The research, which found early damage to the hands of otherwise healthy players, is reported in the current issue of the Journal of Bone & Joint Surgery.
"We found signs of early blood vessel damage that could lead to significant symptoms and could end a player's career," said T. Adam Ginn, M.D., chief resident in orthopaedics at Wake Forest Baptist, and one of the study's researchers. "The gloves' current design does not protect the hand from trauma."
The study examined 36 players on four minor league baseball teams in North Carolina. It was conducted from April to September 2001 and included nine catchers, seven infielders, five outfielders and 15 pitchers.
"Professional baseball players may be exposed to more repetitive hand trauma than any other sport," said L. Andrew Koman, M.D., professor of orthopedic surgery at Wake Forest University School of Medicine, and a co-researcher. "We found a greater incidence of hand symptoms in catchers than in other players, despite the fact that 89 percent of them used additional protective padding."
Catchers may receive 150 pitches per game at speeds, many at speeds over 90 m.p.h. The repetitive impact of the ball hitting the gloved hand has been shown to lead to damage to blood vessels. Over time, blood flow can be significantly reduced and nerves may be bruised, causing numbness and tingling, reduced sensitivity to cold and bluish-colored skin.
"Despite well-padded catchers' mitts and the use of additional padding, the catchers examined in this study continue to demonstrate changes to the gloved index finger consistent with trauma," said Ginn. "There should be further study into glove design."
The researchers used ultrasound and other testing to look at blood circulation in the hands. They also looked for enlarged fingers, a sign of injury, and asked players about hand symptoms.
Circulation testing revealed abnormalities in blood flow to the gloved hands of catchers. In addition, catchers had significant index finger enlargement in the gloved hand compared to the other hand, with an average increase of almost two ring sizes.
The current design of catcher's mitts ensures that most pitches are caught at the base of the webbing, at the bottom of the index finger, where many vessels and nerves are located. Pitchers and field players tend to catch the ball in the webbing itself, away from the hand.
Catchers were more likely than any other position to have hand weakness, with 44 percent reporting this symptom. Catchers reported more symptoms of weakness, numbness, tingling and pain in their gloved hands (56 percent) versus than throwing hands (11 percent).
Because these symptoms occurred during games, rather than at rest, the researchers believe they are related to nerve trauma in the hand, rather than to significantly reduced blood flow. But, the early vessel damage found in the study could lead to permanent circulation problems.
While none of the players in the study were yet limited in their duties, the long-term effects of repetitive trauma can be significant.
"We suspect that at least some of the players would demonstrate a progressive decline eventually leading to additional numbness and tingling," said Koman.
Other researchers were Adam M. Smith, M.D., Jon R. Snyder, M.S., Beth Smith, Ph.D., and Julia Rushing, statistician, all at Wake Forest Baptist at the time of the research.
Contacts: Karen Richardson, firstname.lastname@example.org; Shannon Koontz, email@example.com; at 336-716-4587.
About Wake Forest University Baptist Medical Center: Wake Forest Baptist is an academic health system comprised of North Carolina Baptist Hospital and Wake Forest University Health Sciences, which operates the university's School of Medicine. The system comprises 1,282 acute care, psychiatric, rehabilitation and long-term care beds and is consistently ranked as one of "America's Best Hospitals" by U.S. News & World Report.