Biomechanical Evaluation Following Loop Modification of a Three-loop Pulley Pattern in an Ex-vivo Canine Common Calcaneal Teno-osseous Avulsion Repair Model

Introduction: 3-loop-pulley (3LP) modification by increasing the number of suture loops may lead to improvements in the biomechanical properties of the repair and its resistance to gap formation.

Objective: The aim of the study is to compare the biomechanical properties and gapping characteristics following loop modification of a traditional 3LP pattern in a canine common calcaneal tendon (CCT) avulsion repair model.

Materials and Methods: CCTs were randomized to one of four experimental groups (n = 14/group). Groups consisted of a 3LP, 4LP, 5LP, or 6LP patterns with adjacent loops placed 60 degrees apart using 0 USP polypropylene. Yield, peak and failure loads, construct stiffness, loads to produce a 3-mm teno-osseous gap and failure mode were evaluated and compared between groups.

Results: Yield (p = 0.001), peak (p < 0.0001), and failure loads (p <0.001), construct stiffness (p = 0.0003), and loads to 3 mm gap formation (p = 0.0049) were all significantly greater for 6LP compared with all other groups. Mode of failure did not differ among groups (p = 0.733) with 75% of repairs failing by mechanism of core sutures pulling through the tendinous tissue.

Discussion/Conclusion: Pattern modification by increasing the number of loops increased the repair site strength by 1.4, 1.6, and 1.8 times for 4LP, 5LP, and 6LP compared with 3LP, respectively. Increasing the number of suture loops is a relatively simple technique modification that significantly increases teno-osseous repair site strength and loads required to cause 3-mm gap formation. The Results of this study justify further focused investigation in vivo for teno-osseous CCT repair in dogs with tendinopathy.

Acknowledgements: There was no proprietary interest or funding provided for this project.

Publication History

Article published online:
26 October 2022