Microprocessor prosthetic ankles: comparative biomechanical evaluation of people with transtibial traumatic amputation during standing on level ground and slope

Abstract

Background

The compensations occurrence due to the alteration of the posture and the gait of persons with lower limb amputation is still an issue in prosthetic fitting. Recently, prosthetic feet designed to reproduce the physiological behaviour of the ankle using a microprocessor control have been commercialized to address this issue.

Objectives

Investigate the relevance of these microprocessor prosthetic ankles (MPAs) in the ability of standing on both level and inclined surfaces.

Methods

Six persons with transtibial amputation usually fitted with energy storing and returning (ESR) foot tested three MPAs: Elan^® Endolite (MPA1), Meridium^® Ottobock (MPA2), ProprioFoot^® Ossur (MPA3). Each MPA data acquisition was preceded of a 2 weeks adaptation period at home and followed by a 3-weeks wash-out period with their ESR. Lower limb angular position and moment, Centre of Pressure (CoP) position, Ground Reaction Forces (GRF) and functional scores were collected in static, on level ground and 12% inclined slope.

Results

MPAs allowed a better posture and a reduction of residual knee moment on positive and/or negative slope compared to ESR. Results also reflect that the MPA2 allows the best control of the CoP in all situations.

Conclusions

An increased ankle mobility is associated with a better posture and balance on slope. Gait analysis would complete these outcomes.

Clinical relevance

This study compares three MPAs to ESR analysing static posture. Static analysis on level ground and slope represents the challenging conditions people with amputation have to cope with in their daily life, especially outdoors. Having a better understanding of the three MPAs behaviour could help to adequately fit the prosthesis to each patient.

Implications for rehabilitation

• This is a study comparing three MPAs.

• The static analysis in standard and constraining conditions (slope) reflects the balance of people with amputation in their daily life, especially outdoors.

• Having a better understanding of the behaviour of each foot could help to adequately fit the prosthesis to each patient.

Keywords:

• Microprocessor-controlled feet
• transtibial amputee
• posture
• ramp
• centre of pressure

Acknowledgements

The authors would like to thank Didier Azoulay and Geneviève Leroy from CERAH.

Disclosure statement

The authors declare that there is no conflict of interest. All authors contributed equally in the preparation of this manuscript.