Footwear Design: Reducing Mechanical Shock Loading for Arthritis Patients.

Abstract

Arthritis is a prevalent inflammatory condition. A commonly occurring type is knee osteoarthritis, which affects 29 million individuals in the US, prompting a yearly medical cost of approximately $165 billion (Maetzel, 2004; Dillon, Hirsch, Rasch and Gu, 2007; Blackburn et al., 2016). This aims to design a midsole to minimise shock load on the knee for osteoarthritis suffers during gait. Evaluations of midsole thickness (20, 30, 40mm of 40 Asker C) and hardness (40, 50, 60, 65 Asker C) took place, with tests featuring gait simulations. This generated data by way of a dynamic representation of the lower extremities, in turn determining the effect of ground reaction forces on knee joints. Use of ground reaction force measurements at the heel phase evaluated the impact of the midsole’s shape by utilising a lateral wedged insole mathematical replica. Moreover, examples of both unaffected and arthritic knees were replicated with the finite element method utilising Apaqus to ascertain the different stresses. Previously collected research data aided this stage of the procedure. The optimum blend of hardness and thickness was adjudged to be 40 Asker C hardness with 40mm thickness. This lessened the heel strike transient by 6.55 per cent. Moreover, the 10° lateral wedged insole of matching hardness and thickness cut both the external knee adduction moment and the medial loading compartment by 50 per cent and 21.41 per cent respectively. Additionally, the finite element replica demonstrated that utilising a 10° lateral wedged insole apace with 40 Asker C with 40mm lessened the von Mises stress by 24.22 per cent for an arthritic knee. Adjusting the midsole attributes of footwear diminishes the shock and medial compartment loading in addition to the external knee adduction moment. This research proposes that using such a midsole can also reduce pain, cut therapeutic costs and lessen von Mises stresses.