Biomechanical Comparison of Knotted and Knotless Stabilization Techniques of the Medial Collateral Ligament in Cats: A Cadaveric Study

Introduction: Distal extremity injuries often lead to medial instability in cats. Current surgical techniques rely on coaptation to protect healing in the postoperative period. A new knotless reconstruction technique has recently shown promising clinical results, but biomechanical data are lacking. The purpose of our study was to compare a new knotless stabilization technique and the standard reconstruction technique utilizing bone tunnels.

Materials and Methods: Samples consisted of 24 tarsi harvested from euthanatized cats. A previously described technique using bone tunnels and polypropylene suture and the knotless anchor technique utilizing FibreWire (Arthrex Inc.) were used. The two parts of the medial collateral ligament were tested separately requiring four treatment groups. A cyclic tensile test (600 cycles) was performed sequentially for the intact ligament and the reconstruction techniques. The prosthetic reconstruction was finally tested in load to failure. Total elongation, peak-to-peak elongation, stiffness and load to failure were compared with the intact condition. Significance was set at p < 0.05.

Results: No difference in stiffness, total and peak-to-peak elongation was found between knotless anchor technique and intact condition, whereas the tunnel technique showed a significantly less strong reconstruction (p < 0.02). Load to failure was not different between techniques (p > 0.09). Mode of failure for the tunnel groups was suture breakage. Anchor groups predominantly failed through suture slippage.

Discussion/Conclusion: The results showed that knotless anchor technique is more similar to the intact ligament than bone tunnel technique. These characteristics support its use as a coaptationless repair technique.

Acknowledgement: The implants were donated by Arthrex Inc. The authors work as part time consultants for Arthrex.