Football Helmet Research Articles

Do football helmets reduce acceleration of impact in blunt head injuries?

Several recent studies suggest that acceleration of the head at impact during sporting activities may have a detrimental effect on cognitive function. Reducing acceleration of impact in these sports could reduce neurologic sequelae. To measure the effectiveness of a regulation football helmet to reduce acceleration of impact for both low- and moderate-force impacts. An experimental paired study design was used. Male volunteers between 16 and 30 years of age headed soccer balls traveling approximately 35 miles per hour bareheaded and with a helmet. An intraoral accelerometer worn inside a plastic mouthpiece measured acceleration of the head. The helmet also had an accelerometer placed inside the padding. For more forceful impacts, cadaver heads, both with and without helmets, were instrumented with intraoral (IO) and intracranial (IC) accelerometers and struck with a pendulum device. Simultaneous IO and IC accelerations were measured and compared between helmeted and unhelmeted cadaver heads. The main outcome was mean peak acceleration of the head and/or brain associated with low- and moderate-force impacts with and without protective headgear. Mean peak Gs, measured by the mouthpiece accelerometer, were significantly reduced when the participants heading soccer balls were wearing a helmet (7.7 Gs with vs 19.2 Gs without, p = 0.01). Wearing a helmet also significantly lowered the peak Gs measured intraorally and intracranially in cadavers subjected to moderate-force pendulum impacts: 28.7 Gs with vs 62.6 Gs without, p < 0.001; and 56.4 Gs with vs 81.6 Gs without, p < 0.001, respectively. A regulation football helmet substantially reduced the peak Gs associated with "heading" a soccer ball traveling at moderately high velocities. A helmet was also effective in reducing the peak acceleration both intraorally and intracranially for impacts significantly more forceful than heading a soccer ball.

10 Questions about Football–Helmet and Face–Mask Removal: A Review of the Recent Literature

10 Questions about Football–Helmet and Face–Mask Removal: A Review of the Recent Literature

Exact Misclassification Probabilities for Plug-In Normal Quadratic Discriminant Functions. I. The Equal-Means Case

We consider the problem of discriminating, on the basis of random “training” samples, between two independent multivariate normal populations, Np(μ, Σ1) and Np(μ, Σ2), which have a common mean vector μ and distinct covariance matrices Σ1 and Σ2. Using the theory of Bessel functions of the second kind of matrix argument developed by Herz (1955, Ann. Math.61, 474–523), we derive stochastic representations for the exact distributions of the “plug-in” quadratic discriminant functions for classifying a newly obtained observation. These stochastic representations involve only chi-squared and F-distributions, hence we obtain an efficient method for simulating the discriminant functions and estimating the corresponding probabilities of misclassification. For some special values of p, Σ1 and Σ2 we obtain explicit formulas and inequalities for the probabilities of misclassification. We apply these results to data given by Stocks (1933, Ann. Eugen.5, 1–55) in a biometric investigation of the physical characteristics of twins, and to data provided by Rencher (1995, “Methods of Multivariate Analysis,” Wiley, New York) in a study of the relationship between football helmet design and neck injuries. For each application we estimate the exact probabilities of misclassification, and in the case of Stocks' data we make extensive comparisons with previously published estimates.

