Influence of Pitching Release Location on Ulnar Collateral Ligament Reconstruction Risk Among Major League Baseball Pitchers

Pitch-Specific Advanced Analytic and Pitch-Tracking Risk Factors for Ulnar Collateral Ligament Injuries in Major League Baseball Pitchers

BACKGROUND

The utilization of new pitch-tracking metrics has driven player development and provides more predictive pitch-specific data on physical characteristics and performance. Given the differences in each pitcher's arsenal, these pitch-specific metrics provide new potential variables to investigate ulnar collateral ligament (UCL) injury risk.

PURPOSE

To evaluate the association of several pitch-specific advanced analytic and pitch-tracking metrics on UCL surgery rates in Major League Baseball (MLB) pitchers.

STUDY DESIGN

Case-control study; Level of evidence, 3.

METHODS

We performed a retrospective case-control study on all MLB pitchers who underwent primary UCL reconstruction or repair from April 2018 to November 2023. Exclusion criteria included pitchers without 2 qualifying seasons of preoperative pitch-tracking data or who previously underwent UCL surgery. Matched controls were identified in a 2:1 manner by using season, age, position, handedness, and pitch count as covariates. Pitch-specific advanced analytic and pitch-tracking metrics used commonly in the evaluation of MLB players were collected from public web sources sponsored by MLB. Statistical analysis consisted of unpaired t tests comparing preinjury metrics between the case and control groups, along with binary logistic regression.

RESULTS

A total of 115 MLB pitchers who underwent UCL reconstruction or repair were compared with 230 matched controls. Increased velocity for fastballs, changeups, and sinkers were all associated with UCL surgery. A decreased horizontal release point for fastballs, curveballs, and sinkers were also associated with UCL surgery, along with an increased horizontal approach angle above average for fastballs and sinkers. An increased spin rate for sliders and an increased release extension for cutters were also associated with surgery. Large statistically significant differences in Pitching+ and Location+ for fastballs, changeups, and sinkers, and in Stuff+ for changeups, were associated with surgery. There were no differences in pitch-specific pitch count, active spin, spin axis, vertical release point or approach angle, or overall pitch movement between cases and controls. Binary logistic regression showed that higher velocity fastballs, sliders, and changeups were all associated with UCL surgery, along with sliders with a higher spin rate and cutters with a longer release extension.

CONCLUSION

This study demonstrated that pitch-specific associations with UCL surgery exist compared with matched controls. Specifically, higher velocity fastballs, sliders, and changeups were all associated with UCL surgery, along with sliders with a higher spin rate and cutters with a longer release extension. Fastballs, changeups, and sinkers with superior ability (Pitching+) and command (Location+) were also associated with UCL surgery. While fastball velocity appears to play a role in the rise of UCL injuries, recent trends in decreased fastball usage and improved secondary pitches suggest that an increased focus on entire pitching arsenals is warranted. This study investigated a number of pitch-specific advanced analytic and pitch-tracking metrics as potentially new variables to assess UCL injury risk.

Advanced Analytic and Pitch-Tracking Metrics Associated with UCL Surgery in Major League Baseball Pitchers: A Case-Control Study

Background

Ulnar collateral ligament (UCL) injury rates have been rising steadily, while the recent development of advanced analytics and pitch-tracking analysis now drives player development and evaluation throughout Major League Baseball (MLB).

Purpose

To evaluate the association between several advanced analytic and pitch-tracking metrics on UCL surgery rates in MLB pitchers.

Study Design

Case-control study.

Methods

Included in this study were MLB pitchers who underwent primary UCL reconstruction or repair from April 2018 to November 2023. Exclusion criteria were pitchers without 2 qualifying seasons of preoperative pitch-tracking data and those who previously underwent UCL surgery. Uninjured matched controls were identified in a 2:1 ratio using season, age, position, handedness, and pitch count as covariates. Advanced analytics (eg, FanGraphs wins above replacement [fWAR], expected fielding-independent pitching [xFIP], physical pitch qualities [Stuff+] strike-zone command [Location+], and overall pitching ability [Pitching+]) and various pitch-tracking metrics used commonly in MLB player evaluation were collected from public web sources sponsored by MLB and used in previous studies. Statistical analysis consisted of unpaired t tests comparing cases and controls and binary logistic regression.

