Factors Related to Injury in Youth and Adolescent Baseball Pitching, with an Eye Toward Prevention

Torso kinematic patterns associated with throwing shoulder joint loading and ball velocity in Little League pitchers

The purpose of this study was to investigate the associations between kinematic patterns of the torso segment and shoulder joint loading as well as pitching performance in youth pitchers. Twenty-four Little League pitchers threw fastballs while motion capture and force plate data were collected and ball speed was measured with a radar gun. Three-dimensional torso segment kinematics (absolute angles and angular velocities) and shoulder net joint moments (NJM) and forces were calculated. The time-series kinematic data were used as inputs to a principal components analysis to extract torso movement patterns. Associations between torso movement patterns and discrete peak shoulder NJM, compressive force, and ball speed were investigated with nonparametric correlations. Torso segment motion patterns related to forward flexion, lateral flexion (away from pitching arm), and axial rotation and rotational velocities were associated with shoulder joint kinetics and ball speed. In addition, excessive axial (transverse plane) torso rotation at ball release correlated positively with shoulder joint loads but not ball speed, which may indicate the prospect for decreasing joint kinetics while maintaining pitching performance through targeted interventions. These results provide a deeper understanding about the interrelationships between torso kinematic patterns, shoulder kinetics, and pitching performance.

A narrative review of little league shoulder: proximal humeral physis widening is only one piece of the puzzle, it is time to consider posterior glenoid dysplasia

Baseball athletes across all levels of play are at an increased risk for upper extremity injury due to the supraphysiologic demands on the shoulder and elbow during overhead throwing. Little league baseball players present with a unique subset of injuries that can affect the growth plate, commonly at the shoulder or the elbow. Ascertaining a diagnosis and plan of care for little league shoulder (LLS) historically focuses on the proximal humeral physis in skeletally immature throwing athletes presenting with shoulder pain. However, while not a current standard of care, posterior glenoid dysplasia is often present in youth baseball athletes presenting with LLS, warranting a shift in the way clinicians evaluate for and treat the youth baseball athlete's pathologic shoulder. Therefore, purpose of this narrative review is 2-fold: first, to describe the current standard of care as it relates to a diagnosis of LLS, and second, to critically describe a comprehensive evaluation process for youth throwing athletes with shoulder pain that includes screening for evidence of posterior glenoid dysplasia. This paper summarizes the current state of the available evidence for anatomic considerations of LLS in the baseball athletes throwing shoulder. Additionally, we provide a framework for clinical evaluation using a multidisciplinary approach to evaluate the entire kinetic chain of the youth baseball athlete presenting with LLS and posterior glenoid dysplasia. A case study is presented to describe common presentations, clinical and objective examinations, and a plan of care from time of evaluation to return to throwing.

Shoulder External Over Internal Rotation Ratio Is Related to Biomechanics in Collegiate Baseball Pitching

Altering baseball pitching mechanics affects both performance and the risk of injury. The purpose of this study is to investigate the relationships of shoulder external over internal rotation ratio (SEIR) and other shoulder rotational properties during physical exam and biomechanics of pitching for 177 collegiate baseball pitchers. The shoulder range of motion was quantitatively measured using a custom-made wireless device. Pitching motion data were collected at 240 Hz, and a custom program was created to calculate the throwing arm motion and loading during baseball pitching. Linear regression and analysis of variance tests were performed to investigate the relationships between the shoulder physical exam outcomes and throwing arm biomechanics. SEIR had significant correlations with shoulder horizontal adduction angle at foot contact, maximum shoulder external rotation angle, maximum shoulder linear velocity, and elbow angle at ball release. SEIR groups had significant differences in shoulder proximal force, adduction torque, internal rotation torque, and horizontal adduction torque, and in elbow medial force and varus torque. Glenohumeral internal rotation deficit and total rotational motion deficit had no relationships with throwing arm motions or joint loadings. Shoulder health should be monitored to improve understanding of pitching mechanics in collegiate baseball pitchers.

Return to Sports Following Shoulder Injury: Clinical Evaluation, Isokinetic, and Functional Testing

ABSTRACT

The shoulder is commonly injured in overhead sports. This is associated with a high degree of mobility at the expense of stability, sports specific demands, high volume or intensity of practice and competition, biomechanical deficits, and poor technique. Following injury, the return to competition process includes nonsurgical or surgical treatment, comprehensive rehabilitation, and a structured return to sports program. The return to sports continuum is divided into phases which include return to practice of the sport, return to competition at a lower level or with reduced performance, and return to expected performance. Components of the return to sports decision include clinical evaluation of physical and psychological readiness, measurement of muscle strength using isokinetic tests, evaluation of overhead functional tasks, and progression in a supervised interval throwing program. The evidence for the effectiveness of return to sports programs following shoulder injury is limited but evolving and is an area that will merit continued investigation.

