Background
Footwear with good characteristics offers short-term improvements in foot pain and disability in people with gout, however, these are not sustained in the long-term. One reason for this may be wear and reduced structural integrity of the shoe over the six-month period. This study tested the effects of wear by comparing the plantar pressures in athletic shoes that had been worn for six months, compared to a new shoe of the same model and size in people with gout.
Methods
40 people with gout participated in a cross-sectional repeated measures study. Plantar pressure variables (peak plantar pressure and pressure time integrals) across seven regions of the foot were measured in random order in two footwear conditions; (1) a new pair of the same model of footwear (new footwear) and; (2) a pair of commercially available athletic footwear that had been worn for six months (worn footwear). Data were analysed using linear mixed models.
Results
The worn shoes had higher medial midsole hardness (P<0.0001), lateral midsole hardness (P<0.0001) and heel midsole hardness (P<0.0001). Signs of outsole wear was evident in the worn shoes, with the majority displaying normal upper (P<0.0001), midsole (P=0.05) and outsole (P<0.0001) wear patterns. No significant differences in peak plantar pressures were observed across the seven masked regions (P<0.007). Lower pressure time integrals were observed at the first metatarsophalangeal joint (P<0.0001), second metatarsophalangeal joint (P<0.0001) and hallux (P=0.003) with the worn shoes compared to the new shoes, consistent with off-loading of this area.
Discussion and clinical relevance
Signs of upper, midsole and outsole wear were evident in the worn footwear following six-months of use. These changes in the mechanical properties of the footwear may impact foot function, as observed by pressure time integral reductions at at the first metatarsophalangeal joint, second metatarsophalangeal joint and hallux.