The demand for noninvasive skin-tightening body procedures is increasing.

Two photonumeric grading scales were created and validated for skin laxity in female patients: Skin Laxity-Posterior Thighs/Buttocks, and Anterior Thighs/Knees. Fifteen aesthetic experts rated photographs of 50 women in 2 validation sessions. Responses were analysed to assess inter-rater and intra-rater reliability.

Overall inter-rater reliability according to intraclass correlation efficient (ICC) 2.1 and weighted kappa was at least "substantial" for both scales in both sessions, and "almost perfect" (≥0.81) for the Anterior Thighs and Knees scale in session 2. Intra-rater reliability was "almost perfect" for both scales (ICC 2.1) and "substantial" to "almost perfect" by weighted kappa. A correlation between the skin laxity scales and body mass index, age, weight, sun exposure, and cellulite severity was observed.

The skin laxity photonumeric grading scales are valid and reliable instruments for assessing laxity on the posterior thighs and buttocks, and anterior thighs and knees. The scales will be of value for standardizing clinical evaluations and quantifying outcome measurements in research and clinical practice.