Introduction: Flexor tendon repair in the hand often results in a poor functional outcome due to adhesion formation between the tendon repair and the surrounding tissues. The most effective method of minimizing adhesions is immediate postoperative mobilization; however this results in an increased rate of repair failure. Many suture techniques have been developed that increase the repair strength at the expense of increased complexity, requiring a high level of skill, excessive handling of the tendon and wide exposure.

Aim: To develop an intra-tendinous device for repair of the flexor tendons of the hand that is quick to perform and provides a tendon repair equivalent in strength to commonly used suture techniques.

Materials and Methods: A device was designed and machined out of Shape Memory Alloy (NiTiNOL) with barbs facing in opposite directions, such that when introduced into tendon substance the barbs hold the tendon ends opposed. The device is drawn into the tendon ends using a length of suture and requires only one passage of the needle in each free tendon end.

80 porcine deep flexor tendons were harvested from adult porcine forelimbs and randomized into four groups of twenty tendons. Three groups were repaired using either a two, four or six strand repair, and the remaining group was repaired with the new device. Half of each group was repaired using a core technique alone; the remainders were supplemented with a Silfverskiöld Peripheral Cross Stitch.

The repairs were pre-loaded to 1N in a Zwick Linear Tensiometer, with subsequent distraction to failure at 10mm/min. When preloaded the tendon dimensions were measured at the repair site as well as above and below in order to assess repair site bulk. During loading the Force to Produce 3mm Gap (FPG) was recorded as was the Ultimate Strength (US) following failure.

Statistical Methods: Data was illustrated diagrammatically using box and whisker plots in order to aid comparison of the new device to the traditional suture techniques. The data was also analyzed using one-way ANOVA.

Results: The three traditional suture techniques showed a significant increase in FPG and US with increasing numbers of strands for both core repairs alone and those with supplemental peripheral repair.

The FPG of the new device was superior to the Cruciate when used alone and was equivalent to the Savage when augmented with a peripheral repair. The US of the new device was superior to the Cruciate both with and without a peripheral repair.

Conclusion: We present a new device for flexor tendon repair which is very simple to use, yet performs as well as traditional suture techniques.

We plan to continue development of the device to optimize its hold on the tendon. We also plan to perform cyclical testing in physiological conditions