Nelson-Cradle Rule Decreases Concussion Injury Rates in High School Wrestlers

ABSTRACT Context: Wrestling is a rapidly growing high school sport with a high incidence of sport-related concussions (SRC). The Nelson-Cradle maneuver, involving head and neck manipulation, was banned by the Michigan High School Athletic Association (MHSAA) beginning in the 2018/19 season as a potential injury prevention strategy. Objective: To compare clinical incidence in years before and after statewide adoption of the banned Nelson-Cradle maneuver among Michigan high school wrestlers. Design: Prospective cohort study. Setting: Michigan High School Athletic Association (MHSAA) sanctioned high school wrestling programs from 2015/16 through 2022/23 academic years. Excluding data from 2020/21 academic year due to sport participation being impacted by the COVID-19 pandemic. Patients or Other Participants: High school wrestlers (boys and girls) competing on MHSAA-sanctioned wrestling teams (746–755 schools annually). Main Outcome Measures: SRC clinical incidence rates per 100 player-seasons, stratified by pre-rule (2015/16–2017/18) and post-rule (2018/19, 2019/20, 2021/22, 2022/23) periods. Relative rate ratios (RR) with 95% confidence intervals (CI) were calculated. Results: A total of 1,591 SRC cases were reported, with 5.8% occurring in girls. Most cases (80.5%) occurred at the varsity level, and surface contact was the most common mechanism (55.1%). The overall clinical incidence of SRC was 2.25 (95% CI: 2.15, 2.37) per 100 player-seasons. Following the rule implementation, SRC incidence decreased significantly from 2.51 (95% CI: 2.33, 2.70) to 2.07 (95% CI: 1.93, 2.22) per 100 player-seasons (RR: 0.83; 95% CI: 0.74, 0.91). Conclusions: The ban on the Nelson-Cradle maneuver coincided with a significant reduction in SRC incidence among high school wrestlers. While causality cannot be inferred from this observational design, the observed trend aligns with the intent of safety-focused rule modifications and supports continued evaluation of sport-specific policies aimed at promoting safer participation.