Arthrology and Infections — MCQs

Arthrology and Infections Indian Medical PG Practice Questions and MCQs

Question 81: Calcification around the joint is seen in which of the following conditions?

A. Pseudogout
B. Hyperparathyroidism
C. Rheumatoid arthritis
D. Gout (Correct Answer)

Explanation: **Explanation:** The correct answer is **Gout**. In chronic tophaceous gout, the deposition of Monosodium Urate (MSU) crystals leads to the formation of **tophaceous deposits**. While pure urate crystals are radiolucent, they frequently undergo secondary **dystrophic calcification** over time. This appears on X-rays as irregular, radio-opaque masses in the periarticular soft tissues, often associated with characteristic "punched-out" or "martel’s" erosions with overhanging edges. **Analysis of Options:** * **Pseudogout (CPPD):** While this involves calcium pyrophosphate deposition, the hallmark is **Chondrocalcinosis** (calcification of the articular cartilage or fibrocartilage, like the meniscus), rather than generalized periarticular soft tissue calcification. * **Hyperparathyroidism:** This condition typically presents with subperiosteal bone resorption (especially in phalanges), brown tumors, and salt-and-pepper skull. While it can cause metastatic calcification in soft tissues, it is not a primary feature of joint-specific pathology compared to Gout. * **Rheumatoid Arthritis:** This is characterized by **periarticular osteopenia** (decreased bone density) and uniform joint space narrowing. Calcification is not a feature; in fact, the inflammatory process leads to bone destruction rather than deposition. **High-Yield Clinical Pearls for NEET-PG:** * **Gout Gold Standard:** Polarized microscopy showing **needle-shaped, negatively birefringent** crystals. * **Radiological Sign:** "Punched-out" erosions with **overhanging edges** (Martel’s sign). * **Common Site:** First metatarsophalangeal joint (Podagra). * **Drug of Choice:** NSAIDs for acute attacks; Allopurinol (Xanthine oxidase inhibitor) for chronic management. *Note: Never start Allopurinol during an acute attack.*

Question 82: What is the earliest radiological change observed in rheumatoid arthritis?

A. Decreased joint space
B. Articular erosion
C. Periarticular osteopenia (Correct Answer)
D. Subchondral cyst

Explanation: **Explanation:** In Rheumatoid Arthritis (RA), the primary pathology is **synovitis**. The inflamed synovium (pannus) releases inflammatory cytokines and increases local blood flow (hyperemia). This hyperemia leads to increased osteoclast activity and the leaching of calcium from the bone surrounding the joint, resulting in **Periarticular Osteopenia** (also known as juxta-articular osteoporosis). This is the **earliest** radiological sign of RA. **Analysis of Options:** * **Periarticular Osteopenia (Correct):** The earliest change caused by local inflammatory hyperemia before structural bone destruction occurs. * **Decreased Joint Space:** This occurs later as the pannus destroys the articular cartilage. In RA, joint space narrowing is typically **uniform/symmetrical**, unlike the asymmetrical narrowing seen in osteoarthritis. * **Articular Erosion:** These are "marginal erosions" that occur at the "bare areas" (where the bone is not covered by cartilage). While characteristic of RA, they appear after osteopenia. * **Subchondral Cyst:** These are more characteristic of degenerative conditions like Osteoarthritis (Geodes). While they can occur in late-stage RA, they are not an early or primary feature. **NEET-PG High-Yield Pearls:** 1. **Earliest Sign (Overall):** Soft tissue swelling (due to effusion/synovitis). 2. **Earliest Bony Sign:** Periarticular osteopenia. 3. **Characteristic Feature:** Symmetrical involvement of small joints (MCP, PIP) sparing the DIP joints. 4. **Late Radiological Signs:** Subluxations (e.g., Atlanto-axial), ulnar deviation of fingers, and ankylosis. 5. **MRI** is the most sensitive imaging modality to detect early synovitis and bone marrow edema before they appear on X-rays.

Question 83: Which of the following is NOT a complication of acute osteomyelitis?