Stand-up test could be a helpful adjunct for screening elbow disorders in Little League baseball players

BACKGROUND

The purpose of this study is to justify the result of the modified Stand-Up test (MSUT) in Little League baseball players and to clarify the association with sports related disorders in the elbow.

METHODS

A total of 245 (240 boys and 5 girls) Little League baseball players aged 9 to 12 underwent physical examination, elbow ultrasonography and questionnaires during a routine medical checkup. In addition, the MSUT, based on the Japanese Orthopaedic Association (JOA)'s original Stand-Up test to evaluate the risk of Locomotive syndrome, was performed.

RESULTS

Seventeen osteochondritis dissecans (OCD) of capitellum and 4 medial epicondylar fragmentation (MEF) cases were diagnosed with ultrasonography in 242 players. Based on the MSUT, five boys could not stand up from 40 cm platform with the single leg stance, two of whom complained of current elbow pain, three of whom diagnosed with a positive finding with ultrasonography. Odds ratio (95% confidence limits) of risk factors for failing to the 40 cm-MSUT with the single leg stance were: incidence of current elbow pain 5.7 (0.9-35.5); OCD (Grade 1b and 2) 8.2 (0.8-83); and MEF 19.5 (1.7-230).

CONCLUSION

Two percent of Little League baseball players were unable to stand up from a 40 cm high platform/stool with the single leg stance by the MSUT and it was associated with an increase in MEF or OCD diagnosis by ultrasonography and presence of elbow pain. These results suggest that players who failed to the 40 cm-MSUT with the single leg stance are at risk of elbow disorders. Also, these results are consistent with previous research on throwing injuries that have associated poor control in the legs or trunk with pain and injury involving the upper extremities. MSUT, a relatively simple procedure, may be a helpful adjunct for screening to estimate readiness for resuming general physical activity in Little League baseball players.

Reliability of an Observational Biomechanical Analysis Tool in Adolescent Baseball Pitchers

BACKGROUND

Improper pitching mechanics are a risk factor for arm injuries. While 3-dimensional (3D) motion analysis remains the gold standard for evaluation, most pitchers and clinicians do not have access to this costly technology. Recent advances in 2-dimensional (2D) video technology provide acceptable resolution for clinical analysis. However, no systematic assessment tools for pitching analysis exist.

PURPOSE

To determine the reliability of the Assessment of biomeChanical Efficiency System (ACES) screening tool using 2D video analysis to identify common biomechanical errors in adolescent pitchers.

STUDY DESIGN

Cross-sectional.

METHODS

Adolescent baseball pitchers underwent analysis using 2D video in indoor settings. Observational mechanics were collected using a 20-item scoring tool (ACES) based on 2D video analysis. Fleiss' kappa, interclass correlation coefficients (ICC), and frequencies were used to examine intra-/interrater reliability based on common pitching errors.

RESULTS

Twenty asymptomatic pitchers ages 12-18 years were included. Total ACES scores ranged from 1 to 13, normally distributed. ACES total score demonstrated excellent intra-rater reliability within each rater (ICC for rater 1 = 0.99 (95% CI; 0.98, 0.99); ICC for rater 2 = 0.94; 95% CI: 0.84, 0.97); ICC for rater 3 = 0.98 (95% CI: 0.96, 0.99)). There was excellent interrater reliability across the trials and raters (ICC = 0.91; 95% CI: 0.82, 0.96). The ACES tool demonstrated acceptable kappas for individual items and strong ICC 0.91 (95% CI: 0.82, 0.96) for total scores across the trials. Regarding identification of biomechanical errors, "front side position" was rated erroneous in 84/120 ratings (70%), stride length in 52/120 ratings (43.3%) and lead hip position in 53/120 ratings (44.2%).

CONCLUSIONS

The 20-item ACES scoring tool with 2D video analysis demonstrated excellent intra- and interrater reliability when utilized by raters of different musculoskeletal disciplines. Future studies validating 2D vs. 3D methodology are warranted before ACES is widely disseminated and utilized for adolescent pitchers. ACES is a practical and reliable clinical assessment tool utilizing 2D video analysis for coaches, instructors, and sports medicine providers to screen adolescent pitchers for common biomechanical errors.

LEVEL OF EVIDENCE

3b.

The Intra- and Inter-rater Reliability of an Arm Care Screening Tool in High School Baseball Coaches

BACKGROUND

Preseason movement screening can identify modifiable risk factors, deterioration of function, and potential for injury in baseball players. Limited resources and time intensive testing procedures prevent high school coaches from accurately performing frequent movement screens on their players.

PURPOSE

To establish the intra-rater and inter-rater reliability of a novel arm care screening tool based on the concepts of the Functional Movement Screen (FMS™) and Selective Functional Movement Assessment (SFMA™) in high school coaches.

