RESUMEN
OBJECTIVE: To describe the development and validation of the 5-grade photographic IBSA inner upper arm scale. METHODS: From 2 real-life pictures, a scale made up of 5 morphed images showing increasing severity of inner upper arm laxity was created. For validation, a set of 50 images (half of which real and the other morphed) was developed and sent to 5 trained physicians in two rounds 30 days apart. Raters' task was to make a selection of each image according to the given scale. Inter-rater and intra-rater reliability were evaluated in both rounds. RESULTS: As to intra-rater reliability, single-rater kappa scores between 0.74 and 1.00 and a global kappa score of 0.846 were observed, while inter-rater agreement was calculated with intra-class correlation coefficient reporting scores higher than 0.91, which indicate excellent reliability. CONCLUSION: IBSA inner upper arm laxity scale proved to be a validated and reliable tool.