Changes in Ground Reaction Forces in Modified Short-leg Walkers during Gait

Abstract

It has been shown that short-leg walking boots alter kinematics, joint kinetics and ground reaction forces (GRFs) during gait. The altered GRF variables may be associated with the increased heel height on the walker side compared to the shoe side. By modifying the walking boots, it was hypothesized that the diminished heel height difference between the walker side and the shoe side would restore GRF characteristics closer to those in normal walking. PURPOSE: To examine effects of heel height modifications on the walker and shoe sides on GRF characteristics during level walking. METHODS: Ten (four males, six females) subjects performed five level walking trials in each of six randomized conditions: lab shoes (Shoe), Gait walker (GW), Gait Walker with heel insert (GWHI), Gait walker modified (GWM), Equalizer walker (EW), and Equalizer walker with heel insert (EWHI). A force platform (1200 Hz) and a seven-camera motion analysis system (120 Hz) were used to collect GRF during the testing session. Visual 3D and customized computer software were used to obtain GRF data. A two-way (2 × 6: side × condition) mixed design ANOVA was used to examine selected peak GRF related variables and post hoc comparisons with an alpha level (p < 0.05) adjusted for multiple comparisons through a Bonferroni procedure. RESULTS: The application of a walker created a peak GRF prior to the normal peaks associated with the loading response in both vertical and anteroposterior GRFs. Wearing a walker introduced an elevated minimum vertical GRF in GW (0.88 BW), GWHI (0.89 BW), GWM (0.89 BW) and EWHI (0.88 BW) compared to Shoe (0.82 BW) on the shoe (left) side. Peak propulsive GRFs were smaller in all five walker conditions (0.13 - 0.15 BW) compared to Shoe (0.20 BW) on the walker side. The same peak was smaller in GWHI, EW and EWHI on the walker side compared to the shoe side whereas it was greater on the right side than the left side in Shoe. CONCLUSION: The application of heel insert in GWHI and GWM (on shoe side) does not diminish the minimum vertical GRF as hypothesized. Wearing a walker decreases the peak propulsive ground reaction force on the walker side and induces asymmetrical loading.