STUDY DESIGN

Methodological intra- and inter-rater reliability study.

METHODS

Thirty-one male high school baseball players (15.9 years ± 1.06) were independently scored on the Arm Care Screen (ACS) by three examiners (two coaches, one physical therapist) in real-time and again seven days later by reviewing video recordings of each players' initial screening performance. Results from each examiner were compared within and between raters using Cohen's kappa and percent absolute agreement.

RESULTS

Substantial to excellent intra-rater and inter-rater reliability were established among all raters for each component of the ACS. The mean Cohen's kappa coefficient for intra-rater reliability was 0.76 (95% confidence interval, 0.54-0.95) and percent absolute agreement ranged from 0.82-0.94 among all raters. Inter-rater reliability demonstrated a mean Cohen's kappa value of 0.89 (95% confidence interval, 0.77-0.99) while percent absolute agreement between raters ranged from 0.81-1.00. Intra- and inter-rater reliability did not differ between raters with various movement screening experience (p>0.05).

CONCLUSIONS

High school baseball coaches with limited experience screening movement can reliably score all three components of the ACS in less than three minutes with minimal training.

LEVEL OF EVIDENCE

Level 3, Reliability study.

Shoulder External Rotational Properties During Physical Examination Are Associated With Injury That Requires Surgery and Shoulder Joint Loading During Baseball Pitching

BACKGROUND

Throwing arm injuries are common because of the demand on the shoulder. The shoulder is qualitatively checked regularly by team physicians. Excessive instability and joint loading in baseball pitching are risk factors for throwing arm injuries. Knowledge of shoulder flexibility, range of motion, and joint loading may provide new insights for treatments to reduce the likelihood of injury incidence.

PURPOSE

To investigate the relationship among injuries, shoulder external rotational properties, and shoulder joint loading in baseball pitchers.

STUDY DESIGN

Descriptive laboratory study.

METHODS

Pitching kinetics, shoulder rotational tests, and self-reported injury questionnaires were used to study 177 collegiate baseball pitchers. Pitching motion data were collected at 240 Hz using a motion capture system. A custom program calculated the shoulder joint loading. The shoulder rotational test quantitatively records shoulder range of motion and flexibility using a custom-made wireless device. Self-reported injury questionnaires were filled out during tests and yearly follow-ups. The total length of the study was 5 years. Analysis of variance, chi-square, and regression tests were performed to compare differences among groups and detect correlations with surgery and shoulder joint loadings.

RESULTS

There were significant differences in shoulder flexibility among surgery groups. Shoulder external rotational properties during physical examination were significantly associated with shoulder joint loading in baseball pitching. High shoulder external rotation was associated with 14% to 36% lower shoulder posterior force and adduction, internal rotation, and horizontal adduction torque (P < .05). High shoulder flexibility was associated with 13% higher anterior force (P < .05). High shoulder external rotation before external rotation torque was applied was associated with 13% to 33% lower shoulder inferior force and adduction, internal rotation, and horizontal adduction torque (P < .05). There were no significant differences in shoulder joint loading among the surgery groups.

CONCLUSION

Shoulder injuries that require surgery were associated with shoulder external rotation flexibility. High shoulder external rotation may be advantageous because it lowers the force and torque on the shoulder joint.

CLINICAL RELEVANCE

The ability to understand shoulder external rotational properties, joint loading, and injury during baseball pitching helps further our understanding of injury mechanisms. The shoulder rotational test should be used as a screening tool to identify players at risk.

Decreased Shoulder and Elbow Joint Loads During the Changeup Compared With the Fastball and Curveball in NCAA Division I Collegiate Softball Pitchers

BACKGROUND

Baseball leagues have implemented pitch count and pitch type restrictions based on biomechanical concepts associated with pitch type. Softball has not yet adopted these practices, although softball pitchers continue to pitch at a high volume and learn multiple pitches at a young age.

PURPOSE

To examine shoulder and elbow kinetics between the fastball, curveball, and changeup, as well as to provide descriptive upper extremity pain data in National Collegiate Athletic Association (NCAA) softball pitchers.

STUDY DESIGN

Descriptive laboratory study.

METHODS

Study participants consisted of 27 female NCAA Division I softball pitchers (age, 20.2 ± 1.9 years; height, 175.7 ± 5.7 cm; weight, 83.6 ± 12.7 kg). The participants pitched 3 balls of each pitch type, and kinetic data were recorded. A one-way within-participants repeated-measures multivariate analysis of variance was used to determine significant differences in kinetics and pitch speed between pitch types.

