Strength of ulnar fixation in ulnar collateral ligament reconstruction: a biomechanical comparison of traditional bone tunnels to the tension-slide technique.

BACKGROUND

Surgical reconstruction of the ulnar collateral ligament after rupture has evolved substantially since the original description. Reconstruction techniques vary significantly at the ulnar and humeral interface. The purpose of this study was to develop a model to isolate, test, and compare the ulnar fixation of the traditional bone tunnel technique and a new technique, the tension slide.

MATERIALS AND METHODS

Six matched pairs of cadaveric arms were dissected to isolate the ulna. Pairs were randomized to the bone tunnel or tension-slide ulnar fixation technique, and consistent tendon grafts were used for each reconstruction. A specialized tendon clamp was used to grip the grafts. Specimens were preloaded with a valgus force to 1 N x m and tested to failure in torsion at 4.5°/s. Statistical analysis was performed with 1-way analysis of variance with the Tukey post hoc test (α = .05).

RESULTS

The bone tunnel technique exhibited higher initial and total stiffness, as well as higher torsional torque at 10° and 30° of valgus angulation and at ultimate failure. The tension-slide technique exhibited significantly higher angular displacement at 3 N x m but not at ultimate failure. The bone tunnel technique exhibited higher work at 10° and 30° of valgus angulation.

CONCLUSION

In this model, traditional bone tunnels performed superior to the tension-slide construction in terms of both strength and stiffness. Whether there is a kinematic benefit to the tension slide, which moves the ulnar fixation to within the native ulnar collateral ligament footprint, is yet to be determined. Further study is needed to assess the clinical benefit of a stronger ulnar fixation.