Results

A total of 117 MLB pitchers who underwent primary UCL reconstruction or repair were compared with 234 matched controls. Cases had significantly superior pitch velocity, fWAR, xFIP, Pitching+, and Location+ compared with controls. There was no significant difference between cases and controls in pitch counts, spin, release points, release extension, approach angles, or overall pitch movement. Binary logistic regression identified velocity, Pitching+, and decreased fastball usage as being associated with UCL surgery (P < .10 for all).

Conclusion

In this analysis of several modern advanced analytic and pitch-tracking metrics, MLB pitchers who underwent UCL surgery threw harder with less fastball usage, and had superior overall pitching ability (Pitching+) and strike-zone command (Location+) than matched controls.

Return to Performance After Ulnar Collateral Ligament Surgery in Major League Baseball Pitchers

BACKGROUND

Even though return to play is important for Major League Baseball (MLB) pitchers and teams, return to performance after ulnar collateral ligament (UCL) surgery using several advanced analytic and pitch-tracking metrics has not been well studied.

PURPOSE

To evaluate return to performance in MLB pitchers using modern advanced analytic and pitch-tracking metrics at 1, 2, and 3 seasons after UCL surgery.

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

A retrospective analysis was performed on 129 MLB pitchers who underwent primary UCL reconstruction or repair between November 2017 and November 2023 and reported return-to-play and return-to-performance rates at 1, 2, and 3 seasons postoperatively. Return-to-performance data were then collected for 58 MLB pitchers who had at least 2 seasons of postoperative data using public sources affiliated with MLB and used in previous studies. Return-to-performance analysis consisted of paired and unpaired t tests comparing preoperative and postoperative metrics. The percentage of pitchers who returned to their preinjury performance for each respective advanced analytic or pitch-tracking metric was also recorded for each season after surgery. Return to full performance, defined as a pitcher returning to form in each key metric including expected fielding independent pitching, FanGraphs wins above replacement (fWAR), velocity, fastball velocity, and spin rate, was also evaluated. Data on advanced analytics released in 2020 measuring the physical quality of pitches (Stuff+), command of the strike zone (Location+), and overall pitching ability (Pitching+) was also examined for the first time. Binary logistic regression was conducted to evaluate for any predictive factors of return to performance.

RESULTS

The mean age was 27.6 ± 3.0 years. 1.6% returned to play at 1 year, 71.9% at 2 years, and 82.0% at 3 years from reported date of surgery with a mean of 584 ± 194 days. At 3 seasons postoperatively, pitchers returned to performance in pitch count (55%), expected fielding independent pitching (68%), fWAR (48%), velocity (76%), fastball velocity (80%), horizontal movement (81%), vertical movement (66%), Stuff+ (78%), Location+ (89%), and Pitching+ (78%) at varying degrees. Only 3.9%, 11.8%, and 28.1% of pitchers returned to full performance by 1, 2, and 3 seasons postoperatively, respectively. Only an additional 19.3% of pitchers met 4 out of 5 full performance criteria. Binary logistic regression identified starting pitchers and preoperative faster velocity and older age as strong negative predictors of return to full performance.

CONCLUSION

Pitchers provided only half of their value to teams at 3 years postoperatively, despite presumably being physically recovered. Even though most pitchers regained their previous form in various pitching metrics, the majority of pitchers did not return to full form. Overall, being a starting pitcher was the strongest negative predictor of returning to full performance, followed by faster preoperative velocity and older age. The return-to-performance rate for each pitching metric improved season to season after returning from an injury. Despite returning to play at high rates, pitchers still needed time to recover their performance.