RESULTS

Results revealed a statistically significant main effect for pitch type (Wilks λ = .087; F = 36.523; P < .001). Post hoc testing showed that the changeup produced less anterior elbow force compared with the fastball (P < .001) and the curveball (P = .012). In addition, the changeup produced less shoulder distraction force compared with the fastball (P < .001) and the curveball (P = .001). Additionally, there was a significant difference in pitch speed between all 3 pitch types (P = .006). The curveball revealed no statistically significant kinetic differences compared with the fastball.

CONCLUSION

The fastball and curveball placed similar stress on the upper extremity in collegiate softball pitchers. However, in comparison with the changeup, the fastball and curveball placed increased stress on the upper extremity. More research is needed to fully explain the differences seen between pitch type and injury risk.

CLINICAL RELEVANCE

Sports medicine professionals, coaches, and athletes should use the current study results to note these differences in shoulder distraction and elbow anterior forces between softball pitch types. The study results can be used as a reference and basis for future research investigating kinetic differences across varying pitch types.

Quantifying Throw Counts and Intensities Throughout a Season in Youth Baseball Players: A Pilot Study

Overuse injuries in youth baseball players due to throwing are at an all-time high. Traditional methods of tracking player throwing load only count in-game pitches and therefore leave many throws unaccounted for. Miniature wearable inertial sensors can be used to capture motion data outside of the lab in a field setting. The objective of this study was to develop a protocol and algorithms to detect throws and classify throw intensity in youth baseball athletes using a single, upper arm-mounted inertial sensor. Eleven participants from a youth baseball team were recruited to participate in the study. Each participant was given an inertial measurement unit (IMU) and was instructed to wear the sensor during any baseball activity for the duration of a summer season of baseball. A throw identification algorithm was developed using data from a controlled data collection trial. In this report, we present the throw identification algorithm used to identify over 17,000 throws during the 2-month duration of the study. Data from a second controlled experiment were used to build a support vector machine model to classify throw intensity. Using this classification algorithm, throws from all participants were classified as being "low," "medium," or "high" intensity. The results demonstrate that there is value in using sensors to count every throw an athlete makes when assessing throwing load, not just in-game pitches.

Early Sport Specialization Linked to Throwing Arm Function and Upper Extremity Injury History in College Baseball Players

BACKGROUND

Evidence suggests that shoulder and elbow injuries account for 31% to 37% of all National Collegiate Athletic Association (NCAA) baseball injuries, and up to 69% of NCAA baseball injuries are the result of noncontact and overuse mechanisms. Early sport specialization may contribute to the high rates of upper extremity injuries in college baseball players.

HYPOTHESIS

Higher specialization by age 13 years would be associated with worse subjective throwing arm function and a greater history of shoulder and elbow injury.

STUDY DESIGN

Cohort study.

LEVEL OF EVIDENCE

Level 2.

METHODS

Survey data were collected from college baseball players (N = 129) during midseason of the spring 2019 baseball season. Participants were stratified in low, moderate, and high specialization groups based on a 3-criteria sports specialization questionnaire. Participants' throwing arm function was measured using the Functional Arm Scale for Throwers and the Kerlan-Jobe Orthopaedic Clinic shoulder and elbow questionnaires. Participants' history of a shoulder or elbow injury that resulted in missing ≥2 weeks of baseball activity at any point in their baseball career was also collected.

RESULTS

The high specialization group reported worse subjective throwing arm function on the Functional Arm Scale for Throwers questionnaire than the low (P = 0.03) and moderate (P = 0.01) specialization groups. The high specialization group was over 5 times more likely to report a history of shoulder injury than the moderate (odds ratio [OR] = 5.42; 95% CI [1.71, 17.2]; P = 0.004) and low (OR = 5.20; 95% CI [1.87, 14.5]; P = 0.002) specialization groups, and over 3 times more likely to report a history of elbow injury than the moderate specialization group (OR = 3.77; 95% CI [1.05, 13.6]; P = 0.04).

CONCLUSION

College baseball players that were highly specialized by age 13 years reported worse subjective throwing arm function and were more likely to have a history of upper extremity injury than players that were moderate or low specialization.

CLINICAL RELEVANCE

Early specialization in baseball may be detrimental to long-term upper extremity health in college baseball players.

Current Concepts in Arm Care Exercise Programs and Injury Risk Reduction in Adolescent Baseball Players: A Clinical Review

CONTEXT

Awareness of important injury risk factors associated with excessive pitching volume has been highlighted in the literature, but injury rates remain high. Shoulder pain in baseball players is associated with various changes in musculoskeletal movements, which presents as measurable impairments throughout the kinetic chain. Baseball coaches and rehabilitation professionals have utilized exercise programs targeting strength and flexibility of the throwing arm to prevent injuries. The purpose of this review is to summarize the current evidence regarding the effectiveness of arm care exercise programs in reducing upper extremity injury rates in adolescent baseball players.

