Shoulder Injuries in the Skeletally Immature Baseball Pitcher and Recommendations for the Prevention of Injury

Energy generation, absorption, and transfer at the shoulder and elbow in youth baseball pitchers

Performance during the baseball pitch is dependent on the flow of mechanical energy through the kinetic chain. Little is known about energy flow during the pitching motion and it is not known whether patterns of energy flow are related to pitching performance and injury risk. Therefore, the purpose of this study was to quantify energy generation, absorption, and transfer across the shoulder and elbow during the baseball pitch and explore the associations between these energetic measures, pitch speed, and traditional measures of upper extremity joint loading. The kinematics of 40 youth baseball pitchers were measured in a controlled laboratory setting. Energy flow between the thorax, humerus, and forearm was calculated using a segmental power analysis. Regression analyses revealed that pitch speed was best predicted by arm cocking phase shoulder energy transfer to the humerus and peak elbow valgus torque was best predicted by arm acceleration-phase elbow energy transfer to the forearm. Additionally, energy transfer across the shoulder and elbow generally exhibited the strongest correlations to pitch speed and upper extremity joint loads. These data reinforce the importance of energy transfer through the kinetic chain for producing high pitch speeds and provide descriptive data for energy flow during baseball pitching not previously found in the literature.

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.

A Model for Causality of Pitching-related Overuse Injuries in Women's Fastpitch Softball

Fastpitch softball is a popular women's sport, and athletes, particularly pitchers, are at high risk for overuse injury. Softball-related injury rates are low; however, the prevalence of overuse injuries is high. Injuries at the high school and collegiate levels occur early in the season, and approximately 50% of shoulder and elbow injuries in softball are attributable to overuse. Survey research showed 77% of high school pitchers pitch with pain, and 73% of collegiate pitchers reported an overuse injury in the previous season. Modifiable and non-modifiable intrinsic and extrinsic risk factors contribute to injury risk in a model that can be used in history taking, clinical examination, and management of softball-related injuries. In this manuscript, we present a scoping review of fastpitch softball injury research by competitive levels from 1990 to present. We also introduce a model for overuse injury causality in this athlete population. With this information, clinicians will be able to identify risk factors related to injury in softball pitchers. More research is needed to make evidence-based recommendations for injury prevention in this athlete population.

Youth Sport Specialization and Risk of Injury: A General Review

OBJECTIVE

The purpose of this literature review was to analyze, understand, and disclose prior empirical findings about the injury risks associated with youth sport specialization.

DATA SOURCES

Articles were included in this review if they examined the association between youth sport specialization status and injury. Nine articles from 5 journals met these criteria. All articles summarized the findings of cross-sectional (N = 5) or cohort studies (N = 4).

MAIN RESULTS

Each article included in this review indicated that specialized youth athletes are more susceptible to injury. Only 5 studies assessed the injury risks linked to specialization independent of sport training volume. These studies produced contradictory results.

CONCLUSIONS

Although specialized youth athletes are more prone to injury, future research is needed to determine the independent and inherent injury risk associated with specialization. Nevertheless, youth athletes should refrain from specialization until at least adolescence.

Injury Prevalence among Young Elite Baseball Players

This study aimed to describe the injury profiles of young Korean baseball players according to position and age as the proportion and distribution of injuries based on playing position and age remains unclear. A total of 271 elite youth baseball players aged 8 to 16 years were divided into two groups: elementary school (ES) (n = 135) and middle school (MS) (n = 136). The participants' basic, baseball practice, and injury information were collected. Injuries in the MS group were not limited to the elbow and shoulder, and injury prevalence varied by age group and baseball position. The most injured body region in the ES group was the elbow joint, regardless of the position. In contrast, the most injured body region in the MS group was the lower back, except for infielders whose elbows were the most injured. Additionally, the MS group was more likely to experience injuries to the lower back (OR = 4.27, 95% CI = 2.47-7.40), shoulder (OR = 1.93, 95% CI = 1.08-3.43; p = 0.024), and knee (OR = 2.15, 95% CI = 1.17-3.94; p = 0.012). Our findings indicate that excessive practice and a lack of rest during MS (growth spurt period) can significantly increase the risk of lower back problems in young baseball players.

