Elbow Issues

Patellar Tendonitis

Causes
Patellar tendonitis occurs most often as a result of stresses placed on the supporting structures of the knee. Running, jumping, and repetitive movements from knee flexion into extension (e.g., rising from a deep squat) contribute to this condition. Overuse injuries from sports activities is the most common cause but anyone can be affected, even those who do not participate in sports or recreational activities.

There are extrinsic (outside) factors that are linked with overuse tendon injuries of the knee. These include inappropriate footwear, training errors (frequency, intensity, duration), and the surface or ground (hard surface, cement) being used for the sport or event (such as running). Training errors are summed up by the rule of "toos". This refers to training too much, too far, too fast, or for too long. Advancing the training schedule forward too quickly is a major cause of patellar tendonitis.

Intrinsic (internal) factors such as age, flexibility, and joint laxity are also important. Malalignment of the foot, ankle, and leg can play a key role in tendonitis. Flat foot position, tracking abnormalities of the patella, rotation of the tibia (called tibial torsion), and a leg length difference can create increased and often uneven load on the quadriceps mechanism.

An increased Q-angle or femoral anteversion are two common types of malalignment that contribute to patellar tendonitis. The Q-angle is the angle formed by the patellar tendon and the axis of pull of the quadriceps muscle. This angle varies between the sexes. It is larger in women compared to men. The normal angle for men or womenis usually less than 15 degrees. Angles more than 15 degrees create more of a pull on the tendon, creating painful inflammation.

Any muscle imbalance of the lower extremity from the hip down to the toes can impact the quadriceps muscle and affect the joint. Individuals who are overweight may have added issues with load and muscle imbalance leading to patellar tendonitis.

Strength of the patellar tendon is in direct proportion to the number, size, and orientation of the collagen fibers that make up the tendon. Overuse is simply a mismatch between the load or stress on the tendon and the ability of that tendon to distribute the force. If the forces placed on the tendon are greater than the strength of the structure, then injury can occur. Repeated microtrauma at the muscle-tendon junction may overcome the tendon’s ability to heal itself. Tissue breakdown occurs, often triggering an inflammatory response that leads to tendonitis.

Chronic tendonitis is really a problem called tendonosis. Inflammation is not present. Instead, degeneration and/or scarring of the tendon has developed. Chronic tendon injuries are much more common in older athletes (30 to 50 years old).

Symptoms
Pain from patellar tendonitis is felt just below the patella. The pain is most noticeable when you move your knee or try to kneel. The more you move your knee, the more tenderness develops in the area of the tendon attachment below the kneecap.

There may be swelling in and around the patellar tendon. It may be tender or very sensitive to touch. You may feel a sense of warmth or burning pain. The pain can be mild or in some cases the pain can be severe enough to keep the runner from running or other athletes from participating in their sport. The pain is worse when rising from a deep squat position. Resisted quadriceps contraction with the knee straight also aggravates the condition.