Overview
Arthritis of the knee is a result of wearing away of the cartilage within the knee joint. Normally, cartilage protects a joint and allows it to move smoothly. When cartilage breaks down and wears away, the bones in the knee rub together, causing pain, swelling, and stiffness. Over time, the breakdown of tissues within the joint can cause the bones in the knee to move out of their normal position or become misaligned. The joint may angle inward (knock-kneed) or angle outward (bow-legged).
Review Date 6/20/2024
Updated by: C. Benjamin Ma, MD, Professor, Chief, Sports Medicine and Shoulder Service, UCSF Department of Orthopaedic Surgery, San Francisco, CA. Also reviewed by David C. Dugdale, MD, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.