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Achilles Tendon Ruptures Print

achilles-tendon-ruptures-dr-allen-f-anderson-nashville-orthopaedic-sports-medicine-figure-1

Spontaneous rupture of the achilles tendon generally occurs in patients in their third to fifth decade. Most patients are men and most injuries occur during sporting activities. The most common mechanism of injury is pushing off forcefully with the affected foot while extending the knee.

The primary blood supply to the tendon is through the anterior mesotendon.  With aging, this anterior blood flow decreases, resulting in an area of relative hypovascularity approximately 3-4 cm above the insertion of the tendon onto the calcaneus. This decreased blood flow can result in degeneration in the tendon. It is in this area that ruptures usually occur. Also, as one ages, changes in collagen cross-linking result in increased stiffness and loss of viscoelasticity. This, when coupled with degenerative changes in the tendon, can predispose it to rupture when exposed to excessive mechanical forces. However, microscopic analysis of resected specimens suggests that this hypovascularity and degeneration play a secondary role to sudden over-loading as the predominant cause of injury.

Clinical Presentation

Most patients relate hearing a "pop" or "snap" at the time of injury and experience immediate pain in the region of the achilles tendon. However, the intense pain subsides rather quickly and with some limited ability to plantar flex the foot, many do not seek medical attention. However, this injury can be readily diagnosed if suspected. Patients generally present with weakness in plantar flexion, pain with dorsiflexion of the foot and a palpable defect along the course of the tendon. They are usually unable to perform a single leg toe-raise on the affected side. A very valuable test for diagnosis is the Thompson test. This test is performed by having the patient lie face down with the feet hanging over the end of the bed. The calf is then squeezed which will cause the foot to plantar flex slightly in the normal leg. Lack of this plantar flexion suggests disruption of the tendon.

achilles-tendon-ruptures-dr-allen-f-anderson-nashville-orthopaedic-sports-medicine-figure-2Ruptured Achilles Tendon

Another test that is more invasive and therefore seldom used is the O'Brien test. A needle is placed percutaneously into the proximal portion of the tendon and the foot is run through a passive range of motion. Movement of the needle shows continuity of the tendon. Lack of motion suggests disruption of the tendon.

Diagnostic Imaging

Plain X-rays are useful to rule out fractures and other injuries, but are of limited value in the diagnosis of tendon ruptures. Plain X-rays will show a rupture consistently, only if there is calcification of the tendon. On some films, defects in the tendon are suggested, but accurate diagnosis is seldom made purely on the basis of these findings.

MRI has added a new dimension to soft tissue imaging. Injuries to the achilles tendon are clearly visible and can be very accurately diagnosed using MRI. Not only is it helpful in the diagnosis, a good scan gives information concerning the quality of the tissue remaining, the size of the defect and orientation of the tear. Many classify injuries to the tendon in four groups based on their MRI appearance. Type I lesions show inflammatory changes only with an intact tendon. Type II lesions have areas of degeneration, but the tendon remains in continuity. Type III lesions are incomplete tears and type IV lesions are complete tears.

Achilles Tendon Ruptures, Dr. Allen F. Anderson, Nashville, Orthopaedic Sports Medicine, Figure 3

Ultrasonography was the imaging study of choice for some years before MRI and was very reliable in diagnosing this injury. However, it has largely been replaced by MRI.

It should be noted that clinical tests for this injury are very sensitive and specific and the above tests, which are very expensive, are usually not necessary to make the diagnosis.

Treatment Options

Controversy exists as to the best form of treatment for this injury. There are many who believe non-surgical treatment is the best option, and just as many who believe that all of these should be treated surgically.

The advantages of non-surgical treatment are obvious. Non-surgical treatment lacks all of the common complications associated with surgery such as infections, wound breakdown, anesthesia complications and so on. However, many have reported a higher re-rupture rate with this form of treatment. The literature reports re-rupture rate between 10 and 40%, less push off strength and less endurance when compared to surgically treated patients.

Surgery, on the other hand, offers a lower reported re-rupture rate (0-4%), a greater chance of returning to sports, greater strength, and more endurance. However, there can be complications associated with surgery and the literature reports rates of major complications (such as infection, wound slough etc) to be as high as 20%.

Non-Operative Treatment

The mainstay of non-surgical treatment is immobilization to allow tendon healing. Most recommend casting with the foot is equinus (plantar flexed) for a period of 8 weeks. Some surgeons will change the cast to one with less equinus at 4 weeks, but shorter periods of immobilization should be avoided as this can lead to increased rates of re-rupture. Once the cast is removed, active and passive motion are begun. Some surgeons will continue to protect the tendon in a brace for 4 more weeks.

Achilles Tendon Ruptures, Dr. Allen F. Anderson, Nashville, Orthopaedic Sports Medicine, Figure 4Surgical Treatment

Surgery of achilles tendon ruptures consists of directly re-approximating the torn ends (if possible) and reinforcing the repair as necessary. Generally, the patient is placed face down and given either general or local anesthetic. 

An incision is made just medial to the midline and the covering of the tendon (paratenon) is exposed. The ends of the tendon are examined and debrided as necessary. The ruptured ends of the tendon are then brought together with large non-absorbable sutures and over-sewn with smaller absorbable sutures to achieve a smooth repair. Sometimes, if the injury is chronic or the tissue is poor, local tissue such as tendon grafts or fascia can be used to reinforce the repair. In extreme cases, allograft tissue (cadaver tissue) is used to augment the repair.

Post-operatively, the patient is immobilized in much the same way as non-surgically treated patients. The foot is immobilized in a plantar flexed position for 6-8 weeks and motion is gradually begun after this.

 

 
© Allen F. Anderson, M.D. 2017