Biomechanical Comparison of the Achillon® Tendon Repair System and the Krackow Locking Loop Technique

Abstract

Background: The Achillon® Achilles tendon repair system combines the benefits of open repair and percutaneous repair and has excellent clinical results with minimal complications. The Krackow locking loop has been the standard suture technique for many surgeons in open Achilles repair. We determined to see how the Achillon® repair compared with the Krackow locking loop in a biomechanical pull-out study. Methods: Paired lower limbs of ten human cadavers were randomly split to receive repair via Krackow locking loop or via Achillon® in concordance with the manufacturer's manual. Following repair, the study groups were subjected to the same tissue processing and tensioned to failure in an Instron® 8841 device. From load-displacement curves, initial linear stiffness, load to failure, and work to failure were determined. Results: The predominant mechanism of failure for the Krackow stitch was the breakage of the sutures or knots. The predominant failure mechanism of the Achillon® repairs was the tearing of the suture loops through the tendon tissue. Repairs using the Krackow stitch possessed an average maximum load to failure of 128.3 ± 30.3 N and a work to failure of 2199.1 ± 669.7 N mm. After excluding outliers, repairs with the Achillon® technique resulted in a maximum failure load of 178 ± 35.4 N and a work to failure of 3999.8 ± 942.7 N mm that were both significantly higher than the Krackow stitch ( p < 0.05). The initial stiffness of the repairs was significantly higher using the Krackow stitch (10.4 ± 2.0 N/mm) compared to the Achillon® technique (6.6 ± 2.3 N/mm) ( p < 0.05). Conclusion: The results indicate a properly performed Achillon® repair can be stronger (higher load to failure) and tougher (higher work to failure) than an open repair using the Krackow locking loop, although the Krackow repair tends to be stiffer prior to plastic deformation in this model. Clinical Relevance: Applied correctly, the Achillon® repair system offers an effective, minimally invasive alternative to traditional open repair.