+ David H. Janda, + Donald E. Wild and * Robert N. Hensinger
+ Institute for Preventative Sports Medicine, and Orthopedic Surgery Associates, PC, Ann Arbor, Michigan, USA * Pediatric Orthopedic Section, Department of Surgery, University of Michigan Hospitals, and Institute for Preventative Sports Medicine, Ann Arbor, Michigan, USA

See the Abstract

The National Electronic Surveillance Systems of the United States (NEISS) Consumer Products Safety Commission has estimated that softball causes more injuries leading to emergency room visits in the United States than any other sport. Between 1983 and 1989, 2655404 injuries were documented through selected emergency rooms throughout the United States by the Consumer Products Safety Commission. Although this figure is an underestimate of the total number of injuries, because it does not include nonhospitalisation physician visits, it does indicate the magnitude of the current problem (NEISS 1983-1989). Furthermore, the Amateur Softball Association of the United States has estimated that 40 million individuals nationally participate in organised softball leagues playing an estimated 23 million games per year. In addition to a wide variation in age in these leagues, there is also a wide range in physical condition and athletic ability.

The cost of recreational sports injuries can be categorised into short term and long term expenditures. Short term expenditures include: acute medical care costs, time lost from work, and expenses related to the injured player's employer concerning replacement or lost production. The long term expenditures include: medical care costs, restriction of future athletic activities, permanent functional impairment, and escalating insurance premiums for the injured player, his or her employer, the field owner and the softball league itself (Janda et al. 1990). The potential cost of these injuries can be staggering; therefore, prevention is of utmost importance. Injury prevention is a major public health issue throughout the world. The work place, consumer products, and public service are all governed by regulations designed to protect the individual from unnecessary risks. In addition, athletes are also governed by rules and equipment regulations designed to prevent injuries during competition (Janda et al. 1990).

An athlete's risk of sustaining a sports-related injury is influenced by several factors. High impact sports, such as football, place the athlete at an in creased risk of musculoskeletal trauma. Governing rules that regulate the games can modify injury patterns. An example has been born out with restricting pitching times in little league baseball. Strict enforcement of rules by vigilant officials can foster the safety of the players and greatly reduce the threat of injury (Janda et al. 1990).

Peterson's (1970) analysis of injury rates in foot ball, led to the elimination of cross-body blocking and, hence, a substantial reduction in football in juries. Unfortunately, many injuries that predispose the recreational athlete to injury are difficult to control. Poor technique, such as sliding, inadequate coaching, lack of conditioning, or concomitant use of alcohol may all contribute to the problem. It is difficult to control and regulate adherence to safety rules in recreational athletics, even when games are officiated As a consequence, passive preventive measures that do not depend on the athlete, referee, level of competition, or skill should be incorporated into the sport.

An example of passive preventive measures can be seen in driver education programmes where de spite improved road markings and better road construction, motor vehicle accidents continue to occur. The use of seat belts is an appropriate semipassive preventive measure. However, seat belt use is dependent upon the driver fastening the belt. An example of a pure passive preventive system is the recent institution of air bags in cars in the United States. The use of seat belts or air bags does not change any of the underlying causative effects of the accident. They do, however, alter the severity of injury to the driver (Janda et al. 1990).

Examples of similar extrinsic or passive preventive measures in sports include using protective eye wear during racquet sports as illustrated by Pashby et al. (1982) and head gear during batting.

In the United States, the vast majority, if not the entirety of physicians' training, focuses on treatment and rehabilitation of the injured individual. Little, if any, attention is given to the development of a preventive approach to a problem, let alone an emphasis on the skills needed to evaluate a problem from a preventive approach. This article highlights the aetiology of injuries associated with softball, which has previously been identified as the leading cause of emergency room visits in the United States.

In addition to highlighting the aetiology of injuries occurring in organised recreational league softball play, we will focus on previous preventive studies and the methodology employed which have been instituted in the United States to curb the alarming rate of injuries secondary to softball.

