Clinical utility of in-socket residual limb volume change measurement: case study results

Abstract

Bioimpedance analysis was used to measure conductive tissue extracellular fluid (ECF) volume changes in the residual limbs of four unilateral transtibial amputee subjects during standing and walking conditions. Results showed that all residual limbs experienced ECF volume decreases during 5 min standing intervals. During 5 min of walking immediately after a standing interval, the residual limbs of healthy subjects increased in ECF volume while those of diseased subjects, one with peripheral vascular disease and another with cardiovascular insufficiency and a high-salt intake, decreased. One subject demonstrated less absolute value ECF volume change during standing and walking at 12 months post-surgical revision compared with at six months. Presentation of bioimpedance data to patients improved compliance to practitioner recommendations and patient understanding. Results were useful towards clinical assessment, patient education, and decision-making about treatment.

Figures

FIGURE 1. Subject ready for bioimpedance analysis testing

Current injecting and voltage sensing electrodes were positioned on the residual limb and the attached wires strain relieved.

FIGURE 2. Results from a healthy subject (Case 1)

Data from the central part of a session are shown.

FIGURE 3. Results from a subject with vascular insufficiency (Case 2)

Data from the central part of a session are shown. The subject’s limb, conductive tissue, volume decreased over the course of the session.

FIGURE 4a,b. Subject transitioning to a stable limb volume (Case 3)

Only one set of stand and walk segments is shown in each plot. The ranges on the vertical axes are the same for both panels. (a) 6 months after amputation. (b) 12 months after amputation. Absolute, conductive tissue, volume changes during standing and walking segments were less 12 mo after amputation than at 6 months post amputation.

FIGURE 5a,b. Results from a congestive heart failure patient (Case 4)

Only one set of stand and walk segments is shown in each plot. The ranges on the vertical axes are the same for both panels. (a) On a healthy diet. (b) After 3 wk on a high salt diet. Conductive tissue volume reductions during the stand and walk segments were much greater after 3 wk on a high salt diet than on a healthy diet.