Correlates With History of Injury in Youth and Adolescent Pitchers

Kinematic Modeling of Pitch Velocity in High School and Professional Baseball Pitchers: Comparisons With the Literature

Background

Kinematic parameters predictive of pitch velocity have been evaluated in adolescent and collegiate baseball pitchers; however, they have not been established for high school or professional pitchers.

Purpose

To create multiregression models using anthropometric and kinematics features most predictive for pitch velocity in high school and professional pitchers and compare them with prior multiregression models evaluating other playing levels.

Study Design

Descriptive laboratory study.

Methods

High school (n = 59) and professional (n = 337) baseball pitchers threw 8 to 12 fastballs while being evaluated with 3-dimensional motion capture (480 Hz). Using anthropometric and kinematic variables, multiregression models for pitch velocity were created for each group. A systematic review was conducted to determine previous studies that established kinematic models for ball velocity in youth, high school, and collegiate pitchers.

Results

Leg length was predictive of pitch velocity for high school and professional pitchers (P < .001 for both). When compared with previously established models for pitch velocity, almost all groups were distinct from one another when assessing age (P maximum < .001), weight (P max = .0095), and pitch velocity (P max < .001). Stride length was a significant predictor for the youth/high school pitchers, as well as the current study's high school and professional pitchers (P < .001 for all). Maximal shoulder external rotation (collegiate: P = .001; professional: P < .001) and maximal elbow extension velocity (high school/collegiate: P = .024; collegiate: P < .001; professional: P = .006) were shared predictors for the collegiate and current study's professional group multiregression models. Trunk flexion at ball release was a commonly shared predictor in the youth/high school (P = .04), high school/collegiate (P = .003), collegiate (P < .001), and the current study's professional group (P < .001).

Conclusion

Youth, high school, collegiate, and professional pitchers had unique, predictive kinematic and anthropometric features predictive of pitch velocity. Leg length, stride length, trunk flexion at ball release, and maximal shoulder external rotation were predictive features that were shared between playing levels.

Clinical Relevance

Coaches, clinicians, scouts, and pitchers can consider both the unique and the shared predictive features at each playing level when attempting to maximize pitch velocity.

Avulsion and Soft Tissue Injuries of the Ulnar Collateral Ligament in Children and Adolescents

BACKGROUND

Although pediatric medial epicondylar fractures and apophysitis are well studied, patterns of subapophyseal avulsion and ligamentous injuries of the medial elbow in this population merit investigation to inform optimal treatment strategies.

PURPOSE

To describe the occurrence and demographic correlates of ulnar collateral ligament (UCL) avulsion and soft tissue injuries of the pediatric and adolescent elbow.

STUDY DESIGN

Cross-sectional study; Level of evidence, 3.

METHODS

An institutional review board-approved review was conducted to identify consecutive patients with medial elbow injuries treated in a tertiary pediatric sports medicine practice between 2016 and 2021. Radiographs were obtained during injury evaluation, and patients with nondisplaced medial epicondylar apophysitis and complete epicondylar fracture were excluded, resulting in 150 patients with soft tissue injuries occurring distal to the medial epicondyle apophysis (subapophyseal) for study. Radiographs were evaluated for bony avulsion of the UCL from either the medial epicondyle proximally or the ulnar sublime tubercle distally. Injuries without radiographic evidence of bony avulsion, but with clinical examination findings consistent with ligamentous injury, were classified as radiographically negative UCL injuries, and magnetic resonance imaging (MRI) was performed to further evaluate these injuries if moderate to severe medial swelling of the elbow or significant concern for medial structural injury was present on examination. These MRI scans were evaluated to classify the UCL injury and assess for periosteal or cartilaginous avulsions.

RESULTS

A total of 150 patients (mean age, 12.5 ± 3.4 years; 70 female), 55% (150/274) of the entire medial elbow injury population, had a subapophyseal injury. Of these patients, 62 had a bony avulsion detected on radiograph, and 88 had a radiographically negative injury. In addition to the 62 radiographic avulsions, the 61 MRI scans obtained on those radiographically negative injuries revealed 33 complete UCL disruptions, resulting in 63.3% (95/150) of patients sustaining a complete ligamentous disruption. With the MRI scans, 37 (61%) cases of cartilaginous or periosteal avulsion of the UCL were diagnosed. Overall, 66% of all 150 subapophyseal injuries had a bony, cartilaginous, or periosteal UCL avulsion. Patients with cartilaginous (mean age, 10.3 years) and bony (mean age, 10.6 years) avulsions were younger than those with central ligament injury (mean age, 14.2 years) or periosteal (mean age, 14.2 years) avulsions (P = .005). There was a significant association between the mechanism of injury and the location of UCL tear identified on MRI scans: traumatic falls were associated with distal tears, and throwing injuries were associated with proximal tears (P < .001).

CONCLUSION

UCL central ligament and avulsion lesions may be frequently diagnosed after injury to the pediatric medial elbow, the majority of which are complete injuries, and may require MRI for diagnosis. The mechanism of injury may predict the location of ligamentous injury, and osteocartilaginous avulsions are more likely to present at younger ages than injuries to the soft tissue of the UCL or periosteum. The prevalence of these injuries merits further investigation into best protocols of nonoperative treatment or surgical repair techniques and outcomes.

Unaccounted for Pitch Volume Among Adolescent Baseball Pitchers During a Travel Baseball Season

OBJECTIVE

The primary aim was to compare differences in live game pitch counts (LGPCs) with all pitch counts (APCs) over the course of a youth baseball season.

DESIGN

Prospective longitudinal study.

SETTING

Midwest youth travel baseball.

PARTICIPANTS

Ten male baseball players part of a youth baseball travel team.

VARIABLES

Demographic data, pitch counts (practice, game, warm-up, and bullpen), innings pitched, and recommended rest days.

MAIN OUTCOME MEASURES

Live pitch counts compared with APCs and the relationship to recommended rest days.

RESULTS

During the season, 7866 pitches were recorded among 9 pitchers. By using the LGPC method alone, 42.5% of the pitches were unaccounted for. When considering age-specific rest days suggested by Pitch Smart Guidelines (PSGs), there were 104 rest days unaccounted for by using the live game pitch method.

CONCLUSION

There is a high number of unaccounted for pitches and an underestimation of rest days per outing when using live game methods. Revisions to the PSGs that include all pitches should be considered to accurately reflect pitching volume, which may be associated with the rising rate of injuries among these athletes.

Workload Risk Factors for Pitching-Related Injuries in High School Baseball Pitchers

BACKGROUND

Pitch counts are only one measure of the true workload of baseball pitchers. Newer research indicates that workload measurement and prevention of injury must include additional factors. Thus, current monitoring systems gauging pitcher workload may be considered inadequate.

PURPOSE/HYPOTHESIS

The purpose of this study was to develop a novel method to determine workload in baseball pitchers and improve processes for prevention of throwing-related injuries. It was hypothesized that our pitching workload model would better predict throwing-related injuries occurring throughout the baseball season than a standard pitch count model.

STUDY DESIGN

Cohort study; Level of evidence, 2.

METHODS

This prospective observational study was conducted at an academic medical center and community baseball fields during the 2019 to 2023 seasons. Pitchers aged 13 to 18 years were monitored for pitching-related injuries and workload (which included pitching velocity; intensity, using preseason and in-season velocity as a marker of effort; and pitch counts).

RESULTS

A total of 71 pitchers had 313 recorded pitcher outings, 11 pitching-related injuries, and 24,228 pitches thrown. Gameday pitch counts for all pitchers ranged from 19 to 219 (mean, 77.5 ± 41.0). Velocity ranged from 46.8 to 85.7 mph (mean, 71.3 ± 5.8 mph). Intensity ranged from 0.7 to 1.3 (mean, 1.0 ± 0.08). The mean workload was 74.7 ± 40.1 for all pitchers. Risk factors significant for injury included throwing at a higher velocity in game (P = .001), increased intensity (eg, an increase in mean velocity thrown from preseason to in-season; P < .001), and being an older pitcher (P = .014). No differences were found for workload between injured and noninjured pitchers because the analysis was underpowered.

CONCLUSION

Our workload model indicated that throwing at a higher velocity, throwing at a higher intensity, and older age were risk factors for injury. Thus, this novel workload model should be considered as a means to identify pitchers who may be at greater risk for injury.

The influence of a single 30-pitch session on elbow laxity in adolescent and collegiate baseball pitchers

BACKGROUND

Ulnar collateral ligament (UCL) injuries are a source of significant injury among baseball players, and are increasingly evaluated under ultrasound. The purpose of this study is to determine the effect of a single session of pitching upon UCL thickness and laxity via a cross sectional, controlled ultrasonographic study. We hypothesize that a single session of pitching will cause the ulnar collateral ligament to thicken and become more lax.

METHODS

This was a cross sectional comparative study of collegiate and high school pitchers. Pitchers underwent an ultrasonographic assessment of the UCL before and after a thirty-pitch bullpen warm-up. Laxity was measured as the change in the distance between the ulna and the trochlea with and without a 5-pound weight held in hand with the elbow at 30° of flexion. Pre- and post-throwing UCL thickness and medial laxity were statistically compared with paired tests.

RESULTS

Our study included 15 pitchers, 8 collegiate and 7 high school level athletes. All played baseball at least 6 days a week, and nearly all played for at least 10 months a year. Pitchers reported a peak velocity of 89 ± 6 (77 to 98) miles per hour. In the prior season, these pitchers pitched 56 ± 33 (10 to 120) games, throwing 62 ± 34 (25-140) pitches per game on average. After throwing, there was significantly less UCL laxity (P = .013). Post-throwing laxity was significantly positively correlated with both peak pitch velocity (P = .009) and an average number of pitches thrown per game (P = .10).

CONCLUSION

Throwing 30 pitches significantly decreases medial elbow laxity with stress, possibly due to flexor-pronator activation. Post-throwing medial laxity is correlated with both peak pitch velocity and average number of pitches thrown per game. Future studies should be conducted to determine the number of throws at which laxity begins to increase, as this may provide a workload management guideline for injury prevention.

Impact of Climate on Stress Ultrasound Findings of the Elbow Ulnar Collateral Ligament in Professional Baseball Pitchers: An 18-Year Study

Background

The ulnar collateral ligament (UCL) is the primary soft tissue stabilizer to valgus stress in the elbow and is placed under this valgus stress during the throwing motion. Although there are known risk factors for UCL injury, it is unknown whether the UCL undergoes adaptive changes in athletes from different climates.

Purpose

To compare elbow stress ultrasound (SUS) findings between professional baseball pitchers from warm climates versus cold climates and assess significant differences in adaptive and morphologic changes in the UCL.

Study Design

Cross-sectional study; Level of evidence, 3.

