Suture tape augmentation of the lateral ulnar collateral ligament increases load to failure in simulated posterolateral rotatory instability

PURPOSE

Simple elbow dislocations are accompanied with lateral ulnar collateral ligament ruptures. For persisting instability, surgery is indicated to prevent chronic posterolateral rotatory instability. After lateral collateral ligament (LCL) complex repair the repair is protected by temporary immobilization, limited range of motion and hinged bracing. Internal bracing is an operative alternative augmenting the LCL repair using non-absorbable suture tapes. However, the stability of LCL repair with and without additional augmentation remains unclear. The hypothesis was that LCL repair with additional suture tape augmentation would improve load to failure. Secondary goal of this study was to evaluate different humeral fixation techniques. A humeral fixation using separate anchors for the LCL repair and the augmentation was not expected to provide superior stability compared to using only one single anchor.

METHODS

Twenty-one elbows were tested. A cyclic varus rotational torque of 0.5-3.5 Nm was applied in 90°, 60°, 30°, and 120° elbow flexion to the intact, torn, and repaired LCLs. The specimens were randomized into three groups: repair alone (group I), repair with additional internal bracing using two anchors (group II), repair using one humeral anchor (group III). A load-to-failure protocol was conducted.

RESULTS

Load to failure was significantly higher in groups II (26.6 Nm; P = 0.017) and III (23.18 Nm; P = 0.038) than in group I (12.13 Nm). No significant difference was observed between group II and III. All specimens lost reduction after LCL dissection by a mean of 4.48° ± 4.99° (range 0.66-15.82). The mean reduction gain after repair was 7.21° ± 4.97° (2.70-21.23; mean over reduction, 2.73°). The laxity was comparable between the intact and repaired LCLs (n.s.), except for varus movements at 30° in group II (P = 0.035) and 30° (P = 0.001) and 120° in group III (P = 0.008) with significantly less laxity. Inserting the ulnar suture anchor showed failure in the thread in 10 cases.

CONCLUSION

LCL repair with additional internal bracing yielded higher load to failure than repair alone. Repair with additional internal bracing for the humeral side using one anchor was sufficient. A higher primary stability would facilitate postoperative management and allow immediate functional treatment. Reducing the number of humeral anchors would save costs.