Affiliation:
1. Department of Biomechanics, University of Nebraska Omaha, Omaha, NE, USA
2. Department of Health and Kinesiology, University of Utah, Salt Lake City, UT, USA
Abstract
Background: Diabetic patients with foot ulcers are commonly prescribed assistive walking devices to unload the affected foot and promote tissue healing. However, the effect on shear loads to the contralateral foot is unknown. This study investigated the effect of a wheeled knee walker (WKW), compared to common devices, on compressive and shear plantar forces carried by the propulsive foot during walking in patients with type 2 diabetes mellitus. A secondary objective investigated plantar forces’ correlations with body weight unloaded (BWU). Methods: Participants walked a maximum of 200 m per condition during normal walking or when using crutches, a standard walker, and a WKW in randomized order. Plantar forces were measured with force plates, and wireless force-sensitive pads measured BWU through the hands. The WKW was instrumented to measure BWU onto the seat and handlebars. Three-dimensional motion capture confirmed gait events. Results: The WKW produced the lowest vertical, braking, propulsive, and medial shear forces but the highest lateral shear force among all conditions. Using crutches or a walker had negligible medial and lateral shear (mean = −6.69 N and −7.80 N), with normal walking producing the highest medial shear. There was a poor relationship between BWU and assistive walking devices and shear force values. Conclusion: A WKW could be the preferred assistive device for unloading a diabetic foot ulcer. The magnitude of lateral force would need further investigation to determine ulceration risk, given patient susceptibility and neuropathy. Clinical Relevance: Understanding shear forces on the propulsive foot is important for minimizing contralateral limb tissue damage risk while treating an ulcer. Different assistive walking devices change walking patterns and affect shear forces on the plantar surface of the foot. Although the WKW minimizes several loading metrics, a clinical trial investigating assistive walking device compliance and wound healing in diabetic foot ulcer patients across devices is needed.