Knee osteoarthritis

Knee osteoarthritis is the gradual breakdown of cartilage and underlying bone in the knee joint, producing pain, stiffness and reduced function.

It is the most common form of arthritis in the knee and becomes more likely with age, prior injury, excess body weight and repetitive loading. Cartilage thins, bone spurs form at the joint margins, the joint lining can become inflamed, and the surrounding muscles often weaken. Typical features are pain that worsens with activity and eases with rest, stiffness for a short time after sitting or on waking, grinding sensations, swelling and difficulty with stairs or rising from a chair.

Diagnosis rests on history and physical examination, supported by weight-bearing X-rays that show joint-space narrowing; MRI is reserved for unclear cases. Severity is graded on radiographic scales and tracked with questionnaires such as the WOMAC. Management is multidisciplinary, centered on exercise, weight management, physical therapy and, when needed, medications, injections or joint replacement. Cannabinoids have been studied for osteoarthritis pain in animal models and small human studies, including some in the knee, but the evidence is limited and no cannabinoid has an approved use for osteoarthritis.