Training and equipment to prevent athletic head and neck injuries

Clin Sports Med 22 (2003) 639 – 667

Training and equipment to prevent athletic head and neck injuries Kevin M. Cross, MEd, ATC, PT*, Catherine Serenelli, MS, ATC, CSCS University of Virginia Sports Medicine, PO Box 400834, McCue Center, Emmet Street and Massie Road, Charlottesville, VA 22904, USA

Due to the relative risk and generally poor outcome of neurotraumas (ie, concussions and spinal cord injuries) and cervical spine injuries in sports, coach and athlete compliance with preventative measures is very important. The success of such preventative programs is best demonstrated by the results of rule changes in football which modified the use of the head. During the 1975 football season, a significantly high number of cervical spine injuries were documented in New Jersey and Pennsylvania. In the vast majority of injuries, the mechanism was an axial load to the cervical spine. The National Collegiate Athletic Association (NCAA) responded by imposing rules that prohibited intentionally striking a runner with the crown of the helmet, and the deliberate use of the helmet to ‘‘butt or ram an opponent,’’ and that redefined spearing as deliberate use of the helmet to punish an opponent. Similarly, the National Federation of State High School Associations (NFSHA) revised football rules to prohibit ‘‘techniques involving a blow with the face mask, frontal area, and top of the helmet driven directly into an opponent as the primary point of contact either in close line play or open field.’’ The consequence of the rule changes was an approximate 60% decrease in cervical spine injuries within two years [1]. Regardless of the sport, there are certain areas that the sports medicine practitioner may successfully address in prevention of neurotraumatic injuries. Strength training, sporting techniques, and sports equipment are the fundamental means of addressing this issue [2]. Strength training has limitations in its effectiveness at preventing neurotraumatic injuries. With proper sporting tech-

* Corresponding author. University of Virginia Sports Medicine, PO Box 400834, McCue Center, Emmet Street and Massie Road, Charlottesville, VA 22904. E-mail address: [email protected] (K.M. Cross). 0278-5919/03/$ – see front matter D 2003 Elsevier Inc. All rights reserved. doi:10.1016/S0278-5919(02)00099-6

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niques and equipment use, however, coaches and athletes may reduce the risk of acquiring a neurotrauma.

Strength training Cantu [2] notes that strength training of the cervical musculature may provide absorption of energy occurred from a head impact. The severity of the concussion, therefore, may be minimized. We believe that the primary role of strength training in the prevention of neurotraumas, however, is to influence the severity of cervical spine injuries, predominantly noncatastrophic ones. The discussion of strength training that follows refers to the prevention of cervical spine injuries. The reader may also consider theoretically the preventative effects that such strength training may have on concussion incidence and severity. To understand the relevance of strength training for cervical spine injury prevention, one must consider the biomechanics of cervical spine injury. Historically, exaggerated cervical extension and especially flexion were considered to be the primary mechanisms for cervical neurotrauma [1]. The actual mechanism, which has been established by means of cinematographic and laboratory analysis of the injury, is axial loading, disregarding the concomitant motion in the neck [3 –6]. Specifically, Roaf [6] published the results of a classic study in which he applied a variety of forces from various planes to cadaveric cervical spines. He reported not one incident of a hyperflexion injury to the cervical spine. He did report, however, that compression injuries, associated with flexion and rotation, created typical cervical spine injury patterns [6]. While providing axial loads to cadaveric cervical spines, Nightingale et al [5] noted that injury occurred to the cervical spine 2.2 to 18.8 milliseconds after an axial impact. This short time lapse does not permit motion of the cervical spine to occur. Moreover, reflexive responses of cervical muscles range from 50 to 65 milliseconds, which is considerably longer than the time for injury following impact [5]. Nightingale et al [5] caution, however, that these results may not be applicable to injuries caused by ‘‘non-accidental circumstances, such as . . . spear-tackling . . . .’’ Cervical injuries that are not catastrophic, such as nerve root or spinal nerve pathologies (ie, stingers, disc protrusions, joint pathologies) may benefit from strengthening of the cervical spine. Most cervical spine injuries, especially stingers, occur with compressive or tensile insults to the surrounding tissue [7]. A mechanism of injury may be a direct force that separates the head and shoulder to the extreme ranges of motion, or the mechanism may be atraumatic and occur secondary to repetitive movements of hypermobile segments. Weinstein [7] states the importance of cervicothoracic stabilization in the rehabilitation of such injuries. Hypermobility injuries of the cervical spine result in degeneration of the discs and joints of the cervical spine and may cause arthritic symptoms. The consequent discal degeneration and joint arthopathy also result in neuroforaminal narrowing and predisposition to nerve root or spinal nerve pathology [7]. To manage such

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pathologies, several sources recommend general cervical muscle strengthening exercises, specifically cervicothoracic stabilization [2,7 –9]. We contend that the incorporation of such exercises may also be of great benefit as preventative measures against hypermobility of spinal segments and violent excursion of the cervical spine, which may lead to a noncatastrophic injury to the cervical spine. When managing patients with cervical spine pain, addressing patient posture is very important. Typically, the patient presents with a forward-head posture. The upper cervical spine is in relative hyperextension and the lower cervical spine and cervicothoracic junction are in relative hyperflexion. The consequence of this malalignment on the adjacent musculature has been theorized by Florence Kendall [10]. Essentially, those muscles which have been lengthened, primarily the short cervical flexor muscle group, will become weaker due to the alteration from the length-tension relationship. Consequently, the patient will have difficulty reducing the hyperextension of the upper cervical spine, and thus difficulty maintaining a theoretically proper cervical lordosis. We believe that such emphasis on cervical posture is also important for preventing cervical spine injuries. Grimmer and Trott [11] studied the relationship between poor cervical posture and deep cervical, short flexor-muscle endurance. First, the authors analyzed the cervical excursion, or the extent of cervical lordosis, of 427 subjects. Subjects then were placed in a supine position and instructed to perform a chin tuck and flex their neck until their head was 2 cm from the plinth. The authors theorize that the deep cervical, short flexor-muscle endurance may be quantified from the time between assuming the test position and the position being lost to a ‘‘chin thrust.’’ Data analysis identified a strong negative relationship between the degree of upper cervical excursion into hyperextension and deep cervical, short flexor-muscle endurance. Essentially, poor cervical short flexor-muscle endurance was associated only with head postures demonstrating exaggerated cervical lordosis [11]. Assuming that Grimmer and Trott’s [11] endurance measure demonstrates good construct validity, one may still question the relative importance of the intrinsic cervical muscle function in cervical injury prevention. Kettlera and Hartwig [12] performed in vitro testing on six occipito-cervical spine specimens. Muscle forces were simulated by cables that were attached to the anatomical attachment of three intrinsic cervical muscle groups—the splenius capitus and the semispinalis capitus posteriorly, and the longus colli anteriorly. The range of motion of the segments C1 through C2 were compared among (1) a comparison condition with no cable tension; (2) an experimental condition with cable tension of 10 N per splenius and semispinalis muscle groups, and 30 N per longus colli muscle group; and (3) an experimental condition with the same cable tension as in (2), but with transection of the left alar and adjacent ligaments followed by transection of the right alar and adjacent ligaments [12]. The data analysis indicates the relative importance of the intrinsic cervical muscles, with heavy emphasis on the deep cervical flexors, to spinal stabilization. Concerning the condition with nondisrupted ligaments, simulated muscle tension of 20 N posteriorly and 30 N anteriorly reduced axial rotation to 46% to 58% of the comparison condition, lateral bending to 60% to 71% of the comparison condition,

