Tissue response to silicone tubes used to repair human median and ulnar nerves

Silicone tubes of appropriate sizes were used to enclose the injured zone o f transsected ulnar and median nerves in the human forearm as an alternativ e to conventional microsurgical repair of the nerve trunk. A gap measuring 3-5 mm was left intentionally between the nerve ends inside the tube. The c linical early results from a prospective randomised study that compared the se two principles have recently been presented. Seven patients (five men an d two women), aged 15-49 years (median 20) were reexplored 12-44 months (me dian 22) after the initial procedure because of local discomfort from the t ube in four patients. There was a new nerve structure bridging the former g ap and in most cases it was impossible to distinguish the site of the injur y. In all cases there was a thin capsule around the silicone tube that micr oscopically consisted of connective tissue with thin walls and no signs of inflammation granuloma or macrophages (n = 4), while in two cases a mild fo reign body reaction was seen at a single site (n = 1) or at patchy areas (n = 1). These results indicate that after more than one year there is a limi ted tissue reaction around silicone tubes used to repair median and ulnar n erves in humans.