Introduction: Controlled weight bearing is paramount to having a successful outcome following knee surgery. Recent advances in total knee replacement arthroplasty, re-alignment osteotomies, and articular cartilage surgical repair procedures have prompted the need for greater control over post-operative weight bearing progressions. Unilateral lower extremity weight bearing reduction is usually achieved by the application of upper extremity forces through crutch handles. The purpose of this study was to compare the axillary weight bearing Easy Strutter Functional Orthosis System (ESFOS) (Orthotic Mobility Systems, Inc., Kensington, MD) to axillary crutches for peak palmar and plantar force and pressure magnitude and onset timing. Methods: Thirty eight subjects (14 female, 24 male) between 40–65 years of age who were ≥ 1 year status post patient confirmed successfully rehabilitated unilateral total knee or total hip replacement surgery participated in this crossover effect controlled study. The involved (surgical side) foot and hand were instrumented with force/pressure sensors (Pedar System, Novel, Minneapolis, MN). Data were collected while subjects performed modified 3-point gait using a heel - toe progression, while attempting to maintain approximately 50% weight bearing at the involved lower extremity. During testing, subjects ambulated at a self determined comfortable pace for 20 feet on a flat surface followed by ascending a single flight of stairs, turning, descending the stairs, and ambulating 20 feet to a chair (50 ft total distance). Statistical analysis assessed mean differences between involved side palmar and plantar force and pressure magnitudes and onset timing (p < 0.05). Results: Peak plantar forces and pressures did not differ between devices. Peak plantar force timing relative to initial ground contact was delayed using the ESFOS (1.03 sec vs. .62 sec). Peak palmar forces (Fig. 1) and pressures (Fig. 2) were decreased at the upper extremity ipsilateral to the involved lower extremity during flat surface ambulation with the ESFOS (45% reduction in peak palmar force and a 50% reduction in peak palmar pressure). Peak palmar force onset timing (Fig. 3) was also delayed when subjects used the ESFOS.Fig. 1: Crutches Easy Strutters Peak Palmar ForceFig. 2: Crutches Easy Strutters Peak Palmar PressureFig. 3: Crutches Easy Strutters Peak Palmar Force OnsetDiscussion: Reduced and delayed peak palmar forces and pressures, and delayed peak plantar force onset timing suggest that the ESFOS helped facilitate a biomechanically more efficient gait pattern than axillary crutches. Reduced and delayed peak palmar forces and pressures provide evidence of decreased upper extremity loads during the impact forces of initial stance phase. Delayed peak plantar force and peak palmar force onset timing suggests that peak forces were generated more to assist with forward propulsion during terminal stance phase rather than for impact force attenuation purposes during early stance phase. The improved gait characteristics provided by the ESFOS may enhance the ambulatory function of a wide variety of patients with disabilities related to musculoskeletal, cardiopulmonary, or neuromuscular impairments.