Biomechanical effects of foot placement during pitching

Baseball coaches often focus on the landing position of a pitcher's front foot as a key aspect of mechanics. Furthermore, controversy persists regarding positioning the rear foot on the first base or third base end of the rubber. The purpose of this study was to determine the effect of rear and front foot placement on pitching biomechanics. Our hypotheses were that there would be significant kinematic and kinetic differences associated with foot placement. This was a retrospective review including 144 healthy right-handed adult baseball pitchers divided into groups based on their rear and front foot placements: first base open (1B-Open), first base closed (1B-Closed), third base open (3B-Open), and third base closed (3B-Closed). Two-way ANOVAs detected no statistically significant main effects for kinetic variables but several for kinematic variables. Open pitchers had less shoulder abduction at the time of ball release and greater maximum shoulder internal rotation velocity in comparison with closed pitchers. They also had less forearm pronation at the time of ball release and greater maximum elbow extension velocity. Additional statistically significant results were found; however, low effect sizes may lessen the clinical significance of many of the results.

Changes in Pitch Velocity and Selection in Major League Baseball Pitchers Following the Ulnar Collateral Ligament Reconstruction

BACKGROUND

The ulnar collateral ligament (UCL) is a soft-tissue stabilizer of the elbow, that is commonly injured among baseball pitchers due to excess valgus stress in overhead throwing motions. The location of a UCL tear typically ranges from the central aspect of the ligament to an avulsion-type injury at its proximal insertion site on the medial epicondyle of the humerus, or its distal insertion site on the ulna. The effect of UCL reconstruction on pitching performance has become a well-studied topic in medical literature. In our study, we aimed to identify general performance patterns amongst those having undergone UCL reconstruction surgery.

METHODS

Data for patients with UCL reconstruction performed between 2010 and 2020 were extracted from publicly available databases. Pitching data was extracted from Brooks Baseball, a publicly available database for Major League Baseball (MLB) player statistics. We identified patients who played at least one full season after surgery and rehabilitation. Patient characteristics were evaluated for intergroup differences.

RESULTS

Of 109 patients with UCL reconstruction, 87 were included in the final analysis. Compared to the preoperative group, the average postoperative fastball usage rate was less despite there being an increase in the off-speed usage rate. Velocity analysis demonstrated shifts of less than 1% for all three pitch groups compared to preoperative velocity average values (all P-values <0.05). Earned Run Average (ERA)+ demonstrates a decrease in the postoperative group; this finding was not significant (P=0.61).

CONCLUSIONS

 Patients treated surgically demonstrated a throwing tendency for their secondary and tertiary pitches and a decreased usage of fastballs. Further studies are needed to explore the factors contributing to the change in pitching performance.

Forearm Pronation at Foot Contact: A Biomechanical Motion-Capture Analysis in High School and Professional Pitchers

Background

It has previously been speculated that baseball pitchers who display excessive forearm pronation at foot contact (FC) have a higher propensity toward ulnar collateral ligament injury and subsequent surgery.

Purpose

To evaluate the association between degree of forearm pronation/supination at FC and throwing arm kinetics in high school and professional pitchers, at both the individual (intrapitcher) and the group (interpitcher) level.

Study Design

Descriptive laboratory study.

Methods

High school (n = 41) and professional (n = 196) pitchers threw 8 to 12 fastballs while being assessed with a 3-dimensional motion-capture system (480 Hz). Pitchers at each playing level were divided into a supination or pronation subgroup depending on degree of forearm pronation at FC. Regression models were built to observe the relationship between forearm pronation at FC and kinetic and kinematic parameters of interest.

Results

At both the individual and the group level of high school and professional pitchers, there was no significant correlation between forearm pronation at FC and elbow varus torque (P _min = .21). For every 10° increase in forearm pronation at FC in the individual high school pitcher, elbow flexion at FC decreased by 5°, whereas maximum elbow extension velocity was achieved 0.6% later in the pitch. In addition, elbow medial force increased by 4.1 N and elbow varus torque increased by 0.8 N·m for every 10° increase in forearm supination at FC. For every 10° increase in forearm supination in the individual professional pitcher, ball velocity increased by 0.5 m/s, shoulder external rotation at FC decreased by 11°, and elbow medial force decreased by 5.5 N.

