Osteoarthritis (OA) refers to a group of abnormalities involving the degradation of joints, characterized by the wearing of cartilaginous tissue at the end of bones. This wearing down results in bone rubbing against bone, causing pain, decreased movement, atrophic muscles, and lax ligaments. The most commonly affected joints are those in the hands, neck, lower back, knees, and hip. Clinical symptoms of OA include joint pain and tenderness, loss of flexibility, stiffness, grating sensations, bone spurs, and locking. There are several causes that precipitate OA, the most important of them being aging. Normal wear and tear of cartilages ensures that almost everyone has at least some minor symptoms of OA by the time they reach the seventh decade of their life. Female gender is another risk factor for OA. Over the age of 55, more women than men are affected. Being overweight increases the risk for OA, especially those affecting the joints in the hip and legs. Other risk factors predisposing to OA include having a family history, long-term overuse of the joints, bleeding disorders, and other types of arthritis.

OA is the most common joint disorder worldwide. The diagnosis of OA requires a detailed clinical examination. X-ray analysis can help confirm the diagnosis. The condition tends to gradually worsen with time, and unfortunately, no cure exists. Treatment can, however, relieve the symptoms, and slow down disease progression. Management strategies include taking analgesics (e.g., paracetamol and NSAIDs) to combat the pain and modifying lifestyle to tackle the progression. Severe and debilitating pain may require joint replacement surgery. Lifestyle changes include rest, exercise, and losing weight if overweight. Application of cold and hot packs over affected joints is also helpful.

Epidemiological studies of family histories have confirmed the significant genetic component of OA. Twin studies suggest a heritability of more than 50%. Several association studies have linked OA to loci on chromosomes 2p, 2q, 3p, 9q, 11q, 16p, and 20q. Some of these loci code for proteins that are involved in building up the cartilage matrix. FRZB (Frizzled Related Protein) gene is known to confer susceptibility to osteoarthritis-1.