Methods

Dynamic SUS evaluations were performed over 18 years on the dominant and nondominant arms of 643 professional pitchers from warm and cold climates as determined by the player's country/state of origin. Studies were compared with respect to relative UCL thickness (dominant arm vs nondominant arm), relative glenohumeral joint laxity (joint space distance under stress vs joint space distance at rest), and the presence of morphologic changes such as tears or calcifications. In addition, a subgroup analysis was performed to compare the progression of SUS findings over 3 years in players with sequential yearly data.

Results

Players from warmer climates had significantly greater relative UCL thicknesses than players from colder climates (1.75 vs 1.50 mm, respectively; P = .047). There were no differences between these 2 groups in terms of relative ulnohumeral joint laxity (P = .201), presence of morphologic changes (P = .433), 3-year progression of relative UCL thickness (P = .748), or relative joint laxity (P = .904).

Conclusion

Professional pitchers from warm climates had a greater side-to-side difference in UCL thickness between the dominant and nondominant arms. This may be due to the potential for year-round throwing among baseball players from warm climates. There was no difference in laxity, thickness progression, laxity progression, or the presence of additional morphologic changes.

Evaluation of Hip Characteristics in Baseball and Softball Athletes with and Without Throwing Arm Pain

During throwing, the lower extremity assists in the generation and transfer of momentum. Lower extremity stability assists in this transfer by providing a base for distal mobility of the arm segments. This study aimed to determine differences between hip rotational range of motion and strength based on the presence of throwing-arm pain (yes/no) and throwing sport (baseball/softball). We hypothesized those experiencing pain would display decreases in hip range of motion and strength, and that softball players would display greater range of motion than baseball, but less strength based on sex-specific characteristics. Forty-four baseball (13±2 years, 165.2±13.0 cm, 58.5±13.4 kg) and 50 softball players (13±2 years, 160.9±11.2 cm, 62.7±17.9 kg) participated. Multivariate analysis of variance tests (2×2) determined differences in bilateral hip range of motion, total arc of motion, and strength between pain status and sport. There were no significant interactions (>0.05) for pain status and sport on hip range of motion, total arc of motion, and strength. Furthermore, no significant main effects (>0.05) were found for pain status or sport alone on range of motion or strength. Future work should be directed at explaining the effects of hip characteristics on the throwing motion and how it equates to throwing-arm health.

Reliability of ulnar collateral ligament findings in magnetic resonance imaging

BACKGROUND

Ulnar collateral ligament (UCL) tears are common in baseball players. Although magnetic resonance imaging (MRI) is the most used imaging modality for UCL injuries, the inter-rater reliability of MRI analyzing specific characteristics of UCL pathology has not been defined. The purpose of this study was to define the inter-rater reliability of MRI for evaluating UCL characteristics.

METHODS

Three surgeons analyzed 45 noncontrast MRIs: 15 without UCL tears, 15 with intraoperatively confirmed partial-thickness tears, and 15 with intraoperatively confirmed full-thickness tears. Findings evaluated included ligament characteristics (periligamentous or osseous edema, ligament hypertrophy, calcifications, and partial- or full-thickness tearing) and location of the pathology (proximal, midsubstance, or distal). Fleiss' κ coefficients were used to assess interobserver reliability.

RESULTS

There were high rates of agreement for midsubstance (κ: 0.50) and distal (κ: 0.69) ligament edema and proximal osseous edema (κ: 0.48). There were low rates of agreement for proximal ligament edema (κ: 0.08), ligament thickening (κ: -0.02 to 0.20), and proximal to midsubstance calcifications (κ: -0.04 to 0.10). Midsubstance (κ: 0.55) and distal full-thickness tears (κ: 0.63) demonstrated higher agreement than proximal (κ: 0.29). Proximal partial-thickness tears (κ: 0.45) had higher agreement than midsubstance (κ: -0.02) or distal (κ: -0.02).

CONCLUSIONS

In our study, there was high inter-rater reliability regarding proximal osseous edema, midsubstance, and distal ligament edema and full-thickness tears. There was no agreement for midsubstance and distal partial-thickness UCL tears, but fair agreement for proximal tears. UCL tissue characteristics including ligament thickening and calcifications demonstrated low agreement. Challenges remain in effectively evaluating UCL tissue characteristics on noncontrast MRIs.

Early single sport specialization does not improve pitching velocity, motion, strength, or utilization in high school baseball pitchers

Background

The impact of single-sport specialization on performance and injury risk in youth and adolescent athletes remains debated. The purpose of this study was to determine the incidence of single-sport specialization and its association with pitch velocity, pitcher utilization, range of motion, strength, and injury history.

Methods

High school pitchers in the Northeastern, Southeastern, Midwestern, and Western Regions of the United States were prospectively recruited. Prior to the season, pitchers were surveyed about their basic demographics, sport participation history, and injury history. At this timepoint, a standardized physical examination was performed and max pitch velocity was measured. They were then prospectively followed over the ensuing high school season, where pitch utilization and counts were followed and injuries were tracked.

Results

Across the study, 115 pitchers were recruited, of whom 53% played baseball as their only sport and 47% played other sports. Single- position specialization within baseball was uncommon as 90% of athletes played positions other than pitcher. There were no differences in range of motion, strength, or pitch velocity between multisport athletes and single-sport specialists. Within the multisport group, 26% reported a history of injury, while 38% of the single-sport specialists reported a history of injury (P = .179). There were no significant differences in pitcher utilization between multisport athletes and single-sport specialists. Only a single prospective injury occurred in the 115 players.

Conclusion

Although single-sport specialization is common, nearly half of all high school pitchers in this study were multisport athletes. While injury history was generally similar between the two groups, single-sport baseball players did not have the following: improved motion, increased strength, higher ball velocity, or greater pitching volumes during the high school baseball season compared to multisport athletes. Accordingly, single-sport specialization did not have a competitive advantage for these high school pitchers based on the performance factors studied. Further prospective studies are necessary to understand the association between single-sport specialization and injury risk in high school baseball players.

Characteristics Associated With Noncompliance of Current Pitch Smart Guidelines in High School Baseball Pitchers Throughout the United States

Background

Although pitch count and rest guidelines have been promoted for youth and adolescent baseball players for nearly 2 decades, compliance with guidelines remains poorly understood.

Purpose/Hypothesis

The purpose of this study was to determine the frequency of compliance with Major League Baseball (MLB) Pitch Smart guidelines as well as the association between compliance and range of motion (ROM), strength, velocity, injury, and pitcher utilization. It was hypothesized that pitchers in violation of current recommendations would have increased strength, velocity, and injury.

Study Design

Case-control study; Level of evidence, 3.

Methods

This was a prospective, multicenter study of 115 high school pitchers throughout the United States. Pitchers were surveyed about their compliance with current off-season, rest-related guidelines, and history of injury. During the preseason, pitchers underwent standardized physical examinations, and pitch velocity was measured. Pitch counts were collected during the baseball season that followed. Dynamometer strength testing of shoulder forward flexion, and external rotation as well as grip strength was recorded. We compared pitchers who were compliant with recommendations with those who were noncompliant using Student t and Mann-Whitney U tests.

Results

Based on preseason data, 84% of pitchers had violated current Pitch Smart guidelines. During the season, 14% had at least 1 violation of the Pitch Smart guidelines. Across both the preseason survey and in-season pitch counts, 89% of players had at least 1 violation of the Pitch Smart guidelines. While there were no significant differences in ROM or strength, the noncompliant group had higher maximum pitch velocity than the compliant group (74 ± 8 vs 69 ± 5 mph [119 ± 13 vs 111 ± 8 kph], respectively; P = .009). Players' self-reported velocity differed significantly from the direct measurement, for both peak velocity (80 ± 6 vs 73 ± 8 mph [129 ± 9 vs 117 ± 13 kph], respectively; P < .001) and mean velocity (73 ± 8 vs 53 ± 27 mph [117 ± 13 vs 85 ± 43 kph], respectively; P < .001).

Conclusion

Most high school pitchers were not fully compliant with current Pitch Smart guidelines, and they tended to overestimate their peak velocity by 7 mph (11 kph). Pitchers who threw with greater velocity were at higher risk for violating Pitch Smart recommendations.

Measuring the Average Peak Timing of Kinematic Variables in Youth and Adolescent Baseball Pitchers

Background

Previous studies have examined the timing of peak kinematic variables during the pitching cycle in high school, collegiate, and professional pitchers. These same variables have been studied less in younger populations.

Purpose

To determine whether youth and adolescent baseball pitchers will experience peaks in certain kinematic variables at different times throughout the pitching cycle compared to professional/collegiate pitchers.

Study Design

Cross-sectional, descriptive study.

Methods

Twenty-four participants were recruited for testing consisting of five recorded pitches using 3-Dimensional VICON® motion analysis system. The maximum values and timing of the peak kinematic variables were averaged across all trials using VICON Polygon® data analysis software. These values were recorded as percentages of the pitching cycle, defined from foot contact (0%) to ball release (100%). The following variables were examined: shoulder external rotation range of motion, shoulder internal rotation velocity, trunk rotation range of motion, trunk rotation velocity, pelvic rotation velocity, and stride length. Descriptive outcomes were calculated and results were compared to previous studies examining the same variables in collegiate and professional pitchers.

Results

Twenty-four male participants (mean age 12.75 years, SD ± 2.02) were included in the study. Mean and standard deviations were identified for peak kinematic variables of shoulder external rotation ROM (158.71°, ±9.32), shoulder internal rotation velocity (92.26 rad/sec, ±19.29), trunk rotation velocity (15.94 rad/sec, ±1.68), trunk rotation ROM (23.57°, ±8.14), and average stride length (81.97% height ±4.57). Additionally, mean and standard deviations of peak kinematic variables were expressed as percentages to reflect when they occurred in the pitching cycle and included trunk rotation ROM (8.45%, ±12.72), pelvic rotation velocity (33.26%, ±16.42), trunk rotation velocity (41.59%, ±9.27), shoulder external rotation ROM (71.34%, ±6.61), and shoulder internal rotation velocity (86.93%, ±6.45).

Conclusion

The sequential order of each variable was similar in youth and adolescents in comparison to collegiate and professional pitchers. However, the timing of each variable within the pitching cycle occurred approximately 10% earlier in the younger pitchers. The findings suggest differences in pitching mechanics exist between younger and more experienced populations.

Level of Evidence

Level 3.

Effects of Repetitive Pitching on Trunk Muscle Endurance and Thoracic and Shoulder Kinematics

Background

Baseball players are aware of the potential of shoulder problems due to repetitive throwing. However, few studies have examined how pitching repeatedly affects the thoracic spine and shoulder.

Purpose

This study aimed to determine the effects of pitching repeatedly on the endurance of trunk muscles and kinematics of the thoracic spine and shoulder.

Study design

Cohort study.

