Knee pain is very common in the general population from children to seniors. The most common knee pain is in the front of knee, worse when stepping down stairs and aches when sitting still for a while. This is caused by the mistraction of the kneecap along the femoral trochear groove. If not corrected, the cartilage at the lateral section of both kneecap and femoral trochea will degraded slowly and become arthritic.
Second common knee pain is at the medial joint gap of the knee, and the knee will become inversely curved slowly with age if not corrected. It is caused by increased pressure at the medial compartment of the knee joint between the medial condyle of the tibia and femur. the treatment would be targeting the muscles at the medial regions of the leg.
The third common knee pain is behind the knee. The common symptom is the jarring feeling behind the knee and unstable feeling when the knee is extended fully. Pain behind the knee is common when the knee is fully flexed. In most cases the cause of this type of knee pain is not in the knee, but from the lower back. It is a symptom of sciatica.
Other types of chronic knee pain are rare but occasional seen in the clinic, including lateral friction, subcutaneous bursitis, fat pad impingement etc.