Chondromalacia Patellae

Chondromalacia patellae describes the wearing away, or arthritic deterioration, of the cartilage beneath the knee cap. The rather complicated-sounding name comes from the word roots "chondro-" (meaning "cartilage"), "malacia" (meaning "soft") and "patellae" (meaning "knee cap")

Anyone can get it if their knee sees enough abuse over time--a wear and tear cause, but those most predisposed are those with a biomechanical misalignment where the thigh muscles (the quadriceps) are oriented in such a way where they pull the knee cap off its normal path on the bone below, thereby causing excessive wear to the cartilage underneath the knee cap.

The angle between the thigh and the patellar tendon is known as the Q-Angle, (see diagram to the right), and chondromalacia patellae is more common in those with an increased Q-Angle, as the pull of the tendon on the knee cap is more oblique.

First, it could be from a structural issue. For example, the bones in the leg and thigh may have developed crooked relative to each other. This is relatively common, as the angle between the thigh bone and leg bone change relative to each other during development. Sometimes the position between these two bones may not end up being ideal.

It should be noted that women are one group who commonly demonstrate an increased Q-angle as a result of structural differences. This is due to the difference in the structure of the hip, resulting in an altered angle the thigh bone takes as it leaves the hip.

Second, an increased Q-angle may be a biomechanical issue. In this case, the leg and thigh bones may be normal in terms of basic structure, but may become crooked during gait. This may occur for a biomechanical reason, like if the foot is overly pronated in gait. In this case, the foot would flatten excessively while walking or running, and this may cause the leg bones to internally rotate in compensation, increasing the Q-angle.

Symptoms usually begin in the teenage years with a complaint of pain around the knee cap. Pain is usually worse with increased activity--particularly with sports. Pain may also be experienced in the arch of the foot, the leg muscles (shin splints), hip and low back. X-rays don't show any pathology in the early stages.

As time progresses, the cartilage begins to wear, the pain typically worsens, and arthritis develops.

Chondromalacia patellae is best treated early before arthritis develops, so a thorough examination of the patient should be conducted as soon as symptoms develop. All too often the condition is left to deteriorate until surgery is necessary.

First, treating the patient biomechanically is essential. If there is a leg-length discrepancy, for example, this can usually be addressed with modifications to the shoe or with an over-the-counter insert. Knee braces may be used in other cases. If the patient has a pronated foot type as a primary or secondary cause, a custom-made functional orthosis will usually control the problem, often preventing unnecessary deterioration of the knee. It's important to emphasize that the biomechanical causes of this condition are ignored (as they often are), all other treatments will have limited success, and the pain is likely to continue.

Second, proper athletic training (such as building up the muscles that help balance those that are pulling the knee cap abnormally) and instruction in proper stretching are also important. These measures can often slow down the wear on the knee.

You can also treat the condition symptomatically--with anti-inflammatories, physiotherapy, massage, acupuncture, and so forth, but these measures don't really resolve the underlying cause.

Finally, surgical intervention may be considered. This may mean arthroscopic surgery--where worn cartilage is removed from the knee through a small incision, and possibly a procedure to attempt to rebalance the muscles pulling the knee cap in an abnormal direction. Or in severe cases, it may mean realignment of the major leg bones.