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*David H. Janda, M.D., +Richard Maguire, *Derek Mackesy, M.D.,
#Richard J. Hawkins, M.D., $Peter Fowler, M.D., and ||Joel Boyd, M.D.
*
Orthopaedic Surgery Associates and Institute for Preventative Sports Medicine,
Ann Arbor, Michigan; + Bucknell University, Lewisburg, Pennsylvania; #
Steadman-Hawkins Clinic and American Shoulder and Elbow Society, Vail, Colorado,
U.S.A.; $ Section of Sports Medicine, University of Western Ontario, London,
Ontario, Canada; and || Orthopaedic Consultants, Minneapolis, Minnesota,
U.S.A.
See the Abstract
It has been estimated by the National Electronic Injury Surveillance System
of the United States Consumer Product Safety Commission that softball and
baseball are two of the main sports leading to emergency room visits in the
United States. Between 1983 and 1989, the Consumer Product Safety Commission
documented 2,655,404 injuries sustained by individuals playing either softball
or base ball [6]. Although this figure is an
underestimate, because it does not include nonhospitalization physician visits,
it does indicate the magnitude of the current problem. As the fitness
consciousness level of recreational athletes across the United States has been
raised, a large number of individuals continue to flock into softball and
baseball, the most popular team sports in the United States. In fact, it has
been estimated by the American Softball Association that 40 million individuals
nationally participate in organized softball leagues playing an estimated 23
million games per year. It has also been estimated that several million children
and young adults are involved in little league baseball, pony league base ball,
Babe Ruth baseball, and high school baseball. In addition to the participation
of individuals at a recreational level, a higher echelon of baseball has been
developed. This higher echelon consists of individuals playing at the college
and professional levels, which include minor and major league baseball. The
National Collegiate Athletic Association (NCAA) has 712 teams involved in
intercollegiate baseball. In addition, in the professional ranks there are 26
major and 168 minor league teams participating in the highest-skill level of
baseball.
The cost of a sports-related injury, either recreational, semiprofessional,
or professional can be categorized into short- and long-term expenditures. The
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. Long-term expenditures include medical care costs, restriction
of future athletic activities, permanent functional impairment, and escalating
insurance premiums for the injured player, his employer, and the field owner and
the softball or baseball league itself [5]. These
injuries, and their associated costs can be staggering; therefore, prevention is
of utmost importance. The health-care cost containment aspect of various
preventative techniques has been found to be significant.
In a previous retrospective study conducted by Janda et al. [2] analyzing sliding-related injuries in the
recreational softball population, 71% of all soft ball-related injuries
sustained were consequent to sliding. Wheeler et al. [7] determined the leading cause of missed days in team
sports within the military to be softball injuries-a large percentage of which
were related to sliding. In a previous biomechanical study of sliding by Corzatt
et al. [1], sliding was analyzed kinematically. Four
phases were identified; the sprint, attainment of the sliding position, the
airborne phase, and the landing phase. The authors indicated that injuries
occurred in the last phase, the landing phase, where a small area of the body
was not only used to absorb the shock of impact, but also was subjected to high
horizontal velocities as the bases were contacted. In various organizations'
rule books, it has been stated that stationary bases may be up to 5" in height
and they must be secured to the ground. The standard stationary base, which is
used throughout the United States, is bolted to a metal post that is sunk into
concrete in the ground. It takes 3,500 foot-pounds of force to separate the
white portion of the exposed base from its moorings. It should be noted that the
common denominators of sliding-related injuries are poor musculoskeletal
conditioning, poor technique, occasional alcohol consumption, and, above all, a
late decision to slide [2]. A follow-up investigation
by Janda et al. [6], investigated preventative
techniques in regard to the sliding injury scenario. Instructional courses were
offered, but failed be cause of lack of attendance by the league participants.
Instituting a no sliding rule failed because of participants' concerns that it
would alter the game to a drastic degree. Utilizing recessed bases failed
because umpires had difficulty making safe versus out calls. Finally, break-away
bases were instituted. In this investigation, a 96% reduction in injuries was
realized when break-away bases were utilized. The difference was statistically
significant (p < 0.001). In addition, a 99% reduction in health care
costs was determined [3]. The Centers for Disease
Control then performed an actuarial analysis on the data from the study
performed at the University of Michigan and combined it with data from the
Consumers Product Safety Commission and concluded that across the United States
with the implementation of break-away bases, a potential reduction of 1.7
million injuries per year could be sustained with a savings in health care costs
of $2 billion per year nationally [4].
