**Question:** In a 3-year-old child with polio paralysis, tendon operation is done at:

A. Elbow
B. Wrist
C. Ankle
D. Knee

**Core Concept:** Poliomyelitis, caused by the poliovirus, is a viral infection that primarily affects motor neurons in the spinal cord and brainstem, leading to weakness, paralysis, and dysfunction of the muscles innervated by the affected neurons. In polio-induced paralysis, tendon transplants are performed to restore functional movement.

**Why the Correct Answer is Right:** In polio-induced paralysis, the primary motor neurons are damaged, leading to muscle weakness and paralysis. This results in impaired muscle function and joint instability, necessitating reconstructive surgeries like tendon transplants. In the case of a 3-year-old child, a tendon transplant is typically performed at the ankle (C) due to the immature and unstable joints, making the ankle joint an ideal site for tendon transplants to improve muscle function, stability, and overall mobility.

**Why Each Wrong Option is Incorrect:**

A. Elbow (Option A): Although the elbow joint can be affected in severe cases, the primary focus of paralysis in polio is the lower limbs, particularly the ankle and knee joints. Performing the surgery at the elbow is less common and less effective compared to the ankle.

B. Wrist (Option B): Similar to the elbow, the wrist joint is less commonly affected in polio paralysis, making it an even less suitable site for tendon transplant surgery compared to the ankle.

D. Knee (Option D): The knee joint is usually spared in polio paralysis, and performing surgery here is less effective for the restoration of functional movement and stability.

**Clinical Pearl:** In poliomyelitis, tendon transplants at the ankle (C) provide the most significant improvement in muscle function, stability, and overall mobility due to the prevalence of lower limb involvement and the immature nature of the child's joints at this age.

**Correct Answer: C. Ankle**

**Core Concept:** Tendon transplants are performed to improve muscle function, stability, and mobility in patients with poliomyelitis-induced paralysis. The choice of surgical site depends on the severity and location of muscle weakness, joint instability, and the child's age. In a 3-year-old child, the ankle (C) is the most suitable site for tendon transplant surgery due to the immature nature of the child's joints and the higher prevalence of lower limb involvement in poliomyelitis. This choice ensures better restoration of muscle function, stability, and overall mobility compared to other options.