Health care ergonomics Part II: Location of body structures by palpation - A reliability study

Twenty physical therapists participated in an experiment that measured within- and between-rater reliability palpation. Four body landmarks that differed in form and depth were palpated. The lateral ligament of the knee (KNEE), posterior superior iliac spine (PSIS), spinous process L4 (SPL4), and transverse process of L4 (TPL4) were palpated and marked with invisible ink. This process was repeated after five minutes. The marks were illuminated with ultra violet light in order to make them visible. The distance between marks made on the same structure was measured. A repeated measures ANOVA showed significant (p < 0.05) differences between different locations and raters. Paired t-tests for within- and between-rater results were significant (p < 0.05) for each location except SPL4. Palpation of KNEE was most reliable, both within and between raters. The mean distances between identification marks were 8 mm and 12 mm for within- and between-raters respectively. PSIS was reliable for within-rater (8 mm), but not for between-rater assessment (25 mm). Identification of TPL4 was least reliable both within (14 mm) and between (25 mm) raters. SPL4 had the second highest error level being 12 mm for within and 16 mm for between-raters. Deeper and less clearly defined structures were associated with more error. In addition there was a high variability of skill across individuals. The poor reliability of many clinical tests is partially explained by the error in landmark location.