Reported by: DH Janda, MD, D Mackesy, MD, Institute for Preventative Sports Medicine, Ann Arbor, Michigan. R Maguire, Bucknell Univ., Lewisburg, Pennsylvania. RJ Hawkins, MD, Steadman-Hawkins Clinic, Vail , Colorado. P Fowler, MD, Univ. of Western Ontario, London, Ontario, Canada. J Boyd, MD, Orthopaedic Consultants, Minneapolis. Epidemiology Br., Div. of Injury Prevention and Control, CDC.

Softball and baseball are among the most frequent cause of sports related emergency department visits in the United States, accounting for an estimated 321,000 injuries in 1989.[1] Approximately 71% of softball-related injuries are caused by sliding. [2] The use of breakaway bases substantially decrease the risk for or occurrence of sliding-related injuries among recreational softball league players.[3] This report summarizes the findings of a study on the impact of breakaway base use on sliding injuries among college and professional minor league players.[4]

During 1990 and 1991, 19 team participating in the study used breakaway base on their home fields and stationary bases during away games for one of the two seasons. During the first season, the teams comprised one college and six professional minor league teams; during the second season, seven college and five minor league teams were added to the study. Base-sliding injuries and comments about the bases were recorded on a standard form by team physicians, athletic trainers, managers, or administrative staff for these teams.

During the 2-season period, the teams played an aggregate 498 away games using stationary bases and 486 home games using breakaway bases. Ten sliding injuries were recorded (3.0 per 100 games) during away games and two (0.4 per 100 games) during home games (relative risk=4.9; 95% confidence interval=1.2-19.2).

Of the 10 injuries involving stationary bases, seven were ankle sprains (average participation time missed: 12 days), and three were knee injuries (one medial collateral ligament sprain and two meniscus tears that required surgery [both were season ending]). Of the two injuries involving breakaway bases, one was a minor shoulder contusion incurred when the player slid head first into a base that did not release. The second injury occurred when a player slid toward the base a sustained an ankle fracture; however, the player did not make contact with the base.

Surveys of managers and trainers indicated that all teams planned to continue using breakaway bases. Umpires reported that breakaway bases did not complicate judgment calls (i.e., "safe" versus "out") when the bases releases (54 [2.7%] of 2028 total slide on breakaway bases).

CDC Editorial Note: The findings in this report suggest that breakaway bases decrease the risk and severity of sliding injuries among college and minor league teams.[4] The potential public health impact of increased use of breakaway bases is important: In the United States, 712 college and 168 minor league teams compete in organized baseball. In addition, an estimated 40 million adults participate in organized softball leagues that play approximately 23 million games per year.[3,5]

Most of the base-sliding injuries result from judgment errors of the runners, poor sliding technique, poor timing, and/or inadequate physical conditioning. [3] Breakaway bases are a passive intervention that modifies the outcome of these factors. The quick-release feature of the breakaway bases decreases the impact load generated against the athlete's limb and subsequent trauma.

Additional studies should assess the usefulness of age-appropriate breakaway bases in organized baseball and softball for children. Furthermore, such studies should attempt to address the effect of potential biases (e.g., nonblinding with respect to the hypothesis being tested and the need for uniform definition of injury). The findings in this report suggest breakaway bases should be used at all levels of adult softball and baseball play.

REFERENCES

1. US Consumer Product Safety Commission. National Electronic Injury Surveillance System: January-December 1989, NEISS Data Highlights 1990:13.
2. Janda DH, Hankin FM, Wojtys EM. Softball injuries: cost, cause and prevention. Am Fam Physician 1986;33:143-3.
3. Janda DH, Hankin FM, Wojtys EM, et al. Softball sliding injuries: a prospective study comparing standard and modified bases. JAMA 1988:259:1848-50.
4. Janda DH, Maguire R, Mackesy D, Hawkins RJ, Fowler P, Boyd J. Sliding injuries in college and professional baseball: a prospective study comparing standard and break-away bases. Clinical Journal of Sports Medicine (in press).
5. CDC. Softball Sliding injuries - Michigan, 1986-1987. MMWR 1988;37:169-70.

This article was published as:
"Sliding-Associated Injuries in College and Professional Baseball - 1990-1991"
Morbidity and Mortality Weekly Report
Vol. 42, No. 223, 1993; pp. 229-230
Janda DH, Mackesy D, Maguire R, Hawkins RJ, Fowler P, Boyd J

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