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flexion to 73% to 77% of the comparison condition, and extension to 81% to 86% of the comparison condition. To a much lesser extent, with disrupted ligaments the simulated muscle tension reduced many of the available ranges of motion of the C1 through C2 segments [12]. We recognize the inability to confidently generalize Kettlera and Hartwig’s [12] results to in vivo situations and to middle and lower cervical segments. The art of sports medicine, however, permits us to appreciate that coactivated instrinsic cervical muscles do in fact reduce cervical range of motion at upper cervical segments. Moreover, proper strength and endurance training of the intrinsic cervical muscles may indeed prevent or minimize cervical injury, specifically noncatastrophic injuries, due to excessive movement of a spinal segment. Few exercises have been presented in the literature that specifically focus on strengthening the intrinsic cervical musculature. Grimmer [13] presents an isometric exercise that has been used as a dependent variable of cervical short flexor muscle endurance in various research projects. To perform this exercise, athletes are instructed to lie supine with a prepositioned chin tuck, or cervical nod. They are next instructed to flex their cervical spine until the posterior aspect of the head is approximately 2 cm from the table (Fig. 1). The sports medicine practitioner may initially prescribe three to five sets of the exercise and tell the athlete to hold the contraction for ten seconds. As the athlete’s endurance improves, the practitioner may increase the difficulty by increasing the hold time or the number of sets. To address the intrinsic cervical muscles, Kisner and Colby [9] outline general guidelines and provide general exercise ideas for cervical stabilization. As with learning any new skill, the general principles of motor learning should be observed. Initially the patient must identify the most comfortable and natural position of his cervical spine. This position should come close to the ‘‘ideal’’ cervical posture, with the ear over the shoulder. This position should also be dynamic and the spine should be permitted to move within a small range during activity, thus providing a ‘‘functional range.’’ The athlete, however, should not experience any discomfort or

Fig. 1. An isometric supine cervical short muscle endurance exercise.

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pain when performing activities while maintaining the cervical spine in the functional range. The first goal of cervical stabilization is for the patient to immediately identify his functional position and to isometrically hold this position while supine. If the athlete cannot consistently identify and hold his functional position, then he should not be progressed to the next stage. It is very important that the athlete initially be monitored when beginning these exercises. The athlete should not be permitted to train erroneous movement patterns. Frequent feedback, after every repetition if necessary, is preferred to properly train the athlete in cervical stabilization. We believe that most practitioners do not keep their athletes in this stage of exercise long enough. Athletes are not properly monitored and they are progressed to more advanced exercises without being able to consistently approximate a functional position in the cervical spine. Consequently, the athletes practice erroneous movement patterns and do not properly train the musculature to stabilize the spine during dynamic and rhythmic whole body movements. The second progression of cervical stabilization is dynamic/rhythmic/transitional stabilization [9]. Practitioners may advance athletes to this phase by requesting simple extremity movements while the athlete maintains the cervical spine within the functional range. ‘‘Dynamic stabilization’’ implies that the exercise progression begins with bilateral agonist muscle contraction—bilateral shoulder flexion [9] (Fig. 2). The athlete should progress to a ‘‘rhythmic stabilization’’ subphase wherein alternating antagonist muscle contractions are used in attempt to perturb the cervical spine—alternating shoulder flexion and extension (Fig. 3). Finally, the athlete will progress to a ‘‘transitional stabilization’’ subphase that requires cervical stabilization in the functional range while performing transitions between body postures—squats and lunges (Fig. 4). The maintenance of the cervical spine in the functional range during these activities requires that the athlete develop and refine proprioception of the cervical spine. As the athlete becomes more consistent in maintaining the cervical spine during simple movements, the exercise program should be altered to provide

Fig. 2. Dynamic stabilization: standing bilateral shoulder flexion with the cervical spine maintained in the functional range.

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Fig. 3. Rhythmic stabilization: standing alternating shoulder flexion and extension with the cervical spine maintained in the functional range.

interruption of a given exercise with other movement patterns. For example, the exercise pattern may require the athlete to perform three repetitions of alternating shoulder flexion and extension followed by three repetitions of shoulder abduction and adduction, or the practitioner may alter the resistance every three repetitions to vary the muscular output. As with stage one, the practitioner initially should be present to provide frequent feedback. As the athlete becomes more advanced in the skill, however, the amount and timing of the feedback should be altered. The practitioner may vary the feedback by allowing the athlete to complete a set of exercises before discussing the performance, or the practitioner may choose not to provide feedback unless the athlete’s performance was unacceptable. The level of exercise difficulty and the focus of the exercise may be altered by varying the surface on which the exercises are performed. The progression is from a stable surface to an unstable surface, and from weight bearing through the legs to the trunk and to the head. Our general exercise surface transition is as follows:

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Fig. 4. Transitional stabilization: athlete performs lunges while holding dumbbells with the cervical spine maintained in the functional range.

