A 60-year old man with diabetes mieelitus presents with painless, swollen right ankle joint. Radiographs of the ankle show destroyed joint with large number of loose bodies. The most probable diagnosis is –
**Core Concept**
The patient's presentation of a painless, swollen ankle joint with radiographic evidence of joint destruction and loose bodies is suggestive of a degenerative joint disease. This condition is characterized by cartilage breakdown, bone-on-bone contact, and the formation of loose bodies within the joint space.
**Why the Correct Answer is Right**
The patient's symptoms and radiographic findings are consistent with osteoarthritis (OA), a degenerative joint disease that occurs due to the wear and tear of joint cartilage. In OA, the cartilage that cushions the joint is gradually destroyed, leading to bone-on-bone contact and the formation of loose bodies, which are fragments of cartilage or bone that break off and float within the joint space. The absence of pain in this patient is also consistent with OA, as it often presents with a painless, swollen joint.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is likely incorrect because OA is a degenerative joint disease that typically affects weight-bearing joints, such as the hips, knees, and spine, rather than the ankle joint.
**Option B:** This option is incorrect because osteonecrosis, also known as avascular necrosis, is a condition that occurs when there is a loss of blood supply to a bone, leading to cell death and joint destruction. While osteonecrosis can cause joint destruction, it typically presents with pain and is not typically associated with loose bodies.
**Option C:** This option is incorrect because rheumatoid arthritis (RA) is an autoimmune disease that causes inflammation and joint destruction, but it typically presents with pain and stiffness, rather than a painless, swollen joint.
**Clinical Pearl / High-Yield Fact**
A useful mnemonic to remember the key features of OA is "PAINLESS": P - Painless joint, A - Absence of morning stiffness, I - Insidious onset, N - No systemic symptoms, L - Loose bodies on radiograph, E - Elderly patients, S - Swollen joint, S - Slow progression.
**Correct Answer: C. Osteoarthritis**