Emergency Removal of Football Equipment: A Cadaveric Cervical Spine Injury Model

Study objective: To determine the influence of football helmet and shoulder pads, alone or in combination, on alignment of the unstable cervical spine. Methods: The alignment of the intact cervical spine in 8 cadavers was assessed radiographically under 4 different football equipment conditions: (1) no equipment, (2) helmet only, (3) helmet and shoulder pads, and (4) shoulder pads only. Each specimen was then surgically destabilized at C5-C6 to simulate a flexion-distraction injury. Repeat radiographs were obtained under the same 4 equipment conditions, and alignment of the unstable segment was analyzed. Results: Before the destabilization, neutral alignment was maintained when both helmet and shoulder pads were in place. The “helmet only” condition caused a significant decrease in lordosis (mean, 9.6±4.7 degrees), whereas the “shoulder pads only” condition caused increased lordosis (13.6±6.3 degrees). After destabilization, the “helmet-only” condition demonstrated significant mean increases in C5-C6 forward angulation (16.5±8.6 degrees), posterior disc space height (3.8±2.3 mm), and dorsal element distraction (8.3±5.4 mm). Conclusion: Our flexion-distraction model demonstrated that immobilization of the neck-injured football player with only the helmet in place violates the principle of splinting the cervical spine in neutral alignment. By extrapolation to an extension-type injury, immobilization with only the shoulder pads left in place similarly violates this principle. In order to maintain a neutral position and minimize secondary injury to the cervical neural elements, the helmet and shoulder pads should be either both left on or both removed in the emergency setting. [Gastel JA, Palumbo MA, Hulstyn MJ, Fadale PD, Lucas P: Emergency removal of football equipment: A cadaveric cervical spine injury model. Ann Emerg Med October 1998;32:411-417.]

A Football Helmet in Our Archives?

A Football Helmet in Our Archives?

On-field management of potential cervical spine injury in helmeted football players: leave the helmet on!

Improper handling of an unstable neck injury in the prehospital setting may result in potential iatrogenically induced neurologic injury. On-site management of the neck-injured, helmeted football player differs from that of other traumatic cervical spine injuries. Controversy still exists regarding helmet removal protocols for stabilizing the cervical spine of helmeted football players with a suspected neck injury. This article provides a critical review of the scientific evidence on cervical spine management in helmeted football players with a suspected cervical spine injury. A computerized literature search of databases (MEDLINE, Sportdiscus) and a manual search of journals from the sports medicine, emergency medicine, orthopedic, and athletic training literature identified articles related to the topic. Additional references were reviewed from the bibliographies of the retrieved articles. Conclusions are based on five quasi-experimental study designs evaluating motorcycle, football, and hockey helmet removal. In addition, an attempt was made to correlate articles relating to airway and cervical spine management in general trauma to the helmeted athlete. Several studies support the recommendation not to remove the helmet or shoulder pads in the prehospital setting unless absolutely necessary. If necessary, both helmet and shoulder pads should be removed together as a unit. There are neither published studies in support of helmet removal nor any case reports of increased morbidity to athletes because of failure to remove the helmet in the prehospital setting. Although studies support the notion that iatrogenic neurologic deterioration may occur with improper handling and attempted removal of the helmet in the prehospital setting, there is no literature to support increased morbidity associated with not removing helmet and shoulder pads. Stabilization of the cervical spine in an injured football player does not require routine prehospital removal of the helmet and shoulder pads before transport.

Cervical spine alignment in the immobilized football player. Radiographic analysis before and after helmet removal.

We investigated the effect of football helmet removal on the sagittal alignment of the cervical spine. A quantitative radiographic assessment of relative cervical spine position in subjects immobilized to a standard backboard wearing shoulder pads either with or without a helmet was performed. Comparison was made to a control situation with subjects on a backboard wearing no equipment. Ten subjects were studied using lateral computed tomographic scout films; each subject served as his own control. Radiographs were measured for overall sagittal cervical alignment and the amount of lordosis or kyphosis present within specific segments of the cervical spine. Mean values for each of the three defined situations (no equipment, shoulder pads and helmet, shoulder pads alone after helmet removal) were calculated and subjected to statistical analysis. No statistically significant difference in cervical sagittal alignment was noted when either no equipment or both shoulder pads and helmet were worn. In contrast, a statistically significant increase in cervical lordosis (extension) was found when comparing the control situation to that when only shoulder pads were worn after the helmet had been removed. The majority of this increase occurred in the subaxial spine. Therefore, the authors recommend that football players with a potential cervical spine injury be immobilized for transport with both their helmet and shoulder pads left in place, thereby maintaining the neck in a position most closely approximating "normal."

