In a healthy joint, a rubbery tissue called cartilage cushions the ends of the bones at contact points. A thin, smooth tissue called the synovial membrane covers the other surfaces and releases a fluid that lubricates the knee.
Knee With Osteoarthritis
Osteoarthritis in the knee begins with the gradual deterioration of cartilage. Without the protective cartilage, the bones begin to rub together, causing pain, loss of mobility, and deformity.