Nerve capping treatment using a bioabsorbable nerve conduit with open or closed end for rat sciatic neuroma

Background and aims: Nerve capping treatment using bioabsorbable nerve conduits has recently been introduced for painful amputation neuroma. However, no clinical or experimental data are available for comparing nerve conduits with open distal ends and closed distal ends. Here, we investigated the nerve conduit with open or closed distal ends as the superior capping device, using a commercially available polyglycolic acid (PGA) nerve conduit in a rat sciatic nerve amputation model.

Methods: Ninety-one rats were assigned to three groups: no-capping (n = 30), capping the resected nerve stump with open ends (n = 31), and closed-end nerve conduits (n = 30). Twelve weeks after sciatic neurectomy, with or without capping, the evaluation of neuropathic pain using the autotomy score was performed. Stump neuromas with perineural scars and neuroinflammation were evaluated histologically.

Results: The mean autotomy scores in the closed-end nerve conduit group were significantly lower than those in the no-capping group. However, the difference between the open-end nerve conduit and the closed-end nerve conduit groups was insignificant. Histologically, distal axonal fibers expanded radially and formed neuromas in the no-capping group while they were terminated within the PGA conduit in both capping groups. In particular, the closed-end version of the PGA nerve conduit blocked scarring from intruding through the open end and protected the nerve stump with less neuroinflammation. Nerve capping with the closed-end version of the PGA nerve conduit most effectively suppressed perineural neuroinflammation and scar formation around the resected nerve stump.

Interpretation: Nerve capping with the PGA nerve conduit, particularly those with closed ends, after rat sciatic neurectomy prevented amputation neuroma and relieved neuropathic pain.