**Question:** Tennis elbow', is characterized by -

**Core Concept:** Tennis elbow is a common term used to describe lateral epicondylitis, which is an inflammation of the tendons that attach the muscles of the forearm to the bone at the outer side of the elbow.

**Why the Correct Answer is Right:** Tennis elbow is caused by overuse injuries due to repetitive or forceful actions of the forearm muscles, particularly those of the extensor group. The inflammation in lateral epicondylitis leads to pain and tenderness on the outer side of the elbow, and may cause limited elbow movement.

**Why Each Wrong Option is Incorrect:**

A. "Tennis elbow" typically affects both sides of the body, not just one.
B. This option is not specific to lateral epicondylitis, as other causes of elbow pain may present similarly.
C. This option is too broad, as various other conditions can cause elbow pain, such as fractures, infections, and neurological disorders.
D. This option is incorrect because tennis elbow is not directly caused by playing tennis; it is a result of overuse injuries from various activities involving repetitive or forceful forearm movements.

**Clinical Pearl:** Tennis elbow is often misdiagnosed as a result of its common association with tennis, leading to unnecessary avoidance of tennis activities. However, tennis elbow can occur in various occupations involving repetitive wrist and forearm extension, such as plumbers, carpenters, and office workers using a keyboard.

**Correct Answer:**

D. Tennis elbow is characterized by pain and tenderness on the outer side of the elbow, resulting from overuse injuries due to repetitive or forceful actions of the forearm muscles, particularly those of the extensor group.