Rabbit model study of Achilles tendon rupture: biomechanical and histological comparison between h-loop knotless double-row and Krackow repair.

Abstract

BACKGROUND: Achilles tendon rupture is a frequent and significant injury encountered in sports medicine and clinical practice. Among the various tendon repair techniques, the Krackow suture method is the most widely used due to its proven reliability. However, the Krackow suture has several limitations, such as insufficient mechanical strength, inadequate preservation of the surrounding blood supply, and suboptimal support for tendon healing. To address these challenges, the authors have developed a novel surgical method called the H-loop knotless double-row repair (HLDR) technique, which aims to enhance tendon fixation, improve vascular protection, and provide better support for tendon healing during the recovery phase. PURPOSE: To compare the biomechanical and histological outcomes of HLDR and Krackow for Achilles tendon rupture in a rabbit model. STUDY DESIGN: Controlled laboratory study. METHODS: Acute transverse rupture models were created on the Achilles tendons of 36 New Zealand White rabbits. The animals were sacrificed at 4-, 8- and 12-weeks post-surgery, with 18 rabbits allocated for histological evaluation and the remaining 18 for biomechanical and MRI testing. RESULTS: Biomechanical analysis demonstrated that the HLDR group exhibited greater ultimate load to failure and stiffness at 8 and 12 weeks compared to the Krackow group. Furthermore, radiological and histological evaluations indicated that the HLDR technique was more effective than the Krackow technique in promoting neovascularization and facilitating tendon healing. CONCLUSION: In a rabbit model, the H-loop knotless double-row technique showed notable improvements in biomechanical strength at 8-12 weeks and earlier histological maturation relative to Krackow, while some endpoints converged by 12 weeks. These preclinical findings support HLDR as a promising approach warranting further clinical evaluation. CLINICAL RELEVANCE: This animal study suggested that HLDR might be an alternative for Achilles tendon rupture in humans to increase histological healing and reduce re-rupture.