The Lethal Weapon: How the Plastic Football Helmet Transformed the Game of Football, 1939-1994

Under the Friday night lights of October 23, 1971, Senn High School battled Kennedy High for football victory. In the third period, to avoid a rush from the Kennedy tacklers, the Senn quarterback scrambled and threw to his halfback, Marco Cervates. Cervates caught the ball, turned and put his head down to run for extra yardage as his teammates and fans cheered. A two hundred-pound linebacker abruptly stopped Cervates' run. Cervates fell to the turf, unconscious. On November 3, 1971, at the age of seventeen, Marco Cervates died.(1)

When Football Players Have a Suspected Cervical Injury, Leave the Football Helmet On!

When Football Players Have a Suspected Cervical Injury, Leave the Football Helmet On!

Complete Isolated Axillary Nerve Palsy in College and Professional Football Players

Axillary nerve injuries are infrequently sustained in football and are most often a consequence of glenohumeral instability. We present six cases of football players who sustained complete axillary nerve palsies secondary to a direct blow to the lateral aspect of the shoulder from a football helmet. This study is the first to document this injury. The initial presentation, physical examination, treatment, and anatomy are discussed. All lesions were complete, as documented by physical examination and serial EMGs. All patients had an electromyographic/nerve conduction velocity examination 3 weeks following the date of injury and follow-up EMG/NCV at 5 months. Initial electromyographic studies revealed fibrillation potentials with no voluntary motor activity, compatible with a complete axillary nerve injury. All patients were initially treated nonoperatively, emphasizing strengthening of the rotator cuff and electrical stimulation of the deltoid. One patient was treated with exploration of the axillary nerve after a delay in evidence of axillary nerve return. All patients returned to their high level of athletic activity. The time to return to competitive sports was prolonged, averaging 9 months, with maximal recovery occurring at 12 months. The overall follow-up has ranged from 2 to 4 years.

Emergency Removal of Football Helmets.

In brief when a football player has a brief suspected head or neck injury, when and how to remove the football helmet become critical issues. Protocols differ; however, the National Collegiate Athletic Association guidelines, which state that the helmet should only be removed on the field under very special circumstances, are appropriate. An understanding of the technologically advanced design and tight fit of modern football helmets will help guide medical personnel through each step of the helmet removal process.

LIGHTNING STRIKE TO THE HEAD

A case is presented of a teen-aged athlete who sustained a direct lightning strike to the head while wearing a football helmet. The helmet, the presence of sweat, and aggressive resuscitation were instrumental in his survival and complete recovery. This appears to be the first documentation of a lightning strike to an individual wearing protective headgear.

Energy Absorption Characteristics of Football Helmets under Low and High Rates of Loading

The purpose of this study was to examine the force-deformation characteristics of football helmets subjected to compressive loading on the crown surface. Tests were conducted at quasi-static and dynamic rates of loading. Energies were computed from the force-deformation data. The padding systems represented by the helmets differed in their ability to absorb energy under varying loading rates. Helmets using pneumatic or combination pneumatic-foam padding systems were the most successful while suspension helmets were able to absorb the least amount of energy. The evaluation of energy absorption characteristics is an alternative method of describing the effectiveness of football helmets in preventing head injury.

Thigh compartment syndrome in a football athlete

Although contusions of the thigh are common in all sports, a compartment syndrome from closed blunt trauma without a femur fracture is rare. Thigh compartment syndrome is unusual due to increased compliance of the thigh to accommodate increased expansion from hematoma or third space fluid. Compartment syndrome of the thigh is characterized by unrelenting pain, swelling, and limited knee range of motion. A single case of a thigh compartment syndrome caused by a direct blow to the anterior aspect of the thigh from a football helmet during kickoff occurred. Immediate thigh fasciotomy was performed. Early diagnosis with appropriate emergency treatment can avoid serious and permanent complications.

