (pus-forming) osteomyelitis. It is classically associated with Sickle Cell Anemia. Since the question specifies "non-suppurative," this option is incorrect. **Clinical Pearls for NEET-PG:** * **SAPHO Syndrome:** Look for the "Bull’s head" sign on a bone scan (increased uptake at the sternoclavicular joints). * **CRMO:** This is considered the pediatric equivalent or a component of the SAPHO spectrum. * **Treatment:** First-line treatment typically involves NSAIDs; bisphosphonates or TNF-alpha inhibitors are used for refractory cases. * **Garré’s Sclerosing Osteomyelitis:** Another form of non-suppurative osteomyelitis, but it is typically unifocal (usually the mandible) and associated with dental infections.

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 10–15% of all extrapulmonary TB cases. **1. Why Spine is the Correct Answer:** The **Spine (Pott’s Disease)** is the most common site of skeletal tuberculosis, accounting for approximately **50%** of all osteoarticular TB cases. The infection typically involves the paradiscal region of the vertebral bodies. The high incidence is attributed to the rich vascular supply (Batson’s venous plexus) which allows for the hematogenous spread of *Mycobacterium tuberculosis* from a primary focus (usually the lungs or lymph nodes). **2. Analysis of Incorrect Options:** * **Hip (Option C):** This is the **second most common** site of skeletal TB (roughly 15%). It is the most common site in the extremities. * **Knee (Option B):** This is the **third most common** site. Like the hip, it is a weight-bearing joint, making it more susceptible than upper limb joints. * **Shoulder (Option D):** TB of the shoulder (often presenting as *Caries Sicca*) is relatively rare compared to the weight-bearing joints of the lower limb and the spine. **3. NEET-PG High-Yield Pearls:** * **Most common site in Spine:** Lower Thoracic and Upper Lumbar vertebrae. * **Most common type of vertebral involvement:** Paradiscal (leads to disc space narrowing). * **Cold Abscess:** A hallmark of skeletal TB; it lacks the typical signs of inflammation (heat/redness). * **Order of frequency:** Spine > Hip > Knee > Elbow > Shoulder. * **Diagnosis:** Gold standard is tissue biopsy for histopathology (granulomas) and Culture (Lowenstein-Jensen medium) or GeneXpert.

Q: Pseudoflexion deformity of the hip is typically seen in which of the following conditions?

Iliopsoas abscess. ### Explanation **Correct Answer: A. Iliopsoas Abscess** **Why it is correct:** The term **Pseudoflexion deformity** refers to a clinical presentation where the hip appears to be in a fixed flexion deformity (FFD), but the underlying joint itself is healthy. In an **Iliopsoas abscess**, the collection of pus irritates the iliopsoas muscle, causing it to go into a protective spasm. Since the iliopsoas is the primary flexor of the hip, the patient holds the hip in flexion to minimize tension on the muscle and reduce pain. The key diagnostic feature is that while extension is painful and restricted, **internal and external rotation of the hip are preserved and painless** when the hip is in a flexed position. This distinguishes it from true intra-articular pathology where all movements are restricted. **Why other options are incorrect:** * **Tom Smith Arthritis:** This is septic arthritis of the infancy. It involves the destruction of the femoral head/epiphysis, leading to a **true deformity** and global restriction of all hip movements. * **Rickets:** Typically presents with bony deformities like coxa vara, genu valgum, or genu varum due to softened osteoid, but it does not cause an acute pseudoflexion deformity. * **Posterior Dislocation of the Hip:** This presents with a characteristic position of **flexion, adduction, and internal rotation**. This is a true structural deformity resulting from the displacement of the femoral head, not a "pseudo" deformity. **High-Yield Clinical Pearls for NEET-PG:** * **Psoas Sign:** Pain on passive extension of the hip; a classic sign of psoas irritation (abscess or retrocecal appendicitis). * **Thomas Test:** Used to measure Fixed Flexion Deformity (FFD). In pseudoflexion, the test may be positive, but the preservation of rotations helps localize the pathology to the muscle rather than the joint. * **Triad of Psoas Abscess:** Fever, flank pain, and limp (or restricted hip extension).

Q: Which of the following is NOT a deformity of rheumatoid arthritis?

Claw hand. **Explanation:** The correct answer is **Claw hand** because it is a neurological deformity, not a primary manifestation of Rheumatoid Arthritis (RA). 1. **Claw Hand:** This deformity results from **peripheral nerve palsies**, most commonly the **Ulnar nerve** (at the wrist or elbow). It is characterized by hyperextension at the Metacarpophalangeal (MCP) joints and flexion at the Interphalangeal (IP) joints. While RA can cause nerve entrapment (like Carpal Tunnel Syndrome), "Claw hand" is classically associated with conditions like Leprosy, Syringomyelia, or Brachial Plexus injuries (Klumpke’s palsy). 2. **Why other options are incorrect (RA Deformities):** * **Swan neck deformity:** Caused by laxity of the volar plate, leading to **hyperextension of the PIP joint** and flexion of the DIP joint. * **Boutonnière deformity:** Results from the rupture or attenuation of the **central slip** of the extensor tendon, leading to **flexion of the PIP joint** and hyperextension of the DIP joint. * **Hallux valgus:** RA frequently involves the forefoot. Synovitis of the first MTP joint leads to lateral deviation of the great toe (Hallux valgus) and bunion formation. **Clinical Pearls for NEET-PG:** * **Earliest sign of RA on X-ray:** Periarticular osteopenia (juxta-articular rarefaction). * **Most common joint involved in RA:** MCP joints (specifically the 2nd and 3rd). * **Z-deformity:** Refers to radial deviation of the wrist with ulnar deviation of the fingers. * **Mnemonic for Boutonnière:** "Central slip is ripped" (Flexed PIP). * **Mnemonic for Swan Neck:** "Volar plate is late" (Extended PIP).

