This is thought to be caused by the process of “wear and tear” of the articular cartilage. It may be predisposed by:
Fracture of a bone going through the joint
Articular cartilage damage from any injury
Abnormal alignment of the leg, for example bow legs, knock knees
Injury which has led to damage of knee ligament or the meniscus
Certain sporting activities, for example, prolonged running
Damage to the articular cartilage is progressive. Eventually it may become completely worn away in patches exposing bare bones, which then may rub against each other causing pain. Debris of cartilage floating in the joint may also cause irritation and inflammation in the joint lining and this is a second source of pain. One may feel the joint to be ‘grinding’.
X-rays show narrowing of the ‘joint space’ along with other features of arthritis. There is no blood test for osteoarthritis.