A Study of Impact Protection of Metacarpal Gloves

Abstract

Work-related wrist, hand, and finger injuries are highly prevalent in manufacturing and extractive industries. An analysis of mining-related hand injury data from over the past two decades (Alessa et al., 2020) showed that hand injuries caused by insufficient protection against impact loads (e.g. struck by accidents) were categorized with high severity. Existing literature lacks clear classification and quantification methods for the protection provided by impactresistant gloves (i.e. metacarpal gloves). A new method to establish a quantitative measure of performance for commonly used metacarpal gloves was developed and evaluated. In the first specific aim, an experimental study using cadaveric hand specimens was performed to understand how human hand react to blunt impacts by comparing peak impact reaction forces (PRF) and number of fractures on unprotected and protected hands using two types of metacarpal gloves. The specimens were impacted at the proximal interphalangeal joints, the metacarpophalangeal joints, and the middle section of the metacarpal bones. 71% of the impacts on unprotected hands produced fractures compared to 40% for the protected hands. In the second specific aim, surrogate hands were developed using 3D printing and gel casting techniques. The surrogate hands were calibrated and validated using the impact response data obtained from Aim #1. The PRF values of surrogate hands were within 1 standard deviation of the cadaveric hands, with the coefficient of restitution differing by only 4%. Using the surrogate hands, the protection performance of three commonly used metacarpal gloves was assessed. 77% of the impacts on unprotected hands produced fractures compared to 33% for the protected hands. PRF values for protected hands were significantly less than unprotected hands and different gloves delivered different levels of protection. Results of this study could aid safety professionals in improving their gloves selection process and could also be utilized to improve current standards for metacarpal gloves classification. Furthermore, the testing methodology and protocol presented in this research could be useful in future gloves safety studies.