Arthrology and Infections Practice Questions

Q: Most common cause of AVN of the hip is -

Idiopathic. ***Idiopathic*** - The most common cause of **avascular necrosis (AVN)** of the hip is **idiopathic**, meaning no specific underlying cause can be identified. - While many risk factors are associated with AVN, a significant proportion of cases occur without a clear etiology, making **idiopathic AVN** the most frequent presentation. *Corticosteroid use* - **Corticosteroid use** is a major **risk factor** for AVN, but it is not the most common cause overall, as not all cases are associated with steroid exposure. - Long-term use of **high-dose corticosteroids** can disrupt blood supply to the bone by various mechanisms, including **fat emboli** and **vasoconstriction**. *Alcoholism* - **Alcoholism** is another significant **risk factor** for AVN, contributing to a substantial number of cases. - Excessive alcohol consumption can lead to **fatty liver disease** and fat emboli, which can obstruct the blood vessels supplying the femoral head. *Fracture neck of femur* - A **fracture of the neck of the femur** is a well-known cause of **traumatic AVN** due to damage to the blood supply, particularly the **medial circumflex femoral artery**. - However, when considering all causes, including non-traumatic forms, fractures represent a specific subgroup rather than the overall most common cause.

Q: For a distended knee joint, which of the following positions is most comfortable?

30° flexion. ***30° flexion*** - A position of approximately **30 degrees of flexion** is the most comfortable for a distended knee joint because it maximizes the joint volume, thereby reducing intracapsular pressure. - This position allows for some relief from the pressure caused by the excess fluid within the joint capsule. *90° flexion* - **90 degrees of flexion** leads to increased intracapsular pressure in a distended knee, often causing more pain and discomfort. - This position significantly compresses the joint capsule, exacerbating pain when the joint is swollen. *Full extension* - In **full extension**, the knee joint capsule is taut, leading to increased intracapsular pressure when the joint is distended. - This position does not provide sufficient space for fluid accumulation, resulting in significant pain. *60° flexion* - While better than full extension, **60 degrees of flexion** still results in higher intracapsular pressure compared to 30 degrees of flexion. - This position does not allow for optimal expansion of the joint capsule to accommodate the excess fluid.

Q: Choose the wrong statement regarding chondromalacia patella _____:

There is increasing osteoporosis of the patella. ***There is increasing osteoporosis of the patella*** - This statement is incorrect because **chondromalacia patella** is characterized by the softening and breakdown of the **articular cartilage** of the patella, not by **osteoporosis** of the patellar bone itself. - While prolonged disuse or altered biomechanics might lead to some bone changes, **osteoporosis** is not a primary or defining feature of chondromalacia patella. *It primarily affects the articular cartilage of the patella* - This statement is correct. **Chondromalacia patella** refers specifically to the damage and softening of the **hyaline cartilage** on the posterior aspect of the kneecap. - This condition involves the **degeneration** of the smooth, protective cartilage that allows the patella to glide smoothly over the trochlear groove of the femur. *It is commonly associated with vastus medialis weakness* - This statement is correct. Weakness of the **vastus medialis obliquus (VMO)** can lead to an imbalance in the forces acting on the patella, causing it to track laterally. - This **improper tracking** increases stress and friction on the patellar cartilage, contributing to the development or exacerbation of chondromalacia patella. *It commonly affects the lateral facet and central ridge of the patella* - This statement is correct. Due to the biomechanics of the patellofemoral joint, especially in cases of **maltracking**, the **lateral facet** and the **central ridge** of the patella are frequently subjected to increased pressure and friction. - This concentrated stress on these specific areas makes them particularly vulnerable to **cartilage softening and erosion** in chondromalacia patella.

Q: A 10-year-old child with known hemophilia presents with ankle pain. X-ray shows a lytic lesion with sclerotic rim at the calcaneum. What is the most likely diagnosis?