The effect of a football helmet accessory on impact characteristics and moments of force at the neck

The effect of a football helmet accessory on impact characteristics and moments of force at the neck

Influence of materials and structure on performance of a football helmet

AbstractA nonlinear finite element model for the static analysis of football helmets is developed as a first step in a methodology for the mathematical modeling of helmets. Polycarbonate and acrylonitrile‐butadiene‐styrene are considered as the shell material for the helmet. Such a methodology can be used to predict helmet response to loading and impact and can be incorporated in a computer program studying injuries caused by helmeted head collisions in football. Numerical results in terms of force‐deflection curves, maximum stresses, and work of deformation are given. The influence of the polymeric material forming the helmet shell on energy absorption is studied. The effect of the internal padding material and suspension system is also considered.

Reward for Increasing Football Helmet Safety? Leqal Hassles

Football helmets have become safer in the past few years, but liability claims have increased. Manufacturers and school districts are considering solutions such as new designs, insurance coverage, and education programs.

The inertial and geometrical properties of helmets.

The center of gravity (CG) and the principal mass moments of inertia about the CG of Army aviator, American football, and bicycle helmets were experimentally determined by a variation of the classic differential weighing and torsional pendulum techniques. In the course of these experiments, an innovative method for three-dimensional (3D) digitization was found. An electronic caliper, which measured length, was used with a computer algorithm to achieve 3D digitization. The results of the above measurements show that the weight of the helmet and the distances from the CG to the orthogonal coordinate axes intercepts with the outer shell surface were highly correlated with its principal mass moments of inertia. A set of regression equations was derived on theoretical considerations and served to unify the experimentally obtained data. Our results indicate that the principal mass moments of inertia of helmets vary linearly with its mass but nonlinearly with size and shape. For a helmet, given its weight and certain geometrical distances, the regression equations estimate the principal mass moments of inertia to within 5% of its experimentally-determined values. For the helmets studied in this series, a modified linear-regression relationship between the principal mass moments of inertia and its mass was found. This result is reasonable because the mass distribution of the current generation of helmets are set primarily by the head size and secondarily by helmet size, shape, and materials.

Variability and Sampling Inspection in the NOCSAE Standards for Football Helmets

Abstract Because of increasing numbers of serious sports-related injuries at all levels of participation, the National Operating Committee on Standards for Athletic Equipment (NOCSAE) was formed. Among their activities aimed at improving the safety of sports participation was the development of standards for impact resistance in both new and refinished football helmets. These standards include not only recommendations as to safe levels of resistance to impact but recommendations as to the number of helmets to be tested from each group of helmets undergoing a refinishing process. In this study the various sources of variability in the testing procedure are examined. These sources include helmet-to-helmet variability, testing variability, and basic measurement error. A careful examination of this variability in the context of the NOCSAE-recommended testing procedures for recertifying helmets reveals an inadequacy in the NOCSAE standard, in that the probability of returning unsafe helmets to the playing fiel...

An evaluation of football helmets under impact conditions.

The impact attenuating characteristics of a sample of 81 football helmets used in competitive high school programs were determined using a Hodgson-Wayne State University (WSU) headform and a modified National Operating Committee on Standards for Athletic Equipment (NOCSAE) test protocol. The helmets, classified by liner type as suspension (37), padded-suspension (22), and padded (22) had been in use for 6 to 8 years. Each was subjected to two consecutive right rear boss impacts from a drop height of 1.5 m, onto a rigid anvil covered with a 45 durometer hardness rubber pad. Analogue signals from a triaxial accelerometer located at the center of gravity of the headform were analogue to digital (A/D) converted at 6060.6 Hz and processed on a Hewlett Packard 9845B minicomputer to yield a resultant acceleration-time curve from which peak acceleration (gpeak) and the Gadd Severity Index (GSI) were determined. The mean gpeak was 205 g for helmets with suspension liners, 165 g for helmets with padded-suspension liners, and 156 g for helmets with padded liners. Twenty-four suspension helmets and five padded or padded-suspension helmets had GSI values greater than 1200. Using a criterion of GSI1500, the failure rate for suspension helmets was 19% compared to 2% for padded and padded-suspension helmets combined. If the criterion chosen was GSI1200, the failure rate for suspension helmets was 65% as opposed to 11% for the padded and padded-suspension helmets combined. Suspension helmets are decidedly inferior under impact conditions to the padded and padded-suspension helmets.