Concussion in Professional Football: Reconstruction of Game Impacts and Injuries: In Reply

Abstract

OBJECTIVE: Concussion in prolessional foothell was stodied with respect to impact types and injury biomechanics. A combination of viden surveillaece and laborratory recoostroction of game impacts was used to evaluate concussion biomerbanes. METHODS: Between 1996 and 2001, videctapes of concussions and sigeificant head impact were collected from National Football Leagrue games. There were clear views of the direction and location of the heimel impact for 182 cases. In 31 cases the speed of impact could be determined with analysis of multiple videos. Those cases were reconstructed in laboratory tests using helmeted hybrid III dumnies and the same impact veloxity, direction, and head kireanatics as in the garne. Translational and rotational accelerations were measured, to define concussion biomechanics. Several studes were performed to ensure the accuracy and reproducibility of the video analysis and laboratory methods used. RESULTS: Concussed players experienced head impacts of 9.3 ± 1.9 m/s (20.8 ± 4.2 miles/h). There was a rapid chapge in head velocity of 7.2 ± 1.8 m/s (1.61 ± 4.0 miles/h), which was significantly greater than that for uninjured struck players (3.0 ± 1.1 m/s, 11.2 ± 2.5 miles/h) t = 2.9, P < 0.005) or striking players (4.0 ± 1.2 m/s, 8.9 ± 2.7 milex/h) t = 7,6, P < 0,001), The peak head acceleation in concussion was 98 ± 28 g with a 15-millisecond half-sine duration, which was statistically greates than the 60 ± 24 g for uninjured struck players (t = 3.1, P < 0.005). Concussion was primarily related to translational acceleration resulting from impactis on the facemale or side or falls on the back of the helmet. Concussion could be assessed with the sererity index or head injury criterion (the conventional measures of head injury risk). Nominal tolerance levels for concussion were a severity index of 300 and a head injury criterion of 250. CONLUSION: Concussion occurs with considaciable head impact seloclty and selocity change in prolessional football. Current National Operating Committes on Standards for Athletic Equipment standards primarity address impacts to the periphery and crown of the helinet, whereas players are experioncing injuries in impact to the factimask, side and back of the helmet. New tests are needed to assess the performance of frelmets in reducing concussion risks involving high velocity and long-duration injury biomechanics.