The Strength of Achilles Tendon Repair: A Comparison of Three Suture Techniques in Human Cadaver Tendons

Abstract

Background: A previous study suggests the double Krackow suture (locking-loop) weave technique is nearly twice as strong as the single Bunnell or single Kessler suture repair techniques. Our hypothesis was that the strength of different repair techniques would be comparable if a similar number of suture strands cross the repair site. Materials and Methods: Twenty-four fresh-frozen human cadaver Achilles tendons were used to test maximum strength of three suture techniques (double Bunnell, double Kessler, and double Krackow). The simulated ruptures were created in the midsubstance of the Achilles tendon, five centimeters proximal to its calcaneal insertion. All repairs were performed with No. 2 polyester (Mersilene, Ethicon, Sommerville, NJ) nonabsorbable suture in standard fashion for each technique, with four strands crossing the repair site. The tendons were then anchored to a materials testing machine (Instron, Canton, MA) through a calcaneal pin distally and a modified soft tissue clamp proximally. Tendons were loaded with continuous tension at a head speed of 0.85 cm/s. Results: All repairs failed at the site of the suture knots, none pulling out through the substance of the tendon. A one-way analysis of variance was performed on the maximum force at failure of each repair technique. No statistically significant difference was noted between the double Krackow weave (199.9 ± 20 N), the double Bunnell weave (196.2 ± 45 N), and the double Kessler weave (166.9 ± 51 N). Conclusion: We found that in a laboratory model of cadaveric Achilles tendon repairs there was no significant difference in strength between the Krackow, Bunnell, and Kessler suture techniques, when each was performed with a double suture weave. Clinical Relevance: This is a cadaveric study that attempts to simulate the clinical parameters of Achilles tendon ruptures, repairs, and repair failures to examine the strength of different repair techniques.