Silicone rubber tubulization in peripheral sensory nerve reconstruction: An experimental study in rabbits

Silicone rubber (polydimethyl siloxane) tubes are used clinically in periph eral nerve reconstruction. A disadvantage of this procedure is that the mat erial often has to be removed owing to its mechanical properties. The aim o f our study was to investigate the healing of reconstructed sensory nerves tubulized by silicone rubber in an animal model. In our experiments, we rec onstructed the saphenous nerves in 27 rabbits. In series 1 (n = 12), silico ne rubber tubes were slid over a nerve suture without a gap. In series 2 (n = 12), silicone rubber tubes were slid over a 10-mm nerve gap. In series 3 (n = 12), conventional suturing was performed in the collateral saphenous nerves of the animals of the series 1. Epineurial suturing was performed. T hree other collateral nonoperated saphenous nerves served as controls. The healing was studied after 3, 6, and 12 months. Morphometric analysis of the regenerating axons was performed by using our new method for quantificatio n of nerve fibers in cross sections stained by immunohistochemistry and usi ng confocal laser scanning microscopy. Data analysis was carried out using a software program especially developed for this purpose. Our results showe d in the silicone procedures that at 12 months significantly fewer axons pe r fascicle area were present compared with conventional suturing. However, mean axon diameters in the distal nerve stump of the silicone procedures di d not differ significantly compared with the conventional suturing procedur e. The ratio of total axon area to total fascicle area in the distal nerve stumps of the silicone procedure without gap was significantly smaller comp ared with the conventionally sutured nerve. The percentage outgrowing axons from the proximal nerve stump into the distal one in the silicone rubber p rocedure without gap was 57%. This was significantly higher than in the sil icone rubber procedure with 10-mm gap (48%). However, in conventional sutur ing, the percentage of outgrowing axons (99%) was significantly higher than in both tubulization procedures. It appeared that tubulization by silicone rubber of sutured nerves without gap did not enhance axon regeneration. Co nventional suturing gave significantly better results. If a gap was present , the use of a silicone rubber tube was preferable to non-suturing. (C) 200 1 Wiley-Liss, Inc.