Conclusion

Supination- or pronation-predominant forearm motion during the pitch did not significantly differ between playing levels. Excessive forearm pronation at FC was not a significant risk factor for increased throwing arm kinetics for high school or professional pitchers. There was a weak positive association between forearm supination at FC and elbow varus torque in the individual high school pitcher. Ultimately, coaches and pitchers may be better served by redirecting their focus to other mechanical aspects of the pitch that may have stronger associations with injury risk implications as well as performance.

Using Advanced Data to Analyze the Impact of Injury on Performance of Major League Baseball Pitchers: A Narrative Review

Major league baseball (MLB) pitchers are at risk of numerous injuries during play, and there is an increasing focus on evaluating their performance in the context of injury. Historically, performance after return to play (RTP) from injury has focused on general descriptive statistics, such as innings or games played, or rate statistics with inherent variability (eg, earned run average, walks and hits per inning pitched, strikeouts per 9 innings, or walks per 9 innings). However, in recent years, MLB has incorporated advanced technology and tracking systems in every stadium, allowing for more in-depth analysis of pitcher-specific data that are captured with every pitch of every game. This technology allows for the ability to delve into the pitching performance on a basis that is more specific to each pitcher and allows for more in-depth analysis of different aspects of pitching performance. The purpose of this narrative review was to illustrate the current state of injury recording for professional baseball pitchers, highlight recent technological advances in MLB, and describe the advanced data available for analysis. We used advanced data in the literature to review the current state of performance analysis after RTP in MLB pitchers after injury. Finally, we strived to provide a framework for future studies to more meticulously assess RTP performance given the current available resources for analysis.

More Elevated Fastballs Associated With Placement on the Injured List due to Shoulder Injury

Purpose

To evaluate whether impending shoulder injury was associated with changes in pitch location or velocity immediately preceding injury.

Methods

Pitchers placed on the injured list (IL) due to a shoulder injury between 2015 and 2020 were identified in the Major League Baseball transactions database. Four-seam fastball velocity and frequency of pitch location for each pitch type was collected for each player in the season before placement on the IL and within 1 month of placement on the IL with a minimum of 55 pitches thrown of 1 type. Pitch locations were collected as identified by Baseball Savant’s Game-Day Zones. Game-Day Zones were consolidated into high (above the strike zone midpoint) versus low, arm side (closer to the pitcher’s arm side of the plate) versus opposite side, and within the strike zone versus out of zone. Repeated measures analysis of variance determined differences in four-seam velocity and the location distribution of 4-seam fastballs, change-ups, and breaking balls among each group.

Results

In total, 267 pitchers were placed on the IL for a shoulder injury with the majority diagnosed with inflammation (89/267) followed by strain or sprain (69/267). Four-seam fastball locations significantly increased above the mid-point of the zone (45.9% vs 42.4%, P = .008) and out of the strike zone (48.5% vs 46.5%, P = .011) within a month before IL placement. There was no significant change in 4-seam fastball velocity immediately before IL placement.

Conclusions

Pitchers threw more elevated 4-seam fastballs and out-of-zone 4-seam fastballs in the month before IL placement for shoulder injury. These findings suggest that a loss of 4-seam fastball command decreases with impending shoulder injury.

Level of Evidence

IV, prognostic case series.

Using Pitch-Tracking Data to Identify Risk Factors for Medial Ulnar Collateral Ligament Reconstruction in Major League Baseball Pitchers

Background:

Approximately 25% of Major League Baseball (MLB) pitchers undergo medial ulnar collateral ligament reconstruction (UCLR) during their careers.

Purpose:

To identify risk factors for UCLR that are specific to 2 subgroups of MLB pitchers: right (RHPs)- versus left-handed pitchers (LHPs) and starting (SPs) versus relief pitchers (RPs).