The Kerlan-Jobe Orthopaedic Clinic Shoulder & Elbow Score used as a Patient-Reported Outcome Measure for the Youth and High School Aged Baseball Athlete

Background

The Kerlan-Jobe Orthopaedic Clinic Shoulder & Elbow Score (KJOC) provides questions for the overhead athlete that can aid with determining if someone is throwing with or without pain. However, this scale was initially created for the adult baseball athlete and has not been validated for younger male demographics.

Hypothesis/Purpose

To (1) determine if the scores on the KJOC are different between those throwing with and without pain in male youth and high school-aged baseball athletes, and (2) establish a prediction score for whether a young baseball athlete is throwing with symptoms.

Methods

The KJOC questionnaire was used to compare scores in male baseball players between the ages of 10 through 18. This questionnaire consists of 10 questions that each contain a 10-point visual analogue scale (VAS). When all questions are added together the highest possible score is 100 points, with a higher score equating to a better outcome of throwing without symptoms. Retrospective data from 28 subjects with throwing arm pain were compared to 28 prospective subjects actively participating in baseball with no pain. A Mann Whitney-U test was used to compare the mean scores, and regression analysis was used to establish a threshold score between those throwing with and without pain.

Results

Significant differences were found between the groups (U = 698.5, p < .001) with capability to discriminate those throwing with pain versus those throwing without pain (Area Under Curve (AUC) .891). Results indicate this discriminating threshold score to be at 68.6 points, which signifies anyone scoring above this threshold would be throwing with no pain and a score below this number indicating throwing with pain.

Conclusion

The KJOC can differentiate between younger baseball athletes throwing with and without pain. The predictive threshold score can be used in a clinical setting to aid with determining if a youth or high school-aged athlete is suffering from pain while participating in overhead throwing, and to guide rehabilitation management.

Level of Evidence

Level III.

Shoulder and Elbow Injuries in Elite Taiwanese High School Baseball Pitchers From 2016 to 2017

Background

Numerous studies have discussed the risk factors for shoulder and elbow injuries in high school baseball players worldwide.

Purpose

To determine the risk factors for pitching-related shoulder and elbow injuries in Taiwanese high school pitchers.

Study Design

Cross-sectional study; Level of evidence, 3.

Methods

Included in the study were 144 pitchers from 11 top-ranked Taiwanese high school baseball teams between 2016 and 2017 high school baseball season. The participants answered a 55-item questionnaire concerning physical characteristics, pitching activities, injury history, and off-season activities. Univariate analyses were conducted separately for participants with and those without a pitching-related injury in the 12-month study period. The chi-square test or Fisher exact test was applied to categorical variables, and the F test or t test was applied to continuous variables. A stepwise multivariate logistic regression analysis was used to identify factors related to pitching-related injuries, and those results were calculated as odds ratios (ORs).

Results

Having a pitching-related injury was significantly related to the number of pitches per week in the past 12 months (OR, 1.01; P = .006), pain over the shoulder and/or elbow in the past 12 months (OR, 3.56; P = .008), pitching competitive baseball for more than 8 of the past 12 months (OR, 2.53; P = .036), throwing sliders (OR, 2.97; P = .026), and lack of participating in other over-the-shoulder activities (0.03-0.11 fewer odds; P ≤ .010).

Conclusion

For elite high school pitchers in Taiwan, pitching-related shoulder and elbow injuries were related to the number of pitches per week, pitching competitive baseball for more than 8 of the past 12 months, pain over the shoulder and/or elbow in the past 12 months, throwing sliders, and a lack of participation in other sports with over-the-shoulder activities.