standing, standing with ball between head and wall, and alternating exercises between a bridge position with thoracic cage on an unstable surface and bridge position with the head and cervical spine on an unstable surface (Fig. 5A –D). When performing the exercises with the thoracic cage on an unstable surface, an athlete must primarily use his cervical flexors to maintain his cervical spine in the functional range. In contrast, when performing the exercises with his head and cervical spine on an unstable surface, the athlete must primarily use his cervical extensors to maintain his cervical spine in the functional range [9]. During stage three, the athlete will be performing complex movement patterns while automatically maintaining the cervical spine in its functional range. It is thought to take from months to years of training for an individual to reach this stage of learning a new skill. To properly train the cervical stabilizers during this stage, the practitioner must recruit the team coaches and strength and conditioning specialists to observe and cue the athletes as to any stimuli that may disturb the stabilization of the cervical spine. Although spinal stabilization, which focuses on training the ‘‘intrinsic’’ muscles, is the current trend for strength training of the cervical spine, the practitioner must not ignore strengthening the ‘‘extrinsic’’ muscles surrounding the cervical spine. During gross strength testing of the cervical extensors, Jordan et al [14] revealed that the cervical musculature exhibits approximately twice the maximal strength, relative to body weight, as the lumbar musculature. Therefore, it seems imperative to not overlook the obvious strength requirements of the cervical spine. It is our impression that these larger muscle groups—the upper trapezius muscles and the levator scapulae muscles—may be best trained by isotonic exercises. Our reasoning stems from the results of Pollack et al [15], who investigated the effects of frequency and volume on cervical extension strength. Subjects’ cervical extensors were tested isometrically before and after a cervical extension progressive resistive strength training program. Subjects were randomly stratified into one of five groups: (1) nontraining control group, (2) once per week

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Fig. 5. Athlete performing cervical stabilization exercises (bilateral shoulder flexion) across the progression of surfaces. (A) Athlete standing. (B) Athlete standing with ball between head and the wall. (C ) Athlete bridging with upper back on theraball to focus on cervical flexors. (D) Athlete bridging with cervical spine and head on theraball to focus on cervical extensors.

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on isotonic neck machine, (3) once per week on isotonic neck machine and one set of isometrics, (4) twice per week on isotonic neck machine, and ( 5) twice per week on isotonic neck machine and one set of isometrics. After a 12-week program, subjects achieved the greatest changes in isometric cervical extension with exercise on an isotonic neck machine at a frequency of twice per week. The addition of isometrics did not significantly improve the strength gains [15]. There are a variety of weight machines that are designed to strengthen the cervical muscles in gross patterns (Fig. 6). Important aspects of using such machines are maintaining proper posture and cervical alignment, and minimizing assistance from the trunk. Practitioners do not need expensive equipment, however. The practitioner may incorporate cervical isotonic strength exercises by manual resistance (Fig. 7). Manual resistance may in fact be more beneficial, because the practitioner can adjust the resistance throughout the range of motion so that the ‘‘weak point’’ in the range does not limit the resistance provided throughout the range of motion. Important aspects of manual resistance are placing the resisting hand in a comfortable position and providing adequate resistance to challenge the muscles, but not so great a force that the cervical spine does not move smoothly through the range of motion.

Fig. 6. Athlete performing isotonic cervical strengthening exercises on a weight machine.

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Fig. 7. Athlete performing isotonic cervical strengthening exercises against manual resistance.

In addition, when strengthening the cervical spine, kinetic chain advocates promote thoracic and lumbar stabilization as well as scapular/shoulder stabilization. We believe that the general principles mentioned above for cervical stabilization are equally applicable to thoraco-lumbar stabilization. Athletes should understand and perform the technique properly before progressing to more advanced exercises. The level of difficulty may be advanced similarly. The progression is from supine on stable surface, to sitting, to standing with variation between stable and unstable surfaces.

Fig. 8. T exercises focus on strengthening the rhomboids and middle trapezius muscles.

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Fig. 9. Y exercises focus on strengthening rhomboids, middle trapezius, and lower trapezius muscles.

Regarding scapular stabilization, we recommend prone exercises commonly referred to by the letters T, Y, and I. The athlete is placed prone and the practitioner requests him to elevate his arms from the table by only squeezing his scapulae with the following range of motion changes: The T exercises are performed with the glenohumeral joint at 90 degrees of abduction. T’s are theorized to focus on more of the rhomboid and middle trapezius (Fig. 8). The Y exercises are performed with the glenohumeral joint at 135 degrees of abduction. Y’s integrate the lower trapezius muscles with the rhomboid and middle trapezius (Fig. 9). The I exercises are performed with the glenohumeral joints at approximately 180 degrees of abduction. I’s use primarily the lower trapezius and the cervical and thoracic extensors (Fig. 10). It is imperative that the athlete maintain his cervical spine within the functional range, whether the exercise is performed actively or with assistance (Fig. 11A,B).

Sporting technique As noted, the primary mechanism for cervical injuries is an axial load with slight flexion [3]. Governing bodies of high school, collegiate, and professional football have attempted to minimize the opportunities for such cervical loading by penalizing teams whose players intentionally use the crowns of their heads [1]. By observation, however, it is apparent that players continue to instinctively lower their heads when approaching a collision.

Fig. 10. I exercises focus on strengthening primarily the lower trapezius muscles.

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Fig. 11. When performing scapular stabilization exercises, the athlete’s head may be supported in the functional range passively (A) or he may actively stabilize his cervical spine in the functional range (B).

As a consequence it is imperative that coaches begin teaching players at a very young age proper head position when approaching a collision. Such education should instill a proper instinctive response to an anticipated collision. Torg [1] notes that the ‘‘face in the numbers’’ blocking and tackling techniques has not been implicated as causing catastrophic cervical spine injuries. Such technique, therefore, should be taught as the standard for tackling and blocking. To use this technique, players are instructed to assume a natural lordotic cervical posture such that their facemask is placed directly into the number on their opponent’s jersey. Such technique may also be referred to as ‘‘bulling’’ the neck. Techniques used to participate in other sports are important for preventing neurotrauma. Specifically, proper stunting techniques during gymnastics and cheerleading are critical. In addition, performing the proper technique for falling after a missed stunt is as important as performing the stunt with proper technique. Similarly, proper coaching of water entry during swimming and diving is important for preventing the incidence of neurotraumas. With regard to ice hockey, recognition and respect for the rules governing boarding and cross

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checking should be emphasized. Although neurotraumas and cervical spine injuries are rare in soccer, proper heading technique may prevent the rare occasion of cervical injury. Regardless of the sport, all coaches should be well versed in the proper and safe techniques for participation in their sports. This knowledge should then be emphasized to the athlete in order to prevent all severities of head and neck injuries.