Pseudotumor associated with bleeding disorders. ***Pseudotumor associated with bleeding disorders*** - A lytic lesion with a sclerotic rim in the **calcaneum** in a child with **hemophilia** is highly suggestive of a **hemophilic pseudotumor** due to repeated hemorrhage. - These lesions occur from recurrent **intraosseous bleeding** forming a hematoma that stimulates bone resorption and reactive sclerotic rim formation. - Hemophilic pseudotumors are **expansile, blood-filled cystic lesions** that can mimic neoplasms radiologically. - They are one of the most serious complications of hemophilia, requiring differentiation from malignancy. *Ochronosis* - Ochronosis is a rare metabolic disorder (alkaptonuria) characterized by deposition of **homogentisic acid polymer** in connective tissues. - It typically causes progressive **arthropathy** in adults with diffuse degenerative changes and disc calcifications, not a solitary lytic lesion in a child. *PVNS* - **Pigmented villonodular synovitis (PVNS)** is a benign proliferative disorder of the synovium. - It primarily affects the **synovial lining** of joints and tendon sheaths, causing joint erosions and soft tissue masses, but not typically a solitary intraosseous lytic lesion with sclerotic rim in the calcaneum. *Eumycosis* - **Eumycosis (eumycetoma)** is a chronic, progressively destructive fungal infection affecting subcutaneous tissues and bone. - Classical presentation involves **soft tissue swelling, sinus tracts, and grain discharge**, making it less likely in the absence of these features.

Q: 12 years male came with swelling of lower end tibia which is surrounded by rim of reactive bone. What is most likely diagnosis?

Brodie's Abscess. ***Brodie's Abscess*** - A **Brodie's abscess** is a subacute or chronic osteomyelitis characterized by a localized bone abscess, typically with a surrounding **sclerotic rim of reactive bone**. - It often occurs in the **metaphysis of long bones** (like the lower end of the tibia) in children and adolescents, presenting with localized pain and swelling. *GCT* - **Giant cell tumor (GCT)** typically occurs in **skeletally mature adults** (20-40 years old) and is a lytic lesion often found in the **epiphysis** of long bones, rarely with a distinct sclerotic rim. - GCTs are generally more aggressive and demonstrate a **soap-bubble appearance** with cortical expansion rather than a thick reactive bone rim. *Hyper PTH* - **Hyperparathyroidism** causes bone changes such as **osteopenia**, **subperiosteal bone resorption**, especially in the phalanges, and **brown tumors** (lytic lesions). - It does not typically present as a localized lesion with a **sclerotic rim of reactive bone** in a child. *Osteomyelitis* - While chronic osteomyelitis can involve local bone destruction and reactive bone formation, a **Brodie's abscess** is a specific, well-circumscribed form of **subacute osteomyelitis**. - Acute osteomyelitis presents with more diffuse systemic symptoms (fever, malaise) and less defined reactive bone in its early stages compared to the distinct **sclerotic rim** seen in a Brodie's abscess.

Q: A patient had osteomyelitis in their left tibia 2 years ago. They now present with pain and swelling at the same site. X-ray shows bone destruction, sequestrum, and involucrum. What is the most likely diagnosis?

Chronic osteomyelitis. ***Chronic osteomyelitis*** - The presence of **bone destruction**, **sequestrum** (dead bone), and an **involucrum** (new bone formation around infected tissue) is pathognomonic for **chronic osteomyelitis**. - A history of prior osteomyelitis at the same site, followed by recurrent pain and swelling, indicates a **chronic, persistent infection**. *Ewing's sarcoma* - This is a **highly malignant primary bone tumor** that typically presents with a **"onion skin" appearance** on X-ray due to periosteal reaction, which is not described here. - While it causes pain and swelling, the specific radiological findings of sequestrum and involucrum are not characteristic of Ewing's sarcoma. *Osteogenic sarcoma* - Also known as **osteosarcoma**, this is a **primary bone malignancy** characterized by the production of **osteoid**. X-rays often show a **"sunburst" pattern** or Codman's triangle. - While it causes bone destruction and pain, the presence of sequestrum and involucrum points away from a primary bone tumor and towards a chronic infectious process. *Multiple myeloma* - This is a **hematologic malignancy** involving plasma cells, leading to **punched-out lytic lesions** in bones. - It does not typically present with sequestrum and involucrum, nor does it have a direct causal link to prior osteomyelitis in this manner.

