Because you move so much throughout your day, even a slight problem with tracking and the uneven distribution of pressure on the patella can lead to pain and difficulty in movement.

Arthritis, dislocation and tendinitis are commonly associated with patella problems. Plica bands may create symptoms that are similiar to patella problems.

Arthritis: Also called chondromalacia or patellofemoral disease. Occurs as the cartilage on the back of the patella or in the groove of the thigh bone is damaged. Damaged cartilage can't distribute pressure evenly along the back of the patella. And, since cartilage lacks an adequate bloody supply, it has a limited ability to heal. Uneven pressure continues to wear down the cartilage even further, often leading to pain and stiffness.

Dislocation: If one of the patella's `strings' pulls too hard, the patella may come out of its groove. The patella may come completely out of its groove (dislocation) or only a little way out of the groove (subluxation). Usually, dislocation occurs without warning during activity. You may feel sudden, sharp pain or fell your knee `giving out'.

Patella tendinitis: Patellar tendinitis (also called jumper's knee) occurs when the quadriceps muscles are overused or inflexible. When quadriceps are overused, the patellar tendon has to absorb more of the shock created by movement. If the quadriceps are inflexible, the patellar tendon has to withstand more friction during movement. In either case, the tendon may become irritated or damaged. This can result in pain during activity and pain may continue even when you are resting.

Plica bands: Also called medial shelves, they are elastic fibres near the retinaculum. They often disappear early in a child's development. But for some people, plica bands never go away. They usually cause no problems, and you may not even know you have them. However, occasionally they build up scar tissue and become fibrous and painful, sometimes snapping or catching on the end of the thigh bone.