Functional consequences of isolated nerve stretch: experimental long-term static loading.

The maximum longitudinal tension that can be applied to the stumps of a divided peripheral nerve during surgical repair is not precisely defined. Uncertainty about the threshold of unacceptable nerve tension may be due to the lack of studies on isolated and reproducible stretch, i.e., on quantified elongation without concomitant compression, crush, or transection. The authors devised a simple method for producing isolated, long-term static loading of the nerve in vivo without concomitant compression, crush, or transection. Tension was applied to intact and crushed sciatic nerves in the rat, stretching them by 15 or 30 percent of their initial length, and the corresponding functional consequences were evaluated. Results showed that no measurable functional deficit resulted from stretching a segment of intact nerve to a length 30 percent greater than its initial length. In contrast, a significant delay in functional recovery resulted from stretching a crushed nerve by the same amount. A practical conclusion may be that the site of application of stretch forces during surgical repair, i.e., the location of coapting stitches, could play an important role in clinical practice.