In a follow-up prospective study, Janda et al. [5]
changed all fields over to break-away bases. One thousand thirty-five games were
played by recreational softball athletes with two ankle sprains as the only two
sliding injuries. Therefore, in this follow-up study a reduction of 98% of
sliding-related injuries was realized [5].
To date, there has been no investigation of the utilization of break-away
bases within the high performance baseball population. This high performance
population would comprise the collegiate level as well as the professional
level. It is the purpose of this study to investigate the effects of break-away
bases within this high-performance population.
METHODS
The break-away base utilized in this study as well as in previous studies is
anchored by receiving holes fitting into grommets on a rubber mat that is flush
with the infield surface (Fig. 1). The rubber mat is
anchored to the ground by means of a metal post similar to that used with
standard stationary bases. Seven hundred foot-pounds of force or one fifth of
the force needed to dislodge a stationary base from its mooring, is required for
the break away portion of the base to release. Break-away bases were obtained
for use on various collegiate and minor league baseball fields. The Rogers break
away base, which was utilized in this and previous studies, costs approximately
$400 for a set of three bases, which is less than twice the cost of a set of
standard stationary bases. Over a 2-year period, 19 teams utilized break-away
bases on their home field and the same 19 teams played on stationary bases
during their away games. Before the start of each game the players were notified
of the type of base being used. Seven teams were involved in the study during
the first year; these included minor league teams from Fayetteville, North
Carolina; Water town, New York; St. Catharines, Ontario, Canada; Geneva, New
York; London, Ontario, Canada; Dunedin, Florida; and LeMoyne College. Twelve
teams were involved in the study the second year and included Bucknell
University, Shippensburg State University, Swarthmore College, Elizabeth town
College, LeMoyne College, Gettysburg College, Eastern Michigan University, and
the minor league teams from Geneva, New York; Watertown, New York; London,
Ontario, Canada; St. Catharines, Ontario, Canada; and Niagara Falls, New York.
Teams from Fayetteville, North Carolina and Dunedin, Florida as well as college
teams from the University of Michigan, Hofstra, and the University of San Diego,
all utilized the bases; however, no data were kept. Four hundred eighty-six
games were played on break-away bases and 498 on stationary bases by these
teams. Base sliding injuries that occurred with these teams were recorded and
documented by team physicians, athletic trainers, managers, and administrative
staff from the teams or organizations themselves. An injury was defined as an
event which led to a player being removed from competition. A chi-squared
analysis with Yates correction was then utilized to determine statistical
significance of the tabulated injury rates.
Figure 1. The break-away base (left) is anchored by
receiving holes that fit into gromments on a rubber mat (right) that is flush
with the infield surface.
RESULTS
During the two seasons studied, a total of 2,028 slides were recorded on
break-away bases. It was found that these bases broke away approximately 54
times during the slides. This translates into 3% of the slides. During the 486
games on break-away bases, two sliding injuries were documented (Table 1). One injury sustained was a shoulder contusion when
the player slid head first into the base. The base did not release. This player
did not miss any games consequent to his injury (Table
2). The second injury occurred as the individual slid and sustained an ankle
fracture. It should be noted, how ever, the individual never made contact with
the base. However, because the individual slid on a field equipped with
break-away bases, his injury was added to the break-away base injury roster.
As stated previously, 498 games were played on stationary bases. Ten sliding
injuries were documented (Table 1). All injured
individuals impacted with the base. Of the ten injuries, three were to the knee
and seven to the ankle. All seven ankle injuries were sprains and the average
time missed from participation was 12 days (Table 2). Of
the three knee injuries, one was a medial collateral ligament (MCL) sprain and I
month was missed from the season. The two remaining knee injuries consisted of
meniscus tears; both required surgery and were season-ending injuries (Table 2).
One injury was documented every 243 games on the break-away bases, which
translates into 0.41 injuries every 100 games. In regard to the stationary base
injuries, one injury occurred every 49.8 games which translates into 2.01
injuries every 100 games. A chi-squared analysis with Yates correction revealed
a p value >0.05. Therefore, an 80% reduction was noted in the
high-performance baseball population utilizing break-away bases. In addition,
when comparing the break-away base and the stationary base injuries the amount
of time missed was significantly less with the break-away bases. It should be
noted that surveys were taken of team players, managers, and administration
staff of all schools and baseball organizations involved in this study in regard
to the utilization of the break-away bases. All teams were very positive about
them, and all planned on continuing use of the bases. Further, it should be
noted, that in Watertown, New York, in 1991, grommets had broken off the rubber
mat during field maintenance procedures as the underneath portion of the base
was dragged with a mat and the break-away portion of the base characteristics
were altered and, therefore, the bases had to be replaced. It should also be
noted that the umpires and managing staff alike determined that the utilization
of break-away bases did not alter the game in an adverse manner. The umpires did
not have any difficulty with judgment calls (safe versus out) when the bases re
leased. For continuation of play circumstances, when the break-away portion did
separate, the rubber mat that was flush with the infield surface was considered
the base when determining whether the runner was safe or out.
