Correlation between the foot pressure index and the prevalence of plantar hyperkeratosis.

Background: Plantar hyperkeratosis (HK) is a very prevalent foot lesion formed due to an alteration in the keratinisation process, thereby increasing keratynocites and accumulating multiple layers of the stratum corneum that leads to plantar pain. As foot shape and plantar pressures is related with their appearance, the aim of this study is to examine how foot posture and plantar pressure influence the appearance of this keratopathy.

Material And Methods: On a sample of 400 subjects (201 men and 199 women), the plantar pressures were evaluated by the Footscan® platform in 10 zones. The clinical exploration consisted in the valuation of the Foot Posture Index (FPI), and the assessment of the appeerance (and location) or not of plantar calluses or hyperkeratosis.

Results: 6.3% of the feet presented a highly supinated FPI, 15.5% were supinated, 57.3% corresponded to neutral, 17.3% were pronated and 3.8% were highly pronated. The participants with HK on the hallux, on the 1st, 2nd, 3rd or 5th MTH or on the lateral heel had a significantly higher pressure index (p < 0.001), ranging from 24.3 to 44% higher than those with no such alteration. Of the highly pronated feet, 66.7% presented HK in the hallux, while 32.3% of the supinated feet and 60% of the highly supinated feet presented it beneath the first MTH.

Conclusion: Foot posture influences the appearance of HK, though its association with plantar pressures. The participants with HK presented a mean foot pressure that was 32.3% higher than in those with no such condition. These values can be considered predictive for the appearance of HK and should be indicative of the need for preventive treatment.