Protective equipment The range of athletic activities is vast. There are many different sports; some require extensive protective sports equipment whereas others require none. Some of the sports that use protective equipment with the goal of preventing head and neck injury are football, baseball/softball, ice hockey, and men’s lacrosse. Protective helmets A variety of sports require the use of tight-fitting protective helmets. These sports include football, ice hockey, and men’s lacrosse. The purpose of the helmet is to protect the athlete from head trauma such as skull fractures and intracranial injuries. It is essential that sports health care professionals understand the material properties of protective helmets, their design and construction, selection and evaluation, and proper helmet fitting. The material properties include density, strength, rigidity (stiffness), conformability, and durability. Density is the weight per volume. Lighter material minimizes the amount of energy required to support or move the piece of equipment. Strength is the maximal permissible external stressor load a material can possibly sustain. Rigidity or stiffness is the amount of bending or compression that occurs in response to the amount of stress applied. Rigidity is described through ‘‘modulus of elasticity’’ (Chris White, personal communication, 2000). The higher the modulus, the stiffer or more rigid the material. Conformability is how the piece of equipment conforms to the specific body part. Finally, durability is the ability to withstand repeated stress. Each manufacturer has two to four standard shell sizes. The fitting sizes are 6 1/8 to 8 3/8; most helmets are 6 1/2 and 7 1/2. The helmet should not weigh much over two pounds; a heavier helmet would demand too much of the athlete’s energy just to support it. The helmet is the first line of defense, thus its shape plays an important role. The spherical shape has a performance advantage, because it deflects and dissipates the forces it encounters. The hard outer shell is constructed of a polycarbonate alloy called Lexan. Lexan is a strong, durable plastic with a high modulus of elasticity that gives it great rigidity. The shell is a deflective mechanism and different parts of the shell have different thicknesses that accommodate the different areas of stress. The liners (Fig. 12) act as energy absorbers and help to absorb the effects of the impact. Finally, the helmet includes areas termed stress raisers. These are areas most vulnerable to cracks and impact forces. Areas such as

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Fig. 12. The airliners found in football helmets.

these need to be examined during routine inspections, especially the areas where the holes are. The guidelines for helmet fitting are focused on football but actually pertain to ice hockey and men’s lacrosse as well. The guidelines for proper helmet fitting are established standards of care implemented to assist the sports health care professional and protect the athlete [16]:













The helmet should be inspected for any defects or concerns. Measure the circumference of the athlete’s head with calipers or a tape measure. The athlete should have a seasonal hairstyle and the hair should be wet to simulate game/practice conditions. The helmet should have a snug fit without dependence on the chin strap. The front edge of the helmet should be 1’’ or three finger breadths above the eyebrow. Jaw pads should fit snug without gaps. Ears holes are to line up with the external auditory meatus. The back of the helmet must cover the inferior occipital bone. The chin strap should be equidistant from the sides of the helmet. The examiner should push the helmet inferiorly, slide it laterally and superior/inferior with only the skin moving not the helmet.

From Arheim DD, Prentice WE. Protective sports equipment. In: Principles of athletic training, 9th edition. Chicago: Brown & Benchmark; 1997. p. 116; with permission.

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Football helmets The football helmet was patented in 1939 by Gerry Morgan and mandated by the NCAA at that time. In 1940, the first plastic helmet was designed, and then in 1943 the National Football League (NFL) mandated the use of such helmets (Chris White, personal communication, 2000). The plastic shell provided strength, durability, decreased weight, less rotation, and a better mounting surface for the face guards. Throughout the 1950s and 1960s, research and testing showed that the padded/suspension types of helmets had the best results. Therefore, the Riddell TK-2 emerged. The TK-2 suspends the helmet from the head and lets the helmet take the jolt. Epidemiological data revealed that there had been an increased incidence of catastrophic head and neck fatalities since the middle 1950s. It was during this time period that organized football mandated the use of the hard-shelled helmet and face mask. This increase in head and neck injury was attributed to an increase use of the tackling technique called spearing. Spearing occurs when the athlete uses the helmet as the initial and primary contact area during blocking and tackling [17]. In 1976 there was a major rule change in football that eliminated spearing [17]. This rule change was responsible for reducing the number of fatalities and serious head injuries during the 1977 football season [18]. The regulating agency responsible for setting the standards for football helmets is the National Operating Committee on the Safeguards of Athletic Equipment (NOCSAE). Development on the standard began in 1970 and it was ready for publication in 1973. A revised standard was published in April of 1996 and is now the NOCSAE standard 002-96. Their testing tries to simulate game situations. The NOCSAE standard testing procedures include the helmet fitted onto a humanoid head that is dropped onto a firm anvil twice. Each drop is 75 seconds apart, from 60 inches high, and occurs at six different locations at a temperature of 75° F. There are two additional drops onto the front corner of the helmet from a height of 60 inches after the helmet has been heated at 120°F for at least four hours. One of each size for each helmet model is tested. The strict testing and standards resulted in a drastic decrease in the number of football helmets available for purchase. In 1972, there were 85 helmet models available for purchase, as opposed to 25 in 1992. The severity index (SI) is frequently referred to when describing helmets. It is a measure of the severity of impact, with respect to the instantaneous acceleration experienced by the human head model at impact. The SI predicts the helmet’s ability to decrease forces at impact and to effectively protect the brain [19]. The lower the SI the less the risk of injury. The SI standard was 1500, but was revised as of 1996 and is now 1200. Forty helmet reconditioners found an average SI to be 715 in 1990, however. There are certain rules governing football helmets set by the National Collegiate Athletic Association (NCAA) [20]: (1) the face mask and helmets must be secured by a four- point chin, (2) the helmet must have manufacturer or reconditioner certification indicating satisfaction of the NOCSAE test standard, (3) There must be a warning label regarding risk of injury on the

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outside of the helmet. The NOCSAE warning statement is also located on a card that comes with each helmet. It is wise for the sports health care professional to have the athlete or parents read the label and sign an agreement acknowledging having read and understood the warning of potential injury as well as the maintenance instructions. The NOCSAE warning statement says [21]:

Do not strike an opponent with any part of this helmet or facemask. This is a violation of football rules and may cause you to suffer severe brain or neck injuries, including paralysis or death. Severe brain or neck injury may also occur accidentally while playing football. No helmet can prevent all such injury. You use this helmet at your own risk. From NOCSAE Manual. Overland Park (KS): National Operating Committee on Standards for Athletic Equipment; 2000; with permission.

