Summary

The novel technique Clavicle Tunnel Helical Suture- bridge (CTHS) reconstruction is biomechanically stronger than a conventional coracoclavicular ligament reconstruction

Abstract

Introduction

Acromioclavicular (AC) joint injuries are common, compromising approximately 12% of shoulder injuries. Stability of the AC joint is conferred by the acromioclavicular and coracoclavicular (CC) ligaments. Currently many procedures are focused on CC ligament reconstruction to address vertical instability. This does not adequately address horizontal stability. The aim of this biomechanical cadaveric study is to evaluate the horizontal and vertical stability of 2 techniques for AC joint stabilization.

Methods

8 human cadaveric specimens (mean age 78 ± 7 years) were randomly allocated to 2 treatment groups: Clavicle Tunnel Helical Suture- bridge (CTHS) reconstruction and Clavicle Tunnel (CT) only. The CTHS group underwent a single tunnel CC ligament reconstruction using Dog-Bone (Arthrex Inc.) and FiberTape sutures (Arthrex Inc.), with incorporation of an additional helical suture over the AC joint to reconstruct the AC ligament. The other group only had the former procedure. Using a specialised jig and materials testing machine (MTS), superior-inferior (vertical) and anterior-posterior (horizontal) stiffness and displacement were measured in the intact, AC cut, AC+CC cut and reconstructed joints when a 70N load was applied to the distal clavicle.

Results

Preliminary results using the CTHS repair for reconstruction restored anterior-posterior displacement (mean= 10.31±1.43mm), similar to displacement of the intact AC joint (mean = 8.58 ±1.06 mm) with a p-value > 0.05. The CTHS reconstruction was also able to restore superior-inferior displacement (mean = 10.38 ± 2.16mm) to similar values to that of the intact joint (mean = 9.82 ± 2.19mm), with a p-value > 0.05. However, for the CT reconstruction group (mean 12.70 ± 2.26mm), the anterior-posterior displacement was significantly higher when compared to the intact joint (mean = 9.82 ± 2.19mm), with a p-value < 0.05

Superior-inferior displacement and anterior-posterior displacement was also significant between intact joint and AC+CC cut joint (mean = 12.79 ±1.35; 16.11 ± 4.60mm) with a p-value < 0.05. Regarding stiffness, there were no significant differences in either direction found between groups (p>0.05).

Conclusion

These results show that CTHS reconstruction is better able to restore bi-directional instability in a joint that has both AC and CC ligaments torn, as compared to CT only reconstruction. This information is vital as it can influence the choice of surgical procedure in cases of AC joint instability