EVIDENCE ACQUISITION

A search of electronic databases, including CINAHL with full text, MEDLINE, and SPORTDiscus was conducted to retrieve available articles in English from the years 2010 through 2020. The search terms injury prevention, exercise, and adolescent baseball were used.

STUDY DESIGN

Clinical review.

LEVEL OF EVIDENCE

Level 4.

RESULTS

Improving shoulder internal rotation range of motion by stretching the posterior shoulder muscles daily was associated with a 36% risk reduction of shoulder and elbow injuries. Group-based arm care exercise programs that target multiple musculoskeletal impairments demonstrated an approximately 50% reduced risk of elbow injury.

CONCLUSION

For adolescent baseball players, arm care injury prevention programs focusing on important musculoskeletal impairments are effective at reducing injury incidence rates. Multimodal injury prevention programs that improve multiple musculoskeletal impairments are more comprehensive and may result in better injury reduction than programs focusing on a singular impairment.

Peak horizontal ground reaction forces and impulse correlate with segmental energy flow in youth baseball pitchers

The purpose of this study was to determine associations between horizontal ground reaction force (GRF) kinetics and energy flow (EF) variables in youth baseball players. Twenty-four youth baseball players pitched fastballs in an indoor laboratory while motion capture and force plate data were collected. Horizontal GRF variables were extracted (peak GRF and GRF impulse) while EF was calculated by integrating magnitudes of mechanical powers transferred into and out of the pelvis, trunk, and arm segments via joint force power (JFP) and joint moment power (JMP) components. Peak propulsive GRF of the drive (back) leg correlated with EF into proximal segments, whereas peak braking GRF of the stride (lead) leg correlated with EF into distal segments. Furthermore, peak GRF of the drive leg and GRF impulse of both legs correlated with the JFP components of EF into the pelvis and trunk segments. In contrast, peak GRF and GRF impulse of the stride leg both correlated with the JMP components of EF into the arm segment. These results suggest that horizontal GRF impulse from the drive and stride leg contribute to EF between major segments of the lower and upper extremity. In addition, these results also suggest that propulsion kinetics of the drive leg play a role in transferring linear power via the pelvis and trunk segments in the throwing direction of the pitch, whereas braking kinetics of the stride leg play a role in creating rotational power that is transferred between the trunk and arm segment via the shoulder joint.

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.

Pediatric Sports Injuries

With increasing pediatric participation in organized sport and the early specialization of children in single sports, the number of injuries seen in the pediatric and adolescent athletic population continues to increase. Children experience acute traumatic injuries during practice and competition as well as chronic overuse injuries secondary to the repetitive stress on their developing bodies. The unique nature of the pediatric patient often requires a different diagnostic, prognostic, and treatment approach to sports injuries compared with their adult counterparts.

The Role of Lumbopelvic-Hip Complex Stability in Softball Throwing Mechanics

Context: Studies have found that a 20% reduction in energy generation from the lumbopelvic-hip complex during overhead throws leads to a 34% increase in load on the shoulder. Objective: The purpose of this study was to assess the effects of lumbopelvic-hip complex stability, via the single leg squat assessment, on throwing mechanics of softball athletes. Design: Prospective cohort study. Setting: Laboratory setting. Participants: A total of 50 softball athletes (164.0 [104.0] cm, 65.6 [11.3] kg, 16.3 [3.8] y, 8.61 [3.62] y of experience) performed 3 overhead throws and a single leg squat on each leg. Intervention: Four stability groups were derived: (1) stable on both legs (bilateral stability), (2) unstable on the throwing side leg (TS instability) and stable on the nonthrowing side leg, (3) unstable on the nonthrowing side leg (NTS instability) and stable on the throwing side leg, and (4) unstable on both legs (bilateral instability). All throws were analyzed across 4 throwing events: foot contact (FC), maximum external shoulder rotation (MER), ball release (BR), and maximum internal shoulder rotation (MIR). Main Outcome Measures: Mann–Whitney U tests revealed significant differences between the bilateral stability and the TS instability groups in trunk flexion at BR; the bilateral stability and the NTS instability groups in trunk flexion at BR, shoulder horizontal abduction at FC, shoulder rotation at FC, and pelvis flexion at MIR; the TS instability and the bilateral instability groups in trunk rotation at FC; and the NTS instability and the bilateral instability groups in trunk flexion at MER and shoulder rotation at FC. Conclusion: These findings demonstrate the different mechanisms in which energy can be lost through lumbopelvic-hip complex instability as evident in throwing mechanics. The findings from this study suggest that the current methods used for classification could act as a tool for coaches, physicians, and athletic trainers when assessing their athletes’ injury susceptibility.

Changes in humeral retrotorsion and the development of little league shoulder: A case study

OBJECTIVE

To present the case of a 15 year-old baseball player with Little League Shoulder (LLS) and describe how developmental changes in the angle of humeral retrotorsion (HRT) may contribute to the underlying pathology of this condition.