A. Chronic osteomyelitis
B. Septicemia
C. Recurrence
D. Osteoclastoma (Correct Answer)

Explanation: **Explanation:** **1. Why Osteoclastoma is the Correct Answer:** Osteoclastoma (Giant Cell Tumor) is a **primary benign bone tumor**, not a sequela of infection. Its etiology is related to the neoplastic proliferation of mononuclear stromal cells, whereas acute osteomyelitis is an inflammatory process caused by pyogenic bacteria (most commonly *Staphylococcus aureus*). There is no pathophysiological link between acute infection and the development of this neoplasm. **2. Analysis of Other Options (Complications of Acute Osteomyelitis):** * **Chronic Osteomyelitis:** This is the most common complication, occurring if the acute infection is inadequately treated, leading to bone necrosis (sequestrum formation). * **Septicemia:** Since acute osteomyelitis is often hematogenous in origin, bacteria can re-enter the bloodstream from the bone, leading to systemic sepsis, multi-organ failure, or metastatic abscesses. * **Recurrence:** Even with treatment, bacteria can remain dormant in the canaliculi or within necrotic bone, leading to recurrent bouts of infection months or years later. **3. NEET-PG High-Yield Pearls:** * **Most common site:** Metaphysis of long bones (due to hair-pin arrangement of vessels and sluggish blood flow). * **Most common organism:** *Staphylococcus aureus* (overall); *Salmonella* (in Sickle Cell Anemia patients). * **Pathognomonic features:** **Sequestrum** (dead bone) and **Involucrum** (new bone formation around the dead bone). * **Cloaca:** An opening in the involucrum through which pus and sequestra are discharged. * **Malignant transformation:** While Osteoclastoma is not a complication, **Squamous Cell Carcinoma** (Marjolin’s ulcer) can occur in the skin of a chronic discharging sinus tract.

Question 84: What is the treatment for a displaced proximal olecranon fracture?

A. Excision and resuturing
B. Tension band wiring (Correct Answer)
C. Immobilization of the elbow by cast
D. Open reduction and external fixation

Explanation: **Explanation:** The olecranon is an intra-articular structure and the site of insertion for the **triceps brachii** muscle. When fractured, the triceps exerts a powerful proximal pull, leading to displacement and loss of active elbow extension. **Why Tension Band Wiring (TBW) is the Correct Answer:** TBW is the gold standard for **displaced, transverse, non-comminuted** proximal olecranon fractures. It operates on the **"Tension Band Principle,"** which converts distracting tensile forces (from the triceps) into compressive forces across the fracture site during elbow flexion. This promotes primary bone healing and allows for early range of motion, preventing joint stiffness. **Analysis of Incorrect Options:** * **A. Excision and resuturing:** This is only considered in elderly, low-demand patients with highly comminuted fractures where internal fixation is impossible. It requires reattaching the triceps to the distal fragment but often leads to joint instability. * **C. Immobilization by cast:** This is reserved for **undisplaced** fractures. In displaced fractures, casting fails to counteract the triceps pull, leading to non-union and permanent loss of extension. * **D. Open reduction and external fixation:** External fixation is rarely used for olecranon fractures unless there is severe soft tissue compromise or an open "mangled" extremity. For comminuted fractures, **Plate and Screw fixation** is the preferred surgical alternative to TBW. **High-Yield Clinical Pearls for NEET-PG:** * **Indication for TBW:** Transverse fracture distal to the midpoint of the trochlear notch. * **Indication for Plate Fixation:** Comminuted fractures, Monteggia fracture-dislocations, or fractures distal to the coronoid process. * **Complication:** The most common complication of TBW is **symptomatic hardware** (prominent K-wires) requiring removal after union. * **Nerve Injury:** The **Ulnar nerve** is the most commonly at-risk structure during surgical approach.

Question 85: What is the most commonly affected joint in syphilis?

A. Ankle
B. Knee (Correct Answer)
C. Hip
D. Elbow

Explanation: **Explanation:** The **Knee joint** is the most commonly affected joint in both congenital and acquired syphilis. The clinical presentation typically manifests in two distinct forms: 1. **Clutton’s Joints (Congenital Syphilis):** This is a hallmark manifestation occurring typically between ages 8 and 15. It is characterized by symmetrical, painless bilateral swelling (effusion) of the knees. It is a chronic hydrarthrosis that does not lead to joint destruction. 2. **Charcot’s Joint (Tertiary Syphilis):** In late-stage acquired syphilis (Tabes Dorsalis), the loss of proprioception and pain sensation leads to a neuropathic joint. The knee is the most frequent site for this "painless, deformed, and unstable" joint, characterized by the "6 Ds": Destruction, Debris, Density, Disorganization, Dislocation, and Distension. **Analysis of Incorrect Options:** * **Ankle:** While the ankle can be involved in neuropathic arthropathy (Charcot’s), it is less common than the knee in the context of Tabes Dorsalis. * **Hip:** Syphilitic involvement of the hip is rare. Hip pathology is more commonly associated with tuberculosis or avascular necrosis. * **Elbow:** Upper limb joints are rarely the primary site for syphilitic arthritis; it predominantly affects weight-bearing joints due to the mechanical stress involved in neuropathic changes. **High-Yield Clinical Pearls for NEET-PG:** * **Clutton’s Joint triad:** Bilateral knee effusion + Painless + Congenital syphilis. * **Hutchinson’s Triad:** Interstitial keratitis, sensorineural deafness, and notched central incisors (Hutchinson’s teeth). * **Pathognomonic sign:** The presence of a "painless but flail joint" should immediately raise suspicion of a Charcot’s joint (Syphilis or Diabetes Mellitus).