Treatment of upper and lower extremity traumatic injuries sustained in softball will not be the focus of this essay. Hundreds of articles and manuscripts have been written in reference to treatment of ankle, knee, shoulder, elbow, wrist, and finger injuries (Nicholas & Hershman 1986, 1990). To our knowledge, there have been very few manuscripts written on the preventive aspect of these injuries and we would like to focus our attention and efforts on the previous studies which have been accomplished in regard to preventive measures. If our preventive efforts truly have an impact, the need for treatment will be drastically reduced.

1. Aetiology of Injuries

Prior to implementation of any preventive measures, the aetiology and distribution of injuries must be ascertained. Softball-related injuries can be grouped into 3 categories: (a) sliding-related in juries; (b) collision-related injuries, such as person versus person, person versus stationary object (e.g. back stop or fence) and persons versus ball; and (c) falls sustained by the player.

In a previous retrospective study conducted by Janda et al., (1986) sliding related injuries were found to comprise 71% of all softball-related injuries sustained in a recreational softball league at the University of Michigan. The majority of the injuries sustained in this retrospective study were to the ankle and foot as the lead extremity impacted the stationary base. In numerous organisations' rule books throughout the United States, it has been stated that the bases may be up to 5 inches (12.7 cm) in height and they must be secured to the ground. The standard base which is used throughout the United States is bolted in a metal post and sunk into the ground and into concrete. It has been found it takes 3500 foot pounds of force to separate the white portion of the exposed base from its moorings. It should be noted, that in the retrospective study performed at the University of Michigan, the common denominators in the sliding-related injuries were poor musculoskeletal conditioning, poor technique, occasional alcohol consumption and, above all, a late decision to slide (Janda et al. 1986). The cost of these traumatic injuries were found to be significant both in the short term and in the long term. The costs consisted of lost wages, restriction of future athletic activities, and long term functional impairment. The unexpected costs of the traumatic events were investigated in order to facilitate and emphasise a discussion of their prevention. The costs of injury to the player, his or her employer and the sponsoring softball organisation itself were found to be significant. For example, athletic knee injuries are common, and can pose high morbidity for participants. The average cost for a knee ligament injury treated in a university hospital setting was between $US300 and $US500 (Janda et al. 1988a). If the traumatic knee injury necessitated a reconstruction such as an anterior cruciate ligament reconstruction, this figure rapidly escalated to between $US7000 and $US10000, again treated in a university hospital setting. It should be noted, these figures did not include the time lost from work and future functional impairments. Preventive efforts to reduce the most common cause of injuries, sliding, will be highlighted and explored later in this essay.

In a prospective investigation of slowpitch softball injuries occurring in the military, 25% of the injuries were caused by jamming or collision and 17% of the injuries were due to falls sustained by the athlete (Wheeler 1984). Wheeler found that jamming injuries to the upper extremity struck by a ball are caused by lack of hand-eye coordination and concluded that there did not appear to be any way of preventing these injuries other than practice and good coaching Further preventive efforts in regard to collisions include improved padding of back stops and immobile objects, such as the out field walls and dugouts.

The most appropriate preventive measure in regard to falls includes meticulous maintenance of playing fields to prevent individuals from stumbling into holes or over roughened areas.

2. Preventative Efforts

As outlined in section I in reference to collision injuries, deformable walls and padded back stops and field maintenance will prevent the majority of injuries secondary to collisions and falls. Better coaching techniques will reduce the number of player versus player collisions. Several measures have been undertaken in the Ann Arbor, Michigan area to prevent sliding related injuries. softball and baseball will always be heavily steeped in tradition. In the second and third phases by a study by Janda et al. (1988a, 1990) various options were tried in order to prevent sliding related injuries from occurring. as previously stated, 71% of all softball related injuries in the Ann Arbor area were found to be secondary to sliding. It was found that making sliding illegal was impractical since giving up sliding w s unacceptable to the participants. Instructional courses were then offered; however, few of the recreational athletes attended. Recessed bases, such as home plate, are a viable alternative; however, umpires objected because poor visualisation made safe versus out calls an overwhelming problem. These solutions did not deal with the problem of indecision in the mind of the base runner, poor musculoskeletal conditioning, occasional alcohol consumption, and a desire to impress one's teammates and fans. Considering these factors it was felt an altered base design, such as a quick release or break-away base, would provide a practical, reliable and cost-effective means of reducing sliding injuries Because most injuries occur during rapid deceleration against a stationary base, quick release bases were chosen to modify this mechanism of injury (Janda et al. 1990).