DESIGN

Case report.

SETTING

Two years earlier, the patient had participated in a healthy player screening program at which time measurements of height, weight, shoulder motion, and HRT were obtained. These same measures were obtained during the initial evaluation after injury. Between measurements, the patient grew more than 12 cm in height and demonstrated a large shift in proximal humeral torsional alignment with a change of 13° and 19° of HRT in the dominant and non-dominant sides respectively.

PARTICIPANT

15 year-old male (1.88 m, 79.8 kg), right hand dominant baseball pitcher and 3rd baseman diagnosed with right LLS.

CONCLUSION

The pathoanatomical factors contributing to LLS are not well understood. The degree of HRT is a developmental characteristic that changes over the course of physiological maturation. The large changes in HRT seen in this case, may implicate rapid changes in HRT angle create a window of increased susceptibility to physeal damage, and contribute to the development of LLS.

Season-Ending Shoulder Injuries in the National Collegiate Athletic Association: Data From the NCAA Injury Surveillance Program, 2009-2010 Through 2013-2014

BACKGROUND

Examination of the incidence of shoulder season-ending injury (SEI) in the collegiate athlete population is limited.

PURPOSE

To determine the incidence of shoulder SEI in the National Collegiate Athletic Association (NCAA) and to investigate the risk factors for a shoulder injury ending an athlete's season.

STUDY DESIGN

Descriptive epidemiology study.

METHODS

All shoulder injuries from the NCAA Injury Surveillance Program database for the years 2009-2010 to 2013-2014 were extracted, and SEI status was noted. The incidences of SEI and non-SEI were calculated for athlete, activity, and injury characteristics and compared via univariable analysis and risk ratios to determine risk factors for an injury being season ending.

RESULTS

Shoulder injuries were season ending in 4.3% of cases. The overall incidence of shoulder SEI was 0.31 per 10,000 athlete exposures (AEs), as opposed to 7.25 per 10,000 AEs for all shoulder injuries. Shoulder instability constituted 49.1% of SEI, with an incidence of 0.15 per 10,000 AEs, while fractures had the highest rate of being season ending (41.9%). Men's wrestling had the highest incidence of shoulder SEI (1.65 per 10,000 AEs), while men's soccer had the highest proportion of shoulder injuries that ended a season (14.6%). Overall, men had a 6.3-fold higher incidence of SEI than women and a 2.4-fold increased likelihood that an injury would be season ending.

CONCLUSION

Injury to the shoulder of an NCAA athlete, while somewhat infrequent, can have significant implications on time lost from play. Incidence of these injuries varies widely by sport and injury, with a number of associated risk factors. Athletes sustaining potentially season-ending shoulder injuries, with their coaches and medical providers, may benefit from these data to best manage expectations and outcomes.

Effect of Predraft Ulnar Collateral Ligament Reconstruction on Future Performance in Professional Baseball: A Matched Cohort Comparison

BACKGROUND

In recent years, there has been a dramatic rise in the annual number of ulnar collateral ligament (UCL) reconstructions performed in amateur baseball pitchers. Accordingly, increasing numbers of players are entering professional baseball having already undergone the procedure; however, the effect of prior UCL reconstruction on future success remains unknown.

PURPOSE

(1) To provide an epidemiologic report on baseball players who undergo UCL reconstruction before being selected in the Major League Baseball (MLB) Draft, (2) to define the outcomes in terms of statistical performance, and (3) to compare these results with those of matched controls (ie, non-UCL reconstruction).

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

The MLB Amateur Draft Database was queried to identify all drafted pitchers who underwent UCL reconstruction before being drafted. For each pitcher drafted from 2005 to 2014 with prior UCL reconstruction, 3 healthy controls with no history of elbow surgery were randomly identified for matched analysis. A number of demographic and performance comparisons were made between these groups.

RESULTS

A total of 345 pitchers met inclusion criteria. The annual number of pitchers undergoing predraft UCL reconstructions rose steadily from 2005 to 2016 ( P < .001). For matched control analysis, 252 pitchers with a UCL reconstruction and a minimum 2-year follow-up (drafted between 2005 and 2014) were matched to 756 controls (non-UCL reconstruction). As compared with the non-UCL reconstruction group, pitchers who underwent predraft UCL reconstruction reached the MLB level with greater frequency (20% vs 12%, P = .003), and their MLB statistical performances were similar for all measures. Compared with all other pitchers drafted during that period, players who had a predraft UCL reconstruction demonstrated an increased likelihood of reaching progressive levels of play (Full Season A, AA, and MLB) within a given time frame ( P < .05 for all).

CONCLUSION

The number of UCL reconstructions performed in amateur baseball players before the draft increased year over year for the entire study period. Professional pitchers who underwent UCL reconstruction as amateurs appear to perform at least as well as, if not better than, matched controls without elbow surgery.