An important organization for the protection of athletes and protective equipment is the National Athletic Equipment Reconditioners Association (NAERA). The NAERA is an organization of athletic equipment reconditioners whose purpose is to recondition and recertify helmets according to the NOCSAE standards and guidelines. The reconditioning process includes a standard testing procedure in which the helmet is dropped 16 times onto a firm rubber pad: two drops each from a height of 60 inches on six locations at ambient temperature (76°F). Impact measurements are taken to determine if the helmet meets the established SI value of 1500. If the SI is met then the helmet is considered NOCSAE recertified. The three common shell sizes of 6 5/8, 7 1/4 and 7 5/8 are tested. If these sizes pass the testing, it is assumed that the other helmet sizes in that model will pass as well. Helmets also have a wide variety of accessories, including frontal pads/front sizers, crown pads, side pads, back pads/back sizers, nose bumpers, stabilizer pads, and jaw pads. The frontal pad/front sizer is crucial for fit because if it is too tight, it can cause pressure on the forehead and possibly give the athlete headaches. The crown pad is located on the superior portion and is mostly seen on padded helmets. Back pads/back sizers are bars on the back of the helmet. They extend below the occipital bone and are crucial for proper fit because if they fit too high or too low, they can act as a fulcrum and predispose the athlete to injury. Also, if the helmet fits superior to the occipital protusion, it could slide and hit the athlete’s nose. Finally, jaw pads should be available in a wide variety and are usually 1/2" to 1 1/4" thick.

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Once sports health care professionals are aware of and understand the testing procedures and standards for football helmets, they can research the different helmet models available and help in choosing the correct helmet to protect athletes. The two main manufacturers of football helmets are Ridell and Shutt. Ridell has three primary adult models: the VSR4, the WD-2, and the Revolution. The Revolution is Ridell’s best seller, and has an air inflation fitting system that provides conformability to a variety of head shapes. The outer shell is constructed of a Kra-Lite II polycarbonate Lexan that makes the helmet light and requires minimal energy for support without sacrificing protective quality. The helmet extends into the mandible region to provide extra protection. The Z-pad design attenuates the energy and reduces the impact of blows to the side of the head, face, and jaw area. In addition to the standard SI requirement, the Revolution has a head impact power index, which accounts for linear and rotational forces. This index is important because diffuse brain injuries are the result of dynamic loading with rotational acceleration and associated shearing forces. The brain spins inside the cranium and the rotational component causes greater injury. The VSR-4 is constructed with an inflatable air liner system. It contains crown, back, and side pads, all individually inflatable, and provides better conformability. It is the heaviest of Ridell’s helmets, so it requires more energy expenditure from the athlete. The disadvantages to this helmet are reported problems with changes in altitude, subcutaneous fat lost in the face, air leakage, and the valve cover popping out and causing pressure loss. The WD-2 does not require inflation, unlike the revolution and the VSR-4. The WD-2’s energy absorption capabilities are found in its Aero-Cell liner system. This system has individually sized liners constructed of dual density foam. The two most common adult Shutt football helmets are the Pro Air II and the Air Power. These helmets have a pneumatic airliner with pads inside the helmet. The airliner creates a closed system. In addition to absorbing shock, this distributes the force of an external impact evenly throughout the entire helmet. This type of airliner has the ability to return to its original shape quickly after impact and can handle repeated impact. Having airliners instead of pads is a good feature, because pads compress over a period of time and become hard. These two helmets are best used by athletes from high school to the professional level. They have both met the NOCSAE standards, have the lowest SI values, contain three different air panels, and offer good protection. The airliners are rotationally molded, which means that there are not any seams and they resist leaking. The outer shell is constructed of tough GE Lexan polycarbonate alloy. The Pro Air II and Air Power both have foam stabilizer systems, but the Pro Air II has a single airliner and the Air Power has a dual airliner. There are some disadvantages to these helmets, however. There have been problems with changes in altitude. If the athlete looses subcutaneous fat from his face the fit changes. In addition, even though their seams are rotationally molded, there is a possibility of air leakage. Therefore, they might require more maintenance then other helmets.

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In addition to the traditional helmet design, in recent years a new accessory has been developed—the Procap II Eliminator, an addition to the athlete’s regular helmet. It is constructed of a soft outer material, hard shell, and soft liner. It is essentially a cap that sits on top of the helmet and is secured in place by Velcro. Its biggest selling point is that it is supposed to be good for those athletes who are prone to concussions. Reports have shown these caps to hold up well with the standard SI value for football helmets. The Procap II Eliminator is not endorsed by sports medicine professionals or equipment manufacturers, and if added to a Shutt or Ridell helmet, it will void the helmet warranty. There are a few concerns with the use of such a product, such as the outside being constructed with a soft material. If the material is soft, then its deflective mechanism is decreased and it might not be able to deflect impacts as well. It has a lower modulus of elasticity, and therefore is not as stiff.

Men’s lacrosse helmets Men’s lacrosse is a high-impact collision sport that requires the use of protective head gear. During the 1999 NCAA men’s lacrosse season head injuries accounted for 13% of game-related incidents, with most of the injuries diagnosed as concussions [22]. As of August 2002, however, practice and game injury rates were slightly lower than in previous years. The head, upper leg, and knee were the top body parts injured in game situations, and accounted for 47% of injuries [23]. The NOCSAE is the regulating agency for men’s lacrosse helmets. The standard was set in 1990 and has not been revised since. The testing procedure for safe use includes a 60-inch drop from seven locations at ambient temperature, then several 60-inch drops onto the side of the helmet after 4 hours at 120° F. Finally, it is struck with the handle of an oak stick at 50 mph. The SI value for these helmets should be no greater than 1500. Since 1990, no revisions in the testing procedures or the approved SI value have been made. The helmets are constructed with a hard outer shell for deflective purposes. Depending on the individual helmet, the inside contains either a liner or air bladder system that absorbs the energy from the impacts. Cascade is a popular manufacturer of. several lacrosse helmets models such as the Ultralite, the C Pro, the C2, the Cascade, and the Cascade Expand. The newest helmet is the C2. It is constructed with a microadjusting wedge fit system that provides better conformability. It also has triple density padding for impact absorption. The Cascade is the lightest helmet. This is a good feature to have because it decreases energy expenditure for the athlete. The Cascade is a fitted helmet, so conformability is greater. Finally, the Cascade Expand has the features of the traditional Cascade but contains an air bladder system located between the shell and the liner. Air is pumped into this system, which provides a custom fit for the athlete and improves comfort and conformability. All men’s lacrosse helmets must have the NOCSAE sticker on the out-

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side, a facemask, and a four-point chinstrap. The NOCSAE warning statement says [21]:

Do not use this helmet if the shell is cracked or deformed, or if the interior padding is deteriorated. Severe head or neck injury, including paralysis or death may occur to you despite using this helmet. No helmet can prevent all head injuries or any neck injuries a player might receive while participating in lacrosse. From NOCSAE Manual. Overland Park (KS): National Operating Committee on Standards for Athletic Equipment; 2000; with permission.

