Swelling of the knee can be caused by direct injury to the joint, problems with the menisci (Cartilages) or arthritis. It is always a symptom of an underlying problem.
Lateral tracking Patella.
Also know as ‘snapping kneecaps’. This is a consequence of an imbalance of the tension within the four muscles of the quadriceps muscle group. These are the muscles, which straighten the knee. The muscle on the outer side becomes tighter that the muscle on the inner side causing the kneecap to be pulled to the outside as the knee joint is flexed and straightened. As it is pulled out of its natural pathway the underside of the patella can be irritated and become inflamed and painful. Some times a clunking feeling or a clicking noise is reported.
Ligamentous injury.
There are many strong ligaments to stabilise the knee joint during movement and when standing. They can be strained or sprained by direct injury or become weakened as a result of degenerative changes. Patients complain of pain, swelling, giving way of the joint and loss in confidence of the joint during activity.
Meniscal damage/ Cartilage injury.
Meniscal tears are usually a result of a sporting injury, when a twisting strain is put through a flexed, weight-bearing joint. Symptoms include pain, swelling, locking of the knee and pain on straightening the joint.
Menisci can also degenerate with the aging process, causing tenderness along the joint line, sometimes for no apparent reason.
Osteoarthritis
This is a very common problem due to the stresses of weightbearing, with or without previous injury
Referred pain.
This is pain, felt in the knee arising from a problem elsewhere, such as in the lower back, hip, ankle or foot, either from altered mechanics in the joint or from irritation of the nerves supplying the joint.