Positional Effects of the Knee and Ankle on the Ends of Acute Achilles Tendon Ruptures

Abstract

Conservative management of acute Achilles tendon ruptures in a plantarflexed short leg cast or functional brace is a viable alternative to surgery. The ideal plantarflexion angle to allow the free ends of the tendon to oppose one another has not been clearly defined. The purpose of this cadaveric study was to define a plantarflexion angle where the free Achilles tendon ends reliably oppose one another. Ten cadaveric legs amputated at the distal femur were obtained. A laceration of the Achilles tendon was made 4 cm above the calcaneal insertion. A joint-spanning external fixator was placed across the knee. With differing degrees of knee flexion (0, 45, and 90 degrees), the diastasis between the free ends of the Achilles tendon was measured as the ankle was moved from 20 degrees of dorsiflexion to 30 degrees of plantarflexion (-20, -10, neutral, 10, 20, and 30 degrees). Regardless of knee flexion angle, the ankle plantarflexion angle where the free ends of the Achilles tendon opposed one another was 28.0 (95% confidence interval: 25.0-33.6) degrees. The ideal ankle angle in which to immobilize patients appears tightly clustered around 28 degrees of plantarflexion.

Prevention of Peritendinous Adhesions Using an Electrospun DegraPol Polymer Tube: A Histological, Ultrasonographic, and Biomechanical Study in Rabbits

“…In contrast, other studies denote the importance of the specific postoperative casting regime [32]. Besides the length of the application period of the cast, the ankle angle is one important parameter [5]. …”

“…Hence, different antiadhesion strategies to improve the gliding capability of the regenerating tendon are being developed [4]. First of all, the postoperative treatment has to be optimized with respect to its impact on the adhesion extent as it is well known that for example in Achilles tendon regeneration the ankle angle plays a crucial role [5]. Secondly, physical antiadhesion barriers consisting of biomaterials such as fibronectin [6], collagen [3], or silk [7] have been reported to show positive effects with respect to reducing adhesion formation.…”

Conservative Management of Bilateral Tendoachilles (TA) Rupture—A Case Report

“…Sekiya, et al [24] and Wray, et al [25] have demonstrated in cadaveric studies that knee flexion position does not influence the separation of the tendo Achilles ends while the plantarflexion position of the ankle does significantly affect the separation of the tendoachilles ends. Wray, et al [25] also showed that the ankle needs to be in at least 28 degrees of plantarflexion for the two ruptured ends of the tendoachilles to meet. Therefore the only factor to be controlled is the ankle position, which can be controlled in a below knee cast and an above knee cast is not necessary.…”

Effect of Knee Position on Gap Size Following Acute Achilles Rupture

“…Two cadaveric studies have examined and supported this principle with regards to the position of the knee. 3,18 In a study of six fresh frozen cadaveric Achilles tendons, measurement of the tendon gap with the knee and ankle in varying positions was made. The study showed that maximal independent reduction in tendon gap was achieved by plantarflexing the foot, with apposition of the tendon ends at 60 degrees plantarflexion and a mean gap of 20 mm with the ankle in neutral.…”

“…Complete tendon apposition was shown to occur at 28.0 degrees (95% confidence interval 25.0 to 33.6 degrees) regardless of the position of the knee. 18 There is no published evidence to show whether tendon gap changes with the position of the knee in the physiological environment of an acute rupture. Thus, the question remains whether in the conservative treatment of an acute Achilles tendon rupture, with the ankle in plantarflexion the knee should also be immobilized in a flexed position.…”