A study of using a simple 2D image analysis method to monitor the surface area of hypertrophic scars on hand during pressure therapy

Hypertrophic scars are usually evaluated based on scar assessment scales such as Vancouver Scar Scale (VSS) and the Patient and Observer Scar Assessment Scale (POSAS) which are difficult in recording small changes in the scar conditions over time. This study adopts a simple method to quantify the size of hypertrophic scars on hands by using a camera and tripod set-up for image capturing and a free software, ImageJ, for analysis. The ability to record the changes in scars condition and healing progress of this method were investigated. Four hypertrophic scar samples on the hands were captured at 8 time-points during 24-week of pressure therapy. Three operators were trained for 2 h to use the software and then carried out image analysis on 32 scar images to obtain the surface areas of the hand and the scars and repeat the entire measurement for 3 times. The results show that the measured scar surface areas have good intra-operator reliability with an intraclass correlation coefficient (ICC) of 0.943 (0.922, 0.96) and moderate inter-operator reliability with an ICC of 0.554 (0.063, 0.795). No significant within-subject effect of the repeat of measurements (p > 0.05) and between-subject effect of the three operators (p > 0.05) were found on the scar area measurements and the proportion of the scars on hands but significant differences were found between different time-points of the image capturing (p < 0.05). The image analysis method is more sensitive to the change of scars conditions over time than the VSS record. This is an economical and relatively easy method to quantify the changes in the hypertrophic scars which could be useful for monitoring the progress of therapy and encourage treatment compliance.