The NeuraGen® Nerve Guide is an absorbable collagen tube designed to be an interface between the nerve and the surrounding tissue and to create a conduit for axonal growth across a nerve gap. Although the axons of severed peripheral nerves regenerate spontaneously, they will not establish functional connections unless the nerve stumps are surgically reconnected. The NeuraGen Nerve Guide offers a rapid method for rejoining severed peripheral nerves, in contrast to conventional microsurgical techniques.

Potential advantages of nerve guides compared to nerve graft repair include the following:

• Rapid and effective tensionless nerve repair
• No donor nerve graft harvest eliminates an additional surgical procedure
• Function at the potential donor site is preserved
• Guided tissue repair through the nerve guide prevents axonal escape at the repair site and potentially reduces neuroma formation
• Simplifies nerve repairs in locations that are normally difficult to reach

The technology behind the NeuraGen Nerve Guide is based on a semi-permeable collagen tube that isolates and provides an environment for the extension of axons and growth of Schwann cells that are the elements responsible for functional recovery following nerve injury. The fibrillar structure of the collagen is maintained throughout manufacture, permitting the construction of a tubular matrix that has great mechanical strength and defined permeability (Archibald et al. 1991; Li et al.1992). The structural stability of the NeuraGen Nerve Guide is increased with a cross-linking agent that also determines the rate of in vivo absorption.

• NeuraGen Nerve Guide is flexible to accommodate movement of joints and associated tendons.
• NeuraGen Nerve Guide retains its shape and is resistant to occlusive forces of the surrounding tissues.
• NeuraGen Nerve Guide is biocompatible.

The level of functional recovery achieved with the NeuraGen Nerve Guide is equivalent to direct suture repair (animal trials, Archibald et al. 1995) and is stable over long period of time (3 to 4 years). In animal trials, there were no episodes of compression neuropathy reported with other more rigid or non-biodegradable materials (Mackinnon et al.1985). A critical property of the NeuraGen Nerve Guide is that the absorption process is complete and operates via normal metabolic pathways. In these studies, there was no reported scar tissue or inflammatory response to this material (Archibald et al.1991; Li et al.1992). It's complete absorption minimizes the possibility of nerve entrapment and thereby degradation of the repair.

References
1. Archibald S. J., J. Shefner, C. Krarup, and R. D. Madison (1995) Monkey median nerve repaired by nerve graft or collagen nerve guide tube. J. Neurosci. 15(5): 4109-4123.
2. Archibald, S.J., C. Krarup, S.T Li, and R.D. Madison (1991) A collagen-based nerve guide conduit for peripheral nerve repair: an electrophysiological study of nerve regeneration in rodents and nonhuman primates. J. Comp. Neurol. 307: 1-12.
3. Li, S.T., S.J. Archibald, C. Krarup, and R. Madison (1992) Peripheral nerve repair with collagen conduits. Clinical Materials 9: 195-200.
4. Mackinnon. S.E., A.L. Dellon, A.R. Hudson, and D.A. Hunter (1985) A primate model for chronic nerve compression. J. Reconstr.Microsurg. 1: 185-194.