Reliability, validity and diagnostic accuracy of palpation of the sciatic, tibial and common peroneal nerves in the examination of low back related leg pain.

This study investigated the reliability, validity and diagnostic accuracy of manual palpation of the sciatic, tibial and common peroneal nerves in the examination of 45 subjects with low-back related leg pain. The nerves were palpated manually and with an algometer, to determine pressure pain thresholds (PPTs). A second examiner performed the straight leg raise (SLR) and slump tests to determine nerve trunk mechanosensitivity. The procedure was repeated by another examiner to determine inter-rater reliability (n = 20). Kappa scores for agreement between raters for manual palpation were 0.80, 0.70 and 0.79 for the sciatic, tibial and common peroneal nerves respectively, demonstrating excellent reliability. PPTs were significantly lower on the symptomatic side, for each of the three nerves, in subjects who were positive on manual palpation. In subjects who were negative on manual palpation, PPTs were not significantly different between sides, demonstrating criterion-based validity, using PPT as the criterion. Highest scores of diagnostic accuracy were obtained when two or more of the three nerves were positive on palpation (sensitivity = 0.83; specificity = 0.73).