The Lower Limb Functional Index - A reliable and valid functional outcome assessment in burns

Lower limb injuries account for up to 40% of all burns in Western Australia and affect physical function. Lower limb specific functional assessments are available to monitor recovery, yet no scale has been assessed for use in burns. The Lower Limb Functional Index (LLFI) which is validated in musculoskeletal patients was investigated for applicability in burn. Reliability was assessed using Cronbach's alpha, principal components analysis and Rasch analysis. Validity was assessed using Spearman's correlation coefficient with quality of life assessments (BSHS-B & SF-36) and physical assessments (TUG & ankle ROM). Regression analysis was performed with burn severity measures, time of recovery and location of the burn. The LLFI-10 was applied 1368 times on 739 patients at regular time points. It was internally consistent (α>0.8) and unidimensional. Associations were demonstrated with the BSHS-B and SF-36 (rho=-0.56 to -0.72, p<0.001), TUG (rho=0.41, p<0.001) and ankle ROM (rho=-0.31 to -0.35, p<0.001). The LLFI-10 also showed associations (p<0.001) with time since injury (rho=-0.29), age (rho=0.12) and TBSA (rho=0.12). The LLFI-10 is a reliable and valid tool to assess function in lower limb burns. This study supports the use of the LLFI-10 as part of a battery of assessment for lower limb burn recovery.