Methods

Trunk muscle endurance was assessed in flexion, extension, and lateral flexion positions in 12 healthy amateur baseball players. The positions of stride foot contact (SFC) during the early cocking phase and maximal shoulder external rotation (MER) during the late cocking phase were used to compute the thoracic and shoulder kinematics in degrees. Participants were then asked to throw 135 fastballs (~9 innings with 15 throws per inning). Throwing motions were monitored throughout the first, seventh, eighth, and nine innings, whereas trunk muscular endurance was assessed before and after the repetitive throwing activity. Ball speed during pitching was measured using a radar gun. All outcome measures were statistically compared to examine differences over time.

Results

The trunk muscle endurance declined after the throwing task. In the eighth inning, compared with the first inning, the thoracic rotation angle at the SFC increased toward the throwing side. In contrast, the shoulder horizontal adduction angle at MER decreased in the seventh and ninth innings.

Conclusion

With repeated pitching, trunk muscle endurance gradually declines, and repetitive throwing significantly altered kinematics of the thoracic rotation at SFC and shoulder horizontal plane at MER.

Level of Evidence

2a.

Hidden Pitches in Major League Baseball: What Are the Injury Implications of These Often Overlooked Pitches?

Background

Pitch counts are tightly monitored in Major League Baseball (MLB). Hidden pitches-including warm-up pitches before and between innings and pitches before the starting/relieving pitcher's appearance in a game-are not as closely monitored.

Purpose/Hypothesis

To report the number of hidden pitches thrown per game and over the course of a season for a single organization. We hypothesized that players who threw more hidden pitches would be at an increased risk of injury compared with those who threw fewer hidden pitches.

Study Design

Case-control study; Level of evidence, 3.

Methods

All pitchers who played for a single MLB organization in the 2021 season were included. Hidden pitches, in-game pitches, and total pitches thrown during all games in the season were recorded. Injuries to these pitchers were also recorded. Players were defined as having an injury if they spent any time on the injured list.

Results

Overall, 137 pitchers were included, 66 (48%) of whom sustained an injury and were placed on the IL during the 2021 season (mean time on IL, 53.6 ± 45.6 days). Of the 66 players who sustained an injury, 18 (27.3%) sustained an elbow injury, while 12 (18.2%) sustained a shoulder injury. Only 1 player sustained an ulnar collateral ligament tear. When comparing hidden pitches, in-game pitches, and total pitches between pitchers who sustained an injury and those who did not, there were no significant differences between groups (P = .150; P = .830; and P = .377, respectively). On average, hidden pitches made up 45.4% of the total number of pitches thrown during the course of the season. When evaluating the number of hidden pitches as a percentage of the total number of pitches thrown in a season, there was no significant difference between pitchers who sustained an injury and those who did not (P = .654).

Conclusion

MLB pitchers who sustained an injury did not throw more hidden pitches than those who did not sustain an injury. Larger scale studies are needed to confirm the results of this single-team study.

Effect of High School Showcase Exposures and Timing of Ulnar Collateral Ligament Tear on Professional Baseball Careers in Elite Pitchers

BACKGROUND

Showcase participation has been considered a risk factor for elbow injuries. It remains unclear whether high school (HS) showcase volume negatively affects pitchers' career paths. Because pitchers are achieving 90 mph thresholds at younger ages, it is unknown whether shorter time intervals between achieving 90 mph thresholds and dates of ulnar collateral ligament reconstruction (UCL-R), known as time to tear (TTT), may affect career trajectory.

HYPOTHESIS

Elite pitchers with higher HS showcase volumes would be less likely to reach Major League Baseball (MLB) level compared with elite pitchers with fewer HS showcase appearances. Elite pitchers with longer TTT intervals would be more likely to achieve MLB level.

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

Demographic, HS showcase and professional performance, and injury data from pitchers selected in the first 5 rounds of the MLB draft (2011-2017) were gathered from publicly available databases. Continuous and categorical variables were compared for the following subgroups: UCL-R group and pitcher group not undergoing UCL-R; "early" and "late" UCL-R groups; and pitchers achieving and pitchers not achieving MLB level. Multivariable analysis was performed using logistic regression. Standard deviations of ±1 SD were used to define early career versus late career UCL-R subgroups after normal distribution was confirmed (Shapiro-Wilk test; P = .227). The early UCL-R group was defined as those pitchers undergoing UCL-R ≤-1 SD from the mean age at first injury (group mean age, 19.43 years), whereas the late UCL-R group was defined as ≥+1 SD from that age (group mean age, 25.19 years).

RESULTS

Of 611 pitchers, 455 (74.5%) had HS showcase performance data, and 608 (99.5%) had professional performance data. In total, 184 (30.1%) pitchers underwent UCL-R. Fewer pitchers who underwent early UCL-R achieved the MLB level compared with pitchers who underwent late UCL-R (48.1% vs 86.2%; P = .006). Elite pitchers who pitched in ≥10 showcases in HS had half the odds of achieving the MLB level compared with pitchers who participated in <10 HS showcases (adjusted odds ratio, 0.50; 95% CI, 0.29-0.86; P = .012). For every year longer that an elite pitcher did not tear his UCL after achieving the 90 mph threshold at an HS showcase (TTT after 90 mph [per year]), the likelihood of achieving the MLB level increased by 24% (adjusted odds ratio, 1.24; 95% CI, 1.02-1.52; P = .032).

CONCLUSION

Higher HS showcase volume in elite pitchers was associated with a lower likelihood of achieving MLB level. A longer TTT after 90 mph (per year) was significantly associated with achieving MLB level in elite pitchers.

Ulnar Collateral Ligament Tears: A Modified Consensus Statement

PURPOSE

The purpose of this study was to establish consensus statements on the treatment of UCL injuries and to investigate whether consensus on these distinct topics could be reached.

METHODS

A modified consensus technique was conducted among twenty-six elbow surgeons and 3 physical therapists/athletic trainers. Strong consensus was defined as 90-99% agreement.

RESULTS

Of the 19 total questions and consensus statements 4 achieved unanimous consensus, 13 achieved strong consensus, and 2 did not achieve consensus.

CONCLUSION

There was unanimous agreement that the risk factors include overuse, high velocity, poor mechanics, and prior injury. There was unanimous agreement that advanced imaging in the form of either an MRI or MRA should be performed in a patient presenting with suspected/known UCL tear that plans to continue to play an overhead sport, or if the imaging study could change the management of the patient. There was unanimous agreement regarding lack of evidence for the use of orthobiologics in the treatment of UCL tears as well as the areas pitchers should focus on when attempting a course of non-operative management. The statements that reached unanimous agreement for operative management were regarding operative indications and contraindications for UCL tears, prognostic factors that should be taken into consideration in when performing UCL surgery, how to deal with the flexor-pronator mass during UCL surgery and use of an internal brace with UCL repairs. Statements that reached unanimous agreement for RTS were regarding: portions of the physical exam should be considered when determining whether to allow a player to RTS, unclear how velocity, accuracy, and spin rate should be factored into the decision of when players can RTS and sports psychology testing should be used to determine whether a player is ready to RTS.

LEVEL OF EVIDENCE

Expert opinion (Level V).

Comparison of Trunk and Pelvic Kinematics in Youth Baseball Pitchers With and Without Upper Extremity Pain: A Cross-Sectional Study

Background

Motion of the pelvis and trunk during baseball pitching is associated with increased upper extremity (UE) kinetics. Increased kinetics on the UE may lead to throwing-arm pain in youth pitchers. Limited biomechanical comparisons have been conducted on youth pitchers with and without throwing-arm pain to identify mechanical risk factors associated with pain.

Purpose

To examine trunk and pelvic kinematics in youth baseball pitchers with and without UE pain.

Study Design

Cross-sectional study; Level of evidence, 3.

Methods

A total of 26 male youth baseball pitchers (mean age, 12.7 ± 1.5 years; mean height, 162.2 ± 12.9 cm; mean weight, 52.6 ± 13.1 kg) were recruited to participate. An electromagnetic tracking system was used to obtain kinematic data during the fastball pitch. Data from a health history questionnaire was examined. Participants who answered "yes" to experiencing pain and who selected a region on their UE as the pain location were placed into the UE pain group. Participants who responded "no" to experiencing pain were placed into the pain-free group. We compared between-group differences in trunk rotation, flexion, and lateral flexion; pelvic rotation, anteroposterior tilt, and lateral tilt; and hip-shoulder separation from peak knee height to ball release of the baseball pitch using 1-dimensional statistical parametric mapping with an alpha level set at .05.

Results

No statistically significant differences were observed between the UE pain and pain-free groups in the 7 trunk and pelvic kinematics analyzed from peak knee height to ball release (P > .05).

Conclusion

Trunk and pelvic kinematics during the pitching motion did not differ between pain and pain-free groups of youth baseball pitchers.

Increased Pitch Velocity Is Associated With Throwing Arm Kinetics, Injury Risk, and Ulnar Collateral Ligament Reconstruction in Adolescent, Collegiate, and Professional Baseball Pitchers: A Qualitative Systematic Review

PURPOSE

To assess the relationship between pitch velocity and throwing arm kinetics, injury, and ulnar collateral ligament reconstruction (UCLr) among high school, collegiate, and professional baseball pitchers.

METHODS

The Cochrane Database of Systematic Reviews, the Cochrane Central Register of Controlled Trials, PubMed (2008-2019), and OVID/MEDLINE (2008-2019) were queried for articles that reported on pitch velocity predicting throwing arm kinetics, injury, or UCLr. The Methodological Index for Non-randomized Studies checklist was used to evaluate the quality of all included studies. Descriptive statistics with ranges were used to quantify data where appropriate.

RESULTS

A total of 24 studies examining 2,896 pitchers, with Level of Evidence II-V were included. Intergroup analysis noted pitch velocity was significantly correlated with elbow varus torque in high school (R² = 0.36), collegiate (R² = 0.29), and professional (R² = 0.076) pitchers. Elbow distraction force was positively associated with ball velocity in interpitcher analyses of high school (R² = 0.373), professional (R² = 0.175), and mixed-cohort evaluations (R² = 0.624). Intragroup analysis demonstrated a strong association between pitch velocity and elbow varus torque (R² = 0.922-0.957) and elbow distraction force (R² = 0.910) in professional pitchers. Faster ball velocity was positively associated with a history of throwing arm injury (R² = 0.194) in nonadult pitchers. In 2 studies evaluating professionals, injured pitchers had faster pitch velocity before injury compared with uninjured controls (P = .014; P = .0354). The need for UCLr was positively correlated with pitch velocity (R² = 0.036) in professional pitchers. The consequences of UCLr noted little to no decrease in pitch velocity.

CONCLUSIONS

Professional baseball pitchers with faster pitch velocity may be at the greatest risk of elbow injury and subsequent UCLr, potentially through the mechanism of increased distractive forces on the medial elbow complex. When a pitcher ultimately undergoes UCLr, decreases in pitching performance are unlikely, but may occur, which should encourage pitchers to caution against maximizing pitch velocity.

