Abstract
Introduction
In order to prepare hamstring autograft, suture fixation to the tendon is required to secure and handle the tendon during harvest and preparation. We use a simple, grasping suture which doesn't require suture of the tendon, thus saving time and avoiding violation of the graft itself. We present this technique, with results of mechanical testing compared to a standard whip suture, traditionally used to handle hamstring autograft.
Methods and materials
Twelve uniform ovine flexor tendons were prepared. A number two braided polyester suture was used in all cases. Six tendons were prepared with a standard, non-locking whip-suture, maintaining uniformity of suture bite and working length between samples. Six tendons were prepared with the utility suture, also taking care to maintain uniformity. The suture was applied by tying the thread around the tendon with a single-throw granny knot then symmetrically wrapping the suture ends from proximal to distal and securing with another single throw, allowing compression of the tendon with longitudinal tension on the suture. All the samples were tested to failure in uniaxial tension in a materials testing machine. Peak load values and load/displacement curves were acquired and results analysed with a two-sample T-test assuming significance at P<0.05.
Results
Modes of failure between the groups, as characterised by the load/displacement curves were quite distinct. Peak load to failure was lower in the utility suture group but all failures occurred when the suture snapped. Thus the peak load to failure of the suture/tendon construct exceeded the breaking strain of the suture material.
Conclusion
The grasping utility suture described here is sufficiently strong to harvest and handle hamstring autograft without passing a needle through the graft, saving time and avoiding violation of the graft itself. The lower loads at failure, despite failure occurring due to suture snapping, may reflect differing knot orientation between groups.