Manufacturers have redesigned helmets in recent years in an attempt to decrease head injury rates. The new helmets are lighter and shaped differently. Caswell and Deivert [24] compared four different helmets: two traditional and two contemporary models. The traditional models were the Sport Helmets Ultralite and Bacharach Ultralite. The contemporary models were Sports Helmets Cascade and Cascade Air Fit. The main purpose of their study was to compare the helmets’ ability to attenuate forces when subjected to repeated impacts. The helmets were dropped several times at two different drop sites— the front drop site (FD) and the rear boss drop site (RD). The front drop site simulated a head-on collision and the rear boss drop site simulated a blindsided impact. The results of this study were broken down depending on the drop site. The FD drop site resulted in the Bacharach Ultralite having the greatest SI value (1222.8) and the Sports Helmets Ultralite having the lowest (857). As for the RD sites, the contemporary helmets, the Sports Helmets Cascade and the Sports Helmets Air Fit, had the lowest SI values of 974.5 and 1022, respectively. The greatest SI values for the RD drop site were from the traditional models—the Sports Helmets Ultralite (1376.3) and the Bacharach Ultralite (1496.5). All of the SI values were under the approved NOCSAE recommendation, but the study also showed that the SI value increased as the number of drops increased. The NOCSAE mandates football helmet reconditioning at the conclusion of each football season, and impact testing on a certain percentage of helmets. The NOCSAE doesn’t have as strict recommendations on lacrosse helmets, however. NOCSAE and manufacturers recommend but do not mandate rectification of lacrosse helmets on an annual basis, or discarding them after three years of use. As shown in the study mentioned above, several helmets decrease in protective ability after repeated drops. Therefore, if an athlete wears the same helmet for a long period of time without reconditioning or rectification, he might be subjecting himself to an increased potential for head injury.

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Ice hockey helmets Hockey players sustain head trauma and impact forces similar to football players, such as axial loading, and being struck with an object, such as a puck. The difference is that in football the forces seem to occur multiple times. Hockey helmets must be able to withstand high-velocity impacts such as being hit by a puck, or high-mass, low-velocity forces that are a result of running into the sideboards [16]. There is not much research done on hockey helmets that proves their effectiveness in decreasing the rate of concussions or other head injuries. The helmets weigh about two or three pounds, with the less weight the better, because it uses less of the athlete’s energy. The two most popular hockey helmet manufacturers are CCM and Bauer. Hockey helmets are constructed to protect the athlete from multiple blows. Their conformability is not as strong as the football and lacrosse helmets, however. The hard outer shell of the helmet is designed as a protective mechanism to deflect an object and dissipate the forces over a large area. In addition to the conformability factor, the helmets do not restrict medial and lateral rotation of the head. As discussed earlier, many concussions are the result of rotational forces to the head. The helmets have an ear flap that is either open or covered with clear plastic. The covered flap does a better job at protecting the athlete against ear injuries. The energy absorbing inner linings are made of closed-cell foam padding. The padding decelerates the forces caused by the blows. Ice hockey helmets are regulated by the Hockey Equipment Certification Council (HECC). Currently, there are no set standards. The NOCSAE has created a proposed standards document and statement for newly manufactured hockey helmets as of January of 2002. The NOCSAE warning statements says [21]:

No helmet can prevent all head or neck injuries a player might receive while participating in hockey. Do not use this helmet to butt an opposing player. This is in violation of the hockey rules and such use can result in severe head or neck injuries, paralysis or death to you, and possible injury to your opponent. From NOCSAE Manual. Overland Park (KS): National Operating Committee on Standards for Athletic Equipment; 2000; with permission.

The testing procedures include testing at least four of each model in each critical helmet size. Two tests are performed at ambient temperature, one at high and one at low temperature. They are tested in at least two and not more than four locations; one must be at random. The SI should not exceed 1200.

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As of now, there are no mandated standards for reconditioning and recertification. Most helmets are reconditioned by the manufacturer on an annual basis, however. Baseball helmets Baseball helmets are regulated by the NOCSAE and must possess the NOCSAE certification seal on the outer shell of the helmet. The testing procedure uses a humanoid head on a free-moving carriage. The ball is released twice from a cannon at 24 inches from the head. It travels at 60 mph and impacts at six locations, with one of the locations being randomly selected. There is another impact to the right side of the helmet after four hours at 120° F. The SI value is 1200. There are also ball standards that are set by the NOCSAE. The NOCSAE warning statement on helmets says [21]:

Do not use this helmet if the shell is cracked or deformed; or if the interior padding is deteriorated. Severe head or neck injury, including paralysis or death, may occur to you despite using this helmet. No helmet can prevent all head injuries or any neck injuries a player might receive while participating in baseball or softball. From NOCSAE Manual. Overland Park (KS): National Operating Committee on Standards for Athletic Equipment; 2000; with permission.

