The Achilles tendon is the extension from the two large muscles in the calf region, the gastrocnemius and the soleus. These two muscles combine to form the Achilles tendon. The tendon forms in the lower one third of the leg and extends to the back of the heel bone (calcaneus). When the muscles of the calf contract this produces tension on the Achilles tendon pulling on the back of heel causing the heel to rise and the foot to point downward. It is during this motion that high-tension force is transmitted through the Achilles tendon during pushing and jumping activity. This high tension force can cause the Achilles tendon to tear or rupture. This happens in 3 common locations. The most common location for a tendon tear is within the tendon substance just above the heel. The second and third most common locations are where the Achilles tendon attaches into the heel bone and higher in the leg, where the tendon begins.
Common causes of an Achilles tendon rupture include the progression of or the final result of longstanding Achilles tendonitis or an overuse injury. An injury to the ankle or a direct blow to the Achilles tendon. As a result of a fall where an individual lands awkwardly or directly on the ankle. Laceration of the tendon. Weakness of the gastrocnemius or soleus muscles in people with existing Achilles tendonitis places increased stress on the tendon. Steroid use has been linked to tendon weakness. Certain systemic diseases have been associated with tendon weakness. A sudden deceleration or stopping motions that cause an acute traumatic injury of the ankle. Injection of steroids to the involved tendon or the excessive use of steroids has been known to weaken tendons and make them susceptible to rupture. Contraction of the calf muscles while the foot is dorsiflexed (pointed toward the head) and the lower leg is moving forward.
A sudden and severe pain may be felt at the back of the ankle or calf, often described as "being hit by a rock or shot" or "like someone stepped onto the back of my ankle." The sound of a loud pop or snap may be reported. A gap or depression may be felt and seen in the tendon about 2 inches above the heel bone. Initial pain, swelling, and stiffness may be followed by bruising and weakness. The pain may decrease quickly, and smaller tendons may retain the ability to point the toes. Without the Achilles tendon, though, this would be very difficult. Standing on tiptoe and pushing off when walking will be impossible. A complete tear is more common than a partial tear.
Diagnosis is made by clinical history; typically people say it feels like being kicked or shot behind the ankle. Upon examination a gap may be felt just above the heel unless swelling has filled the gap and the Simmonds' test (aka Thompson test) will be positive; squeezing the calf muscles of the affected side while the patient lies prone, face down, with his feet hanging loose results in no movement (no passive plantarflexion) of the foot, while movement is expected with an intact Achilles tendon and should be observable upon manipulation of the uninvolved calf. Walking will usually be severely impaired, as the patient will be unable to step off the ground using the injured leg. The patient will also be unable to stand up on the toes of that leg, and pointing the foot downward (plantarflexion) will be impaired. Pain may be severe, and swelling is common. Sometimes an ultrasound scan may be required to clarify or confirm the diagnosis. MRI can also be used to confirm the diagnosis.
Non Surgical Treatment
Non-surgical treatment of Achilles tendon rupture is usually reserved for patients who are relatively sedentary or may be at higher risk for complications with surgical intervention (due to other associated medical problems). This involves a period of immobilization, followed by range of motion and strengthening exercises; unfortunately, it is associated with a higher risk of re-rupture of the tendon, and possibly a less optimal functional outcome.
While it is possible to treat an Achilles tendon rupture without surgery, this is not ideal since the maximum strength of the muscle and tendon rarely returns. The reason is the ends of the tendon are ruptured in a very irregular manner, almost like the ends of a paint brush. As soon as the tendon ruptures, the calf muscle (gastrocnemius muscle) continues to pull on the tendon and the end of the ruptured tendon pulls back into the leg, which is called retraction. Once the tendon retracts, it is never possible to get sufficient strength back without surgery, because the muscle no longer functions at the correct biomechanical length and is now stretched out. There are patients for whom surgery cannot be performed, in particular, due to existing medical conditions that may add to potential for complications following surgery. For these patients, a specially designed boot that positions the foot correctly and takes the pressure and tension off the muscle and tendon is used. Most importantly, a cast is never used because it causes permanent shrinkage (atrophy) of the calf muscle. The special boot permits pressure on the foot with walking. The boot also has a hinge to permit movement of the ankle. Many studies of Achilles tendon ruptures have shown that this movement of the foot in the boot while walking is ideal for tendon healing. If surgery is not recommended, it is essential to obtain special tests to check that the ends of the tendon are lying next to each other so that healing can occur. The best test to do this is an ultrasound and not an MRI.