Youth Baseball Caregiver Understanding of Safe Pitching Guidelines and Player Injury

BACKGROUND

As more athletes participate in youth baseball, there has been an associated increase in upper extremity injuries. Knowledge of baseball injury prevention guidelines continues to be developed and defined as throwing-related injuries rise. The purpose of this study was to evaluate how knowledgeable youth baseball caregivers were about safe pitching guidelines and secondarily determine pitching practices which may be associated with increased risk of player injury.

METHODS

A twenty-two question survey comprised of demographic data, knowledge of overhead throwing guidelines, pitching history, presence of risk factors associated with overhead throwing and pitching habits was distributed to the caregivers of youth baseball pitchers in North Central Florida.

RESULTS

Eighty-three percent (81/98) of those polled were unaware of the existence of safe pitching guidelines, regardless of the pitcher's playing experience (p > 0.05). Those who pitched more than six months out of the year were significantly more prone to experience throwing arm pain after a performance (p < 0.05). Fifty-two percent (51/98) of the caregivers recalled their child having throwing arm pain as a direct result of pitching, with twenty-six percent (25/98) of pitchers having to miss either a game or a pitching appearance. Twenty-seven percent (26/98) of all players went on to seek medical evaluation for arm discomfort due to pitching. Pitchers 13 years of age and older were more likely to throw curveballs and miss games because of throwing arm pain (p < 0.05).

CONCLUSION

Despite implementation and accessibility of safe pitching guidelines, a large portion of those surveyed were unaware or noncompliant with these established recommendations. Given the results of this study, further measures need to be taken to improve caregivers' understanding of current guidelines to help increase compliance and protect youth pitchers.

LEVEL OF EVIDENCE

Cross-sectional survey study, 3b.

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.

Softball pitching mechanics and shoulder injuries: a narrative review

Softball is the third most popular women's collegiate sport in the United States, with 19,680 total athletes as of the 2015-2016 season. Despite its popularity and growth in recent years, research focusing on the biomechanics of the windmill pitch and its associated shoulder injuries is relatively scarce. The incidence of shoulder injury is highest during the preseason and the beginning of the regular season. The windmill pitch can be divided into distinct phases, with the shoulder experiencing the greatest force during the delivery phase. Significant demands placed on the shoulder during the windmill pitch put pitchers at a higher risk of developing shoulder injuries than position players. Maximum shoulder compression/distraction forces during the windmill pitch have been shown to be comparable to those experienced during the baseball overhand throw, dispelling the myth that the windmill pitch is not taxing on the shoulder. Injuries associated with the high compression/distraction forces include lesions to the rotator cuff, glenoid labrum, and biceps brachii. Pitcher-specific training, cross-training, and whole-body conditioning should be incorporated into current training regimens to decrease the risk of shoulder injuries.

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.

Curveballs in Youth Pitchers: A Review of the Current Literature

As the number of young people playing baseball has increased, so have the number of injuries. Throwing arm shoulder and elbow injuries are most common, and lead to both short and long-term consequences. Recent efforts have been made to identify risk factors for injury with corresponding regulations created to protect youth pitchers. Unlike rules enforcing pitch counts, prohibitions against curveballs are based on minimal objective evidence.

Review of Shoulder Range of Motion in the Throwing Athlete: Distinguishing Normal Adaptations from Pathologic Deficits

PURPOSE OF REVIEW

Overhand (OH) throwers demonstrate a unique motion profile of the shoulder joint complex. This manuscript reviews normal adaptations in the OH thrower and contrast findings with pathologic motion deficits.

RECENT FINDINGS

Multiple adaptations in range of motion have been associated with increased risk for arm injury. The use of a more conservative cutoff value for glenohumeral internal rotation deficit and horizontal adduction in younger throwers may help reduce injury risk. Deficits in glenohumeral internal rotation, total range of motion, shoulder flexion, and external rotation insufficiency have all been proposed as means to identify OH throwers at risk for arm injury, but conflicting evidence exists. Understanding normal adaptation due to repetitive stress of throwing is essential to effective management of these athletes. Adaptive change in bone and soft tissues is normal and contributes to the unique motion profiles expected in throwers. The causative link between normal adaptation and shoulder and elbow injury remains uncertain.

