Weiner and Lipscom reported in 1956 that the incidence of closed Achilles tendon rupture was the third highest of all closed tendon ruptures in the body. In 1989, Jozsa et al. reported that Achilles tendon rupture accounted for 40% of all tendon ruptures treated surgically and was the first.
(I) Etiology
The exact cause of closed Achilles tendon rupture is not well understood. Many factors have an effect on Achilles tendon rupture.
1, tendon degeneration theory that: due to the degeneration of the body, disease or trauma and other factors, damage the blood supply within the tendon, resulting in degenerative changes in the Achilles tendon. Under repeated stresses, the Achilles tendon undergoes tiny tears, which cannot be effectively repaired due to the reduced blood supply, and finally ruptures.
2.The mechanical theory believes that the occurrence of Achilles tendon rupture is caused by the abnormal action of mechanical force. Other hormones, such as systemic or local use, can make the collagen fibers develop poorly, which reduces the strength of the Achilles tendon and increases the risk of Achilles tendon rupture.
3, quinolone antibiotics have toxic effects on the Achilles tendon, which can cause Achilles tendonitis and finally can lead to Achilles tendon rupture. Such as pefloxacin can reduce the core glycoprotein production, which changes the structure of the tendon and its biomechanical traits, so that the tendon is easy to fatigue rupture.
4, other: some systemic diseases, such as ankylosing spondylitis, rheumatoid arthritis, gout, etc., can cause inflammation of the Achilles tendon, rupture occurs under the action of external forces. It has been reported that the incidence of Achilles tendon rupture is higher in blood group O.
Arner and Lindholm proposed three types of indirect Achilles tendon injuries.
1, knee extension, forefoot weight-bearing propulsion, such as in the beginning of running or doing some jumping movements.
2, Sudden accidental fall or slip with the ankle jerked back and extended.
3.Sudden strong dorsiflexion of the plantar-flexed ankle joint, such as falling from a height after jumping up. Direct injuries are less common than indirect injuries, and can be closed or open injuries. Closed injuries often occur when the Achilles tendon is ruptured by a direct blow from an external force under low tension. Open injuries often occur when the Achilles tendon is under tension and is cut by a sharp object or crushed.
Chronic tears of the Achilles tendon can be the result of an acute injury that is not diagnosed early or treated appropriately. It can also be the result of chronic inflammation following overuse syndrome and Achilles tendinitis. Partial ruptures or micro-tears of the Achilles tendon can also result from repetitive stress effects and scar tissue can lengthen the Achilles tendon, causing weakness.
Lea, Smith and Shields et al. reported: the site of Achilles tendon rupture, muscle-tendon junction accounted for 4-14%, the middle of the Achilles tendon accounted for 72%-73%, near the heel bone attachment accounted for 14%-24%.
(B) Clinical manifestations and diagnosis
Achilles tendon rupture occurs mostly in young and middle-aged men. The peak age of Achilles tendon rupture is 30-40 years old. The ratio of left to right is 1.2:1, with a slight increase on the left side. Bilateral is extremely rare.
Patients usually have a history of trauma, such as suddenly hearing a sound in the heel during exercise or feeling kicked from behind. Immediately after the injury, the patient feels pain in the heel, weakness in the lower leg, and limping. Later, the heel area gradually swells. Some patients have less pain or no swelling. Some patients may have a painless rupture. Other patients may have symptoms such as localized pain and stiffness before the Achilles tendon rupture. In the case of a sharp cut injury, an open wound is seen in the Achilles tendon with the Achilles tendon exposed.
On examination, the patient with a closed injury may have weakness in plantar flexion of the affected ankle joint, and passive dorsiflexion of the ankle joint may be increased compared to the healthy side. A depression can be palpated at the Achilles tendon rupture and there is obvious pressure pain. If the injury is prolonged and the local swelling is severe, the interrupted end of the Achilles tendon is not easily palpable. The ankle joint can still have partial flexion of the ankle due to the integrity of other tendons with flexion of the ankle. About 20% of patients are missed, resulting in delayed treatment.
A positive Thompson’s test is useful for diagnosis. The patient is placed in a prone or kneeling position with the feet hanging off the edge of the bed, and the affected calf gastrocnemius is squeezed with the hand below the most extended part of the calf muscle on the healthy side and immediately plantarflexed on the healthy side, while the affected ankle does not move. Patients with open injuries can examine the Achilles tendon rupture from the wound.