Unaccounted Workload Factor: Game-Day Pitch Counts in High School Baseball Pitchers-An Observational Study

Background:

Throwing injuries are common in high school baseball. Known risk factors include excessive pitch counts, year-round pitching, and pitching with arm pain and fatigue. Despite the evidence, the prevalence of pitching injuries among high school players has not decreased. One possibility to explain this pattern is that players accumulate unaccounted pitch volume during warm-up and bullpen activity, but this has not yet been examined.

Hypotheses:

Our primary hypothesis was that approximately 30% to 40% of pitches thrown off a mound by high school pitchers during a game-day outing are unaccounted for in current data but will be revealed when bullpen sessions and warm-up pitches are included. Our secondary hypothesis was that there is wide variability among players in the number of bullpen pitches thrown per outing.

Study Design:

Cross-sectional study; Level of evidence, 3.

Methods:

Researchers counted all pitches thrown off a mound during varsity high school baseball games played by 34 high schools in North Central Florida during the 2017 season.

Results:

We recorded 13,769 total pitches during 115 varsity high school baseball starting pitcher outings. The mean ± SD pitch numbers per game were calculated for bullpen activity (27.2 ± 9.4), warm-up (23.6 ±8.0), live games (68.9 ±19.7), and total pitches per game (119.7 ± 27.8). Thus, 42.4% of the pitches performed were not accounted for in the pitch count monitoring of these players. The number of bullpen pitches thrown varied widely among players, with 25% of participants in our data set throwing fewer than 22 pitches and 25% throwing more than 33 pitches per outing.

Conclusion:

In high school baseball players, pitch count monitoring does not account for the substantial volume of pitching that occurs during warm-up and bullpen activity during the playing season. These extra pitches should be closely monitored to help mitigate the risk of overuse injury.

Epidemiology of Shoulder and Elbow Injuries Among United States High School Baseball Players: School Years 2005-2006 Through 2014-2015

BACKGROUND

Shoulder and elbow injuries are common in young athletes, especially high school baseball players. Understanding the risk factors associated with baseball injuries is an essential first step in the development of injury prevention strategies.

PURPOSE

To provide a comprehensive understanding of the epidemiology of shoulder and elbow injuries among high school baseball players in the United States.

STUDY DESIGN

Descriptive epidemiological study.

METHODS

Baseball-related injury data were obtained from the National High School Sports-Related Injury Surveillance Study using High School RIO (Reporting Information Online), an Internet-based sports injury surveillance system. Athletic trainers from high schools across the country uploaded data regarding athlete-exposures (AEs) (defined as practice or game participation) and shoulder and elbow injuries from the school years 2005-2006 through 2014-2015.

RESULTS

A total of 241 shoulder injuries and 150 elbow injuries occurred during 1,734,198 AEs during the study period, for an overall shoulder injury rate of 1.39 per 10,000 AEs and an overall elbow injury rate of 0.86 per 10,000 AEs. The overall rates of injury were higher in competitions compared with practices for shoulders (rate ratio, 1.44; 95% CI, 1.11-1.85) and elbows (rate ratio, 2.15; 95% CI, 1.56-2.96). The majority of shoulder (39.6%) and elbow (56.9%) injuries were sustained by pitchers, and most injuries were chronic and caused by overuse. Position players were more likely to sustain injuries by contact with the playing surface or apparatus. For pitchers, muscle strains were the most common shoulder injuries (38.7%), while ligament sprains were the most common elbow injuries (42.7%). The majority of pitchers with shoulder (70.8%) and elbow (64.6%) injuries returned to play within 21 days. Among pitchers, a higher proportion of elbow injuries (11.4%) resulted in medical disqualification compared with shoulder injuries (5.6%). Among pitchers, the majority of shoulder (89.2%) and elbow (96.4%) injuries were managed nonsurgically.

CONCLUSION

Shoulder and elbow injury rates and patterns in high school baseball players differed between field positions (pitchers vs position players) and by type of exposure (practice vs competition). This study suggests several areas of emphasis for targeted injury prevention interventions, most notably limiting fatigue and preventing overuse injuries.

Evaluation and management of shoulder pain in skeletally immature athletes

Shoulder pain in young athletes generally is a result of poor sports technique and overuse. A number intrinsic causes of shoulder pain have been identified. Pain may also be referred to shoulder area from cervical spine, neck and chest pathology. Overuse stress injury of the proximal humeral physis is important to recognize early in order to prevent later complications. Shoulder impingement syndrome is a general term used to describe multiple underlying lesions and relatively uncommon in young athletes. In adolescent athletes, glenohumeral instability is an important underlying pathomechanical basis for shoulder pain. Other less frequent causes reviewed here include atraumatic osteolysis of the distal clavicle, long thoracic and suprascapular neuropathies.

