Biomechanical evaluation of suture-augmented locking plate fixation for proximal third fractures of the olecranon.

OBJECTIVES

To describe a method of suture augmentation of locking plate fixation (PF) of proximal olecranon fractures and to evaluate the biomechanical effectiveness of the suture augmentation using a human cadaveric model.

METHODS

Six matched pairs of cadaveric elbows were used. Proximal one-third fractures of the olecranon were simulated via a transverse osteotomy. Identical locking PF was performed on each elbow using olecranon locking plates. One elbow of each pair was assigned to suture augmentation of the construct. The choice of left/right specimen for augmentation was performed in an alternating fashion. Augmentation was performed using a no. 2 ultra-high-molecular weight polyethylene-braided suture attaching the triceps to the plate via a modified Krackow stitch. The elbows were mounted into a custom jig and linearly loaded to failure using a hydraulic testing machine. Load to and modes of failure were recorded for each sample. The data were analyzed using the Wilcoxon signed-rank test for nonparametric distributions.

RESULTS

Suture augmentation improved the single load-to-failure strength in all pairs. One pair was excluded due to failure of the triceps attachment to the test machine. A median 398 N (P = 0.04 range, 197-633 N) or a median 48% (range, 30%-130%) improvement in strength was seen. The most common mode of failure was loss of fixation of the proximal olecranon fragment.

CONCLUSIONS

Suture augmentation can significantly increase the single load-to-failure strength of locking PF for proximal olecranon fractures.