Tendo-Achilles electromyography (EMG) activity and ground reaction force during functional rehab: a comparison of two designs of walker boot

S. Chambers, M. Durocher, S. Mannan, S. Stewart, L. Ansley, D. Townshend

Introduction: Functional rehabilitation has been advocated for both post-operative and non-operative management of achilles injuries. A key component is weight bearing in a plantar-flexed walker boot. There are two different designs: an articulated boot with a hinge at the ankle and no heel support, versus a static boot where equinous is effected by the insertion of heel wedges within the boot. We conducted a study to explore whether there was a difference between the achilles load in each different type of boot. We measured ground reaction force and the EMG activity of the gastrosoleus in healthy volunteers wearing the boots.

Hypothesis: There will be no difference in ground reaction force or muscle activity when weight bearing with either walker boot.

Methods: 10 male and 10 female volunteers were recruited and each walked on a running track with embedded force plates while wearing EMG electrodes on the gastrosoleus. The experimental conditions were: control (trainers), ProtecROM at 20 degrees, and Aircast FP with adjustment wedges at 20 degrees. Results were controlled for walking speed and body weight.

Results: Both boots lead to a significant decrease in both EMG muscle activity and ground reaction force when compared with normal trainers. The articulated boot had lower muscle activity than the fixed boot (p=0.0005). The fixed boot lead to lower ground reaction force than the articulated (p=0.001). Males had more muscle activity than females while wearing the walker boots (p=0.03).

Discussion: This study demonstrates significant differences between two types of boot commonly used in functional rehabilitation of achilles rupture. There were also significant differences between male and female subjects. We recommend that these findings are considered when designing rehabilitation protocols and when evaluating the literature.