The Achilles tendon is one of the strongest tendons in the human body. Unfortunately, it is also one of the most commonly injured tendons as well. The tendon connects the calf muscles (gastroc, soleus, plantaris) to the heel bone. These muscles are responsible for pointing the foot downward or plantar flexing the foot. Surrounding the tendon around the heel are fluid-filled sacs called bursa that help cushion the tendon and enhance its movement. (Figure 1)

The Achilles tendon is supplied with blood from three different sources. The most abundant blood supply is located at the tail ends of the tendon. The central portion of the tendon has the poorest blood supply making it more susceptible to injury. This area is usually 2-6 cm above the heel and is called the "watershed area". Also, other conditions in the foot and ankle can compromise blood supply to the tendon weakening it further, for example flat feet.

Achilles tendon tears can be either acute or chronic. Acute tears will cause sharp pain and people usually report hearing a "pop." The injury is described as feeling as if you have been "shot" or "kicked" directly in the Achilles tendon. Most patients then usually are unable to bear weight or return to activity on the injured tendon.  (Figure 2)

Acute tears are usually caused by the sudden application of a force usually a forceful lengthening or eccentric muscle contraction. Eccentric means the muscle is decelerating or attempting to slow down the body. The tendon is unable to handle the sudden force and rupture occurs.

Chronic tears result as a combination of decreased blood supply and repetitive microtrauma, meaning many repeated minor injuries. Over time the tendon becomes weaker due to the repeated injury and lack of sufficient blood and as a result the tendon is never able to fully heal itself. This situation increases the risk of rupture of the Achilles tendon.

The history given on how the injury occurs usually helps with the diagnosis. Diagnosis can be confirmed by palpation and the Thompson test.  In this test, the patient lies on their stomach with their feet hanging off the back of the table. The examiner then squeezes the calf, normally the foot points downward or plantar flexes. If the foot does not move, the tendon has been ruptured and it is unable to produce the movement. Imaging studies such as X-rays, MRI, and ultrasonography have been used to confirm the presence of a ruptured Achilles tendon.  (Figure 3)

The treatment for a ruptured Achilles tendon is surgery. The goal of the surgery is to reconnect the "mop ends" of the tendon to promote healing and restore muscle function. The surgery usually occurs about one week after the injury and is an outpatient procedure.

Following the surgery, the patient is placed in a cast for six to eight weeks to protect the tendon while it is healing. Once the cast has been removed, the tendon is still not ready for full stress and is protected by using a walking boot or heel lift for up to eight weeks. Crutches may be used to help progress the ability to bear weight on the foot.

After the cast has been removed physical therapy begins with gentle active motion and stretching exercises in all planes of movement. The goal initially is to regain the motion lost due to immobilization and swelling. Sometimes the physical therapist may use whirlpool or pool therapy to assist with motion exercises. If any of these activities cause pain and/or swelling the activities should be modified and the pain and swelling must be controlled before progressing on to the next phase of rehabilitation. The physical therapist can use a variety of modalities to attempt to decrease pain and swelling including: ice, elevation, electrical stimulation, and ultrasound.

As the motion begins to improve light strengthening exercises can be started in all the same planes of motion. Initially isometric exercises are used. With these exercises the muscles are contracted but no motion is produced. Eventually, weight-bearing exercises such as heel raises are begun. Balance exercises will also be started at this time. The physical therapist will also begin to help the patient normalize their walking.

Before being allowed to return to high-level activities such as running and sports, the patient must demonstrate full range of motion, normal pain-free gait (walking), and the ability to rapidly perform heel raises. The time to return to these high level activities is therefore different for everyone, but it may usually begin within four to six months following the surgery.

Brotzman SB, Wilk KE. Clinical Orthopaedic Rehabilitation. Mosby, St Louis. 410-412.

Maxey L, Magnusson J. Rehabilitation for the Postsurgical Orthopedic Patient. Mosby, St. Louis. 2001. 323-350.