LAWRENCE — Every baseball season, players from major leagues to youth levels lose time because of injuries to the ulnar collateral ligament in the elbow. A University of Kansas researcher is co-author of a new study that used advanced technology to measure the thickness of baseball players' UCLs, finding the ligaments were thicker in pitchers versus position players and that the common assumption of certain arm slots being less stressful on the elbow was not supported.
The findings, published in the Orthopaedic Journal of Sports Medicine , help demonstrate risks for the injury and how athletes, trainers and coaches can prevent them.
The researchers conducted a study with 22 NCAA Division I college baseball players over the course of a preseason. The players wore a sleeve with an embedded accelerometer that measured elbow torque and other variables while the players completed at least 1,000 throws during data collection. Ultrasounds were taken of their elbows.
Results showed that pitchers had thicker UCLs than nonpitchers and that all players had thicker UCLs in their throwing arm versus nonthrowing arm. Additionally, the study found that a player's arm slot, or the angle of the arm during their throwing motion, did not differ between pitchers and nonpitchers.
Pitchers routinely make more throws — and more high-intensity throws — than other players. That their UCL thickness was greater was not a surprise. But better understanding how factors like elbow torque contribute to the condition of UCLs can help players develop better mechanics and trainers develop players with attributes that can reduce their risk of injury, said Quincy Johnson, assistant professor of health, sport & exercise science and assistant director of the Jayhawk Athletic Performance Laboratory at KU, and one of the study's authors.
Prevention is valuable as players suffer UCL injuries at a high rate. In fact, the condition is even known as "Little League elbow" in youth sports.
"The purpose of this study came from members of the coaching and sports medicine staff who wanted to know if we could measure things like ligament size, and if we could include factors like height, weight and throwing mechanics to see if they make a difference," Johnson said.
Pitchers more commonly suffer UCL injuries, and the procedure that repairs it is commonly known as "Tommy John surgery," named after one of the first major league pitchers to undergo the procedure. But positional players have experienced both the injuries and surgeries as well. Previous research has indicated a positive relationship between UCL morphology, such as thickness, and increased UCL injury risk in 70 professional baseball pitchers. And ultrasound technology has shown to potentially be able to detect changes in the UCL prior to injury, hence better understanding what factors contribute to UCL thickness is valuable, Johnson said.
Conventional baseball wisdom has also long held that arm slot contributes to injury risk, with certain angles believed to be more dangerous or easier on the throwing arm.
"There are a lot of kids being told that there is an optimal arm slot for a pitcher, or others are harder on the arm, but it did not show that it had an effect on players' UCL thickness in our study," Johnson said.
Factors including higher elbow torque, higher-effort throws, volume of throws and speed of the arm during throws all correlated with a thicker UCL.
The study was co-written by Calvin Smith of Syracuse University, Brittany Dowling of Sports Performance Center, Chicago; Elias Williams of Oklahoma State University; Mitchel Magrini of Creighton University; Kase Pennartz of the University of North Texas; and Micheal Luera of Tarleton State University.
The study participants had to meet criteria of not having injuries to their throwing arm or current symptoms in the arm. Eleven were pitchers, and 11 were nonpitchers.
Johnson said the findings accomplish several things, including confirming thicker UCLs in pitchers versus nonpitchers and which factors did contribute to UCL morphology. They also can help coaches, athletes and athletic trainers develop strength and conditioning routines that help players enhance athletic performance, minimize their risk for injury and use better throwing mechanics.
Additionally, the findings refute the common belief factors such as height, weight and even-handedness as predictors for a proper arm slot for a given player.
A former strength and conditioning coach, Johnson hopes to continue research into UCL injury risk factors such as how the type of pitch thrown affects UCL morphology. The Jayhawk Athletic Performance Laboratory is part of the Wu Tsai Human Performance Alliance, which examines human health through understanding peak performance.
Johnson also recently published research on the specific body composition, strength and power characteristics key to different positions on the football field .
Ultimately, the UCL research can help coaches and players reduce injury risk, which can save money and recovery time as well as careers, as many young players never fully come back from UCL injuries. Teams have developed approaches such as maximum pitch counts to reduce risk, but more can be done.
"Is this the best way to go forward, where we're routinely going through arms?" Johnson said. "We need to continue with a set of questions and ideas about things like throw volume and max effort throws to see if we can come up with better throwing development at lower levels of the sport."
