Throwing Arm Injury Research in the Sports Medicine and Research Lab: The Year of Tommy John

This week’s EXSS Impact blog post was written by Joe Myers, PhD, ATC.  Dr. Myers is a Professor in EXSS and serves as the Director of the Human Movement Science Doctoral Curriculum.  Over the past 10 years his research has focused on assessment of shoulder dysfunction using neuromuscular and biomechanical measurement models

Why did you do this study?

unc pitchingThe 2014 Major League Baseball season is being deemed the “Year of Tommy John” with a rash of ulnar collateral ligament elbow injuries being sustained by high profile major league pitchers. As part of the media coverage regarding why these injuries occur, and more importantly, how to prevent these injuries from occurring, much of the discussion focuses on the “damage is already done” by the time a pitcher reaches the major leagues, with that damage occurring during participation at the adolescent and high school level. Yet, we know very little about how this “damage” is occurring in younger players except that these players are simply playing too much. It is not uncommon for players to play for 6-8 teams yearly, often playing for 9 months per year. This results in high levels of tissue stress without adequate rest and recovery. The result is often injury to their throwing/pitching arm whether as a youth, adolescent, or high school player and/or this damage contributes to subsequent injury later in their career.

Injuries to the pitching arm (shoulder and elbow) comprise more than half of all injuries occurring in baseball, often resulting in significant time loss from participation, time loss from general physical activity, decreased performance, and secondary pathology later in life. Epidemiological studies demonstrate that approximately 20-70% of baseball players experience shoulder and elbow pain, respectively with many of these injuries occurring in players 18 years of age or less. Many of these injuries require surgery with the American Sports Medicine Institute reporting that the proportion of upper extremity surgeries performed on high school players increased by 50% over the last decade. Thus, there is a significant need to understand why these injuries are on the rise in the youth, adolescent, and high school aged players. It is speculated that arm injuries result from a combination factors including faculty pitching mechanics, tissue adaptations that result from repeated throwing, and excessive amount of participation without allowing for the necessary rest and recovery. Over the past 7 years, the Sports Medicine Research Laboratory faculty and students have sought to understand why these arm injuries occur in hopes of better implementing injury prevention and participation recommendations to the youth, adolescent, and high school players.

What did you do and what did you find in this study?

Because of the multifaceted and interrelated nature of the risk factors contributing to arm injury, we have spent the last 7 years taken a comprehensive approach studying the causes of these arm injuries in the youth, high school, and collegiate baseball player, with nearly 1500 participants enrolled from across the state of North Carolina. Through generous funding provided by the National Institutes of Health, we focus on a combination of assessments that measure arm injury risk factors including:

1) Faulty pitching mechanics (FIGURE 1)

joe fig 1FIGURE 1: Field and laboratory based assessments of pitching mechanics

2. Tissue adaptations that result from baseball participation in youth, adolescent, and high school players (FIGURE 2)

joe fig 2FIGURE 2: Assessment of tissue adaptations in a youth participant

3. Markers of arm trauma that can be identified following pitching and tracked as means to measure rest and recovery (FIGURE 3)

joe fig 3FIGURE 3: Ultrasound imaging of rotator cuff muscle swelling (in red) that results from pitching

The work of the Sports Medicine Research Laboratory faculty and students has provided a significant contribution to the sports medicine community’s understanding of arm injuries in baseball pitchers including:

  • Identifying the physical characteristics that we see clinically in both healthy players and players who sustain arm injury
  • Reporting on the role that shoulder flexibility plays in injury risk as well as to improve flexibility when tightness is present
  • Describing the role that scapular movement patterns play in arm injury risk as well as effective way to improve abnormal movement patterns
  • Showing the bony adaptations that occur to the humerus (upper arm) as a result of baseball participation prior to skeletal maturity and how these adaptations affect clinical decisions regarding diagnosis and treatment
  • Demonstrating the soft tissue adaptations that occur to the arm that results from participation and when these adaptations may be best addressed clinically.
  • Identifying the role that faulty pitching mechanics play in increasing the injurious forces and torques placed on the shoulder and elbow during pitching.
  • Demonstrating how we can track markers of tissue trauma as a means to provide indicators of increased arm injury risk as well as ways to track rest and recovery (or a lack of rest and recovery in players who participate on multiple teams, leagues, and other showcase opportunities).

How do these findings impact the public?

Currently in the United States, there are nearly 13 million baseball players with a majority of these players being 18 years of age or younger. Accompanying this high amount of participation is a high risk of arm injury, often requiring significant time loss away from the game and surgery. The research being conducted in the Sports Medicine Research Laboratory makes a significant impact on these arm injuries that are occurring by providing parents, coaches, clinicians, and players with research supported strategies to treat and reduce injury. Additionally, education outreach provided to players across the state is hopefully resulting in safe participation by youth and adolescent players across North Carolina.