Biomechanical models in the study of lower limb amputee kinematics: a review

Background: Optoelectronic motion capture may provide a platform for the development of objective biomechanical outcome measures applicable to the young, active individual with lower limb loss. In order to create valid and robust tools, the modelling strategy applied must adequately represent both natural and prosthetic segments and joints. Objectives: To explore existing usage of optoelectronic motion capture and modelling strategies for the analysis of amputee function. Study design: Literature review. Methods: Systematic search of Medline (OVID) and keyword search of the Journal of Prosthetics and Orthotics. Results: Over 60% (n = 32) of the 51 studies extracted adopted a conventional three degree-of-freedom modelling approach. Linear segment representation (15%) and six degree-of-freedom techniques (19%) were employed in the remaining papers. Prosthetic modelling strategies were poorly reported. Landmarks were estimated from corresponding positions on the contralateral intact limb, mechanical joint centres and regression equations. No model defined the residuum and socket independently. Conclusions: In the absence of a definitive solution, it is essential that the limitations of any model are understood in the development and establishment of reliable outcome measures for this population using motion capture technology. Poor reporting and a lack of consistency make comparison of results between studies and institutions impractical. Clinical relevance Standard modelling techniques may not consistently represent the body and prosthesis adequately to produce valid results for the analysis of function of persons with lower limb loss. Variation in modelling techniques limits the utility of findings reported in the literature. Development and application of a uniform, robust modelling strategy would benefit research and clinical practice.