Q: A 25-year-old male presents with chronic leg pain and a draining sinus. What is the most likely diagnosis?

Chronic osteomyelitis. ***Chronic osteomyelitis*** - **Chronic leg pain** combined with a **draining sinus** is highly suggestive of chronic osteomyelitis, indicating persistent bone infection with a tract to the skin. - The draining sinus allows for the discharge of pus and necrotic debris from the infected bone, a classic sign of this condition. *Ewing's sarcoma* - While it can present with bone pain and swelling, a **draining sinus** is not a typical feature of Ewing's sarcoma. - This tumor is often characterized by a rapidly growing mass and systemic symptoms like fever, which are not mentioned. *Osteosarcoma* - This malignant bone tumor typically presents with localized **bone pain and swelling**, often around the knee. - A **draining sinus** is not a hallmark characteristic of osteosarcoma; it is more associated with infection than primary bone malignancy. *Cellulitis* - **Cellulitis** is a superficial soft tissue infection that causes redness, warmth, and tenderness of the skin. - It does not involve the bone and therefore would not present with **chronic bone pain** or a **draining sinus from bone**.

Q: A 10-year-old boy presents with swelling of the knee and fever. Blood tests reveal elevated ESR and CRP. An X-ray of the knee shows periosteal elevation. What is the most likely diagnosis?

Osteomyelitis. ***Osteomyelitis*** - The combination of **fever**, localized swelling (knee), elevated inflammatory markers (**ESR** and **CRP**), and **periosteal elevation** on X-ray in a child is highly suggestive of osteomyelitis. - **Periosteal elevation** indicates inflammation and pus accumulation beneath the periosteum, a characteristic finding in bone infection. *Septic arthritis* - While it presents with **fever** and **joint swelling**, the primary involvement is in the **joint space**, not typically causing bony changes like periosteal elevation on X-ray. - Diagnosis is confirmed by **joint aspiration** showing purulent fluid, not directly by imaging of bone structure. *Osteosarcoma* - This is a **malignant bone tumor** that can cause pain and swelling, but typically presents with a more chronic course without an acute fever. - X-rays would show a **destructive lesion** with a sunburst pattern or Codman's triangle, not just periosteal elevation consistent with infection. *Ewing sarcoma* - This is another **malignant bone tumor** that can present with pain, swelling, and sometimes fever, mimicking infection. - X-rays often show an **"onion-skin" periosteal reaction** (layers of new bone), which is different from the simple periosteal elevation seen in acute osteomyelitis.

Q: What clinical finding is critical for identifying chronic osteomyelitis after sequestrectomy?

Rim sign. ***Rim sign*** - The **rim sign** refers to the presence of a persistent radiolucent 'halo' or rim around the bone post-sequestrectomy, indicating **residual infection** or a cavity that has not obliterated, which is characteristic of ongoing chronic osteomyelitis. - This finding suggests that despite the removal of the necrotic bone (sequestrum), the infection has not been fully eradicated, necessitating further intervention. *Paprika sign* - The **paprika sign** is a diffuse, speckled pattern of increased uptake seen on bone scintigraphy, often associated with **reflex sympathetic dystrophy** or **complex regional pain syndrome**, not chronic osteomyelitis. - It reflects increased peripheral blood flow and bone turnover in the affected limb, a different pathological process from bacterial infection. *Codman's triangle* - **Codman's triangle** is an elevated periosteal reaction seen on radiographs, typically associated with **aggressive bone lesions** such as osteosarcoma or Ewing's sarcoma, or sometimes with rapidly progressing infections. - While it indicates periosteal new bone formation, it is not a direct sign of chronic osteomyelitis itself, nor is it specific to post-sequestrectomy findings. *Sunburst appearance* - The **sunburst appearance** is a classic radiographic finding characterized by radiating spicules of new bone formation perpendicular to the bone cortex, almost exclusively seen in **osteosarcoma**. - This pattern is indicative of a highly aggressive bone tumor and has no relevance to the diagnosis or persistence of chronic osteomyelitis.

Q: What is the most appropriate treatment for a patient with a suspected Brodie's abscess?

