What is the difference between tendonitis and tenosynovitis?

Tendinitis and tenosynovitis are two distinct conditions commonly seen in sports injuries and overuse injuries, frequently occurring in joint areas such as the wrists, fingers, shoulders, and ankles. Below are some key differences between these two conditions:

1. Etiology: Tendinitis refers to inflammation of the tendon itself—tendons are tough connective tissues that attach muscles to bones. When tendons are subjected to stress from overuse, repetitive movements, or injury, symptoms such as pain, swelling, and limited function may develop. In contrast, tenosynovitis may be associated with joint diseases such as rheumatoid arthritis and systemic sclerosis, or can be caused by chronic strain, trauma, and other factors leading to acute or chronic inflammatory reactions of the tendon sheath.

2. Clinical Symptoms: Tendinitis presents with pain when moving or touching the inflamed tendon, and may be accompanied by joint stiffness and muscle atrophy. Tenosynovitis mainly manifests as localized pain, tenderness, and restricted joint movement; some patients may also experience radiating pain extending toward the extremities.

3. Common Affected Sites: Tendinitis commonly occurs in joints such as the elbow, wrist, and shoulder, while tenosynovitis is more frequently seen in the fingers, toes, wrist, and ankle.