Question 86: What is the most common causative organism for acute pyogenic osteomyelitis?

A. Staphylococcus aureus (Correct Answer)
B. Streptococcus pneumoniae
C. Pneumococcus
D. Escherichia coli

Explanation: **Explanation:** **Staphylococcus aureus** is the most common causative organism for acute pyogenic osteomyelitis across almost all age groups (infants, children, and adults). The primary reason for its dominance is its high virulence and its ability to express specific surface receptors (adhesins) that allow it to bind effectively to bone matrix components like collagen, fibronectin, and laminin. It typically reaches the bone via **hematogenous spread**, often originating from a minor skin infection or trauma. **Analysis of Incorrect Options:** * **Streptococcus pneumoniae & Pneumococcus:** While these can cause osteomyelitis, they are much rarer and usually occur secondary to respiratory infections. * **Escherichia coli:** This is a common cause of osteomyelitis in neonates or following urinary tract infections/instrumentation in elderly patients, but it remains less frequent than *S. aureus* overall. **Clinical Pearls for NEET-PG:** * **Overall Most Common:** *Staphylococcus aureus*. * **Sickle Cell Disease:** *Salmonella* is a high-yield association, though *S. aureus* remains a frequent co-contender. * **Neonates:** Group B Streptococcus and *E. coli* are significant pathogens alongside *S. aureus*. * **IV Drug Users:** Increased incidence of *Pseudomonas aeruginosa*. * **Puncture Wounds (Foot):** *Pseudomonas aeruginosa*. * **Most Common Site:** Metaphysis of long bones (due to sluggish blood flow in hairpin medullary loops). * **Gold Standard Investigation:** MRI is the most sensitive early imaging modality; however, Bone Biopsy/Culture is the definitive gold standard for identifying the organism.

Question 87: The paprika sign observed during debridement is crucial in the management of which of the following conditions?

A. Chronic osteomyelitis (Correct Answer)
B. Osteosarcoma
C. Osteoid osteoma
D. Brodie's abscess

Explanation: **Explanation:** The **Paprika Sign** is a vital intraoperative clinical indicator used during the surgical management of **Chronic Osteomyelitis**, specifically during the process of **sequestrectomy and saucerization**. 1. **Why Chronic Osteomyelitis is correct:** The hallmark of chronic osteomyelitis is the presence of a **sequestrum** (dead, avascular bone). Successful treatment requires the complete removal of this necrotic tissue until healthy, vascularized bone is reached. The "Paprika Sign" refers to the appearance of **punctate bleeding points** on the bone surface, resembling paprika spice, after the sclerotic and dead bone has been debrided. This sign confirms that the surgeon has reached viable, living bone with an intact blood supply, which is essential for antibiotic delivery and bone healing. 2. **Why the other options are incorrect:** * **Osteosarcoma:** Management involves wide local excision or limb salvage surgery based on oncological margins, not the assessment of punctate bleeding for viability. * **Osteoid Osteoma:** This is a benign bone-forming tumor characterized by a "nidus." Treatment involves complete excision or radiofrequency ablation of the nidus, rather than extensive debridement to vascular bone. * **Brodie's Abscess:** While a form of subacute osteomyelitis, it is a localized, contained abscess. While debridement is used, the specific term "Paprika Sign" is classically associated with the extensive decortication/saucerization of chronic diffuse osteomyelitis. **High-Yield Clinical Pearls for NEET-PG:** * **Sequestrum:** Dead bone (radiodense). * **Involucrum:** New bone formation around the sequestrum. * **Cloaca:** An opening in the involucrum for pus/debris exit. * **Treatment Goal:** The Paprika Sign ensures an adequate "biological environment" for healing by confirming vascularity.

Question 88: Chronic persistent neutrophilic discharge is seen in which of the following conditions?

A. Chronic osteomyelitis (Correct Answer)
B. Acute osteomyelitis
C. Septic arthritis
D. None of the above

Explanation: **Explanation:** **Chronic Osteomyelitis** is characterized by the presence of necrotic bone, known as a **sequestrum**. This dead bone acts as a persistent nidus for infection because it lacks a blood supply, preventing antibiotics and immune cells from reaching the bacteria. The body attempts to wall off this infection by forming new bone (**involucrum**), but the pus eventually tracks to the skin surface through a **cloaca**, forming a **sinus tract**. This results in a **chronic, persistent neutrophilic (purulent) discharge** that typically lasts for weeks or months. **Why other options are incorrect:** * **Acute Osteomyelitis:** This is a systemic illness presenting with high-grade fever, intense local pain, and swelling. While pus forms, it is usually contained subperiosteally. If it discharges, it is an acute event, not a "chronic persistent" one. * **Septic Arthritis:** This presents as an acute emergency with a hot, swollen joint and restricted range of motion. While the joint aspirate is rich in neutrophils, it does not typically present with a chronic discharging sinus unless it becomes secondarily chronic (which is rare with modern treatment). **High-Yield Clinical Pearls for NEET-PG:** * **Sequestrum:** Dead bone (Radiodense on X-ray). * **Involucrum:** New bone formed around the sequestrum. * **Cloaca:** The opening in the involucrum through which pus/sequestra escape. * **Marjolin’s Ulcer:** A rare but high-yield complication where a long-standing chronic osteomyelitis sinus tract undergoes malignant transformation into **Squamous Cell Carcinoma**. * **Gold Standard Investigation:** MRI is the most sensitive, but a **Sinogram** is used to visualize the extent of the sinus tract.