X-rays: The significance of X-rays is twofold: one can identify concomitant fractures, and the other has some indirect signs on the lateral image that can assist in the diagnosis. For example, the border of the anterior heel triangle is not neat, and the contour is deformed or even disappeared.
Ultrasound: It has the advantages of being less expensive, rapid, reproducible and non-invasive. It can help the doctor to judge the gap of Achilles tendon rupture, and provide a basis for choosing non-surgical treatment when the gap of Achilles tendon rupture is small in ankle plantarflexion. However, ultrasound examination requires a certain technical requirement for the examiner and it is not easy to distinguish between total or partial Achilles tendon rupture.
MRI: It has better resolution for soft tissues, but is expensive and generally not used as a routine examination.
(iii) Treatment
Acute closed rupture, non-surgical or surgical treatment has been controversial for many years. It is generally agreed that surgery should be performed in professional athletes, young patients, elderly patients with high functional requirements, and patients whose Achilles tendon has been ruptured for more than one week. It has the advantage of a lower re-rupture rate and a more accurate restoration of the length of the tendon. Since the surgical repair of the tendon allows the tendon to be subjected to certain stresses at an early stage, which is conducive to the reconstruction of collagen fibers, the muscle strength can be restored more quickly and muscle atrophy can be prevented. Early rehabilitation also makes the function of the tendon after the injury close to normal. The non-surgical treatment is suitable for the elderly, those who do not have high functional requirements and those who do not want surgery. The advantages of non-surgical procedures are no surgical complications, no hospitalization, less expense, less overall recovery time than surgery, and an acceptable functional outcome. However, non-surgical treatment does not preserve accurate alignment of the tendon, fibrous healing or elongation of the tendon, resulting in weakness. The re-rupture rate is higher.
1.Non-surgical treatment
The main principle of non-surgical treatment is to fix the foot and ankle in plantarflexion position with a cast or splint. However, there are different opinions on how long to immobilize the ankle, the position of the ankle when immobilized, and whether to use a long leg cast or a short leg cast, and Taylor recommends immobilizing the ankle in a mildly flexed position (20-30°) with an above-knee cast and a passive plantarflexion position of the ankle. After 8 weeks, the cast was removed and replaced with a removable brace or a cast with heel padding of 2-2,5 cm, and ankle movement exercises were started during the removal of the cast.
2.Surgical treatment
Surgical repair of the Achilles tendon can be divided into three main categories.
(1) Direct suture. Applicable to fresh closed injury or open injury. Incision or percutaneous closed suture. If the Achilles tendon defect is large and cannot be directly sutured, a V-shaped extension of the proximal Achilles tendon followed by suturing is feasible.
(2) Suture followed by fascia and tendon repair, such as reinforcement with gastrocnemius fascia reversal or reinforcement with metatarsal tendon. It is suitable for the repair of old Achilles tendon rupture.
(3) Replacement reinforcement with fascia, tendon or other biomaterials. Suitable for patients with large Achilles tendon defects. For example, broad fascia, gastrocnemius fascia flap, short peroneal tendon, flexor digitorum longus tendon, flexor digitorum longus tendon, allograft Achilles tendon and other materials are used to reconstruct the Achilles tendon. Some biosynthetic materials such as carbon fibers, Marles mesh, and Dacron graft materials have also been reported for repair of the Achilles tendon.
Functional exercise after surgery depends on the quality of the Achilles tendon repair and the strength of the fixation. Akeson and Rasch proposed the concept of ‘Wolff’s law’ of connective tissue healing, which states that connective tissue heals in the direction of the applied stress. If the cast is immobilized for 6-8 weeks, this will reduce the stress on the tendon, and Amiel et al. suggest that this reduction in stress causes a decrease in fibroblast anabolism and an increase in catabolism, resulting in a decrease in collagen production and thus a weakening of the tendon. The extent to which this change occurs depends on the duration of the stress reduction. Other studies have shown that the polymerization of protofibers into mature collagen is accelerated following the application of mechanical stress to the nascent tendon. Therefore, early postoperative activity is important to restore function to the Achilles tendon and to prevent joint stiffness and muscle atrophy. However, there is no surgical method that allows the patient to begin active full range of motion exercises and weight bearing immediately after suturing the Achilles tendon. Early activity has the potential for Achilles tendon rerupture and requires a reasonable postoperative rehabilitation program (Table).