Distance-Based Throwing Programs for Baseball Players From Little League to High School

An estimated 2.4 million children play baseball in 80 countries. The majority of these children have experienced pain with throwing. A key component to a successful rehabilitation after an upper extremity injury for a baseball player is an interval throwing program, which allows a youth athlete to increase the demands of throwing in a progressive and controlled manner. Numerous interval throwing programs are designed for baseball players of high school age and older, but few exist for the baseball player who is skeletally immature. Our interval throwing programs take into consideration various field dimensions, injury types, and position requirements for youth. Our goal is to create a guide for rehabilitation specialists and players to return to throwing as quickly and safely as possible.

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.

[Shoulder pain rehabilitation in young athletes]

Early specialisation in sports continues to increase and is a risk factor for the incidence of injuries in young athletes. In overhead athletes, the shoulder is the most affected joint, related to a combination of impingement and glenohumeral instability, as well as musculoskeletal immaturity. Identification of risk factors and rehabilitation is usually an effective recovery option for these athletes.

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.

Youth Baseball Coach Awareness of Pitch Count Guidelines and Overuse Throwing Injuries Remains Deficient

BACKGROUND

Baseball is one of the most popular youth sporting activities. Youth pitchers remain at high risk for shoulder and elbow overuse injuries despite well-established recommendations on pitch count limits. The purpose of this investigation was to conduct surveys of youth baseball coaches evaluating the current state of understanding and compliance with youth pitch count guidelines and risk factors for overuse injuries.

METHODS

A total of 82 youth baseball coaches in surrounding suburban areas outside 2 separate Midwestern metropolitan cities were asked to answer an anonymous 13-question survey. Survey questions solicited demographic information of youth athletes coached, while assessing for incidence, knowledge of, and compliance with established recommendations on pitch count limits and upper extremity overuse injuries in youth pitchers.

RESULTS

In total, 61 of 82 (74%) coaches returned surveys. The majority of coaches reported coaching male athletes (89%, n=54) primarily between the ages of 11 to 12 years (51%, n=31). A total of 56% (n=34) of coaches reported "always" keeping track of pitch counts; however, 92% (n=56) reporting not keeping track of pitches based on established recommendations by the American Sports Medicine Institute, whereas 56% were noncompliant with age appropriate pitch count recommendations as established by the 2006 US Baseball Medical and Safety Advisory Committee. Only 13% (n=8) of coaches were able to correctly identify risk factors for overuse injuries while acknowledging the necessity of off-season strengthening. Thirty-eight percent (n=23) of coaches reported sitting out an athlete because of overuse injury, with the highest rates found in those coaching the youngest (≤8 and younger) and oldest (≥17 and older) age groups. Meanwhile, 15% (n=9) of coaches were noncompliant with age-based recommendations against throwing breaking pitches.

CONCLUSIONS

Knowledge regarding pitch count guidelines established to prevent overuse injuries to the shoulder and elbow in youth pitchers remains deficient in the cohort of coaches surveyed.

LEVEL OF EVIDENCE

Level IV-Case Series.

Pediatric Pain Syndromes and Noninflammatory Musculoskeletal Pain

Chronic musculoskeletal pain (CMP) is one of the main reasons for referral to a pediatric rheumatologist and is the third most common cause of chronic pain in children and adolescents. Causes of CMP include amplified musculoskeletal pain, benign limb pain of childhood, hypermobility, overuse syndromes, and back pain. CMP can negatively affect physical, social, academic, and psychological function so it is essential that clinicians know how to diagnose and treat these conditions. This article provides an overview of the epidemiology and impact of CMP, the steps in a comprehensive pain assessment, and the management of the most common CMPs.