Study Design:

Case-control study; Level of evidence, 3.

Methods:

We included 109 MLB pitchers who had undergone UCLR between 2007 and 2019 and had sufficient preinjury data in the 3 years before surgery (T3, T2, T1). A 2:1 matched control cohort was selected for comparison. Pitch velocity, release location, and ball movement were compared between the UCLR and control cohorts in both subgroups in the years before surgery (RHPs vs LHPs and SPs vs RPs). Binary logistic regression was used to identify independent risk factors for UCLR.

Results:

The mean horizontal release location for the UCLR group was 5.8 cm more lateral than for the control group (P = .028). For all pitchers, every 2.5-cm lateral shift in release location in the years leading up to UCLR equated to a 3.7% increase in the odds of UCLR. For RPs, this risk was more substantial: a 5.8% increase in odds per 2.5 cm. SPs in the UCLR group demonstrated significantly different T1 horizontal release locations compared with SPs in the control group, though not to a statistically significant change over the 3 years before surgery. However, in the 3 years before surgery, the horizontal release location for RPs in the UCLR group moved 2.1 cm more lateral, as compared with 2.7 cm more medial for RPs in the control group (P = .007). For LHPs, a decrease in mean pitch velocity by 1 mph (1.6 km/h) in the years leading up to surgery increased the odds of UCLR by 45%.

Conclusion:

Increasing lateralization of release point in the years before surgery increased the risk of UCLR, specifically for relievers. Our findings add to the growing body of evidence that release location is an important variable in analyzing the risk of UCLR in MLB and that risk stratification may be dependent on pitcher characteristics such as position, handedness, and weight.

Differences in Shoulder Internal Rotation Strength Between Baseball Players With Ulnar Collateral Ligament Reconstruction and Healthy Controls

Background:

Studies have indicated decreased shoulder internal rotation (IR) and external rotation (ER) strength in the throwing limb of baseball players after ulnar collateral ligament injury. There is limited evidence on the recovery of shoulder rotation strength after primary ulnar collateral ligament reconstruction (UCLR).

Hypothesis:

At the time of return to throwing, baseball players who underwent UCLR would demonstrate decreased IR and ER shoulder strength in the throwing arm as compared with healthy baseball players.

Study Design:

Cross-sectional study; Level of evidence, 3.

Methods:

Male competitive high school and collegiate baseball athletes participated in this study. Athletes who underwent UCLR were compared with healthy controls who were matched by age, height, weight, and position. Bilateral isometric shoulder ER and IR strength was measured using a handheld dynamometer for all participants at the time of initial evaluation (UCLR group) and throughout the course of a season (healthy group). Independent t tests were run to calculate mean differences in ER and IR shoulder strength between the groups, with significance set at P < .05.

Results:

A total of 86 baseball athletes participated in this study (43 UCLR group, 43 healthy group). At the time of return to throwing (mean ± SD, 194 ± 30 days postoperatively), the 2 groups demonstrated no significant differences in nonthrowing arm ER or IR strength (P = .143 and .994, respectively). No significant difference was found between groups for throwing arm ER strength (P = .921); however, the UCLR group demonstrated significantly less throwing arm IR strength than the healthy group (144.2 ± 27.8 vs 157.6 ± 27.1 N; P = .023).

Conclusion:

The results of this study demonstrate that throwing arm rotator cuff strength may not fully recover before the initiation of a return-to-throwing program after UCLR. These data provide a potential framework for clinicians to assist in the management and exercise prescription of the baseball athlete after UCLR and before medical release and the initiation of a return-to-throwing program.

Are Baseball Statistics an Appropriate Tool for Assessing Return to Play in Injured Pitchers? Analysis of Statistical Variability in Healthy Players

Background:

Basic pitcher statistics have been used to assess performance in pitchers after injury or surgery without being validated. Even among healthy pitchers, the normal variability of these parameters has not yet been established.

Purpose:

To determine (1) the normal variability of basic and advanced pitcher statistics in healthy professional baseball pitchers and (2) the minimum pitches needed to predict these parameters.

