Use of Bioelectrical Impedance Analysis and Phase Angle in Adults with Lower-Limb Amputees: A Scoping Review

Abstract Introduction: Adults undergoing LLA due to peripheral arterial disease face high physical demands during prosthetic use, compounded by multimorbidity and accelerated biological ageing. Existing prediction models for prosthetic use rely on demographic and clinical variables rather than direct measures of muscle mass or body composition, even though such measures may potentially be relevant. Together with the limited evidence on BIA and PhA in adults with LLA and their unclear clinical utility, this provides the rationale for exploring whether BIA and PhA can offer additional, clinically meaningful information for prosthetic candidacy and rehabilitation. BIA offers a simple, non-invasive method estimating body composition, while PhA is a model-independent indicator of cellular integrity, nutritional status, and functional capacity. Objective: To map the literature on the application and methodology of bioelectrical impedance analysis (BIA), including phase angle (PhA), in adults with lower-limb amputation (LLA), focusing on body composition, muscle mass, fluid status, prosthetic candidacy, rehabilitation, and knowledge gaps. Inclusion criteria: Adults (≥50 years) with transtibial or transfemoral LLA. Methods: A three-step search strategy will be used, comprising an initial limited search, a comprehensive database search (MEDLINE, CINAHL, Embase), and screening of reference lists. Empirical studies in English, Danish, Swedish, Norwegian, German will be included without date restrictions. Two reviewers will independently screen studies and extract data, using a piloted extraction form, with disagreements resolved by consensus. Conclusion: This review will provide an overview of the existing evidence, identify key knowledge gaps and inform the design of a subsequent feasibility study.