LEVEL OF EVIDENCE

Level IV, systematic review of Level II-IV studies.

Biomechanical comparison of novel ulnar collateral ligament reconstruction with internal brace augmentation vs. modified docking technique

BACKGROUND

Ulnar collateral ligament (UCL) reconstruction (UCLR) is a common surgery among baseball pitchers. UCL repair combined with augmentation using high-strength tape, referred to as an internal brace, was developed as an alternative to UCLR in select patients with the benefit of allowing these athletes to return to sport (RTS) faster. A combined UCLR with an internal brace may allow players indicated for a UCLR to RTS more expeditiously.

METHODS

Twenty-four cadaveric elbows were divided into 3 groups: 12 specimens into the modified docking (MD) group, 6 into the double-docking (DD) group, and 6 into the double docking with internal brace augmentation (DDA) group. This allowed a 1:1 comparison of the MD to the DD and the MD to the DDA. Valgus cyclic testing of native and reconstructed specimens was executed at 90° elbow flexion. After preconditioning, all specimens were cycled between 2 and 10 Nm for 250 cycles. Reconstructed specimens continued to a torque test to catastrophic failure step. Outcome data included intracyclic stiffness, maximum cyclic rotational displacement, gap formation, and failure torque.

RESULTS

Cyclic stiffness of the constructs remained constant throughout the entirety of the torque-controlled cycling phase. The DDA group resulted in a 38% increase in cyclic stiffness from native testing (not statistically significant) and a statistically significant 54% increase from the MD (P = .002). The DDA mean cyclic stiffness was significantly greater than the Native (P < .001), DD (P = .025), and MD (P < .001) groups. Between reconstruction groups, mean gap formation was greatest among the MD group (2.51° ± 1.59°) and least for the DDA group (1.01° ± 0.57°) but did not reach statistical significance.

CONCLUSION

Tape augmentation to the modified UCLR (DDA group) improved cyclic stiffness and reduced gap formation compared with the MD group.

Athletes Perceive Weighted Baseballs to Carry a Notable Injury Risk, yet Still Use Them Frequently: A Multicenter Survey Study

Weighted baseball use in throwing programs is widespread; however, their use remains controversial. Prior research shows that weighted baseball programs can increase ball velocity but potentially increase throwing arm injuries. This study aims to ascertain perceptions of weighted baseballs among elite baseball players.

Ulnar Collateral Ligament Tear in Elite Baseball Pitchers: Are High School Showcase Exposures Associated With Injury?

BACKGROUND

Ulnar collateral ligament reconstruction (UCLR) surgeries have increased significantly in amateur and professional baseball pitchers. Although showcase participation has been considered an injury risk factor, limited data are available to corroborate this association.

HYPOTHESIS

Elite pitchers achieving fastball velocities ≥90, ≥92, and ≥95 mph at younger ages would be more likely to undergo UCLR earlier in their careers compared with pitchers not achieving these velocity thresholds at younger ages. Elite pitchers participating in high showcase volumes would be more likely to undergo UCLR compared with elite pitchers participating in fewer showcases.

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

Descriptive, showcase performance, and injury data from pitchers selected in the first 5 rounds of the Major League Baseball draft (2011-2020) were gathered from publicly available databases. Continuous and categorical variables for pitchers undergoing UCLR and those not undergoing UCLR were compared, and multivariable analysis was performed using logistic regression. We used standard deviations (SDs) of ±1 SD of mean age at first UCLR to define early-career versus late-career UCLR subgroups after normal distribution was confirmed (Shapiro-Wilk test; P = .183). The "early" UCLR group was defined as ≤-1 SD (19.09 years), whereas the "late" UCLR group was defined as ≥+1 SD (24.79 years). Trends in time were evaluated using linear regression.

RESULTS

Of the 845 pitchers selected, 659 pitchers (78.0%) had retrievable showcase performance data. Of the 845 pitchers, 229 (27.1%) underwent UCLR. Peak fastball velocity recorded at showcases was the strongest predictor of UCLR (adjusted odds ratio, 1.19; 95% CI, 1.02 to 1.39; P = .03). Peak fastball velocity in high school (HS) was significantly higher among pitchers who underwent UCLR compared with pitchers in the no-UCLR group (91.57 vs 90.71 mph, respectively; 95% CI, -1.43 to -0.29; P < .01). Age at which pitchers participated in their first HS showcase was significantly younger for the early versus the late UCLR group (15.53 vs 16.51 years, respectively; 95% CI, -1.53 to -0.41; P < .01). Elite pitchers with early UCLR participated in nearly twice as many showcases compared with the late UCLR group (5.38 vs 2.89, respectively; 95% CI, 0.43 to 4.54; P = .02). The mean number of HS showcases that elite pitchers attended more than doubled during the 2011-2020 study period (from 2.88 to 6.00 total showcases; P < .001). Mean age at which pitchers attended their first HS showcase steadily declined as well over the 10-year period (from 16.52 to 15.63 years; P < .001).

CONCLUSION

Peak fastball velocity was the strongest predictor of UCLR in elite pitchers before initiating professional careers. Elite amateur pitchers attended more showcases at younger ages in a decade-long trend. Overall, the variables included in this multivariable analysis were weak predictors, explaining only 3.8% of the variance in UCLR rates.

Glenohumeral Internal Rotation Deficit in the Adolescent Overhead Athlete: A Systematic Review and Meta-Analysis

OBJECTIVE

The objective of this review was to investigate the average glenohumeral internal rotation deficit (GIRD) in the dominant arm of adolescent overhead athletes and to examine the association with shoulder and elbow injuries.

DESIGN

Systematic review and meta-analysis.

SETTING

MEDLINE, Embase, and PubMed were searched from inception to August 1, 2020.

PARTICIPANTS

Adolescent overhead athletes with glenohumeral range of motion (ROM) measurements.

INTERVENTIONS

Nonoperative treatments of GIRD.

MAIN OUTCOME MEASURES

Glenohumeral ROM measurements comparing the dominant and nondominant extremities were pooled in a meta-analysis.

RESULTS

Twenty-five studies were included in this review, which involved 2522 overhead athletes. Pooled internal rotation (IR) deficit of the dominant arm was 9.60° (95% confidence interval [CI] 7.87°-11.32°, P < 0.00001), with an external rotation (ER) gain of 6.78° (95% CI 4.97°-8.59°, P < 0.00001) and a total ROM (TROM) deficit of 1.78° (95% CI -0.70° to 4.26°, P = 0.16). The association between GIRD and shoulder or elbow injury was not clearly defined. Two studies reported treatment, and both used nonoperative treatment in the form of physiotherapy and sleeper stretches.

CONCLUSIONS

The adolescent overhead athlete has roughly 10° of IR deficit in their dominant arm, accompanied by nearly 7° of ER gain, with similar ROM measurements for injured and uninjured athletes. Those with pathological GIRD have a greater degree of IR deficit, but without an accompanying compensatory increase in ER, leading to a TROM deficit of nearly 15°. Surgical treatment in the absence of other indications is rare, whereas physiotherapy and sleeper stretches remain the first-line treatment.

A Comparison of Pitching Biomechanics and Sport Specialization in High School Pitchers

Background

The prevalence of sport specialization in high school athletes continues to rise, particularly among baseball players. Previous research has focused on the incidence of injury among specialized and non-specialized athletes but has yet to examine the level of sport specialization and pitching biomechanics.

Hypotheses/Purpose

The purpose of this study was to investigate differences in pitching volume and biomechanics between low-, moderate-, and high-level specialized baseball pitchers. It was hypothesized that high-level specialized pitchers would have the most pitching volume within the current and previous years while low-level specialized pitchers would exhibit the least amount. The second hypothesis states that kinematics and kinetics commonly associated with performance and injury risk would differ between low-, moderate-, and high-level specialized pitchers.

Study Design

Case-Control Study.

Methods

Thirty-six high school baseball pitchers completed a custom sport specialization questionnaire before participating in a three-dimensional pitching motion analysis. Sport specialization was based off current guidelines and categorized as low-, moderate-, and high-level specialized based upon self-reported outcomes. Pitchers then threw ≈10 fastballs from a mound engineered to professional specifications. Data averaged across fastballs was used for biomechanics variables. Key pitching biomechanical and pitching volume variables were compared between low-, moderate-, and high-level specialized pitchers.

Results

High-level specialized pitchers were older (p = 0.003), had larger body mass (p = 0.05) and BMI (p = 0.045), and threw faster (p = 0.01) compared to low-level specialized pitchers. Pitching volume and pitching biomechanics were similar across groups.

Conclusions

Pitching biomechanics were similar across groups, although high-level specialized pitchers threw with significantly higher throwing velocity compared to low-level pitchers. The low amount of pitching volume throughout the season may be responsible for the lack of additional observed differences. Further research should examine the relationship between pitching biomechanics, upper extremity strength and flexibility, and sport specialization.

Level of Evidence

Level III.

An Investigation of Bilateral Symmetry in Softball Pitchers According to Body Composition

Introduction

High body fat percentage (bf%) is considered a potential injury risk factor for softball pitchers amidst the already high rates of pitching-related injury. Similarly, research points out that large bilateral asymmetries are another risk factor for softball pitchers. As softball pitching is a highly asymmetric sport and the repetitive nature of the windmill pitch places high stress on the body while pitchers are in unbalanced and asymmetric positions, research examining body composition and asymmetry is necessary.

Purpose

The purpose of this study was to compare functional characteristics of softball pitchers with a healthy and a high bf%. Bilateral symmetry was assessed for pitchers' hip and shoulder isometric strength (ISO) and range of motion (ROM) between the following two groups of softball pitchers: (1) those with a high bf% (≥32%) and (2) those with a healthy bf% (<32%).

Methods

A total of 41 high school female softball pitchers from the southern United States agreed to participate (1.69 ± 0.07 m, 76.14 ± 17.08 kg, 15.1 ± 1.1 years). Pitchers completed a dual-energy X-ray absorptiometry (DEXA) scan and were grouped into one of the following two categories based on their bf%: healthy (<32 bf%) and high (≥32 bf%). Bilateral symmetry was assessed for pitchers' hip and shoulder ISO and ROM using a handheld dynamometer and inclinometer, respectively. Bilateral arm bone and lean mass was also measured via the DEXA.

Results

Mixed analyses of variance revealed a significant interaction between bf% groups and side dominance for internal rotation shoulder ROM, F_{(1, 39)} = 14.383, p < 0.001, η²_p = 0.269. Main effects for side dominance were also observed for shoulder external rotation ISO, F_{(1, 39)} = 8.133, p = 0.007, η²_p = 0.173, hip internal rotation ISO, F_{(1, 39)} = 4.635, p = 0.038, η²_p = 0.106, arm bone mass, F_{(1, 39)} = 38.620, p < 0.001, η²_p = 0.498, and arm lean mass, F_{(1, 39)} = 101.869, p < 0.001, η²_p = 0.723.

