Effects of Attachment Sites and Joint Angle at the Time of Lateral Suture Fixation on Tension in the Suture for Stabilization of the Cranial Cruciate Ligament Deficient Stifle in Dogs

Abstract

To investigate the influence of different sites of lateral suture fixation for stabilization of the cranial cruciate ligament (CCL) deficient stifle and different joint angles at time of tightening on suture tension. Controlled laboratory study. Stifle joints (n=9) of dogs >or=20 kg. After CCL transection, each stifle was stabilized using 12 combinations of 4 different methods of lateral suture stabilization (LSS) and 3 different joint angles at time of suture tightening. Load within the suture throughout a full range of passive motion (ROM) was measured for each combination using a custom made load cell. All 4 LSS methods had an increase in suture tension on stifle flexion. LSS with the suture looped around the lateral fabella and secured to the proximal aspect of the tibia through 2 parallel drill holes at the tibial crest had the least change in suture tension during ROM. Tightening the suture at 70 degrees joint angle resulted in a significant loss of suture tension on extension. None of the LSS resulted in constant suture tension, questioning current recommendations regarding "isometric" points for lateral suture fixation. Tightening the suture with the stifle held in flexion may result in joint instability on extension. LSS as commonly performed is associated with a significant increase in suture tension on flexion of the stifle, potentially over-constraining the joint. Tightening should be performed with the stifle in slight extension rather than in flexion.