Disorder of the Achilles Tendon
The Achilles tendon is a strong, fibrous tissue. It connects the muscles in the back of your lower leg, or calf, to your heel bone. The Achilles tendon is the largest and strongest tendon in the body as it bears forces of up to 12 times your body weight, which happens when you sprint. The tendon is surrounded by a tissue called paratenon, which helps the tendon move back and forth and supports the blood vessels that provide nutrients to the tendon. Because the tendon plays such a vital role in bearing weight and moving, it undergoes a lot of stress, which makes it prone to being injured. Problems with the Achilles tendon are among the most common seen in orthopedic clinics in North America.

This article reviews the incidence and etiology, or basis, of Achilles tendon injuries, as well as diagnosis and treatment.

Tissues that surround the Achilles tendon are rich in blood supply to provide nutrients to the tendon. The tendone itself is affected by several factors, such as age, sex, use or disuse, overload, endurance training, and resistance training. As people age, the tendon tissue can become less dense, losing some of its strength. This could be one of the reasons why tendon injuries happen more often in older athletes.

There are three main areas where you can have an Achilles tendon injury:

1- towards the center of the tendon, about two to six centimeters down from the top where it's first felt below the calf. This injury is most common among younger, more active people. This can result in a total rupture (breaking) of the tendon.
2- a bursitis, irritation of the bursa, a fluid-filled sac that helps provide a gliding surface between tissues, just above the heel.
3- degeneration of tissue around where the tendon meets the ankle. This is seen most often as people age.

Some risk factors for problems with the Achilles tendon include obesity, high blood pressure and use of steroids. Sports and vigorous activities are also a risk for injuring the tendon. The most common action that causes injury is running, moving the back of the foot up and down excessively, and wearing incorrect shoes for the activity. According to one study, active athletes who were younger than 30 years were 2.5 times more likely to injure their Achilles tendon than someone who was not as active. An actual rupture, or tear, of the tendon, happens more often in people who participate in occasional sports or activities, after being sedentary for the most part. This happens frequently in sports like basketball and racquetball.

While many athletes stretch before participating in sports, the jury is still out as to whether stretching helps prevent tendon injuries. One theory about why the injuries occur is that the tendon is deteriorating and the tissues are breaking down with use. At some point, the force of movement causes the tendon to snap.

When diagnosing a tendon injury, physicians have used ultrasound. However, it's not always possible to tell the difference between a partial or complete tear. Ultrasounds are good for following progress of treatment. In one study looking at using ultrasound for diagnosing Achilles tendon injuries, 125 patients were followed to see if their ruptured tendons would re-rupture. There were 67 patients who had surgery and 58 who did not have surgery. The ultrasound had been used to determine if the patients should have surgery. Those patients who had gaps larger than five millimeters received surgery. There was no significint rerupture rate found in either group, meaning that the use of ultrasound to find the larger ruptures appears to be successful in determining which patients should have surgery.

Other disorders are diagnosed with magnetic resonance imaging (MRI), which makes images with magnets rather than radiation or sound waves. The MRI can show signs of tendinosis inflammation of the tendon. In fact, one study found that patients who were diagnosed with an MRI with having significant changes in the tendon around the heel area and that they would then be better off having surgery than not.

Treatments for tendon injuries can be non-operative or operative. If a physician chooses a non-operative approach, the patient may be given eccentric training. Eccentric movements involve lengthening muscle fibers. The movements are the opposite of concentric movements, which involve contracting the muscles. Studies have shown that these exercises can reduce pain and speed up recovery of function. However, it appears that the exercises may really be effective only for athletes and not people how are usually not active. In a study of sedentary people with the tendon injury, only slightly more than half saw improvement with this treatment.

Other physicians have used shock wave therapy. Shock therapy uses thousands of targeted shock wave pulses aimed at the injured area. The shock waves cause mild, wanted, trauma to the area. This then causes inflammation or swelling and this breaks down scar tissue that may be causing the pain.

When looking at surgery for treatment, the haglund deformity, which is found at about the level of the top of a shoe at the back of the foot, can be corrected by surgery. While it used to be done with an open incision, now surgeons are working on using less invasive types of surgeries, using smaller instruments and small incisions.

When surgery is not the first choice, it is needed if the non-operative treatments fail. The type of surgery performed depends on the injury, the severity, and the precise location. In some cases,surgeons may choose to make the tendon longer in order to lessen the stress on the tendon. This procedure has been successful, according to results of one study.

If a patient has ruptured the Achilles tendon, surgery can help relieve the stiffness and withering of calf muscles (atrophy). Surgery will also reduce the chances of the patient developing a blood clot or re-rupture of the tendon after healing. The strength of the repaired tendon depends on the type of material the surgeon uses when suturing (stitching) the tendon back together. As well, the strength depends on the post-surgery period.

After surgery, usually the leg is kept in a cast for about six weeks, with the patient not being allowed to bear weight on the foot. After the six weeks, the patient begins exercising and then gradually progresses through more intense exercise until full function or as close to full function is regained. Several studies have been done to see which type of rehabilitation method is best, but the treatments in use now all seem to have the same outcome, more or less.

If a physician chooses to treat a ruptured tendon without surgery, the leg will likely be casted for several weeks, with gradual use and weight-bearing on the foot. However, many physicians do not recommend this treatment as non-operative treatments have a high rerupture rate, longer rehabilitation periods, and lower successful return to previous levels of activity.

In conclusion, the authors write that the common injuries with the Achilles tendon are more common in active people, regardless of their age. The currently used protocols for weightbearing after surgery seems to be relatively successful, although doctors are working on using less invasive methods of surgery, which will also affect rehabilitation. the recommend that future studies be done to gain more insight into the issues of treating Achilles tendon injuries.
John D. Duerden and John J. Keeling, Disorders of the Achilles Tendon. in Current Orthopaedic Practice. May/June 2008.Vol. 19. No. 3. Pp. 253-258.