Q: Which part of the bone is most commonly affected in children with acute osteomyelitis?

Metaphysis. **Explanation:** Acute Hematogenous Osteomyelitis (AHO) is primarily a disease of growing children, and the **Metaphysis** is the most common site of involvement due to its unique vascular anatomy. **Why Metaphysis is the correct answer:** 1. **Hairpin Loops:** The nutrient arteries end in sharp "hairpin" loops at the physeal plate before emptying into large venous sinusoids. This sudden change in direction causes turbulent blood flow and stasis. 2. **Sluggish Blood Flow:** The slow flow in the venous sinusoids allows circulating bacteria (most commonly *Staphylococcus aureus*) to settle and proliferate. 3. **Deficient Phagocytosis:** The capillary loops in this region lack a robust population of functional phagocytic cells (macrophages), making it an ideal environment for infection to take hold. **Why other options are incorrect:** * **Diaphysis:** While it can be involved (e.g., in Sickle Cell Anemia where *Salmonella* is common), it lacks the sluggish venous sinusoids found in the metaphysis. * **Epiphysis:** This is usually spared because the physis (growth plate) acts as a mechanical barrier to the spread of infection. However, in infants ( Proximal Tibia (areas of rapid growth). * **Earliest X-ray sign:** Soft tissue swelling (bone changes like periosteal reaction take 7–14 days to appear). * **Investigation of choice:** **MRI** (most sensitive for early detection). * **Sequestrum:** Dead bone (radiodense); **Involucrum:** New bone formation around the sequestrum.

Question 1

What is the main diagnostic feature of chronic osteomyelitis?

Accepted Answer

Sequestrum

Answer

Bone fracture

Answer

Deformity

Answer

Brodie's abscess

Question 2

Which of the following is NOT true about HIV-associated osteomyelitis?

Accepted Answer

Necrosis is absent

Answer

It is often bilateral

Answer

Periosteal new bone formation is present

Answer

The most common cause is Staphylococcus aureus

Question 3

A patient with tubercular synovitis of the hip joint was treated with anti-tubercular therapy (ATT) and skin traction. Despite prolonged chemotherapy, no improvement is observed. What is the next best step in management?

Accepted Answer

Synovectomy and joint debridement

Answer

Total hip replacement

Answer

Arthrodesis

Answer

Continue the same treatment for 12 months

Question 4

A 36-year-old woman with sickle cell disease presents with increasing pain in her right hip. She has no fever, chills, back or other bone pain, and there is no history of any trauma. On examination, her temperature is 37.3°C, range of motion in the right hip is reduced, she walks with a limp, and the right leg is shorter than the left. Movements of the hip and walking on it are painful. X-rays of the hip are shown. Which of the following is the most likely diagnosis?

Accepted Answer

avascular necrosis (AVN) of the femoral head

Answer

osteomyelitis

Answer

hip fracture

Answer

septic arthritis

Question 5

Multifocal non-suppurative osteomyelitis is seen in which of the following conditions?

Accepted Answer

SAPHO syndrome

Answer

Infantile cortical hyperostosis

Answer

Thalassemia

Answer

Salmonella infections

Question 6

What is the most common site of tuberculosis?

Accepted Answer

Spine

Answer

Knee

Answer

Hip

Answer

Shoulder

Question 7

Pseudoflexion deformity of the hip is typically seen in which of the following conditions?

Accepted Answer

Iliopsoas abscess

Answer

Tom Smith arthritis

Answer

Rickets

Answer

Posterior dislocation of the hip

Question 8

Which of the following is NOT a deformity of rheumatoid arthritis?

Accepted Answer

Claw hand

Answer

Swan neck deformity

Answer

Boutonnière deformity

Answer

Hallux valgus

Question 9

What is true about synovial chondromatosis?

Accepted Answer

Metaplastic cartilage formation occurs throughout the synovium.

Answer

Elderly men are typically affected.

Answer

Bone scan is usually normal.

Answer

Chondrosarcoma is a common complication.

Question 10

Which part of the bone is most commonly affected in children with acute osteomyelitis?

Accepted Answer

Metaphysis

Answer

Diaphysis

Answer

Epiphysis

Answer

Vertebrae

Arthrology and Infections — MCQs

Arthrology and Infections — MCQs

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