Break-away bases were placed on half the softball fields at the University of Michigan. The break away bases used were the Rogers break-away base (Rogers Sports Corporation, Elizabethtown, Pennsylvania) [fig. 1]. Each set of 3 bases costs $US400 which is twice the cost of a standard set of stationary bases It should be noted that each set of break-away bases lasted 4 times as long as the standard stationary bases previously used at the university. The Rogers break-away system consists of a rubber mat which is flush with the in-field surface and is anchored into the ground by a buried metal post similar to that used with standard stationary bases. Rubber grommets arise from a rubber mat which attaches to anchoring sockets on the under surface of the break away portion of the base. This particular system is available in 4 models; youth, teen, adult and professional each differing in the amount of force needed to cause the base to break away and in the consistency of the top portion of the base (i.e. the youth model is less rigidly held and breaks away easier than the teen, adult or professional models). The adult model, which we used required several hundred foot pounds of force for the break-away portion of the base to release or 20% of the force necessary for a stationary base to disassemble. Base sliding injuries that occurred on the study fields were documented by field supervisors and follow-up was performed by one of the authors. In addition, local hospital emergency rooms, the student health service, and private practice orthopaedic surgeons were requested to keep logs of patients if they were injured on the study fields; these patients were also seen in follow-up by the authors.

Fig. 1. The Roger's break-away base utilised in preventative studies in Ann Arbor, Michigan.

In the second phase of the study (Janda et al. 1988a) 633 games were played on break-away base fields and 627 games were played on stationary base diamonds in the Ann Arbor summer league. The players ranged in age from 18 to 55 years and included college students, labourers, executives and physicians. Teams were assigned to one of 4 leagues based on skill level and previous playing experience. Women participated in a co-ed league. Teams were assigned to playing fields on a random and rotating basis. All fields were maintained in the same manner and all experienced the same weather conditions. During the 2 seasons studied in phase 11 of the study, a total of 45 sliding in juries occurred on the stationary base fields, while only 2 sliding injuries occurred on the break-away base fields, a 96% reduction in injuries when break away bases were utilised. This difference was statistically significant (p < 0.001). Of the 45 injuries sustained by players sliding into stationary bases, 43 involved the lead foot or hand. The distribution of ankle injuries sustained on the stationary base fields is shown in table 1. Ankle injuries predominated, accounting for 24 of the 45 total injuries. The total medical charges for these 45 players was approximately $US55 000 ($US1 223 per injury). Two other players were injured when they tripped over the stationary bases as they ran around the diamond. One of these players sustained an ankle fracture and the other a scaphoid fracture. How ever, these injuries were not included in our analysis as they did not occur as a result of sliding, and we were unsure whether break-away bases could have prevented these injuries from occur ring. Two isolated injuries occurred on the break away bases; a nondisplaced medial malleolar ankle fracture and an ankle sprain. The total medical charges for these two players was approximately $US700 ($US350 per injury). It should be noted that in these 2 sliding injuries, the bases did not break away.