Question 89: Which of the following is commonly known as 'Tom Smith's Arthritis'?

A. Pyogenic infection of infancy (Correct Answer)
B. Tuberculosis
C. Rheumatoid arthritis in children
D. Osteoarthritis in middle-aged men

Explanation: **Explanation:** **Tom Smith’s Arthritis** refers to **acute pyogenic (septic) arthritis of the hip in infants** (usually under one year of age). **Why Option A is Correct:** In infants, the branches of the nutrient artery pierce the unossified epiphyseal plate, creating a direct vascular communication between the metaphysis and the epiphysis. Consequently, an osteomyelitis in the metaphysis can easily spread into the joint space. Because the femoral head is largely cartilaginous at this age, the pyogenic infection (commonly *Staphylococcus aureus* or *Streptococcus*) rapidly destroys the capital femoral epiphysis. This leads to a pathological dislocation or a "flail hip," resulting in significant limb shortening and permanent deformity. **Why Other Options are Incorrect:** * **Option B (Tuberculosis):** While TB can affect the hip, it is a chronic granulomatous infection. It does not present with the acute, rapid destruction characteristic of Tom Smith’s Arthritis. * **Option C (Rheumatoid arthritis in children):** This is known as Juvenile Idiopathic Arthritis (JIA). It is an autoimmune inflammatory condition, not a primary pyogenic infection. * **Option D (Osteoarthritis):** This is a degenerative joint disease typically seen in the elderly; it is not associated with the eponymous infant condition. **High-Yield Clinical Pearls for NEET-PG:** * **Clinical Presentation:** The infant presents with a high fever, "pseudoparalysis" of the limb, and pain on passive movement. * **Radiological Sign:** The "empty acetabulum" sign may be seen later due to the destruction of the femoral head. * **Sequelae:** It is a common cause of a **short-limb gait** and Trendelenburg-positive gait in early childhood. * **Treatment:** This is a surgical emergency requiring immediate arthrotomy and drainage to save the joint.

Question 90: Pseudotumor syndrome is seen in which of the following conditions?

A. Systemic Lupus Erythematosus (SLE)
B. Thalassemia
C. Hemophilia (Correct Answer)
D. Hyperparathyroidism

Explanation: **Explanation:** **Hemophilic Pseudotumor** is a rare but serious complication occurring in approximately 1–2% of patients with severe hemophilia. It is caused by recurrent, progressive subperiosteal or soft tissue hemorrhages. 1. **Why Hemophilia is correct:** The "pseudotumor" is actually a chronic, encapsulated hematoma. As the hematoma expands, it exerts pressure on surrounding structures, leading to pressure necrosis of muscles and, more significantly, **bone destruction and remodeling**. Radiologically, it mimics a malignant bone tumor (like osteosarcoma) due to its osteolytic appearance and periosteal reaction, hence the name "pseudotumor." It most commonly involves the femur and pelvis. 2. **Why other options are incorrect:** * **SLE:** Typically presents with non-erosive arthritis (Jaccoud’s arthropathy) or avascular necrosis, but not pseudotumors. * **Thalassemia:** Characterized by marrow hyperplasia leading to a "crew-cut" appearance on skull X-ray and "chipmunk facies," but not localized pseudotumors. * **Hyperparathyroidism:** Associated with **Brown Tumors** (osteitis fibrosa cystica). While these are also "false" tumors, the term "Pseudotumor Syndrome" is classically reserved for the hemophilic entity in orthopedic literature. **High-Yield Clinical Pearls for NEET-PG:** * **Most common site:** Femur (in adults); small bones of hands/feet (in children). * **Management:** Conservative management with factor replacement is tried first, but surgical excision or aspiration is often required if it is large or threatening neurovascular structures. * **Differential Diagnosis:** Must be distinguished from **Brown tumors** (Hyperparathyroidism) and **Giant Cell Tumors**. * **Radiological hallmark:** Large soft tissue mass with adjacent bone destruction and a "soap bubble" appearance.

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

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Antibiotic Prophylaxis

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Implant-Related Infections

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