Comparison of the Easy Strutter Functional Orthosis System and axillary crutches during modified 3-point gait

Abstract

The Easy Strutter Functional Orthosis System ™ (ESFOS) was designed to improve assistive device ambulatory efficiency. This crossover design study compared the ESFOS to axillary crutches during modified 3-point gait. Thirty-eight subjects (40-65 years of age) at > 1 year after unilateral total knee or hip replacement participated in this study. Heart rate, mean peak palmar and plantar force magnitude, and onset timing were monitored during self-directed pace ambulation. Between trials, subjects responded to questions on perceived exertion, stability/security, and comfort. One-way analyses of variance were used to evaluate condition differences for ratio or interval data (p ≤ 0.01). Statistically significant differences were noted for mean peak palmar forces (reduced 45% and delayed 31%), mean peak plantar force onsets (delayed 30%), and energy expenditure index (EEI) (reduced 25%). Wilcoxon signed rank tests were used to evaluate condition differences for ordinal data. Subjects preferred the ESFOS to axillary crutches for comfort and security/stability on flat surfaces and stairs (p ≤ 0.001). Results suggest greater ambulatory gait efficiency during ESFOS use. Further study is indicated with other patient populations.

Experimental characterization of axillary/underarm interface pressure in swing-through crutch walking

“…The factors that appear to be determinants of user comfort are total force, number of maximum, pressure, and/or COF excursion. Other studies show decreases in energy expenditure and palmar pressure and a return to community ambulation through axillary weight bearing on the ESFOS as well as a preference for the ESFOS [12,16]. The preference of the subjects of this study for the ESFOS compared with axillary crutches while supporting some weight on the axillary support likely has a physical basis in the force behavior on the support.…”

“…Such a return to upright ambulation may be related to the decrease in energy expenditure through ESFOS use compared with Lofstrand crutches (observed by Nyland et al [12]). Nyland et al proved that patients supporting weight on the axillary support of the ESFOS also experienced lowered palmar pressures compared with axillary crutches [12]. Their subjects, who were 1 yr postunilateral knee or hip replacement, used a modified 3-point gait and supported the majority of their BW through the underarm while using the ESFOS.…”

“…In a case study involving an adolescent with lumbar-level myelodysplasia who required a wheelchair for community ambulation, Magee and Kenney reported a return to upright community ambulation through use of the ESFOS and weight sharing between the handgrip and axillary support [16]. Such a return to upright ambulation may be related to the decrease in energy expenditure through ESFOS use compared with Lofstrand crutches (observed by Nyland et al [12]). Nyland et al proved that patients supporting weight on the axillary support of the ESFOS also experienced lowered palmar pressures compared with axillary crutches [12].…”

“…The structural support of the ESFOS is pinned at each end, and the support deflects when loaded. The axillary pad of the ESFOS has a larger surface area, ~97 cm 2 , compared with axillary crutches, ~33 cm 2 [12].…”

“…Magee and Kenney [16] and Nyland et al [12] did not attempt to measure whether there is some quantifiable difference between the axillary pad of axillary crutches and the ESFOS that allows weight to be supported on the axillary pad of the ESFOS.…”