Influence of hallux valgus deformity on forefoot pressure distribution of Chinese diabetic patients

Since issues about hallux valgus deformity (HV) in diabetic population were rarely reported, this study was aimed at investigating the influence of HV on their forefoot pressure distribution. Twenty-seven diabetic patients with HV (DMHV) and 27 diabetic control ones without HV (DMC) were recruited. Patients were inspected by an experience clinical expert and those with other deformities, a history of ulceration, neuropathy, or amputation were excluded. Barefoot plantar pressures while walking were measured by Emed-at pressure plate in their selected speed and in a protocol of two-step initial. Variables of relative centre of pressure oscillation in medial-lateral direction (%) (COPxrel), COP velocity (m/s) (COPv), peak pressure (kPa) (PP), relative maximum force (%) (MFrel), relative contact area (%) (CArel), and relative pressure/force-time integrals (%) (PTIrel/FTIrel) were calculated for the area of the hallux and the medial, central, and lateral forefoot. Results of independent t test with a significant level of 0.05 and 95 % confidence interval show that MFrel and CArel of DMHV at hallux were recorded significantly lower than those in DMC by 38.48 % (P = 0.02) and 2.86 % (P = 0.001), while CArel, FTIrel, and PTIrel of DMHV beneath medial forefoot were shown significantly larger than those DMC by 3.99 % (P = 0.002), 31.52 % (P = 0.04), and 7.14 % (P = 0.02). No significant differences between DMHV and DMC were found for variables of COPxrel (P = 0.60) and COPv (P = 0.39), as well as for force load transfer at the forefoot area. Overall, DMHV is featured with pressure off-load under the hallux and pressure over-load at the medial forefoot; moreover, forefoot stability and its normal load transfer mechanism would not be affected by HV when the angle of hallux is less than 25°.