Conclusion

Asymmetries and slight differences in functional characteristics exist between bf% groups. Altered functional characteristics may influence pitchers' windmill pitch movement and should be acknowledged by support staff to improve softball pitchers' health and longevity.

Implications

Insight into asymmetries can help researchers and clinicians understand the implication of excess body fat and further theorize mechanisms of injury among this athlete population.

Effect of Pitching Restrictions and Mound Distance on Youth Baseball Pitch Counts

Background:

Studies have shown that higher pitch counts are directly related to a greater incidence of elbow and shoulder pain among youth baseball pitchers.

Purpose/Hypothesis:

The purpose of this study was to examine the effect of different pitching restriction rules on the number of pitches thrown in youth baseball leagues. We hypothesized that more pitches would be thrown in leagues with inning restrictions versus leagues with pitch count restrictions as well as in leagues with a longer mound distance (from pitching mound to home plate).

Study Design:

Cohort study; Level of evidence, 2.

Methods:

Pitch count data were collected for 2 consecutive years over a 10-week season from 3 different leagues of 9- to 12-year-old baseball players in a single city. The Eastern league had a pitch count restriction and 46-ft (14.02-m) mound distance. The Southeastern and South leagues’ pitching restrictions were based on innings per week. The Southeastern league had a 50-ft (15.24-m) mound distance, while the South league had a 46-ft mound distance. Comparisons of total seasonal pitches thrown were made of the 3 highest-volume pitchers on each team. League averages for each value were then compared utilizing analysis of variance with Bonferroni post hoc analysis. The number of pitchers in each league who threw >600 pitches per season was compared using the chi-square test.

Results:

No significant difference in seasonal pitch counts or innings pitched was noted between the Eastern and South leagues, which differed only in their pitching restrictions. The Southeastern league, with a longer mound distance, was found to have higher seasonal pitch counts per thrower (598 ± 195 pitches) than the South league (463 ± 198 pitches) for the 3 highest-volume throwers for each team (P = .004). The Southeastern league also had a significantly larger number of pitchers who threw >600 pitches per season (33 vs 20 for Eastern and 13 for South; P = .009).

Conclusion:

There was no significant difference in seasonal pitch counts when the leagues in this study differed based on pitching restrictions. However, the league with a greater mound distance (Southeastern) had higher seasonal pitch counts for the highest-volume throwers. Pitching restrictions based on pitch counts, as opposed to innings, may be advisable.

Athlete body composition influences movement during sporting tasks: an analysis of softball pitchers' joint angular velocities

Softball pitchers are often above-average size and frequently injured; therefore, it is necessary to understand how biomechanics can change according to pitcher body composition. The purpose of this study was to examine the relationship between joint peak angular velocities and pitch velocity, as well as examine how pitchers' joint angular velocities differ between high and healthy body-fat percentage (BF%) groups. Forty high-school and college softball pitchers (170.6 ± 6.3 cm, 75.5 ± 16.1 kg, 16 ± 2 years, 34.6 ± 7.4 BF%) completed body composition testing and were placed in one of two groups: 1) high-fat% (≥32%) or 2) healthy-fat% (<32%). Pitchers completed fastball trials. Kinematic data were tracked using an electromagnetic system synced with motion analysis software. Peak and times-series joint angular velocities were tracked over the final 101 frames of the pitch. Pitch velocity was significantly correlated with peak elbow flexion (r = .380, p = .016) and wrist flexion (r = .621, p < .001) angular velocity. A small difference in elbow joint angular velocity was found between body fat percentage groups between ball release and follow-through (SPM(t)1,38 = 3.296, p = .003). Peak joint angular velocities are related to pitch velocity and slight differences in movement patterns exist according to pitcher body fat percentage.

Pitching Behaviors in Youth Baseball: Comparison With the Pitch Smart Guidelines

Background

The Pitch Smart guidelines aim to limit youth baseball pitching behaviors associated with overuse injuries. Despite many youth baseball leagues being compliant with the guidelines, during tournaments, pitch count restrictions or guidelines are often not followed.

Purpose

To perform a quantitative analysis of pitch counts in youth baseball players and evaluate compliance with regard to the Pitch Smart guidelines in the tournament setting.

Study Design

Cross-sectional study; Level of evidence, 3.

Methods

Included in the analysis were 100 youth baseball teams that competed in the 8-and-under to 14-and-under age divisions during the 2019 tournament season. Pitching data were compared with the Pitch Smart guidelines. Violations were identified as (1) exceeding maximum daily pitch count, (2) inadequate rest between pitching events, and (3) pitching more than 1 event on the same day. Pitcher and game factors were analyzed for possible relationships to guideline violations using mixed-effects negative binomial regression models, with comparisons of violations using rate ratios (RRs).

Results

Analysis included 1046 pitchers and 2439 games. There were 1866 total Pitch Smart guideline violations, with 48.6% of pitchers having at least 1 violation. Inadequate rest was the most common reason for violation, with noncompliance occurring in 43.3% of pitchers. The highest rate of any violation (0.32 per appearance) occurred in the 8-and-under age division. High-volume pitchers had increased violation rates in each category compared with low-volume pitchers (P < .001). Violation rates were increased more than twice the rate when pitchers participated in ≥5 consecutive games without a rest day when compared with a single game (RR, 2.48; P < .001).

Conclusion

Noncompliance with Pitch Smart guidelines in tournament settings occurred in more than 90% of teams and almost half of all pitchers. Factors associated with noncompliance included younger pitcher age, high-volume pitching, and pitching in multiple consecutive games. Education of tournament directors, coaches, parents, and athletes regarding pitching guidelines is warranted in order to limit the risk of injury.

Risk Factors for Throwing-Related Shoulder and Elbow Pain in Adolescent Baseball Players: A Prospective Study of Physical and Developmental Factors

Background:

Throwing-related shoulder and elbow pain continues to be reported among adolescent baseball players. Few prospective studies have specifically examined the association between throwing-related shoulder and elbow pain and physical and developmental changes.

Purpose:

To evaluate the changes in physical and developmental characteristics during 1 year with respect to throwing-related shoulder and elbow pain in adolescent baseball players.

Study Design:

Case-control study; Level of evidence, 3.

Methods:

This 1-year prospective follow-up study investigated 164 baseball players aged 7 to 13 years. Player data (age, height, weight, field position, and pitch count), lower extremity muscle tightness, and range of motion (ROM) of the shoulder, elbow, and hip joints were assessed during the 2016 and 2017 preseason medical examinations. After the 2016 season, the participants completed questionnaires related to throwing-related shoulder and elbow pain, defined as an inability to play for ≥1 week because of elbow or shoulder difficulties. For study participants with and without throwing-related shoulder or elbow pain during the 2016 season, we conducted univariate and multivariate logistic regression analysis to identify risk factors for throwing-related shoulder or elbow pain.

Results:

Overall, 21 players (12.8%) reported a shoulder pain episode, 56 players (34.1%) had an elbow pain episode, and 70 players (42.7%) reported having experienced shoulder and/or elbow pain during the 2016 season. In multivariate logistic regression analysis, (1) shoulder pain was associated with 2016 preseason height (odds ratio [OR], 1.06; 95% CI, 1.01-1.11; P = .01) and change in dominant-side elbow extension ROM from 2016 to 2017 (OR, 1.12; 95% CI, 1.02-1.24; P = .02); (2) elbow pain was associated with change in weight from 2016 to 2017 (OR, 1.21; 95% CI, 1.04-1.41; P = .014); and (3) throwing-related shoulder and/or elbow pain was associated with greater 2016 preseason height (OR, 1.04; 95% CI, 1.003-1.68; P = .03) and an increase in height from 2016 to 2017 (OR, 1.17; 95% CI, 1.01-1.35; P = .03).

Conclusion:

Our results indicated that adolescent baseball players who were taller in the preseason and those with an increase in height over the 1-year study period faced significant risks for developing throwing-related shoulder and/or elbow pain.

Increased Upper Arm Length and Loading Rate Identified as Potential Risk Factors for Injury in Youth Baseball Pitchers

BACKGROUND

In the throwing elbow, increased elbow torque has been correlated with increased injury risk. Additional insight into the relationships between anthropometric factors and elbow joint loading is warranted.

PURPOSE

To investigate the relationship among physical limb length characteristics, elbow kinetics, and elbow kinematics in youth baseball pitchers and to examine the relationship between elbow varus loading rate and elbow kinetics.

DESIGN

Descriptive laboratory study.

METHODS

A total of 27 male youth baseball pitchers participated (mean ± SD: age, 15.8 ± 2.7 years; height, 176.3 ± 13.0 cm; weight, 71.7 ± 16.4 kg). Upper arm (UA) and forearm (FA) lengths were measured using a moveable sensor to digitize bony landmarks. Kinematic data were collected at 240 Hz using an electromagnetic tracking system. Participants threw 3 fastballs to a catcher at a regulation distance (60 ft 6 in), and the fastest velocity trial was used for analysis. Linear regression was used to determine the relationship among limb length characteristics, elbow kinetics, and elbow kinematics after accounting for the effects of body weight and height.

RESULTS

Pitchers with longer UA length experienced increased maximum elbow varus torque (P = .005) and maximum net elbow force (P = .001). Pitchers with an increased forearm to UA ratio had decreased elbow compression force (P < .001) and exhibited a more flexed elbow at foot contact (P = .001). Pitchers with greater maximum loading rates experienced greater elbow varus torque (P = .002).

CONCLUSION

In youth baseball pitchers, longer UA length and greater loading rate increase varus torque about the elbow during a fastball pitch.

CLINICAL RELEVANCE

Longer UA length and greater loading rate may place pitchers at risk of injury because of their relationship with kinetic values.

The association of sport participation behaviors with throwing-arm health in Little League Baseball pitchers

Background and Hypothesis

There is increasing concern about the role sport specialization might play in the increasing injury rates observed among youth baseball pitchers. However, existing research on specialization in baseball has focused on high school and professional baseball populations. We hypothesized that pitchers who were highly specialized, reported pitching more than eight months in the past year, received private coaching, or pitched with pain or fatigue in the previous year would report worse throwing-arm health.

Methods

One-hundred eighty-four Little League pitchers (boys N = 181, age 9.8 ± 1.6 years old) between 7 and 12 years of age completed an anonymous, online questionnaire with their parents' assistance. The questionnaire consisted of participant demographics, sport specialization status, months of pitching per year, whether they traveled regularly to participate in showcases, if they received private coaching, whether they pitched with elbow or shoulder pain, whether they pitched with fatigue, and the Youth Throwing Score (YTS), a valid and reliable patient-reported outcome measure for youth baseball players. The associations between variables of interest and YTS were examined using multivariable linear regression, adjusting for covariates.

