Gender differences in axial hair strength may explain gender related incidence variation in Pilonidal Sinus patients

Background: Pilonidal sinus disease is a disease of mostly young people with male preponderance and caused by ingrowth of cut head hair. We wondered if the gender difference in Pilonidal Sinus Disease (PSD) incidence of this disease was due to hair characteristics. Objective: To investigate the gender specific hair strength characteristics, linked to standardized PSD incidence. Methods: We analysed the axial strength of human head hair in n=150 females and n=150 males of a northern german healthy population with the methods published recently. Standardised gender different PSD disease incidences were computed with raw data provided from the German Institut of Statistics and Health data. Results: Male axial hair force (1.59g +/- 0.9g) is significantly different from female axial hair force (1.25g +/- 0.76g; p=0.002). Male hair strength exceeds female hair strength by the factor of 1.2. During 2000 and 2017, male standardized PSD incidence exceeds female standardized PSD incidence by a factor of mean 3.1 in Germany. Limitations: During that observational period, PSD incidence rose by 40% in Germany. As age may play a role in axial hair strength, further larger age dependent tests series are planned. Conclusion: A higher pilonidal incidence in males is paralleled with stronger axial hair force in males, as compared to females. Hair strength aka. axial hair force may thus be the major factor in gender specific differences between males and females. Softening the hair can avoid the PSD as a preventive method which is worth testing.