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

Aim: To compare strength the to failure of Silversjold type B repair (SJBR) using bites two, four and six millimetres from the repair site of an ex-vivo porcine flexor tendon model.

Methods: Seventy freshly harvested procine flexor tendons were transected and randomised to repair using either SJBR or simple running epitendinous repair with and without a two strand Modified Kessler repair (MKR), repairs also performed spanning four and six millimetres from the repair site.

Biomechanical testing was performed with a Zwig tensinometer using a one neuton preload and a distraction rate of 20mm/min. Bulking was measured with a digital micrometer and each repair group was tested for mean load to repair failure and mean load to 2mm gap formation. In each case the mechanism of failure was recorded.

Results: The addition of an epitendonous suture statistically increases strength to failure over a core suture alone. The SJB with MKR at all distances was stronger than the the standard epitendonous suture with MK. Optimal strength was obtained at a distance of 6mm from the repair site. Data was assesed using an ANOVA analysis. Repairs failed in all repairs by suture breakage.

Conclusion: The use of an epitendonous suture adds valuable strength to a flexor tendonn repair. The SJBR is somewhat more complicated that a standard running suture however the augmentation in strength makes this worthwhile. The placement of IHM is optimal at 6mm from the repair site and did not statistically increase the tendon bulk.