Results

Sport specialization, pitching year-round, and receiving private coaching were not associated with the YTS (P > .05). Pitching with pain in the previous year was associated with a worse YTS score than pitching without pain (least square mean [standard error]: 49.6 [1.8] vs. 57.8 [1.1], P < .001). Similarly, pitching with fatigue in the previous year was associated with worse YTS scores (least square mean [standard error]: 52.1 [1.4] vs. 55.3 [1.3], P = .01). Pitchers who reported traveling regularly for showcases scored worse on the YTS compared with those who did not travel regularly for showcase events (least square mean [standard error]: 51.0 [2.0] vs. 56.4 [0.9], P = .01).

Conclusions

Pitching with pain or fatigue was associated with worse throwing-arm health in Little League baseball pitchers. While traveling at least once a month to participate in showcases was also associated with worse throwing-arm health, specialization and private coaching were not related to worse throwing health. Clinicians working with pediatric patient populations should be aware that while the factors examined in this article were reported relatively infrequently, screening for Little League pitchers who participate in showcases or pitch with pain or fatigue may be an effective strategy for identifying these individuals who are at higher risk of injury.

Comparison of Biomechanical Factors Before and After UCL Surgery in Baseball Athletes: A Systematic Review With Meta-analysis

BACKGROUND

Ulnar collateral ligament (UCL) reconstruction (UCLR) and repair (UCLr) are the gold standards in the treatment of UCL injuries. Although return-to-play timelines after UCLR have been established, pitching biomechanical variables are speculated to change after surgical intervention.

PURPOSE/HYPOTHESIS

To synthesize the literature and investigate changes in pitching biomechanics in baseball pitchers after UCLR or UCLr. We hypothesized that differences in pitching biomechanics would be observed for both intra- and interpatient comparisons.

STUDY DESIGN

Systematic review; Level of evidence, 3.

METHODS

We searched 4 electronic databases (PubMed, Web of Science, SCOPUS, and Sports Medicine & Education Index) from inception to February 2020. Data extracted included author and year of publication, study design, sample size, study population, and primary outcome variables. Meta-analysis was performed to produce random pooled effect sizes (▵).

RESULTS

We identified 1010 original articles for inclusion. A total of 5 studies were included in the systematic review; of these, 3 studies were included in the meta-analysis. No differences were found in shoulder range of motion (ROM) between post-UCLR and control pitchers (dominant arm external rotation ▵, 0.13°; 95% CI, -0.15° to 4.02°; P = .36); dominant arm internal rotation ▵, -0.20°; 95% CI, -0.74° to 0.35°; P = .48). Mean fastball velocity as well as pitches thrown decreased after UCLR in professional pitchers. Significant differences in elbow extension, elbow extension velocity, and shoulder internal rotation velocity were found among amateur pitchers.

CONCLUSION

The results of this systematic review and meta-analysis show that limited differences exist in pitchers before and after UCLR as well as in post-UCLR pitchers and healthy, age-matched controls. UCLR may influence throwing velocity, but it had no effect on either the throwing biomechanics or theROM of baseball pitchers. Although trends appear to be forming, further evidence is needed to understand the effect of UCLR on throwing biomechanics.

The ulnar collateral ligament responds to stress in professional pitchers

BACKGROUND

Our purpose with this study was to determine the response of the ulnar collateral ligament (UCL) in professional pitchers after exposure to a season of pitching and to rest during an off-season.

METHODS

In a prospective study supported by Major League Baseball, all pitchers within a single professional baseball club were enrolled. An ultrasound of the ligament was then performed by a single fellowship-trained ultrasonographer at the beginning of the season (T1), the end of the season (T2), and the beginning of the following season (T3). We measured the UCL thickness and ulnotrochlear joint opening at 30° of flexion with and without stress. Two ultrasound images were saved. Inter- and intra-rater reliability were determined. A multivariable analysis was conducted.

RESULTS

A total of185 total pitchers were included: 94 pitchers at T1, 83 at T2, and 118 at T3. These pitchers had 12 [7, 15] (median [interquartile range]) years of pitching experience and had a peak velocity of 95 [93, 97] miles/hour. Intra- and inter-rater reliability were excellent. The baseline UCL thickness was associated with peak velocity (P = .031) and prior UCL reconstruction (P = .024). After accounting for pitching experience, peak velocity, and prior UCL reconstruction, thickness increased during the season (P = .002) and decreased during the off-season (P = .001). After accounting for these same variables, valgus laxity at 30° increased during the season (P = .002) and decreased during the off-season (P = .029).

CONCLUSION

The UCL responds to stress in professional pitchers by becoming thicker and more lax, and responds to rest by becoming thinner and less lax.

Prevalence and Consequences of Sport Specialization Among Little League Baseball Players

BACKGROUND

Baseball is one of the most popular boy's youth sports, and there has been a rise in the rates of certain overuse injuries among players. Specialization has been identified as a risk factor for overuse injury in high school athlete populations, but there is little understanding of the prevalence or consequences of sport specialization in Little League baseball players.

HYPOTHESIS

Sport specialization will be highly prevalent among Little League baseball players and specialization will be associated with worse throwing arm health.

STUDY DESIGN

Cross-sectional study.

LEVEL OF EVIDENCE

Level 3.

METHODS

A total of 246 Little League baseball players (male; N = 241; age, 9.5 ± 1.6 years) between 7 and 12 years old completed an anonymous, online questionnaire with their parent's assistance. The questionnaire consisted of participant demographics and baseball participation information, including sport specialization status and the Youth Throwing Score (YTS), a valid and reliable patient-reported outcome measure for youth baseball players.

RESULTS

Only 29 (11.8%) players met the criteria for high specialization. Approximately one-third of all players (n = 77; 31.3%) reported participating in baseball year-round or receiving private coaching outside of their league (n = 81; 32.9%). Highly specialized athletes demonstrated worse scores on the YTS on average compared with low-specialization athletes (mean [SE]: 56.9 [1.6] vs 61.1 [1.2]; P = 0.01). Similarly, pitching in the previous year (P < 0.01) or traveling overnight regularly for showcases (P = 0.01) were associated with a worse score on the YTS.

CONCLUSION

While the prevalence of high sport specialization was low among Little League baseball players, other behaviors associated with specialization such as year-round play and the receiving of private coaching were more common. Highly specialized Little League players demonstrated worse throwing arm health compared with low-specialization players.

CLINICAL RELEVANCE

Little League players and their parents may represent a potential target audience for dissemination campaigns regarding sport specialization.

Grip strength is not related to increased medial elbow joint-space gapping induced by repetitive pitching

BACKGROUND

Pitching induces elbow valgus stress, which can lead to an increase in medial elbow joint-space gapping when repeated. Previous basic research on the medial elbow joint shows that the contraction associated with gripping reduces medial elbow joint-space gapping. However, no studies have investigated the relationship between grip strength and increased medial elbow joint-space gapping during repetitive pitching. The purpose of this study was to investigate whether grip strength is related to medial elbow joint-space gapping during repetitive pitching. Our hypothesis was that increased grip strength would correlate with a reduction in medial elbow joint-space gapping.

METHODS

A total of 25 high school baseball players participated in this study. Each subject pitched 100 times. The medial elbow joint-space gapping and grip strength were measured before and after pitching. Correlation analysis was used to identify the relationship between medial elbow joint-space gapping and grip strength.

RESULTS

Medial elbow joint-space gapping (mm) increased by 25.5% ± 8.0% after 100 pitches (gapping before, 5.0 ± 0.9; gapping after, 6.2 ± 1.1; P < .001). Grip strength (kg) after 100 pitches decreased by 2.8% ± 7.4% to that before pitching (before, 40.4 ± 5.5; after 39.2 ± 5.6; P < .05). There was no significant correlation between the change rate of medial elbow joint gapping and grip strength at any time (grip strength: before pitching, P = .74; after pitching, P = .40; change rate from before to after pitching, P = .24).

CONCLUSIONS

Grip strength is not related to increased medial elbow joint-space gapping induced by repetitive pitching. This indicates that physical ability expressed by grip strength is not associated with preventing increases in medial elbow joint-space gapping during repetitive pitching. Further studies are required to investigate the stabilization mechanism of the medial elbow joint during pitching.

Sport specialization is associated with upper-extremity overuse injury in high school baseball players

BACKGROUND AND HYPOTHESIS

Sport specialization is increasingly common in youth sports and is a risk factor for lower-extremity overuse injuries. However, limited data exist on whether specialization is associated with upper-extremity (UE) overuse injuries, specifically in youth baseball players. We hypothesized that specialization in baseball and being a pitcher would be associated with poorer arm health and UE overuse injury history in the previous year.

METHODS

During the 2019 spring baseball season, 551 high school baseball athletes (aged 15.9 ± 1.3 years) from 3 states (Alabama, n = 200; California, n = 188; and Michigan, n = 163) completed an anonymous questionnaire. Athletes were recruited from 5 high schools in each state, with schools matched based on factors that influence specialization rates. The questionnaire consisted of (1) demographic characteristics, (2) baseball participation information (including sport specialization status), and (3) throwing-arm health and UE injury history in the previous 12 months. Throwing-arm health was assessed using the Youth Throwing Score (YTS), a validated and reliable outcome measure for youth baseball players. Multivariate regression analyses were used to examine the association between variables of interest and the YTS or UE overuse injury history, adjusting for covariates.

RESULTS

After adjustment for covariates, highly specialized athletes were more likely to report a UE overuse injury in the previous year compared with low-specialization athletes (odds ratio [OR], 3.77; 95% confidence interval [CI], 1.39-10.2, P = .009). Both athletes who reported playing baseball for more than 8 months per year (OR, 2.03; 95% CI, 1.12-3.65; P = .019) and athletes who reported being a pitcher (OR, 2.11; 95% CI, 1.20-3.72; P = .010) were more likely to report a history of UE overuse injury. Highly specialized players reported lower (worse) YTS values compared with low-specialization players (least-squares mean estimate ± standard error, 56.5 ± 1.1 vs. 53.3 ± 0.7; P = .034). Players who reported pitching as one of their positions scored worse on the YTS than non-pitchers (least-squares mean estimate ± standard error, 51.6 ± 0.8 vs. 57.2 ± 0.6; P < .001).

CONCLUSION

Although baseball recommendations that discourage sport specialization are widely available for parents, athletes, and coaches, high rates of sport specialization were reported in our sample. We found that being highly specialized in baseball was associated with UE overuse injury history and worse throwing-arm health in high school baseball athletes. Continued education for baseball parents, athletes, and coaches is necessary to raise awareness of the risks associated with high specialization.

Youth Single-Sport Specialization in Professional Baseball Players

Background:

An increasing number of youth baseball athletes are specializing in playing baseball at younger ages.

