Sciatic Functional Index in Smashing Injuries of Rats’ Sciatic Nerves. Evaluation of Method Reproducibility among Examiners

The interpersonal reproducibility of the method for evaluating the Sciatic Functional Index (SFI) was measured by a computer-based program developed for this purpose. Twenty Wistar rats were used, and their right sciatic nerve was addressed using general anesthesia. Those nerves were subsequently smashed in a segment of 5 mm proximal to its trifurcation with a special device, with a fixed load of 5 kg for 10 minutes. Animals’ footprints were taken at preoperative phase and then in a weekly basis, from the 1st to the 8th week, in a gait track. Prints were digitalized, stored and assessed by predetermined parameter measures, by four examiners, always following the same sequence of parameters marking. Results were submitted to statistical analysis, which evidenced the existence of a high correlation among examiners at preoperative evaluation and on the 3rd, 4th, 5th, 7th, and 8th weeks (equal or higher than 0.82), with an eventual drop on 6th week, but still as significant as the others (pF<0.01). On the 1st and 2nd weeks, the correlation index was nearly zero, showing the low reproducibility of the method in that period, in which variation among animals did not differ from the variation among examiners (p=0.24 and 0.32, respectively), due to the poor sharpness of footprints.