TABLE 1
Sliding related injuries
Number of Number of
injuries injuries
involving involving
Types of injury stat. bases B-A bases
Ankle sprains 7
Ankle fracture 1*
Knee MCL sprain 1
Knee meniscal tear 2
Shoulder contusion 1
TOTAL 10 2
*Player never reached base.
TABLE 2
Time missed due to injury
Average days missed
Type of injury of play
Shoulder contusion 0
Ankle sprain 12
Knee MCL sprain 30
Knee meniscal tear Season-ending injuries
DISCUSSION
This prospective study supports the concept that modifying the bases, in the
high-performance base ball population, can alter the pattern and frequency of
sliding-related injuries. An analysis of our injury rates revealed that one
injury occurred every 243 games on break-away bases and every 49.8 games on
stationary bases. The rate ratio was five injuries on stationary bases for every
sliding-related injury on break-away base fields. Injuries will still occur and
most will result from judgment errors by the runner, improper sliding technique,
or poor timing. Break-away bases, however, may modify the out come of these poor
judgments and poor timing errors. The quick release feature of the break-away
bases utilized in these studies decreased 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 fool proof. 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. The ratio of injury
sustained with break-away bases in the recreational population, which was
previously determined to be 0.3 injuries per 100 games is comparable to the
ratio of 0.41 injuries per 100 games in the high-performance baseball population
utilizing break-away bases .
CONCLUSIONS
Injuries are inherent in any sport. In baseball and softball, most base
sliding accidents result from judgment errors of the runners, poor sliding
technique, and, possibly, 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 was also independent of players, umpires, weather, or time of day.
Sports related injuries are expensive to players, the employers, and insurance
carriers. Economic costs are, of course, an important 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 baseball and softball injuries both
at the recreational and high performance levels. Break-away bases are cost
effective and safer than standard stationary bases. In recreational and
high-performance baseball populations, the use of break-away bases should be
mandatory.
Acknowledgment
The authors gratefully acknowledge Dr. Dick Lampman of the Department of
General Surgery, St. Joseph Mercy Hospital, Ann Arbor, Michigan, for his
invaluable help with the statistical analysis. The authors would also like to
thank the Rogers Sports Corporation based in Mt. Joy, Pennsylvania, for their
donation of some of the bases used in this study. The authors also gratefully
acknowledge Mr. Paul Beeston and Mr. Gord Ash with the Toronto Blue Jay
Organization for their involvement in this project. The authors also grate fully
acknowledge the general managers of the Fayetteville, Watertown, St. Cathannes,
Geneva, London, Dunedin, and Niagara Falls teams. The authors gratefully
acknowledge the coaching staff and training staff of Bucknell University,
Shippensburg State University, Swarthmore College, Elizabethtown College,
LeMoyne College, Gettysburg College, Eastern Michigan University, Hofstra
University, University of Michigan, and the University of San Diego.
REFERENCES
- Corzatt RD, Groppel JL, et al. The biomechanics of
head first versus feet-first sliding. Am J Sports Med 1984;12:229
- Janda DH, Hankin FM, Wojtys EM. Softball injuries,
cost, cause, prevention. Am Fam Physician 1986;33:143-4.
- Janda DH, Wojtys EM, et al. Softball sliding
injuries. A prospective study comparing standard and modified bases. JAMA
1988;259:1848 50.
- Janda DH, Wojtys EM, et al. Softball sliding
injuries-Michigan, 1986-1987. MMWR 1988;37:169-70.
- Janda DH, Wojtys EM, Hankin FM, Benedict ME, Hen
singer RN. A three phase analysis of the prevention of recreational softball
injuries. Am J Sports Med 1990;18:632-5.
- National Electronic Injury Surveillance System.
Product summary reports. June 1983 through 1989.
- Wheeler BR. Slow-pitch softball injuries. Am J
Sports Med 1984;12:237 40.
This article was published as:
"Sliding Injuries in College and
Professional Baseball - A Prospective Study Comparing Standard and Break-Away
Bases"
Clinical Journal of Sports Medicine
Vol. 3, No. 2, 1993; pp.
78-81
Janda DH, Maguire R, Mackesy D, Hawkins RJ, Fowler P, Boyd J
It is possible to order a copy of this article.
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