Purpose:

The purpose of our study was to describe the age and prevalence of single-sport specialization in a cohort of current professional baseball athletes. In addition, we sought to understand the trends surrounding single-sport specialization in professional baseball players raised within and outside the United States (US).

Study Design:

Cross-sectional study; Level of evidence, 3.

Methods:

A survey was distributed to male professional baseball athletes via individual team athletic trainers. Athletes were asked if and at what age they had chosen to specialize in playing baseball at the exclusion of other sports, and data were then collected pertaining to this decision. We analyzed the rate and age of specialization, the reasons for specialization, and the athlete’s perception of injuries related to specialization.

Results:

A total of 1673 professional baseball athletes completed the survey, representing 26 of the 30 Major League Baseball (MLB) organizations. Less than half (44.5%) of professional athletes specialized in playing a single sport during their childhood/adolescence. Those who reported specializing in their youth did so at a mean age of 14.09 ± 2.79 years. MLB players who grew up outside the US specialized at a significantly earlier age than MLB players native to the US (12.30 ± 3.07 vs 14.89 ± 2.24 years, respectively; P < .001). Additionally, MLB players raised in the US recalled a significantly higher incidence of sustaining an injury attributed to specializing in baseball than MLB athletes raised outside the US (27.7% vs 20.6%, respectively; P = .05).

Conclusion:

This study challenges the current trends toward early youth sport specialization, finding that the majority of professional baseball athletes studied did not specialize as youth and that those who did specialize did so at a mean age of 14 years. With the potential cumulative effects of pitching and overhead throwing on an athlete’s arm, the trend identified in this study toward earlier specialization within baseball is concerning.

Injuries and associated risk factors of the shoulder and elbow among adolescent baseball pitchers: A systematic review and meta-analysis

OBJECTIVE

The purpose of this study was to perform a systematic review and meta-analysis of the current literature surrounding risk factors associated with shoulder and elbow injuries among adolescent baseball pitchers.

METHODS

Relevant studies were assessed for inclusion and retained from PubMed, EMBASE, SportDiscus, and CINAHL databases. Data was extracted from the retained studies and underwent methodological quality assessment and meta-analysis.

RESULTS

The search resulted in 1238 studies identified with 10 ultimately retained for systematic review. Five studies including one case-control, two prospective cohort, and two cross-sectional studies met inclusion criteria for meta-analysis. This meta-analysis revealed that playing with arm fatigue was a significant risk factor (pooled odds ratio = 13.32, 95% confidence interval: 3.22-55.09). The other three risk factors (long competitive season, pitching for more than one team or league, and playing catcher as a secondary position) were not statistically significant.

CONCLUSION

Pitching with arm fatigue is a significant risk factor for shoulder and elbow injuries among adolescent baseball pitchers. Future efforts in assessment and mitigation of pitching with arm fatigue among this population may help to reduce the risk of arm injuries. Furthermore, investigations of additional risk factors in a more homogeneous population of adolescent pitchers may be warranted.

Sport Specialization and Overuse Injuries in Adolescent Throwing Athletes: A Narrative Review

A significant number of adolescent athletes throughout the world participate in various throwing-dominant sports, including but not limited to baseball, cricket, handball, softball, track and field throwing events, and water polo. Due to the unique stresses placed on the throwing arm and entire body in these sports, a robust volume of literature has highlighted concerns about sport specialization in these athletes and an associated increased risk of injury, particularly to the dominant shoulder and elbow, with sport specialization. This review will highlight the evidence-based literature for this athletic niche, focusing on risk factors for injury, national and international organizations' recommendations for limiting overuse injuries, principles of conditioning and rehabilitative programs, and potential future areas of research to curb the growing incidence of throwing-related injuries among adolescent throwing athletes.

Effect of Fatigue Protocols on Upper Extremity Neuromuscular Function and Implications for Ulnar Collateral Ligament Injury Prevention

Background

As the incidence of overuse injuries to the medial elbow in overhead athletes continues to rise, recent evidence suggests a link between these injuries and alterations in biomechanics produced by athlete fatigue. Previous studies have evaluated the effect of fatigue on elbow injuries using a wide array of fatigue protocols/athletic tasks, and, as a consequence, the results have been heterogeneous.

Purpose

To determine whether there is a uniform alteration in neuromuscular function or biomechanics as the overhead athlete fatigues. Furthermore, this study sought to determine whether player fatigue should be accounted for in ulnar collateral ligament (UCL) injury prevention programs.

Study Design

Systematic review.

Methods

A systematic review of the literature using PubMed and MEDLINE databases was performed. Keywords included fatigue, upper extremity, baseball, pitcher, throwing, and muscle activity. Inclusion criteria consisted of original research articles in the English language involving healthy athletes, use of fatigue protocols, and the evaluation of at least 1 upper limb biomechanical variable.

Results

A total of 35 studies involving 644 athletes (90 females, 554 males; mean age, 20.2 years) met the inclusion criteria. General fatigue protocols were used in 2 investigations, peripheral protocols were used in all 35 studies, and 5 different athletic tasks were studied (simulated baseball game, overhead throwing, high-effort swimming, simulated tennis game, and overhead serving). There was a uniform decrease in muscle force production and proprioception in athletes after completing a fatigue protocol. However, there was no consistency among studies when evaluating other important upper limb biomechanical factors. The fatigue protocols did not consistently produce statistically significant changes in elbow torque, pitching biomechanics, or ball velocity.

Conclusion

A uniform decrease in muscle force production and proprioception was found after fatigue protocols; however, a majority of fatigue protocols published in the current literature are inconsistently measured and produce heterogeneous results. Therefore, currently, no recommendations can be made for changes in UCL injury prevention training programs to account for potential effects of fatigue. The effect of muscle force production and proprioception on upper extremity injuries should be evaluated in future studies.

Successful Performance After Ulnar Collateral Ligament Reconstruction: An Analysis of 88 Drafted Professional Baseball Pitchers With a Matched Comparison Cohort

Background:

Analysis of pitchers entering the Major League Baseball (MLB) draft after ulnar collateral ligament reconstruction (UCLR) is challenging for team physicians.

Purpose:

(1) To define the characteristics of pitchers drafted after UCLR associated with placement in AAA and MLB professional levels and completion of a career of at least 3 years, (2) to define characteristics placing pitchers at risk for reinjury after surgery, (3) to compare the professional-level placement and career duration of the UCLR cohort with a matched control group, and (4) to evaluate the accuracy of team physician predraft risk assessments to predict elbow reinjury in pitchers with a history of UCLR.

Study Design:

Cohort study; Level of evidence, 3.

Methods:

We analyzed pitchers from a single professional baseball team database who were drafted after UCLR from 2010 to 2013. A matched control group based on position and draft year was selected with the MLB database. The following pitcher characteristics were analyzed: age at the time of UCLR, time from UCLR to the MLB draft, pitching role (starter vs reliever), highest level of play attained, body mass index (BMI), throwing-side dominance, and predraft physician risk assessment. Physician assessments to predict risk for elbow reinjury were derived from operative and clinical history and evaluated for accuracy during the follow-up period. Pitcher characteristics were evaluated for correlation with successful AAA or MLB placement with a career duration of at least 3 years and as risk factors for elbow reinjury. The professional-level achievement and career duration of the UCLR cohort were compared with the matched cohort.

Results:

A total of 88 pitchers matched the selection criteria and had at least 5 years of follow-up (range, 5-8 years). Pitcher age at the time of UCLR (P = .55), throwing-side dominance (P = .41), and BMI (P = .86) did not correlate with AAA- or MLB-level placement. Relief pitchers (P = .03) and pitchers with a longer time from surgery to final follow-up (P = .02) were more likely to reach the AAA or MLB level. Similarly, pitcher age at the time of UCLR (P = .56), throwing-side dominance (P = .27), and BMI (P = .69) did not correlate with a duration of play of at least 3 years. Relief pitchers (P = .03) and pitchers with a longer time from UCLR to the final follow-up (P = .005) were more likely to achieve at least 3 years of play. There was no difference in AAA or MLB placement between the UCLR and matched cohorts (P = .22). The UCLR cohort achieved a higher duration of play than the matched cohort (P = .002). Pitchers with a BMI >25 kg/m² had a lower risk of elbow reinjury versus players with a BMI ≤25 kg/m² (P = .012). Patient age at time of UCLR (P = .92), time from UCLR to the MLB draft (P = .18), pitching role (P = .74), and throwing-side dominance (P = .77) did not correlate with elbow reinjury. Physician risk assessment did not accurately predict reinjury (P = .27). Of the 88 patients, 4 (4.5%) required revision UCLR.

Conclusion:

Pitcher age at the time of UCLR, throwing-side dominance, and BMI did not correlate with performance. Relief pitchers and players with a longer time from surgery to final follow-up were more likely to reach AAA and MLB levels and achieve at least a 3-year duration of play. Pitchers with a greater BMI had a lower risk of reinjury. After UCLR, pitchers were able to perform at least as well as the matched nonsurgical cohort. Physician risk assessment at the time of the draft was not accurate at predicting reinjury.

Sport-Specific Associations of Specialization and Sex With Overuse Injury in Youth Athletes

BACKGROUND

Significant evidence has emerged that sport specialization is associated with an increased risk of overuse injury in youth athletes. Several recommendations exist to reduce the risk of overuse injury in youth sports, but the risk of overuse injuries may be dependent on specific movements required by a given sport.

HYPOTHESES

Associations between specialized sport participation and overuse injury will exist in volleyball athletes but not soccer or basketball athletes. Female athletes will be more likely to report an overuse injury in the previous year, regardless of sport.

STUDY DESIGN

Cross-sectional study.

LEVEL OF EVIDENCE

Level 3.

METHODS

Youth athletes between the ages of 12 and 18 years were recruited in-person at club team tournaments, competitions, and events around the state of Wisconsin during the 2016-2017 school year. Participants were asked to complete an anonymous questionnaire that consisted of (1) participant demographics, (2) sport specialization status, (3) monthly and weekly sport volume, and (4) sport-related injury history in the previous year.

RESULTS

A total of 716 youth athletes completed the questionnaire (70.8% female; mean age, 14.21 ± 1.50 years; 43.2% basketball, 19.4% soccer, 37.4% volleyball; 41.8% highly specialized; 32.3% reported overuse injury in the previous year). Sex was associated with overuse injury among basketball athletes, with female basketball athletes nearly 4 times more likely to report an overuse injury compared with male basketball athletes (odds ratio, [OR], 3.7; 95% CI, 2.1-6.6; P < 0.001). High specialization (OR, 2.3; 95% CI, 1.1-4.9; P = 0.02) and participating in a single sport for more than 8 months per year (OR, 2.0; 95% CI, 1.1-3.5; P < 0.05) were associated with overuse injury only among volleyball athletes.