Three-dimensional kinematic analysis of throwing motion focusing on pelvic rotation at stride foot contact

Background

Because the throwing motion can be considered a kinetic chain, pelvic and trunk motion should be included in the analysis. Early pelvic rotation during the throwing sequence has been reported to be a factor leading to overloading of the shoulder and the elbow. A large pelvic rotation angle at the stride foot contact (SFC) was thought to indicate early pelvic opening. This study examined the kinematic features in each motion segment associated with increased pelvic rotation at SFC in pitchers of various ages and competition levels.

Materials and methods

The study included 324 pitchers with various age/competition levels. Throwing motion was analyzed using an infrared-type motion capture system. In the assessment, pelvic rotation angle at SFC was adopted as a parameter for the timing of pelvic opening. Statistical analyses were performed for correlation between pelvic rotation and kinematic variables of other motion segments at the instant of SFC as well as the difference in kinematics between the groups of different levels.

Results

Most of the kinematic results were not significantly different among the 4 groups with different levels. The increase in the pelvic opening angle at SFC was significantly correlated with increased trunk bend to the nonthrowing arm side and decreased hip flexion angle on the throwing arm side.

Discussion and Conclusion

Early pelvic rotation in the throwing motion sequence, as manifested by increased pelvic rotation at SFC, was correlated with changes in kinematic parameters at other motion segments such as increased trunk tilt and decreased hip flexion.

Little League Shoulder in a 15-Year-Old Male Baseball Pitcher

A 15-year-old baseball pitcher presented to physical therapy with a 1-week history of acute right shoulder pain experienced during the acceleration phase of throwing. The week after physical therapy evaluation, the patient returned with radiographs and magnetic resonance imaging results that revealed lateral physeal widening with adjacent edema. Additionally, a nondisplaced labral tear was noted. In this case, imaging was necessary for an accurate diagnosis of lateral physeal widening, commonly referred to as "Little League shoulder." J Orthop Sports Phys Ther 2018;48(1):51. doi:10.2519/jospt.2018.7369.

Overuse Injuries of the Pediatric and Adolescent Throwing Athlete

In the hypercompetitive environment of year round youth baseball, arm pain is commonplace. Although much research has been done about injuries in the overhead throwing athlete, the emphasis has been on the more elite levels, where athletes have reached full development. The anatomy of the skeletally immature athlete, including open physeal plates and increased tissue laxity, raises unique issues in the presentation and treatment of repetitive throwing injuries of the elbow and shoulder. With a focus on "little leaguers," this discussion evaluates five of the most common elbow and shoulder injuries-Little Leaguer's elbow, ulnar collateral ligament sprain or tear, osteochondritis dissecans/Panner's disease, Little Leaguer's shoulder, and multidirectional instability. In the developmentally distinct pediatric athlete, pathogenesis, diagnosis, and treatment may differ from that established for adults. Offering early diagnosis and treatment appropriate to a child's level of development will enable youth to not only continue to play sports but to also maintain full functionality as active adults.

Risk factors for shoulder and elbow pain in youth baseball players

OBJECTIVES

This study sought to quantify the 1-year cumulative incidence of shoulder and elbow pain among youth baseball players and identify risk factors associated with the occurrence of shoulder and elbow pain.

METHODS

In total, 900 youth baseball players (aged 7-11 years) were enrolled in a 1-year prospective follow-up study. One year later, the players were asked whether they had experienced episodes of shoulder or elbow pain and the following risk factors for such pain were investigated: age, position, length of baseball experience, training hours per week, and history of shoulder or elbow pain. Data for the groups with and without shoulder or elbow pain were analyzed using multivariate logistic regression models.

RESULTS

Episodes of shoulder pain were reported by 18.3% of players and episodes of elbow pain were reported by 35.2% of players. Multivariate analysis showed that shoulder pain was associated with pitcher position, catcher position, longer training hours per week, and history of shoulder and elbow pain, and that elbow pain was associated with age, pitcher position, catcher position, longer training hours per week, and history of elbow pain. Length of baseball experience was not associated with shoulder or elbow pain.

CONCLUSION

History of elbow pain, pitcher position, catcher position, and longer training hours per week were associated with both types of pain. History of shoulder pain was associated with shoulder pain but not elbow pain. Age was associated with elbow pain but not shoulder pain.

