Alteration of neuroma formation by manipulation of its microenvironment.

In a primate model a histologic assessment of neuroma formation is reported. Three experimental groups were defined. Transected sensory nerves left adjacent to the incisional wound in an area of movement (wrist) were considered the control group. In the "proximally cut" group the same sensory nerves were positioned well proximal to the incisional wound. In the "muscle-implantation" group these nerves were placed in adjacent muscles. At 6 months a histologic assessment of the neuroma formation in the three experimental groups was carried out. Implantation of the sensory nerve into muscle significantly altered the regenerative potential of that nerve. The muscle completely surrounded the sensory nerve. The minimal neuroma that formed had significantly less scar tissue and contained nerve fibers that were of a smaller diameter and decreased density than either the control or the proximally cut group. There were no histologic differences between these latter two groups. However, regeneration into the overlying skin that was noted in the control neuromas was not seen in those nerves which had been proximally cut.