Baseball helmets are not as elaborate as football, ice hockey, and men’s lacrosse helmets. They all have a hard outer shell that acts as protective mechanism. The outer shape of the shell is spherical, which allows the ball to be deflected and forces to be distributed over a larger area. Most helmets have foam padding on the inside. Recent models are replacing the padding with air bladders. Padding or air bladders both act as energy absorbers and increase conformability. All batters, runners, and on-deck batters’ helmets should have double ear flaps; single ear flaps are illegal. The Consumer Products Safety Commission (CPSC) endorses the use of a face mask in addition to the helmet, especially for the pediatric athlete. Before 2001, there were no certification requirements for catcher’s helmets. Then in 2001 the NOCSAE published a standard for catchers’ helmets that was enforced in the high school and collegiate settings. The NOCSAE mandated that the helmets have a built-in or attached throat guard. The lower the extension, the better the protection for the athlete. Also, the helmets are to be constructed in one piece like a hockey helmet. NOCSAE standards recommended an SI less than 1200, the same as batters’ helmets. The NOCSAE statement for baseball catcher’s helmets says [21]:

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Do not use this helmet if the shell is cracked or deformed; or if the interior padding is deteriorated. Severe head or neck injury, including paralysis or death, may occur to you despite using this helmet. No helmet can prevent all head injuries or any neck injuries a player might receive while participating in baseball or softball. This Helmet does not comply with NOCSAE requirements unless a face guard specifically listed by the manufacturer is attached. From NOCSAE Manual. Overland Park (KS): National Operating Committee on Standards for Athletic Equipment; 2000; with permission.

There are no official reconditioning specifications for baseball helmets. The helmets should be routinely inspected for defects or damages, including problems with the padding or foam such as wearing away, erosion, or missing protection. If these are not intact, then the helmet should be discarded. The NOCSAE has certain certification requirements for the paint that can be on the helmets; thus the sports health care clinical should be aware of those coaches that recondition and repaint their own helmets. Mouthguards Mouthguards are required in football, field hockey, ice hockey, and men’s and women’s lacrosse. In 1990, the NCAA mandated that all mouthguards be a highly visible color so those not wearing them could be identified [25]. Mouthguards can be used with the purpose of reducing the incidence of concussions. Mouthguards were invented in 1890 by Woolf Krause [26] and were designed to protect boxers from lip lacerations. Mouthguards were not manufactured in the United States until 1926, and the focus of their use was for dental protection. Anecdotally, the use of mouthguards also assists in the prevention of concussions or minimization of concussion severity. There are minimal published data, however, regarding their effectiveness at preventing concussions. In 1967 Hickey et al conducted a study using male cadavers. Force directed towards the inferior border of the chin was delivered to the cadavers several times. The results showed a decrease in the amplitude of the intracranaial pressure wave and a reduction in bone deformation when a custom-fitted mouthguard was used [27]. A mouthguard is essentially made to protect the athlete from those concussions caused by blows to the mandible from under the chin [28]. There are three types of mouthguards: custom made, boil and bite, and prefabricated. A custom-fitted mouthguard provides the best protection for athletes competing in collision and contact sports. The other types are not as protective, fit poorly, and interfere with breathing and speech. Currently, there are not any established standards for mouthguards.

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Cervical orthoses Julian Bailes [29] described a total of 3200 spine-injured patients from 1975 to 1987. He found 63 patients (2%) had sports-related injuries. Within this population, 26 (41%) were permanent spinal cord injuries; 18 (29%) were transient spinal cord injuries; and 19 (30%) were vertebral column injuries without spinal cord injury. Although the relative incidence of spine injuries resulting from participation in sports is low, a large percentage of the injuries result in spinal cord pathology. Consequently, the practitioner should be knowledgeable about the pros and cons of various cervical orthoses. There are a variety of cervical orthoses that support, protect, or limit the range of motion of the cervical spine available for use in sports [30]. Some of these orthoses include shoulder pads, cowboy collars, neck rolls, and butterfly restrictors. They should not restrict the cervical spine’s normal range of motion, but should restrict excessive range of motion. To accomplish this goal, the orthosis should be attached to the chest. Football shoulder pads In 1935 the first cantilever shoulder pad system was developed, which changed protective football equipment forever. Prior to 1950, athletes used leather to cover and protect the shoulder during sporting activities. The emergence of plastic shoulder pads came during the 1950s and 1960s. The plastic material provided greater protection and prevention against blows and impact forces. Football shoulder pads are made of a lightweight material with a hard exterior plastic surface that deflects the blows. The inner lining is composed of either closed or open-celled padding that absorbs the shock and distributes the forces over a larger area [25]. These pads protect the shoulder, clavicle, sternum, and scapula. In addition to the main padding system, accessory pads and components can be added to provide protection for the cervical spine, upper extremity, abdomen, ribs, flank, and back. There are two main types of shoulder pad systems used in football today—the cantilever and flat pad system. The flat pads are lighter in weight, less bulky, very position dependent, and do not provide as much protective capability as the cantilever system. They use the ‘‘air management’’ system, a combination of open and closed-cell foam pads encased in nylon, located under the hard plastic exterior. As the athlete’s shoulder comes into contact with another player or object, the air is distributed throughout the padding to create an air pocket between the athlete and the pads [25]. The flat pads sit lower on the shoulder and contain at least one belt that is secured and pulled into an arch-shaped structure for protection. The cantilever system spans the arch plate and makes a plastic bridge over the superior aspect of the acromioclavicular (AC) joint. The material is lightweight, allows the athlete to have maximum range of motion, and distributes the forces and pressures of an impact both anterior and posterior throughout the entire shoulder, chest, and back [25]. The flat and cantilever systems both have clavicle channels. These channels are a series of long, thin pads attached by Velcro

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to the shoulder pads. The clavicle needs to fit down the middle of this space while the AC joint extends out. This helps to dissipate the forces. When choosing and fitting shoulder pads the sports health care professional should be aware of the athlete’s position and any predisposing problems, in order to provide them with the best protective equipment: Proper fitting instructions for football shoulder pads



















The athlete’s position should be taken into account for proper shoulder pad selection. The athlete should be fitted without a T-shirt to ensure proper fitting. The distance from one acromion process to the other is taken. The chest circumference can also be used for athlete measurement. Which method of measurement used should be in accordance with the athlete’s size and manufacturer’s guidelines. Put the straps on the athlete and make sure they fit correctly. To do this, hold the pads in place and move them around so there is minimal slippage. The padding of the pads if not the plastic should cover the xyphoid process. The inferior angle of the scapula should be protected when the arms are moved from adduction to abduction. The pads should extend approximately 1/2" below the insertion of the deltoid muscle. The athlete can now put on a tight jersey and see if the pads cover the deltoid muscle. A tight jersey is better to use than a loose one, which could cause the pads to move and subject the AC joint to injury. Lift the deltoid pad up and make sure that the clavicle and AC joint are in the clavicle channel, which decreases the force. The athlete should have 2– 3 finger widths distance between the neck and the side of the shoulder pads in a normal rested position, such as when the arm is in adduction. The athlete should abduct the shoulder and have 1 – 2 finger widths between the neck and the lateral padding. The athlete should not complain of any pinching or choking sensations in this position.

