In a newborn child, abduction and internal rotation produces a click sound. It is –
**Core Concept**
In newborn children, the hip joint is not yet fully ossified, and the femoral head is still malleable. The process of abduction and internal rotation helps to reduce any hip dislocation or dysplasia, which is a common issue in this age group. This phenomenon is related to the concept of femoral head reduction.
**Why the Correct Answer is Right**
When a newborn child's hip is abducted and internally rotated, the femoral head is gently guided into the acetabulum, which can produce a characteristic click sound. This occurs due to the femoral head moving into its correct position within the acetabulum. The click is often described as a palpable and audible event. The process of femoral head reduction is facilitated by the laxity of the joint capsule and the surrounding soft tissues.
**Why Each Wrong Option is Incorrect**
* **Option A:** This option is not relevant to the phenomenon described in the question.
* **Option B:** The click sound is not related to the reduction of a dislocated shoulder joint.
* **Option C:** The click sound is not a result of the reduction of a congenitally short femur.
**Option D:** This option is the correct answer.
**Clinical Pearl / High-Yield Fact**
The click sound produced by abduction and internal rotation in a newborn child is an important clinical sign for the diagnosis of developmental dysplasia of the hip (DDH). It is essential for pediatricians and orthopedic surgeons to recognize this sign and investigate further to prevent long-term complications.
**Correct Answer: D. Click of Shenton's line and femoral head reduction.**