Modeling Occupational Fingernail Onycholysis Disorders in the Population of US Astronauts Who Have Engaged in Extravehicular Activity

Abstract

Objectives Spacesuits are designed to be reliable personal spacecraft that preserve the life and well-being of the astronaut from the extremes of space. However, materials, operating pressures, and suit design requirements often result in a risk of musculoskeletal discomfort and injury to various areas of the body. In particular, this investigation looked at fingernails and their risk of developing onycholysis. Methods An onycholysis literature review was followed by a retrospective analysis of injury characteristics, astronaut suited training and spaceflight events, hand anthropometry, glove sizing, and astronaut demographics. Multiple logistic regression was used to assess the likelihood of onycholysis occurrence by testing potential risk variables against the dataset compiled from the retrospective data mining. Results The duration of event exposure, type of glove used, distance (delta) between the fingertip and the tip of the glove, sex, and age were found to be significantly related to occurrence of onycholysis (whether protective or injurious). Conclusion An initial risk formula (model) for onycholysis was developed as a result of this investigation. In addition to validation through a future study, further improvement to this onycholysis equation and spacesuit discomfort and injury in general can be aided by future investigations that lead to better definition of the threshold between safe and risky exposure for each type of risk factor. Application This work described a potential method that can be used for EVA spacesuit glove onycholysis injury risk analysis for either iterative glove design or between glove comparisons, such as during a product downselect process.

Human Factors in Spaceflight: New Progress on a Long Journey

“…The hazard of reduced gravity prompts researchers to think in new ways about how the environment will affect physical fitness and readiness, alter gross body movement and fine motor skills, and create research and study design challenges. To examine physical fitness in space, Young and colleagues (2023) provide an overview of anthropometric changes during spaceflight, while Reid and colleagues (2023) focus in on fingernail onycholysis disorders related to astronauts’ extravehicular activities (EVAs). These studies provide measurement and predictive modeling techniques that will inform hardware and spacesuit designers among other vehicle design applications.…”