Objective measurement of scarring by multiple assessors: is the tissue tonometer a reliable option?

Depending on the patient population, the incidence of scarring is as great as 75% after burns. Skin pliability and functional recovery are affected negatively by hypertrophic scarring. Therapists use various treatment strategies to improve scar outcomes. However, a simple, objective, clinically useful method of measuring scar response to treatment eludes us. This study examines the inter-rater reliability and validity of scar pliability measures using the modified tissue tonometer (MTT). Twenty-four patients were tested by two blinded, randomly allocated raters. The MTT was used to assess scar pliability with a standardized, repeated-measures design. One normal and up to three scar points were assessed for each subject. One subject was excluded from the data analyses. Concerning inter-rater reliability, the intraclass correlation coefficient for averaged measures between measurers was 0.957, and the standard error of measurement was 0.025 mm. For validity, a significant difference (P = .0000) between scar (2.64 +/- 0.5 mm) and normal tissue (3.23 +/- 0.46 mm) measurements was demonstrated. Scar pliability scores between raters are extremely reliable and reproducible using the MTT. It can differentiate between injured and uninjured tissue. Hence, it provides clinicians with a reliable, transportable, and objective tool to document scar outcomes. The MTT provides a standardized method to longitudinally measure scar tissue pliability after burn injury.