The plantaris tendon lies in the middle part of the calf muscle, on the back of the leg about halfway between the knee joint and the ankle. It extends from the plantaris muscle and attaches to the Achilles tendon, which is the tendon just above the heel and behind the ankle joint. A relatively small tendon, the plantaris tendon is not as vital to overall function as the Achilles tendon, but it can, on occasion, rupture and cause severe discomfort.
A plantaris rupture occurs most often during sports activities, particularly tennis. As a result, this type of injury is sometimes referred to as "tennis leg." Rapid movements required by tennis players, such as accelerating rapidly toward the net or making abrupt direction changes, can strain this area of the leg, leading to injury. Plantaris ruptures occur more often in male athletes, particularly part-time athletes between 40 and 60 years old.
When the injury occurs, the individual might actually hear or feel the tendon pop and feel an intense, stabbing pain in the calf. Pain accompanying a plantaris tendon rupture is persistent and lies deeper within the calf muscle than if the muscle itself were strained. In some cases, the plantaris muscle and tendon have suffered chronic swelling that finally manifests in a rupture, but most of the time, the injury occurs suddenly.
A plantaris tendon strain can sometimes be mistaken for an injury to the Achilles tendon. Doctors diagnosing the strain must examine the Achilles tendon and evaluate movement in the foot, heel and lower leg to rule out damage to this area. Damage to the Achilles tendon is a more serious condition and requires orthopedic treatment. By contrast, a plantaris tear can be treated with rest, alternating cold and heat, elevation and analgesics to manage the pain. Plantaris tendon strains also can be accompanied by swelling and strain or damage to the calf muscle itself.
To avoid strains, athletes should warm up before strenuous activity. Practicing a comprehensive warm-up and stretching regimen before activities such as playing tennis can increase flexibility in the muscles and tendons so they respond better to strain placed on them during the activity. Any sudden or nagging pain in the calf area should be brought to the attention of a doctor, because prompt treatment can help tendon strains and other injuries heal more quickly and thoroughly.