Elbow Injuries in the Young Throwing Athlete

Baseball pitchers and other throwing athletes place their elbows under tremendous stresses, making them vulnerable to a number of unique injuries. Skeletally immature throwers in particular are at a greater risk for growth plate and other bony injuries, due to the relative strengths of these tissues and the kinematics involved in throwing. Care should be taken to fully evaluate these injuries based on the particular history and presentation to properly direct treatment and rehabilitation. Patients, as well as other athletes, coaches, and families, also should be made aware of the significant risk factors for these injuries, especially those regarding pitch limits, proper mechanics, and sufficient rest.

Predictors of Ulnar Collateral Ligament Reconstruction in Major League Baseball Pitchers

BACKGROUND

Ulnar collateral ligament (UCL) reconstruction surgeries in Major League Baseball (MLB) have increased significantly in recent decades. Although several risk factors have been proposed, a scientific consensus is yet to be reached, providing challenges to those tasked with preventing UCL injuries.

PURPOSE

To identify significant predictors of UCL reconstruction in MLB pitchers.

STUDY DESIGN

Case control study; Level of evidence, 3.

METHODS

Demographic and pitching performance data were sourced from public databases for 104 MLB pitchers who underwent UCL reconstruction surgery and 104 age- and position-matched controls. These variables were compared between groups and inserted into a binary logistic regression to identify significant predictors of UCL reconstruction. Two machine learning models (naïve Bayes and support vector machine) were also employed to predict UCL reconstruction in this cohort.

RESULTS

The binary linear regression model was statistically significant (χ(2)(12) = 33.592; P = .001), explained 19.9% of the variance in UCL reconstruction surgery, and correctly classified 66.8% of cases. According to this model, (1) fewer days between consecutive games, (2) a smaller repertoire of pitches, (3) a less pronounced horizontal release location, (4) a smaller stature, (5) greater mean pitch speed, and (6) greater mean pitch counts per game were all significant predictors of UCL reconstruction. More specifically, an increase in mean days between consecutive games (odds ratio [OR], 0.685; 95% CI, 0.542-0.865) or number of unique pitch types thrown (OR, 0.672; 95% CI, 0.492-0.917) was associated with a significantly smaller likelihood of UCL reconstruction. In contrast, an increase in mean pitch speed (OR, 1.381; 95% CI, 1.103-1.729) or mean pitches per game (OR, 1.020; 95% CI, 1.007-1.033) was associated with significantly higher odds of UCL reconstruction surgery. The naïve Bayes classifier predicted UCL reconstruction with an accuracy of 72% and the support vector machine classifier with an accuracy of 75%.

CONCLUSION

This study identified 6 key performance factors that may present significant risk factors for UCL reconstruction in MLB pitchers. These findings could help to enhance the prevention of UCL reconstruction surgery in MLB pitchers and shape the direction of future research in this domain.

Risk Stratification for Ulnar Collateral Ligament Injury in Major League Baseball Players: A Retrospective Study From 2007 to 2014

BACKGROUND

Ulnar collateral ligament (UCL) injury has become increasingly common in Major League Baseball (MLB) players in recent years.

HYPOTHESIS

There is a significant difference in preinjury fastball velocity between MLB pitchers with tears and matched controls without UCL injury. Pitchers with injuries are throwing harder and getting injured earlier in their MLB careers.

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

From 2007 to 2014, a total of 170 documented UCL injuries (156 pitchers, 14 position players) occurred in MLB. Inclusion criteria for this study consisted of any player who tore his UCL in MLB during this time frame. There were 130 regular-season tears (April-September). From this group, 118 players who pitched more than 100 innings prior to tear were matched to subjects with no tear and were compared using a logistic regression analysis. A subgroup of "early tear" players who threw less than 100 career innings (n = 37) was also identified and compared with the larger tear group using a logistic regression analysis.

RESULTS

Of the 130 tears that occurred during the regular season, a significantly larger number (62%) occurred in the first 3 months (P = .011). The rate of UCL tears per MLB player (P = .001) was statistically significant. In the group of 118 matched tears, the mean fastball velocity was greater in the tear group (91.7 mph) compared with the control group (91.0 mph; P = .014). Furthermore, relief pitchers made up a greater percentage of the early tear group (<100 innings) compared with the later tear group (P = .011). Sixteen of the 170 UCL tears (9.4%) were recurrent tears, with 5 of 16 experiencing both tear and retear within the past 4 years.

CONCLUSION

There is a statistically significant difference in the mean fastball velocity of pitchers who injure their UCL. Small increases in pitcher fastball velocity are a main contribution to the increased rate of tear in MLB. In addition, there has been an increased incidence of injury in the first 3 months of the season. Finally, early tears are more likely to occur in relief pitchers than starters.