A 2 year old 70 kg child presents with limitation of abduction and internal rotation. On examination there is tenderness in scarpa’s triangle. On flexing the hip the limb is abducted. What is the MOST likely diagnosis?
**Core Concept**
The question is testing the understanding of **hip pathology** in children, specifically the presentation and clinical signs of a common condition affecting the hip joint. The **limping child** with limited mobility and tenderness in a specific area suggests a localized problem that requires precise diagnosis.
**Why the Correct Answer is Right**
Given the age, weight, and symptoms of the child, including **limitation of abduction and internal rotation**, along with **tenderness in Scarpa's triangle**, the presentation is highly suggestive of a condition where the femoral head is not properly seated in the acetabulum, leading to restricted movement. The fact that **on flexing the hip, the limb is abducted** indicates a specific mechanical issue related to the hip joint.
**Why Each Wrong Option is Incorrect**
**Option A:** Would not typically present with such specific mechanical findings related to hip movement.
**Option B:** Might present with pain but the specific pattern of limited abduction and internal rotation with relief on flexion is not characteristic.
**Option C:** Could involve the hip but the pattern of symptoms and signs, especially the relief with flexion, does not fit.
**Option D:** Is not a common diagnosis for the symptoms described.
**Clinical Pearl / High-Yield Fact**
A key point to remember is that **developmental dysplasia of the hip (DDH)** can present in various ways, including asymmetrical skin folds, limited abduction, and sometimes a palpable "clunk" as the femoral head moves in and out of the acetabulum. However, the specific presentation here hints more towards a condition that affects the mechanical alignment and movement of the hip joint, suggesting a different but related issue.
**Correct Answer:** D. Developmental Dysplasia of the Hip.