Curettage and drainage. ***Correct: Curettage and drainage*** - **Brodie's abscess** is a subacute or chronic form of osteomyelitis involving a localized collection of pus in the bone - **Surgical intervention** with curettage and drainage is necessary to remove infected tissue and decompress the lesion - This approach directly addresses the localized bone infection, removes necrotic debris, and allows for local antibiotic delivery or culture-guided systemic therapy - Promotes healing and prevents recurrence by eliminating the sequestrum and poorly vascularized tissue *Incorrect: IV antibiotics only* - While antibiotics are crucial for treating osteomyelitis, **IV antibiotics alone** are insufficient for Brodie's abscess - The abscess creates an environment with **poor blood supply** to the central necrotic tissue, limiting antibiotic penetration and efficacy - Surgical debridement is essential to remove the avascular focus and allow antibiotics to work effectively *Incorrect: Amputation* - **Amputation** is an extreme measure reserved for severe, chronic, and uncontrollable osteomyelitis with extensive soft tissue damage or sepsis - Only considered when limb salvage procedures have failed or in cases of life-threatening infection - Not appropriate for a localized Brodie's abscess, which typically responds well to less invasive surgical methods *Incorrect: Radiotherapy* - **Radiotherapy** uses high-energy radiation to treat malignancies - Has **no role** in treating bacterial infections like Brodie's abscess - Would be inappropriate and potentially harmful in this clinical context

Question 1

Most common cause of AVN of the hip is -

Accepted Answer

Idiopathic

Answer

Corticosteroid use

Answer

Alcoholism

Answer

Fracture neck of femur

Question 2

For a distended knee joint, which of the following positions is most comfortable?

Accepted Answer

30° flexion

Answer

90° flexion

Answer

Full extension

Answer

60° flexion

Question 3

Choose the wrong statement regarding chondromalacia patella _____:

Accepted Answer

There is increasing osteoporosis of the patella

Answer

It primarily affects the articular cartilage of the patella

Answer

It is commonly associated with vastus medialis weakness

Answer

It commonly affects the lateral facet and central ridge of the patella

Question 4

A 10-year-old child with known hemophilia presents with ankle pain. X-ray shows a lytic lesion with sclerotic rim at the calcaneum. What is the most likely diagnosis?

Accepted Answer

Pseudotumor associated with bleeding disorders

Answer

Ochronosis

Answer

PVNS

Answer

Eumycosis

Question 5

12 years male came with swelling of lower end tibia which is surrounded by rim of reactive bone. What is most likely diagnosis?

Accepted Answer

Brodie's Abscess

Answer

GCT

Answer

Hyper PTH

Answer

Osteomyelitis

Question 6

A patient had osteomyelitis in their left tibia 2 years ago. They now present with pain and swelling at the same site. X-ray shows bone destruction, sequestrum, and involucrum. What is the most likely diagnosis?

Accepted Answer

Chronic osteomyelitis

Answer

Ewing's sarcoma

Answer

Osteogenic sarcoma

Answer

Multiple myeloma

Question 7

A 25-year-old male presents with chronic leg pain and a draining sinus. What is the most likely diagnosis?

Accepted Answer

Chronic osteomyelitis

Answer

Ewing's sarcoma

Answer

Osteosarcoma

Answer

Cellulitis

Question 8

A 10-year-old boy presents with swelling of the knee and fever. Blood tests reveal elevated ESR and CRP. An X-ray of the knee shows periosteal elevation. What is the most likely diagnosis?

Accepted Answer

Osteomyelitis

Answer

Septic arthritis

Answer

Osteosarcoma

Answer

Ewing sarcoma

Question 9

What clinical finding is critical for identifying chronic osteomyelitis after sequestrectomy?

Accepted Answer

Rim sign

Answer

Codman's triangle

Answer

Sunburst appearance

Answer

Paprika sign

Question 10

What is the most appropriate treatment for a patient with a suspected Brodie's abscess?

Accepted Answer

Curettage and drainage

Answer

IV antibiotics only

Answer

Amputation

Answer

Radiotherapy

Arthrology and Infections — MCQs

Arthrology and Infections — MCQs

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