SLR - September 2018 - Mithun Sivadasan

Decreasing an Offloading Device’s Size and Offsetting Its Imposed Limb-Length Discrepancy Lead to Improved Comfort and Gait

Reference: Crews RT, Candela J. Decreasing an Offloading Device's Size and Offsetting Its Imposed Limb-Length Discrepancy Lead to Improved Comfort and Gait. Diabetes Care. 2018;41(7):1400–1405.

Scientific Literature Review

Reviewed By: Mithun Sivadasan, DPM
Residency Program: Montefiore Medical Center, Bronx, NY

Podiatric Relevance: The Removable Cast Walker (RCW) is commonly used for multiple purposes, such as for Achilles tendon pathology, ankle injuries, postoperative care and as an offloading device. Patient adherence may be a challenge due to the size and weight of the device, changes in gait and imposed limb-length discrepancies that result from its use. This results in slower recovery and poorer wound healing for patients with diabetic foot ulcers (DFUs). This study looks at several combinations of devices and their effect on comfort, gait and plantar pressures.

Methods: Twenty-five subjects at risk for DFUs completed 20-meter walking trials with five variations in footwear: bilateral standardized shoes, a knee-high RCW with and without an external shoe lift contralaterally and an ankle-high RCW with and without an external shoe lift contralaterally. Perceived comfort ratings were recorded through a visual analog scale. A long instrumented carpet with pressure sensors was used to identify spatiotemporal parameters of gait based on timing and location of each step. Pressure insoles were fitted to each subject and placed inside each footwear and analyzed as a whole as well as four regions of the forefoot, including hallux, medial forefoot, intermediate forefoot and lateral forefoot, where DFUs are commonly located.

Results:
Perceived Comfort Ratings:
Both RCW groups without shoe lifts contralaterally resulted in statistically significant poorer comfort ratings than the athletic shoes. There were no significant differences in comfort ratings between both RCW groups with shoe lifts and the athletic shoe group.

Spatial and Temporal Parameters of Gait:
Mean walking velocity was significantly lower for the knee-high RCW group. Walking velocity was not affected by the use of contralateral lifts. No differences in velocity were found between the knee-high and ankle high RCW groups with lift use. Significant reduction in stance time was found in the lift group but did not vary between the two RCW groups.  

Plantar Pressure Recordings:
In the knee-high RCW group, there was a statistical significant difference in reduction of the medial, intermediate and lateral forefoot pressures. When the lift was not used, there was a significant reduction in peak pressures in the intermediate forefoot, lateral forefoot and hallux. On the contralateral foot, the peak pressure exhibited significantly lower pressures only with the use of the shoe lift.

Conclusions:
The authors concluded that an ankle-high RCW with a contralateral lift may serve as the most comfortable combination. Although the data does not support that this group provides the best offloading profile, the small differences in peak pressures may be made up with higher RCW adherence, which would result in increased wound healing. The authors bring important considerations into the spotlight that can lead to patient noncompliance and poorer outcomes. Adjustments in protocol for the use of varied RCWs heights and the incorporation of contralateral shoe lifts may need to be made to optimize patient comfort and to promote adherence in many scenarios depending on the device’s purpose.

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