Table I. Sliding-related injuries 1986-1987

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Type of injury             Number of injuries
                           stationary bases     breakaway bases

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Ankle sprains                 18                   1
Ankle fractures                6                   1
Skin abrasions                 5
Knee MCL sprain                3
Knee ACL tear                  2
Tibia/fibula fractures         1
Shoulder subluxion             1
AC Joint Injury (type 1)       1
Wrist fractures                1
Wrist sprains                  1
Foot contusion/sprain          1
Finger ligament injury
  (volar plate)                1
Finger dislocation             1
Finger fracture                3
Totals                        45                   2

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Abbreviations: MCL = medial collateral ligament; 
       ACL = anterior cruciate ligament; 
       AC = acromioclavicular

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The director of field supervisors was inter viewed 2 to 3 times each month during the study concerning experiences with the break-away bases The field supervisors felt that softball play was not significantly delayed with the use of break-away bases, even though sliding players broke away the bases up to 6 times during each game. Properly seated break-away bases did not detach during routine base running The umpires did not have any difficulty with judgement calls (safe versus out) when the bases released. For continuation of play circumstances, when the break-away portion of the base did break away, the rubber mat that was flush with the in-field service was considered the base when determining if the runner was safe or out. Finally, in the third phase of the study, a follow up 1035 games were played on fields that all had been switched over to break-away bases (Janda et al. 1990). The same surveillance system was used Two injuries occurred during the study period. Each player sustained an ankle sprain that was treated with protected weightbearing. The total medical costs for these injuries was $US400. One player sustained a lateral collateral ligament ankle sprain to his left foot which was not his lead leg. This injury was sustained as the player caught his cleat on the ground; he never reached the base. The second injured player sustained a deltoid ligament sprain to her lead foot while sliding into the base (Janda et al. 1986). These prospective studies sup port the concept that modifying the bases can alter the frequency of sliding injuries. An analysis of our injury rates reveals that I injury occurred in every 13.9 games (7.2%) on stationary base fields, while on the break-away base fields, I injury occurred every 316.5 games (0.3%) in phase II, and every 517.5 games (0.19%) in phase 111

In other words, for each sliding injury on the break-away base fields there were more than 23 sliding injuries on the stationary base fields. It should be noted, even with break-away bases, in juries can still occur. Most will be the result of judgement errors by the runner. Improper sliding technique, poor timing, inadequate physical conditioning, and alcohol consumption contribute to sliding injuries. Break-away bases, however, can modify the outcome when these factors are involved.

In a previous biomechanical study of sliding by Corzatt et al. (1984) sliding was analysed kinematically. Four phases were identified; the sprint, attainment of the sliding position, the airborne phase and the landing phase. The authors indicate that injuries occurred in the last phase, the landing phase, where a small amount of the body area is not only used to absorb the shock of impact, but also is subjected to high horizontal velocities as the base is contacted.

The quick release feature of the break-away base utilised in these studies decreases the impact load generated against the athlete's limb and subsequent trauma inflicted upon it. Sliding players come in all sizes and approach the base from all angles, so that no one preventative system can be completely foolproof The forces generated by the trajectory athlete against the ground or other players may still be more than sufficient to result in severe injuries to the musculoskeletal system (Janda et al. 1990). An actuarial analysis by the section of epidemiology and injury at the Center for Disease Control in Atlanta, Georgia, has estimated based on phase II of the study conducted by Janda and colleagues and data from the Consumer's Power Safety Commission that by changing from stationary to break away bases across - the United States, approximately 1.7 million injuries per year would be pre vented and over $US2 billion in medical care costs per year could be saved (Janda et al. 1988b).

Injuries are inherent in any recreational activity. Most base-sliding accidents result from judgement errors of the runner, poor sliding technique and inadequate physical conditioning Break-away bases can serve as a passive intervention to modify the outcome of these factors. The use of break-away bases decreases injuries without player involvement or altering the play, excitement, entertainment, competition or interest in the game. This intervention is also independent of players, umpires, weather or the time of day (Janda et al. 1990). In this day and age of escalating health care costs, preventive measures must be instituted as illustrated in the Ann Arbor, Michigan study, to diminish the impact upon society. Sports-related injuries are ex pensive for the player, the employer and insurance carrier. Economic costs are, of course, an import ant concern when the long term health of the athlete is impaired by a sliding injury. The use of break-away bases decreases the number and severity of softball injuries to a significant degree. Break away bases are cost-effective and safer than standard stationary bases.

