Cyclic Loading of 3 Achilles Tendon Repairs Simulating Early Postoperative Forces

Abstract

Background Accelerated rehabilitation has been advocated after Achilles tendon repair, but it produces significant forces at the repair site. Hypothesis Stresses applied to the repaired Achilles tendon simulating postoperative forces may exceed the strength of some repairs. Study Design Controlled laboratory study. Methods Fifteen Achilles tendons were incised 4 cm proximal to the calcaneal insertion, then were repaired using either a percutaneous, 4-strand Krackow, or an epitendinous augmented 4-strand Krackow technique. Tendons were cyclically loaded to 1000 cycles each at 100, 190, and 369 N. The number of cycles to initial gapping, 5-mm gapping, and total failure were compared using Mann-Whitney U tests with adjustments for multiple comparisons. Results Gap resistance was significantly greater for augmented Krackow repairs (2208 cycles to initial gapping) versus nonaugmented repairs (502 cycles, P = .024) and for nonaugmented Krackow repairs versus percutaneous repairs (5 cycles, P = .024). All percutaneous repairs failed during the 100-N cycling (102 ± 135 cycles). All nonaugmented Krackow repairs failed during the 190-N cycles (total cycles to failure: 1268 ± 345). All augmented Krackow repairs were intact (no gapping) after the 190-N cycles. Four failed during 369-N cycling (total cycles to failure, 2017 ± 11), and 1 remained intact for 3000 cycles. Conclusion Epitendinous cross-stitch weave augmentation of Achilles tendon repairs significantly increased repair strength and gap resistance. Clinical Relevance Epitendinous cross-stitch weave augmentation of Achilles tendon repairs may better allow for early stretching and ambulation after Achilles tendon repair.