Study Design:

Cross-sectional study; Level of evidence, 3.

Methods:

Publicly available data from the MLB Statcast and PITCHf/x databases were used to analyze MLB pitchers during the 2015 and 2016 seasons who recorded a minimum of 100 innings without injury. Basic and advanced baseball pitcher statistics were analyzed. The variability of each parameter was assessed by computing the coefficient of variation (CV) between individual pitchers and across all pitchers. A CV <10 was indicative of a relatively constant parameter, and parameters with a CV >10 were generally considered inconsistent and unreliable. The minimum number of pitches needed to be followed for each variable was also analyzed.

Results:

A total of 118 pitchers, 55 baseball-specific statistical metrics (38 basic and 17 advanced), and 7.5 million pitches were included and analyzed. Of the 38 basic pitcher statistics, only fastball velocity demonstrated a CV <10 (CV = 1.5), while 6 of 17 (35%) advanced metrics demonstrated acceptable consistency (CV <10). Release position from plate and velocity from the plate were the 2 most consistent advanced parameters. When separated by pitch type, these 2 parameters were the most constant (lowest CV) across every pitch type.

Conclusion:

We recommend against utilizing nonvalidated statistical measures to assess performance after injury, as they demonstrated unacceptably high variability even among healthy, noninjured professional baseball pitchers. It is our hope that this study will serve as the foundation for the identification and implementation of validated pitcher-dependent statistical measures that can be used to assess return-to-play performance after injury in the future.

Association Between Pitch Break on the 4-Seam Fastball and Slider and Shoulder Injury in Major League Baseball Pitchers: A Case-Control Study

Background

Few specific risk factors are known for shoulder injury in professional pitchers. New pitch-tracking data allow for risk stratification based on advanced metrics.

Purpose/Hypothesis

The purpose of this study was to determine the association between shoulder injury, pitch frequency, and pitch metrics (velocity, total break, break angle, and spin rate) for the 4-seam fastball, curveball, and slider. We hypothesized that more frequent use of the 4-seam fastball would be associated with shoulder injury.

Study Design

Case-control study; Level of evidence, 3.

Methods

The Major League Baseball (MLB) database was queried for pitchers who had been placed on the injury list (IL) with a shoulder injury between 2015 and 2019. Injured pitchers were matched 1:1 with controls (pitchers not on the IL with a shoulder injury during the study period), based on age (±1 year), history of ulnar collateral ligament reconstruction, position (starter vs reliever), and pitches thrown during the injury season (±500). Pitch frequency, velocity, horizontal break, vertical break, total break, and spin rate for the season were collected from the Baseball Savant website for the 4-seam fastball, curveball, and slider. Univariate analysis was used to determine group differences for individual variables. Multiple logistic regression was performed to determine odds ratios (ORs) for shoulder injury associated with pitch frequency, velocity, total break, break angle, and spin rate. Covariates included age, position, ulnar collateral ligament reconstruction status, expected weighted on-base average, and total pitches thrown.

Results

Overall, 233 injured pitchers were evaluated. The most common reason for IL placement was inflammation (78/233; 33.5%) followed by strain or sprain (61/233; 26.2%). Increased total pitch break was associated with an increased risk of shoulder injury for the 4-seam fastball (OR, 1.340 [95% confidence interval (CI), 1.199-1.509]; P < .001) and slider (OR, 1.360 [95% CI, 1.206-1.554]; P < .001). For the slider, a decreased spin rate (OR = 0.998 [95% CI, 0.997-0.999]; P = .026) and a more vertical break angle (OR = 1.170 [95% CI: 1.073-1.278]; P = .004) were associated with increased risk of injury.

Conclusion

Increased pitch break of the 4-seam fastball and slider was associated positively with shoulder injury in MLB pitchers. These findings add to the understanding of throwing injury and ability to detect risk using ball-tracking technology.

