How do transtibial residual limbs adjust to intermittent incremental socket volume changes?

BACKGROUND

Strategies to maintain prosthesis users' daily limb volume are needed.

OBJECTIVES

Test how intermittent incremental socket volume adjustments affect limb fluid volume and limb-socket distance.

STUDY DESIGN

Repeated measures.

METHODS

People with transtibial limb loss walked on an outdoor trail wearing a motor-driven adjustable socket that they adjusted a small amount, approximately 0.3% socket volume, every 2 min using a mobile phone app. Limb fluid volume and sensed distance between the socket and a target in their elastomeric liner were monitored. A gradual socket enlargement phase was followed by a gradual socket reduction phase.

RESULTS

An incremental socket enlargement significantly increased limb fluid volume ( < 0.001) but not sensed distance ( = 0.063). An incremental socket reduction significantly decreased both limb fluid volume ( < 0.001) and sensed distance ( < 0.001).

CONCLUSION

Participants' residual limb fluid volume increases during ambulation compensated for incremental socket volume increases. For incremental socket volume decreases, residual limb fluid volume decreases did not compensate and the socket fit became tighter.

CLINICAL RELEVANCE

Results support the hypothesis that for people without co-morbidities, intermittent incremental socket volume enlargements are an effective accommodation strategy to increase limb fluid volume while maintaining socket fit. Intermittent incremental socket volume reductions decreased limb fluid volume but also made the socket fit tighter.