Poster 145: The Natural History of Rotator Cuff Injuries in Professional Baseball
Authors: Tanenbaum Joseph E. , Hartwell Matthew J. , Tenner Zachary , Selley Ryan S. , Buchler Lucas T. , Saltzman Matthew D. , Gryzlo Stephen 
Published: October 2024

Objectives: The objective of this study was to quantify the rate and timing of recurrent rotator cuff injuries among elite baseball players. Whereas several prior works focused on rates of return to play and performance after ulnar collateral ligament (UCL) reconstruction, the literature lacks evidence on recurrence rates for UCL injuries, especially for nonoperative injuries. Addressing this literature gap is important because prior studies suggest that shoulder injuries that require surgery place the player at substantially greater risk of sustaining future injuries. Furthermore, the prevalence of rotator cuff pathology has been shown to exceed 80%, even among asymptomatic baseball players. Thus, although rotator cuff injuries are common, little is known about the natural history of these injuries. The present study is the first to use comprehensive data from Major League Baseball (MLB) on rotator cuff injuries to quantify the frequency of recurrence and when these injuries are likely to recur. Quantifying the recurrence rate of rotator cuff injuries is important for teams, athletic trainers, surgeons, and players across the competitive spectrum. If the recurrence rate of rotator cuff injuries is relatively low, then both teams and players stand poised to benefit from revising their internal grading scales for players with these injuries. Conversely, if rotator cuff injury recurrence is relatively high, then athletic trainers and surgeons can more accurately describe the natural history of this condition to both players and teams. This study addresses this gap in the literature and also identifies the number of seasons until recurrence. The results of this study can be used to derive specific player safety initiatives and rehabilitation protocols. These data will provide critical information to players, team management, and team physicians at all levels of competition with an eye toward better informing health and safety decisions. Methods: Using data from MLB’s Health and Injury Tracking System (HITS) on all MLB and Minor League Baseball (MiLB) players between 2010 and 2021, a comprehensive list of rotator cuff injuries (regardless of initial treatment modality) was generated by reviewing every shoulder injury in MLB and MiLB during the study period. Importantly, prior studies have been shown to mistakenly exclude some rotator cuff injuries when they rely on data from publicly available injury reports. The present study addresses this problem by relying on data generated by athletic trainers, team surgeons, and the league office. These data are therefore comprehensive relative to data sources used in earlier studies of similar questions. Within the HITS, players are given a unique player identifier and each injury event is given a unique injury event identifier. Thus, to measure recurrence, HITS allows players to be tracked over time and to denote if a given injury is a recurrence of a prior injury or a new injury. We calculated the number of rotator cuff injuries in each season between 2010 and 2016 and then determined the 5-year recurrence rate. The 5-year time horizon was chosen because the median professional baseball career length is 5 seasons. We therefore use data from the 2010-2021 seasons to present the 5-year recurrence rate for injuries occurring between 2010 and 2016. We then calculated the median and interquartile range (IQR) for when a recurrence was most likely to occur. Third, we calculated the 5-year recurrence rate among players whose initial injury was managed nonoperatively. Finally, we quantified the rate at which recurrent injuries were managed operatively stratified by initial treatment modality. Results: Throughout the study period (2010-2016), there were 2983 documented rotator cuff injuries. Of these injuries, 133 (4.5%) were managed initially with surgery, 569 (19.1%) recurred within 5 years, with a median of 2 seasons (IQR 1-3 seasons) until recurrence. When a recurrence occurred, 59 players (10.4%) underwent surgery, regardless of initial treatment modality. Among injuries that were initially treated nonoperatively (2850 injuries), 554 players (19.4%) experienced a recurrence within 5 years, with a median of 2 seasons (IQR 1-3 seasons) until recurrence, and 56 players (10.1%) underwent surgery to treat the recurrence. Conclusions: The present study provides the most detailed description to date of the natural history of rotator cuff injuries among baseball players. As prior studies demonstrated, rotator cuff injuries account for a large percentage of all shoulder injuries in baseball players, and understanding whether and to what extent these injuries are likely to recur is critical in developing health and safety protocols around these injuries. We found a relatively high recurrence rate of 19.1% within the median professional baseball career length of 5 years. Most patients were initially treated nonoperatively, with approximately 10% of recurrences undergoing surgery for the recurrence. In a related pathology (SLAP tears), McGahan et al showed that a history of labral injury was associated with a meaningfully worse predraft evaluation among baseball players eligible for the draft. Even among players who had returned to prior levels of performance, concern persisted among team physicians about future injury risk. The results of the present study suggest that that logic may not apply to rotator cuff injuries; although recurrence rates are relatively high, very few injuries are severe enough as to require operative intervention. These findings therefore highlight the importance of understanding the natural history of common injuries among athletes across all levels of competition and can be used to inform risk reduction plans for athletes across the competitive landscape.