The Effect of a Shock Absorber on Spatiotemporal Parameters and Ground Reaction Forces of Forearm Crutch Ambulation

Forearm crutches are a commonly used assistive device to aid the ambulation of people with lower limb impairment. Due to the structure of the joints of the upper limb, the loading patterns during crutch-walking can be detrimental to the user. Shock-absorbed or compliant crutches may reduce ground contact impact, potentially benefitting the user. In this study, the authors performed a biomechanical evaluation of a shock absorber crutch, which uses an elastomeric system to absorb impact. Ground reaction forces (GRFs) and spatiotemporal parameters were compared between shock absorbed and standard crutches. Results indicate no significant differences to spatiotemporal parameters and peak ground reaction forces between the crutches. There is an initial impact spike during crutch strike when using shock absorbed crutches, after which the rate of force development is moderately decreased when compared with a standard crutch. The practical benefit of a small reduction in force is questionable and more work must be undertaken to further optimise shock absorber design.