Report from Centers for Disease Control Morbitity and Mortality Weekly Report
Reported by:DH Janda, MD, EM Wojtys, MD, FM Hankin, MD, ME Benedict, MA, Univ
of Michigan, Ann Arbor, Michigan. Epidemiology Br, Div of Injury Epidemiology
and Control, Center for Environmental Health and Injury Control, CDC.
During the period 1986-1987, a study of the use of break-away bases to reduce
sliding injuries was conducted in Ann Arbor, Michigan . The break-away base that was used in the study is
anchored by rubber grommets to a rubber mat that is flush with the infield
surface. The mat is anchored to the ground by a metal post similar to that used
with standard stationary bases. Seven hundred foot-pounds of force, or one-fifth
the force needed to dislodge a stationary base from its mooring, is required to
release the break-away portion of the base.
The study evaluated injuries sustained during 633 games on two fields with
break-away bases and 627 games on six fields with stationary bases. The players
were college students, laborers, executives, physicians, and others ranging from
18 to 55 years of age. Players were assigned to one of four leagues on the basis
of skill level and experience. Teams were assigned to playing fields on a random
and rotating basis. All fields were maintained in the same manner.
All injuries requiring a player to leave the game were documented by the
umpires. Local hospital emergency rooms, the University of Michigan Student
Health Service, and private practice orthopedic surgeons were asked to keep logs
of patients seen with softball-related injuries. All persons identified by these
three surveillance systems were contacted to see whether their injuries had
occurred while sliding. Patients who had been playing on the study fields were
included in the analysis.
During the study period, there were 45 sliding injuries on the fields with
stationary bases (7.2/100 games) and two sliding injuries on the fields with
break-away bases (0.3/100 games) (rate ratio = 22.7; 95% confidence intervals,
5.6 to 71.4). Forty-three of the 45 injuries to players sliding into stationary
bases involved the lead foot or hand. Twenty-four of the 45 injuries were ankle
injuries; five were skin abrasions; five were knee injuries; three were finger
fractures; and eight were from other causes. Medical charges for these 45
players were approximately $55,050 ($1,223/injury). The two injuries involving
break-away bases comprised a nondisplaced medial malleolar ankle fracture and an
ankle sprain. The total medical expense for these two players was approximately
Editorial Note: In 1986, the National Electronic Injury Surveillance
System of the U.S. Consumer Product Safety Commission estimated that 361,552
baseball-related injuries were treated in emergency rooms in the United States
[2). This figure probably underestimates the actual
number of injuries. The Amateur Softball Association of America estimates that
32 million individuals participate in softball leagues and that teams consist of
an average of 15 persons and play approximately 22 games per year (unpublished
data). Based on these data, it may be further estimated that about 23 million
softball games are played annually in the United States.
Studies of recreational softball injuries have found that base sliding is
responsible for 35% to 71% of injuries occurring during play, including
abrasions, sprains, ligament strains, and fractures [3,4]. These injuries are
caused by the impact of rapid deceleration against stationary bases. Methods
suggested to reduce base-sliding injuries have included prohibiting sliding,
offering better instruction on sliding techniques, using recessed bases, and
using quick-release bases [4,5]. Prohibiting base sliding would be effective but
might be met with resistance from some fans and participants. Holding
instructional clinics on proper sliding techniques is a possibility for
school-related organizations; however, this method might be impractical for
The prospective study in Michigan suggests that modifying the bases can alter
the pattern and frequency of sliding injuries. If the stationary-base sliding
injury rate of 7.2/100 games and the cost per injury of $1,223 reported in the
study are representative, then approximately 1.7 million sliding injuries occur
annually at a cost of over $2 billion. Similar calculations indicate that
exclusive use of break-away bases would reduce injuries to just over 70,000 (a
96% reduction) and medical costs to $24 million (a 99% reduction).
The umpires indicated that break-away bases did not significantly delay play,
even though sliding players dislodged the bases up to six times per game.
Properly seated bases did not detach during routine base running, and the
umpires did not have difficulty with judgment calls when the bases released. The
bases were durable and easy to replace and lasted both seasons.
The use of break-away bases in recreational softball leagues might provide a
significant, cost-effective reduction in softball injuries from sliding.
However, injuries may still occur from runners' errors in judgment, improper
sliding technique, poor timing, inadequate physical conditioning, and alcohol
- Janda DH, Wojtys EM, Hankin FM, Benedict ME.
Softball sliding injuries: a prospective study comparing standard and modified
bases. JAMA 1988;259:1848-50.
- US Consumer Product Safety Commission. The National
Electronic Injury Surveillance System: January-December 1986. NEISS Data
- Wheeler BR. Ankle fractures in slow-pitch softball:
the Army experience. Milit Med 1987; 152: 626-8.
- Janda DH, Hankin FM, Wojtys EM. Softball injuries:
cost, cause and prevention. Am Fam Physician 1986;33:143-4.
- Wheeler BR. Slow-pitch softball injuries. Am J
Sports Med 1984;12:237-40.
This article was published as:
"Softball Sliding Injuries - Michigan,
Morbidity and Mortality Weekly Report
Vol. 37, No. 11,
March 25, 1988; pp. 169-170
Janda DH, Wojtys EM, Hankin FM, Benedict ME
It is possible to order a copy of this article.