Quantification of nerve tension after nerve repair: Correlations with nerve defects and nerve regeneration

This study tested the validity of a quantitative in vitro nerve-tension-mea suring technique, by correlating the tension measurements with functional a nd morphologic assessments of nerve regeneration. Initially, harvested nerv es were used in vitro to determine a K value for lateral displacement in th is tissue. Next, this value was used to calculate the tension of nerve repa ir, following 0-, 3-, 6-, and 9-mm resections of nerves in groups of rats. After quantifying the nerve tensions following excision and repair, the aut hors determined a sciatic function index to evaluate functional recovery an d axon diameter in the animals. Functional recovery was significantly impai red in. animals with elevated measurable tension (9.04 +/- 0.74 g in a 6-mm defect, 27.76 +/- 8.86 g in a 9-mm defect), compared to animals with no or 3-mm excision and measured tension of 3.3 +/- 1.09 g or less. Increased te nsion was also associated with a significant decrease in axon diameter. Thi s study succeeded, therefore, in quantitatively relating the elements of me asured nerve tension, nerve gaps, functional nerve recovery, and morphologi c regeneration. Quantification of nerve tension by lateral displacement in vivo offers a possible solution to clinical management of nerve gaps, when the choice between primary repair and nerve grafting is not a clear one.