Exploring in-shoe plantar pressure differences at the metatarsal pad position for patients with diabetes and toe deformities: A pilot study

Abstract

Patients with diabetes are often prescribed insoles with metatarsal pads intended to prevent and offload forefoot ulcers. However, to our knowledge, the plantar pressures specifically at the metatarsal pad had not previously been researched. The aim of this study was therefore to explore plantar pressures at the metatarsal pad position by comparing three toe deformity groups, claw toe (CT)/hammer toe (HT) and hallux valgus (HV), with a control group (NONE). In-shoe plantar pressures were measured using F-ScanTM and a polygon region of interest at the metatarsal pad position was created. Mean peak pressure (MPP), pressure-time integral (PTI) and percentage foot-insole contact area at the metatarsal pad position (%CA) were analysed from 24 patients (48 feet) in the metatarsal pad area. No significant difference was found between the groups regarding MPP, PTI or contact area. For MPP, the highest value was found in CT/HT (140kPa ± 61) and the lowest in HV (112kPa ± 33). In PTI, the highest value was for CT/HT (2.0 Ns/cm2 ± 1.0) and the lowest for HV (1.3 Ns/cm2 ± 0.4). The %CA was highest in CT/HT/HV (95%) and lowest in NONE (70%). A new quantitative approach was presented, assessing the metatarsal pad pressure effect on its corresponding plantar area of the foot. Further studies are needed to identify the conditions in which a metatarsal pad affects different foot statuses with regard to plantar pressure.