CONCLUSION

Specialization and exceeding 8 months per year in a single sport was associated with overuse injury in volleyball, which is one of the most popular youth sports for female athletes. Specialization was not associated with overuse injury in basketball or soccer athletes. Female basketball athletes were nearly 4 times more likely to report a history of overuse injury compared with male basketball athletes. The sex of a youth athlete and the sport that he or she plays may influence the risk of overuse injury associated with sport specialization.

CLINICAL RELEVANCE

Youth athletes, parents, and clinicians should be aware that the potential risks of specialization might vary based on the athlete's sport and sex.

Do Professional Baseball Players With a Higher Valgus Carrying Angle Have an Increased Risk of Shoulder and Elbow Injuries?

Background:

There are many risk factors for shoulder and elbow injuries in professional baseball pitchers. The elbow carrying angle has not been studied as a potential risk factor.

Purpose/Hypothesis:

The aim of this study was to determine whether elbow carrying angle is a risk factor for shoulder or elbow injuries in professional baseball pitchers. We hypothesized that pitchers with a higher elbow carrying angle would be less likely to sustain an injury during the season than pitchers with a lower elbow carrying angle.

Study Design:

Cohort study; Level of evidence, 2.

Methods:

All professional pitchers for a single baseball club during the 2018 season had the carrying angle of both elbows measured at spring training by a single examiner. The pitchers were followed prospectively throughout the season. Shoulder and elbow injuries were recorded prospectively.

Results:

A total of 52 pitchers (21 [40%] Major League Baseball and 31 [60%] Minor League Baseball) were included. During the season, 23 (44%) pitchers became injured. The mean carrying angle in the throwing arm was 12.5° ± 4.2° versus 9.9° ± 2.8° in the nonthrowing arm (P < .001). Comparing the injured and noninjured groups, there were no differences in level of play (P = .870), throwing hand dominance (P = .683), batting hand dominance (P = .554), throwing-side carrying angle (P = .373), nonthrowing-side carrying angle (P = .773), or side-to-side difference in carrying angle (P = .481).

Conclusion:

The elbow carrying angle was not associated with an injury risk during a single season in professional baseball pitchers.

Increasing Burden of Youth Baseball Elbow Injuries in US Emergency Departments

Background:

Youth athletes are starting sports earlier and training harder. Intense, year-round demands are encouraging early sports specialization under the perception that it will improve the odds of future elite performance. Unfortunately, there is growing evidence that early specialization is associated with increased risk of injury and burnout. This is especially true of pediatric and adolescent baseball players.

Purpose/Hypothesis:

The purpose of this investigation was to analyze national injury trends of youth baseball players. We hypothesized that while the total number of baseball injuries diagnosed over the past decade would decrease, there would be an increase in adolescent elbow injuries seen nationally. A further hypothesis was that this trend would be significantly greater than other injuries to the upper extremity and major joints.

Study Design:

Descriptive epidemiology study.

Methods:

Injury data from the National Electronic Injury Surveillance System, a United States Consumer Product Safety Commission database, were analyzed between January 1, 2006, and December 31, 2016, for baseball players aged ≤18 years. Data were collected on the location of injury, diagnosis, and mechanism of injury.

Results:

Between 2006 and 2016, an estimated 665,133 baseball injuries occurred nationally. The mean age of the injured players was 11.5 years. The most common injuries diagnosed included contusions (26.8%), fractures (23.6%), and strains and sprains (18.7%). Among major joints, the ankle (25.6%) was most commonly injured, followed by the knee (21.3%), wrist (19.2%), elbow (17.7%), and shoulder (16.2%). The incidence of the ankle, knee, wrist, and shoulder injuries decreased over time, while only the incidence of elbow injuries increased. A linear regression analysis demonstrated that the increasing incidence of elbow injuries was statistically significant against the decreasing trend for all baseball injury diagnoses, as well as ankle, knee, wrist, hand, and finger injuries (P < .05). Additionally, the only elbow injury mechanism that increased substantially over time was throwing.

Conclusion:

The current investigation found that while the incidence of baseball injuries sustained by youth players is decreasing, elbow pathology is becoming more prevalent and is more commonly being caused by throwing. Given that the majority of elbow injuries among adolescent baseball players are overuse injuries, these findings underscore the importance of developing strategies to continue to ensure the safety of these youth athletes.

Association Between Parental Understanding of Pitch Smart Guidelines and Youth Baseball Player Injuries

Background

Injuries continue to rise among youth baseball players despite extensive research into prevention and the availability of throwing guidelines such as Pitch Smart. More research is needed to understand whether adherence to the current guidelines decreases injuries.

Purpose

To understand the degree to which parents are aware of the Pitch Smart guidelines, whether parents adhere to the guidelines, and whether adherence results in decreased injuries in youth baseball players.

Study Design

Cross-sectional study.

Methods

An anonymous, internet-based survey consisting of 44 items was distributed to parents of adolescent baseball players affiliated with various youth baseball organizations across the midwestern United States; 15 items on the survey served as assessment questions of the Pitch Smart guidelines. Absolute and percentage correct scores were calculated and compared by use of a Student t test. A chi-square analysis was used to compare discrete data. A binary logistic regression analysis was conducted to determine whether showcase participation predicted player injury.

Results

A total of 853 parents completed the survey. The mean ± SD age of the players on whom parents reported was 11.37 ± 3.5 years (range, 6-20 years). Among the cohort, 422 players regularly pitched. Regarding Pitch Smart guidelines, the percentage of correct answers by parents was 55.44% ± 0.3% for a player with a reported injury history and 62.14% ± 0.2% for a player without an injury history (P = .012). The number of correct answers was 8.03 ± 4.0 for the group with an injury history and 9.17 ± 3.2 for the group with no history of injury (P = .004). Binary logistic regression analysis, which controlled for age, indicated that showcase participation (P = .001, β = 1.043 ± 0.026, R² = 0.178) was a significant predictor of player injury.

Conclusion

Pitchers are at an increased risk of injury compared with nonpitchers. Parents who are knowledgeable about the Pitch Smart throwing guidelines and actively follow them are significantly less likely to have a child with an injury. Excessive showcase participation is predictive of player injury when the analysis controls for age.

A Clinician's Guide to Analysis of the Pitching Motion

PURPOSE OF REVIEW

This review examines recent literature regarding analysis of the throwing motion in baseball players and how modern technology may be used to predict or prevent injury.

RECENT FINDINGS

Proper throwing technique is vitally important to prevent injury and it is easier to correct poor mechanics prior to foot strike. Recent findings suggest that the inverted-W position may not lead to an increased risk of injury, but incorrect trunk or pelvis rotation does. Three-dimensional motion analysis in a laboratory setting is most commonly used to evaluate the throwing motion, but it does not allow for assessment in real game scenarios. Wearable monitors allow for this and have proven to reliably assess pitching workload, kinematics, and kinetics. Injuries in youth baseball pitchers have increased along with the trend towards more single sport specialization. To prevent injury, assessment of a pitcher's throwing motion should be performed early to prevent development of poor mechanics. Classically, three-dimensional motion analysis has been used to evaluate throwing mechanics and is considered the gold standard. Newer technology, such as wearable monitors, may provide an alternative and allow for assessment during actual competition.

Risk Factors for Elbow and Shoulder Injuries in Adolescent Baseball Players: A Systematic Review

BACKGROUND

The incidence of shoulder and elbow injuries among adolescent baseball players is on the rise. These injuries may lead to surgery or retirement at a young age.

PURPOSE

To identify independent risk factors for elbow and shoulder injuries in adolescent baseball players. A secondary aim was to determine whether the literature supports the Major League Baseball and USA Baseball Pitch Smart guidelines.

STUDY DESIGN

Systematic review.

METHODS

A systematic review was performed in accordance with PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines utilizing MEDLINE, SPORTDiscus, and Web of Science. Because of study heterogeneity, a quantitative synthesis was not performed. A qualitative review was performed on 19 independent risk factors for elbow and shoulder injuries in adolescent baseball players. Level of evidence was assigned per the Oxford Centre for Evidence-Based Medicine Working Group, and risk of bias was graded per the Newcastle-Ottawa Scale.

RESULTS

Twenty-two articles met criteria for inclusion. Of the 19 independent variables that were analyzed, age, height, playing for multiple teams, pitch velocity, and arm fatigue were found to be independent risk factors for throwing arm injuries. Pitches per game appears to be a risk factor for shoulder injuries. Seven independent variables (innings pitched per game, showcase participation, games per year, training days per week, pitch type, shoulder external rotation, and shoulder total range of motion) do not appear to be significant risk factors. The data were inconclusive for the remaining 6 variables (weight, months of pitching per year, innings or pitches per year, catching, shoulder horizontal adduction, and glenohumeral internal rotation deficit).

CONCLUSION

The results from this study demonstrate that age, height, playing for multiple teams, pitch velocity, and arm fatigue are clear risk factors for throwing arm injuries in adolescent baseball players. Pitches per game appears to be a risk factor for shoulder injuries. Other variables are either inconclusive or do not appear to be specific risk factors for injuries.

Risk Factors for Baseball-Related Arm Injuries: A Systematic Review

Background:

Contributing factors for arm injuries among baseball players have been described. However, no review has systematically identified risk factors with findings from prospective cohort studies.

Purpose:

To systematically review prospective cohort studies that investigated risk factors for arm injury among baseball players.

Study Design:

Systematic review; Level of evidence, 3.

Methods:

Electronic databases were searched for relevant English-language studies. Titles, abstracts, and full-text articles were screened by 2 blinded reviewers to identify only prospective cohort studies and randomized controlled trials. Two independent investigators screened each article for appropriate criteria.

Results:

Fourteen prospective articles were selected for this review. Youth, high school, and professional baseball players (N = 2426) were pooled, and 43 risk factors were assessed in relation to general arm, shoulder, and elbow injuries. All studies evaluated players for at least 1 season. Deficits in preseason shoulder range of motion and strength were significant risk factors for general arm or shoulder injury among high school and professional players. Elbow and shoulder varus torque at peak external shoulder rotation during pitching, high pitch velocity, and shoulder rotational and flexion deficits were risk factors for elbow injuries among professional pitchers. Pitching >100 innings in 1 year, being aged 9 to 11 years, being a pitcher or catcher, training >16 hours per week, and having a history of elbow pain were significant risk factors for elbow injury among youth players.

Conclusion:

History of elbow pain and age had a high risk of associated elbow injury among youth players. Training or pitching load also increased elbow injury risk for youth athletes. Loss of shoulder range of motion appears to increase risk for elbow injury among professional athletes. Single time-point data collections per season, studies with the same sample population, and studies with self-reported injury and risk factor data may limit the interpretation of these findings. Health care professionals should use caution when assessing injury risk during evaluation and making decisions about the training workload and playing time of baseball players.