THE BIOMECHANICAL PROPERTIES OF A TECHNIQUE FOR RECONSTRUCTION OF THE ANTERIOR CRUCIATE LIGAMENT IN A PORCINE KNEE MODEL

Abstract

Aims: The aims of this study were to evaluate the biomechanical properties and mode of failure of a technique of anterior cruciate ligament (ACL) reconstruction using the Soffix polyester fixation device. A 2-strand equine extensor tendon graft model was used because a previous study has shown it to have equivalent bio-mechanical properties to that of 4-strand human semitendinosus and gracilis tendon grafts.

Method: Ten stifle joints were obtained from 5 skeletally mature pigs, the soft tissues were removed and the ACL and PCL were sacrificed. Tibial tunnel preparation was standardised using the Mayday rhino horn jig to accurately position a guide wire over which an 8mm tunnel was drilled. A 2-strand equine tendon-Soffix graft was used to reconstruct the ACL of the porcine knee using over the top femoral placement with bicortical screw fixation. Mechanical testing of 10 specimens was performed.

Results: The mode of failure included 4 midsubstance tendon failures, 3 Soffix failures and 3 failures at the suture-Soffix interface. The mean ultimate tensile load for the ACL reconstruction was 1360 N (standard deviation (SD) =354), elongation to failure of 41 mm (SD=7.5) and a structural stiffness of 35 N/mm (SD=8.1).

Conclusion: This in vitro study has shown that the technique of ACL reconstruction using the Soffix soft tissue fixation device with a tendon graft placed in the over the top position is biomechanically strong, providing a sufficiently high UTL immediately following reconstruction, therefore allowing early weight bearing and rehabilitation.