Effectiveness of a Polyurethane Football Helmet Cover on the Repeated Occurrence of Cerebral Concussions
Abstract & Commentary
Synopsis: The natural history of recurrent concussions may not be affected by the use of this helmet cover.
Source: Torg JS, et al. Retrospective report on the effectiveness of a polyurethane football helmet cover on the repeated occurrence of cerebral concussions. Am J Orthop 1999; 28(2):128-132.
Concussion, and particularly recurrent concussion, is a serious and not uncommon consequence of playing football. The ProCap polyurethane helmet cover, manufactured by the Protective Sports Equipment Company of Erie, PA, has been used for the last five years or so as a means to try to decrease the incidence of concussive episodes, particularly among competitors who have a history of concussion. The ProCap is a lightweight polyurethane pad that conforms to and attaches snugly to the outside of the helmet. Laboratory studies using the standardized "drop test" show that this device reduces the G-forces transmitted through the helmet to the head by approximately 30% when compared to the helmet alone.
To test the clinical effectiveness of this helmet cover, Torg and associates surveyed 245 individuals who have been identified as having purchased the device. One hundred fifty five purchasers returned the survey, which provided a detailed history of concussions occurring both prior to and during the period that the device was used. All respondents to the survey used the device because they had previously sustained at least one concussion. The rate of concussion recurrence was then calculated and compared to the number of previous concussions sustained by the players. It was found that the rate of concussion recurrence increased proportionate to the number of previous concussions that had been incurred. Torg et al concluded, "The range appeared to reflect a parallel relationship between pre- and post-device concussion experiences: the more concussions experienced prior to adopting the device, the higher the rate of concussion reoccurrence while using the device." Torg et al concluded that the natural history of recurrent concussions may not be affected by the use of this helmet cover. They recommended that further scientific study be conducted in a prospective, randomized manner to see if the device actually does prevent either initial concussions or recurrent concussions. The limited anecdotal evidence currently available led Torg et al to conclude that the ProCap device should not be routinely used prophylactically and that its effectiveness has not been conclusively shown. Because it does not seem to cause any problem, they still recommended that because of the objective evidence of decreased G-forces in the drop-test studies, the device could " be considered for use in individuals with one or two prior concussion injuries."
Comment by James D. Heckman, MD
Torg et al bring to our attention the experience of a large number of players who used a polyurethane helmet cover to reduce recurrent concussive episodes while playing football. This anecdotal evidence is not very conclusive with regard to effectiveness. While there are some objective biomechanical studies that show that impact loading of the head can be decreased somewhat by use of this device, there is not a clear, direct relationship defined between impact loading and the cause of concussion. Indeed, concussion can be caused either by impact loading or, as Torg et al state, impulsive loading. Impulsive loading is more related to shear, tensile, and compressive strains within the brain as opposed to direct impact. Because the exact mechanism of concussion in a football player is not entirely clear, it cannot be assumed that a helmet cover or similar devices will eliminate the problem. Indeed, wearing such a protective helmet cover may give the player a false sense of security, causing him to ignore sensible tackling techniques that have clearly been shown to decrease the incidence of severe head injury among football players. It certainly is clear that more studies need to be conducted to determine the specific mechanisms of concussion in football players and to demonstrate the value of the helmet cover to prevent repeated occurrences of cerebral concussions in these athletes.