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Introduction: Digital nerve injury is often associated with Zone II flexor tendon injury. Zone II tendon injuries are commonly treated with early motion protocols, while isolated nerve injuries have traditionally been treated with immobilization as long as three weeks after repair. We investigate the biomechanical properties of digital nerves repaired primary epineural sutures as well as with collagen tubes in a cadaver model in order to test the ability of these repairs to sustain early motion protocols.

Materials and Methods: Digital nerves were isolated from fresh cadaver specimens and repaired with either primary epineural sutures or with collagen tube nerve repair devices. The repaired constructs were pulled to failure, and mode of failure determined for each specimen. Primary digital nerve repairs and collagen tube nerve repairs were then performed in-situ in fresh cadaveric hand specimens and subjected to a cyclic active finger motion protocol. The condition of the repairs was recorded at intervals and at the end of the protocol.

Results: Isolated cadaver digital nerves repaired with collagen tube nerve repair devices failed at a lower maximal force compared with primary epineural repair, and most commonly by suture breakage. Isolated nerves undergoing primary epinerual repair most frequently failed by suture pullout. In the in-situ cadaver model, there were no repair failures of either type after 750 cycles of active finger motion.

Conclusions: While there is a demonstrable biomechanical difference in isolated cadaver digital nerves repaired with epineural sutures as compared with collagen tube devices, in-situ performance in a cadaveric model of cycled finger motion appears to be similar. These results provide biomechanical evidence for the ability of digital nerves repaired by primary suturing as well as with collagen tube devices to withstand early active motion protocols.