ANTERIOR KNEE PAIN, or CHONDROMALACIA PATELLA or PATELLOFEMORAL PAIN
The patella, or kneecap, can be a source of knee pain when it fails to function properly in people of all ages. Alignment or overuse problems of the patella can lead to wear and tear of the cartilage behind the patella. This produces pain, weakness, and possibly swelling of the knee joint.
Several different problems can affect the patella and the groove it slides through in the knee joint. The patella (kneecap) is the moveable bone on the front of the knee. This bone has two tendons which attach onto it, the quadriceps tendon on top of the patella and the patellar tendon below the patella. Tightening of the quadriceps muscles on the front of the thigh pulls on the quadriceps tendon, which will cause a pull on the patella, and thus the patellar tendon. This action causes the knee to straighten. The patella acts like a fulcrum to increase the force of the quadriceps muscles. The underside of the patella is covered with articular cartilage, the smooth, slippery covering found on joint surfaces. This covering helps the patella glide (or track) in a special groove made by the thighbone, or femur. This groove is called the femoral groove.
Two muscles of the thigh attach to the patella and help control its position in the femoral groove as the leg straightens. These muscles are the vastus medialis obliquus (VMO) and the vastus lateralis (VL). The VMO runs along the inside of the thigh, and the VL lies along the outside of the thigh. If the timing between these two muscles is off, the patella may be pulled off track.
Problems commonly develop when the patella suffers wear and tear. The underlying cartilage begins to degenerate, a condition sometimes referred to as chondromalacia patella. Wear and tear can develop for several reasons. Degeneration may develop as part of the aging process, like putting a lot of miles on a car. The patellofemoral joint is usually affected as part of osteoarthritis of the knee. Additionally, anterior knee pain can be caused by a muscle imbalance at the knee or the hip. For example, when you straighten your knee if the VMO is weak or does not contract at the right time, the VL will do most of the work and the patella will track to the outside of the femoral groove instead of the middle. This will eventually lead to degeneration and pain.
The main symptom of anterior knee pain is pain. The pain is typically diffuse and surrounds the knee. This pain is usually worse when walking or standing for long periods of time, and especially when doing stairs. Also, sitting for long periods of time with your knee bent may also increase pain. The knee may also grind, or you may hear a crunching sound when you squat or go up and down stairs. If there is a considerable amount of wear and tear, you may feel popping or clicking as you bend your knee. This can happen when the uneven surface of the underside of the patella rubs against the femoral groove. The knee may swell with heavy use and become stiff and tight. This is not unique to problems of the patella but sometimes occurs when the knee becomes inflamed.
The initial goal of physical therapy is to decrease pain and inflammation and to improve range of motion. Once this is accomplished, the therapist will instruct you in a variety of exercises and stretches along with performing hands on techniques to improve functioning of the patella, knee joint, hip and feet. These exercises may be directed at not only your knee and thigh, but also your hips and calves. Your therapist may issue a knee brace or instruct you how to apply tape to your knee. Therapists also design special shoe inserts, called orthotics, to improve knee alignment and function of the patella.