There are various accessory pads within the two systems: axillary/deltoid pad, arch plate, arch pad, epaulet, scapular pad, snubbers, extension pads, and straps. The pads pertinent to upper extremity and cervical spine protection are described here. The axillary/deltoid pad is an anterior extension pad that provides great protection for those athletes who receive repeated anterior blows. The arch plate

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is a plastic piece of material that arches over the shoulder and dissipates the forces. Below the arch plate is the arch pad, a combination of open and closedcell foam that absorbs impact. The epaulet is an accessory pad to the arch and protects the athlete from superior blows. Finally, posterior protection is accomplished with the use of a hard plastic scapular pad. Neck rolls Neck rolls, cowboy collars, and butterfly restrictors are designed with the hope of preventing or minimizing injuries to the brachial plexus. These injuries are more commonly referred to as ‘‘stingers’’ or ‘‘burners.’’ Brachial plexus injuries can be caused by hyperextension (with or without rotation) to lateral flexion with depression of the opposite shoulder [31]. The injury causes an intense burning pain in the shoulder that is associated with paresthesias or dysesthesias that may radiate into the arm and hand. The symptoms are usually transient (less than 10 minutes) but may persist and develop into a chronic problem, resulting in muscular weakness or abnormal EMG findings [31,32]. Once an athlete experiences injury to the brachial plexus he is five times more likely to have a reoccurrence [32 – 34]. In 1993, Markey and Di Benedetto [35] studied the effects of shoulder pads on the occurrence of brachial plexus injuries. Their study demonstrated that brachial plexus injuries were more commonly caused by a compression injury than by a stretching of the nerves. The nerves most commonly involved were the axillary, musculocutaneous, suprascapular, and thoracodorsal. The compression injury was a result of the plexus being compressed between the shoulder pad and the superior medial scapula. This occurs when the pad is pushed into an area called Erb’s point. Erb’s point is the area where the brachial plexus is most superficial. Neck rolls are also called extension pads or extension restrictors. The difference in the terminology used stems from liability issues. They are constructed of firm, open-cell foam, coated with vinyl to repel water and perspiration. They are usually sold in 200 or 300 diameters (Fig. 13). They are available in a contoured flat model or a traditional round model. Some models have laces that can be laced into the shoulder pads, and others contain screws that can attach the orthosis directly to the pads and provide a secure attachment. It is very important that the sports health care professional understands that the neck roll is used to prevent excessive range of motion, and not to restrict normal range of motion. Before the athlete is allowed to take the field wearing a neck roll, he must be checked by the sports health care professional. The athlete should be checked in the ‘‘down’’ position to determine whether or not he can still bring his head back with the neck roll attached. The athlete needs to have proper mechanics and sport technique or the neck roll could be more detrimental than preventative. There are several considerations to be aware of when allowing the athlete to wear a neck roll. The neck roll has the possibility of creating a fulcrum between itself and the cervical spine.. It also creates more force on the ipsilateral side. It is very important that the neck roll be properly positioned on the athlete’s shoulder.

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Fig. 13. A neck roll used by athletes to prevent brachial plexus injuries.

Many teams choose not to use any type of cervical orthoses for their athletes. They justify this choice by stressing the importance of cervical spine strengthening and prevention programs. Cowboy collars The cowboy collar is another cervical orthoses used for preventing cervical spine injuries, such as injuries to the brachial plexus. The cowboy collar (Fig. 14) is constructed with a soft collar vest that is reinforced posteriorly by a plastic bolster. It has a biomechanical advantage over the neck roll in that it does not create a fulcrum effect between the device and the athlete’s neck. It does have

Fig. 14. A cowboy collar used to prevent brachial plexus injuries.

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disadvantages, however, such as the elimination of the shoulder pads’ clavicle channel. The elimination of the clavicle channel decreases the ability to dissipate the forces. Another disadvantage is that the cowboy collar raises the height of the shoulder pads because it sits underneath them. This increase in height can possibly increase the potential for injury because it reduces the athlete’s visibility and exposes the lateral shoulder. A study by Hovis and Limbird in 1994 [36] compared the effectiveness of three cervical orthoses in limiting hyperextension and lateral flexion of the cervical spine in football. The three cervical orthoses that were studied were the cowboy collar, neck roll, and a custom-fitted cervicothoracic device. The cervicothoracic device was custom fitted to each player by a certified orthotist in conjunction with a certified athletic trainer. The study showed that all three braces significantly decreased extension of the cervical spine more than shoulder pads alone. Lateral flexion was inconsistently limited, however. The cowboy collar and neck roll were comparable to each other, with the neck roll being more commonly chosen for use. The custom-fitted cervicothoracic device limited hyperextension the most because of its high rigid posterior support that extends up to the occiput. This study showed that devices could be designed to limit hyperextension of the cervical spine while allowing sufficient extension to prevent axial load injuries. The limitation of this study was that the orthoses were tested in a controlled environment with forces at impact much lower than those experienced in sport. The mechanism of injury during actual competition would probably include varying components of rotation and lateral bending in addition to hyperextension, which would not be dependently controlled by the orthoses tested [36]. However, this study showed that the three devices are capable of preventing or minimizing cervical nerve injuries sustained as a result of the hyperextension mechanism. Butterfly restrictors The butterfly restrictor is also termed a hyperextension restrictor. Athletes wear them in hope of preventing extension injuries, such as injuries to the

Fig. 15. A butterfly restrictor used in collision sports to prevent injury to the brachial plexus.

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brachial plexus. Manufacturers developed these orthoses in coordination with football equipment managers. They are constructed of a hard plastic material that is covered with a pad for comfort. The restrictor (Fig. 15) extends down the back of the neck and flares out on the sides. Small side rolls can be added to the restrictor to prevent excessive lateral flexion.

Summary Due to the potential for catastrophic neurotraumas and cervical spine injuries in sport, the sports health care professional must take proper measures to prevent such injuries. Strength training of the cervical spine, teaching of proper sporting techniques, and use of protective sports equipment are three primary means of attempting to prevent neurotraumas and cervical spine injuries in sports. There are other avenues to assist in preventing these injuries, such as flexibility programs. The sports health care professional, therefore, must be knowledgeable of the needs of each individual athlete when developing prevention plans.

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