Would adopting a revised landmark rule for the spinal level of the iliac crests improve the accuracy of lumbar level identification?

This is a secondary analysis of two previous systematic reviews demonstrating cephalad bias in using palpation to enumerate lumbopelvic levels, based on the conventional landmark rule that the spinal level of the palpated iliac crests=L4. Our study included 7 articles which enumerated lumbopelvic levels based on this rule, and furthermore reported data such that the direction and magnitude of errors could be abstracted from the article. The primary goal was to determine if enumeration accuracy would have improved had examiners known that the spinal level of palpated crests was closer to the L3-4 or L3 spinal level, as shown in our previous review. For the articles included, the mean error in spinal level enumeration diminished from 0.79 to -0.21 spinal levels, while accuracy increased from 26.3% to 46.9%. Since accuracy remained <50%, further refinements in iliac crest palpation are unlikely to improve enumeration accuracy, suggesting another method might best be sought.