3. Preventative Research Implementation

Tradition has been one of the major obstructions to introducing new rules or equipment to pre vent injuries. Implementing equipment changes, such as changing balls, bats, bases, or fences, may offend the traditionalist, and undermine traditional aspects of the particular sport. In addition, other obstacles, such as ignorance, and lack of recognition of safety issues can delay or block instituting preventive measures. Unfortunately, the general public may be misled in regards to prevention if unethical promotion of products by the business community is allowed. Implementation of some preventive equipment may be expensive and resisted by communities, schools and organisations as they must pick up the cost but do not benefit directly from the reduction in injuries and their associated costs. Citizens, organisations, physicians, researchers and other health care organisations, must maintain persistent pressure on all organised sports endeavours, school leagues, city leagues and professional sports and colleges to consider and promote improved equipment, safer techniques, and preventive methods. Enrolling the support of local, state and national government representatives, we have found, can aid in limiting unethical promotion and enhancing the public's awareness to preventive measures. It has been found that governmental agencies can act to in crease the awareness and pressure sports organisations to consider preventive alternatives and safer playing methods and conditions. In addition, the media can have an enormous and immediate impact upon disseminating the necessary preventive information to the general public. It is our contention that an informed public will, therefore, be come a safer population.

As physicians, trainers, recreational directors and individuals involved with sporting activities, it is imperative that we turn and focus our attention on prevention. As previously illustrated, recreational softball is the most popular of all team sports in the United States. With more and more individuals flocking into recreational sports for fitness and well being, it is imperative that individuals involved in sporting activities focus their attention on the prevention of these unnecessary injuries. Injuries will still occur, but hopefully as is pointed out in the Ann Arbor study, they can be drastically diminished. The cornerstone to diminished injuries consists of a safer environment for the recreational softball player to participate in. A safer environment consists of well-maintained fields and facilities, padded walls and back stops, a good stretching programme prior to commencement of play, a comprehensive conditioning and techniques programme, a diminution in alcohol consumption and the utilisation of break-away or quick release bases.

REFERENCES

Corzatt RD. Groppel JL, Pfuastsch E, et al. The biomechanics of head-first versus feet-first sliding. American Journal of Sports Medicine 12:229-232, 1984.

Janda DH, Hankin FM. Wojtys EM. Softball injuries: cost, cause, prevention. American Family Physician 33:143-144, 1986

Janda DH, Wojtys EM, Hankin FM, et a1. Softball sliding injuries. A prospective study comparing standard and modified bases. Journal of the American Medical Association 259:1948-50, 1988a

Janda DH, Wojtys EM, Hankin FM, et a1. Softball sliding injuries - Michigan, 1986-1987, Morbidity and Mortality Weekly Report 37(11): 169-170, 1988b

Janda DH, Wojtys EM, Hankin FM, Benedict ME, Hensinger RN. A three-phase analysis of the prevention of recreational softball injuries. American Journal of Sports Medicine 18:632-5, 1990

National Electronics Surveillance System, product summary reports, 1983 to 1989.

Nicholas JA, Hershman EB. The lower extremity and spine in sports medicine, C.V. Mosby, Toronto, 1986

Nicholas JA, Hershman EB. The upper extremity in sports medicine, C.V. Mosby, Toronto, 1990

Pashby TJ, Bishop PJ, Easterbrook WM. Eye injuries in Canadian racquet sports. American Family Physician 28:967-71, 1982

Peterson TR. The cross-body block, the major cause of knee injuries. Journal of the American Medical Association 211:211-214, 1970

Wheeler BK. Slow-pitch softball injuries. American Journal of Sports Medicine 12: 237-240, 1984

This article was published as:
"Softball Injuries - Aetiology and Prevention"
Sports Medicine
Vol. 13, No. 4, 1992; pp. 285-291
Janda DH, Wild DE, Hensinger RN Hensinger.

It is possible to order a copy of this article.