Balance Assessments During Acute Use Of A Knee Crutch Device

PURPOSE Following lower-extremity injury, non-weight bearing recovery is often required. A hands-free, knee crutch allows ambulation with increased manual freedom compared to a traditional axillary crutch. Beyond use as an assistive device, the knee crutch may serve as an analog to a fixed knee prosthetic for transfemoral amputation. Patients in both scenarios typically express modified balance and ambulation as they learn to accommodate the new device. The present study seeks to quantify initial balance impairment to determine best practice for clinical instructions for such devices. METHODS Twenty young healthy participants volunteered. Following informed consent they completed a baseline series of balance assessments, were fit with the knee crutch (iWalk), provided supported ambulation practice, and completed an experimental series of balance assessments wearing the knee crutch. All balance assessments were completed using the BTrackS force plate with Balance Assess software. The Balance and Falls Risk (FR) protocol included 4 trials, 20s each, with eyes closed and the instruction to remain still throughout the trial. A measure of path length and fall risk percentile are provided by the software. The Limits of Stability (LOS) protocol included 3 trials, 20s each, with eyes open and the instruction to cover the largest area of sway possible. Visual biofeedback was provided. A measure of total sway area is provided by the software, as well as quadrant areas from which a lateral bias score was calculated. Paired t-tests compared baseline to experimental assessments. RESULTS FR path length increased from 22.7 cm to 50.2 cm (p < 0.0001), while the percentile decreased from the 51.6 percentile to the 2.6 percentile (p < 0.0001). LOS total area decreased from 403.5 cm^2 to 181.1 cm^2 (p < 0.0001). Lateral bias during LOS decreased from -1.1% to -40.9% (p = 0.0003). CONCLUSION The results of this study indicate clear, large insults to balance ability when using the knee crutch for the first time. This includes increased sway in a “stand still” task, decreased excursion in a “lean most” task, as well as an onset of lateral bias away from the crutched leg. In contrast, all participants reported sufficient balance confidence to attempt independent ambulation while using the knee crutch. Longitudinal follow-up is warranted.