Preventing Tommy John Surgery: The Identification of Trends in Pitch Selection, Velocity, and Spin Rate Before Ulnar Collateral Ligament Reconstruction in Major League Baseball Pitchers

Background:

Ulnar collateral ligament (UCL) reconstruction is a common surgery among Major League Baseball (MLB) pitchers that results in a significant number of missed games. Little has been reported regarding game-by-game trends that can identify those on the verge of becoming injured.

Purpose:

To determine if there is a patterned change in MLB pitchers’ pitch selection, velocity, or spin rate in games leading up to Tommy John surgery that may predict subsequent UCL surgery.

Study Design:

Case series; Level of evidence, 4.

Methods:

A retrospective review of MLB pitchers who underwent primary UCL reconstruction between 2009 and 2019 was performed. Pitch characteristics were evaluated on a game-by-game basis for the 15 games leading up to surgery. A Mann-Kendall trend test was used to identify trends in pitch selection, velocity, and spin rate for multiple pitch types. A Kendall τ_b correlation coefficient was identified, with values closer to 1 or –1 signifying a stronger monotonic trend.

Results:

A total of 223 MLB pitchers underwent UCL reconstruction in the time period. In the 15 games leading up to surgery, decreases in pitch velocity for 4-seam fastballs (τ_b = –0.657; P < .001), 2-seam fastballs (τ_b = –0.429; P = .029), and sliders (τ_b = –0.524; P = .008) were significantly associated with game number closer to injury. There was a significant positive association in the spin rate for cutters (τ_b = 0.410; P = .038) and a significant negative association in spin rate for 4-seam fastballs over the course of these 15 games (τ_b = –0.581; P = .003). In addition, there was a significant positive association in the percentage of curveballs thrown (τ_b = 0.486; P = .013).

Conclusion:

The study results suggest that there is a patterned change in certain pitch statistics in MLB pitchers in the games leading up to Tommy John surgery. Although the absolute change from game to game may be small, it may be possible for these trends to be monitored before a player becomes injured, thus reducing the significant burden Tommy John surgery places on these athletes.

Effect of Younger Starting Pitching Age on Humeral Retrotorsion in Baseball Pitchers With an Ulnar Collateral Ligament Injury

BACKGROUND

Increased humeral retrotorsion (HRT) has been found to be a risk factor for ulnar collateral ligament (UCL) tears in baseball players. Recent work has demonstrated the age of 11 years as a potential watershed age for HRT development.

HYPOTHESIS

In a group of baseball pitchers with UCL injuries, athletes who started pitching before the age of 10 years will demonstrate significantly more dominant limb humeral retrotorsion (DHRT) when compared with a group of baseball pitchers who reported starting pitching at 10 years or older.

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

A total of 84 baseball pitchers with a diagnosed UCL injury were divided into 2 groups based upon the age at which participants began pitching: 33 players reporting a starting pitching age of 10 years or older (group 1) were compared with 51 baseball pitchers reporting a starting pitching age under 10 years (group 2). Participants' DHRT and nondominant limb humeral retrotorsion (NDHRT) were measured using diagnostic ultrasound. Independent t tests were run to compare mean group differences of all patient data, starting pitching age, age at time of injury, DHRT, NDHRT, and humeral retrotorsion difference (HRTdiff).

RESULTS

There were no significant differences between groups with regard to age at time of injury, height, weight, or playing years' experience. There was a statistically significant difference in the participant-reported starting pitching age. Significant differences between groups were noted for DHRT (group 1: 20.0°± 9.4°, group 2: 14.5°± 10.3°, P = .015) and for NDHRT (group 1: 38.6°± 8.8°, group 2: 32.9°± 9.5°, P = .007). No significant differences between groups were found for HRTdiff (P = .940).

CONCLUSION

Baseball pitchers with a UCL injury who reported a starting pitching age younger than 10 years demonstrated significantly greater DHRT and NDHRT when compared with UCL-injured baseball pitchers who reported a starting pitching age at 10 years or later. The results of this study demonstrate that a younger starting pitching age results in increased HRT in players with UCL injuries.