**Core Concept**
Posteromedial bowing of the tibia in a 6-month-old boy is a common congenital deformity involving the long bone of the lower leg. It is characterized by a lateral curvature of the tibia, which can result from various factors, including genetic conditions, intrauterine positioning, or mechanical stress.

**Why the Correct Answer is Right**
The management of posteromedial bowing of the tibia in a child of this age involves observation and reassessment, as most cases will resolve spontaneously by the age of 2-3 years. However, if the deformity is significant or shows signs of progression, treatment may be necessary. In such cases, a thorough evaluation of the underlying cause and a careful assessment of the child's overall health and development are required.

**Why Each Wrong Option is Incorrect**
**Option A:** Surgical correction is not typically recommended in infants, as it may lead to complications and does not address the underlying cause of the deformity.
**Option B:** Casting or bracing may be used in older children to correct the deformity, but it is not the preferred initial management strategy in infants.
**Option C:** Physical therapy may be beneficial in some cases, but it is not a primary treatment for posteromedial bowing of the tibia.

**Clinical Pearl / High-Yield Fact**
In children with congenital lower limb deformities like posteromedial bowing of the tibia, it's essential to monitor for signs of neurovascular compromise or associated musculoskeletal abnormalities, which may require prompt medical attention.

**Correct Answer: D. Observation and reassessment.**