Shoulder pain in adolescent athletes: prevalence, associated factors and its influence on upper limb function

BACKGROUND

Sports that require the constant use of an upper limb demand the maximum kinetic chain efficiency in this segment. Immaturity of the musculoskeletal system, followed by failure in motor skills can expose adolescents to major reports of pain complaints, particularly for the shoulder.

OBJECTIVE

To evaluate the prevalence of shoulder pain in adolescent athletes and identify possible factors associated with the complaint.

METHOD

A total of 310 athletes, of both sexes and aged between 10 and 19 years old participated on this study. The subjects filled out a questionnaire with personal, sports and upper limb function (Quick-DASH) questions. We evaluated the height, body mass, shoulder rotation range and stability of the upper limb using the CKCUES-test. The association between pain and the variables was analyzed using multilevel modeling logistic regression. We used the Mann-Whitney test for comparing between pain and function.

RESULTS

The prevalence of shoulder pain was 43.5%. Athletes between 15 and 19 years, handball and judo practitioners, are 1.86, 2.14 and 3.07 more likely to report shoulder pain, respectively, when compared with other sports and ages. Shoulder pain reduced function scores (p<0.001) and increased changes in the range of motion (p<0.04).

CONCLUSION

Shoulder pain is highly prevalent and is associated especially with older adolescent athletes of handball and judo, and affects the levels of function and the range of the shoulder.

The Youth Throwing Score: Validating Injury Assessment in Young Baseball Players

BACKGROUND

Epidemic levels of shoulder and elbow injuries have been reported recently in youth and adolescent baseball players. Despite the concerning frequency of these injuries, no instrument has been validated to assess upper extremity injury in this patient population. Purpose/Hypothesis: The purpose of this study was to validate an upper extremity assessment tool specifically designed for young baseball players. We hypothesized that this tool will be both reliable and valid.

STUDY DESIGN

Cohort study (diagnosis); Level of evidence, 2.

METHODS

The Youth Throwing Score (YTS) was constructed by an interdisciplinary team of providers and coaches as a tool to assess upper extremity injury in youth and adolescent baseball players (age range, 10-18 years). The psychometric properties of the test were then determined.

RESULTS

A total of 223 players completed the final survey. The players' mean age was 14.3 ± 2.7 years. Pilot analysis showed that none of the 14 questions received a mean athlete importance rating less than 3 of 5, and the final survey read at a Flesch-Kincaid level of 4.1, which is appropriate for patients aged 9 years and older. The players self-assigned their injury status, resulting in a mean instrument score of 59.7 ± 8.4 for the 148 players "playing without pain," 42.0 ± 11.5 for the 60 players "playing with pain," and 40.4 ± 10.5 for the 15 players "not playing due to pain." Players playing without pain scored significantly higher than those playing with pain and those not playing due to pain ( P < .001). Psychometric analysis showed a test-retest intraclass correlation coefficient of 0.90 and a Cronbach alpha intra-item reliability coefficient of 0.93, indicating excellent reliability and internal consistency. Pearson correlation coefficients of 0.65, 0.62, and 0.31 were calculated between the YTS and the Pediatric Outcomes Data Collection Instrument sports/physical functioning module, the Kerlan-Jobe Orthopaedic Clinic Shoulder and Elbow score, and the Quick Disabilities of the Arm, Shoulder, and Hand (QuickDASH) score, respectively. Injured players scored a mean of 9.4 points higher after treatment ( P < .001), and players who improved in their self-assigned pain categorization scored 16.5 points higher ( P < .001).

CONCLUSION

The YTS is the first valid and reliable instrument for assessing young baseball players' upper extremity health.

Epidemiology of shoulder and elbow pain in youth baseball players

OBJECTIVES

There are relatively few published epidemiological studies examining the differences in the risk of shoulder and elbow pain in young baseball players. The purpose of this study was to investigate risk factors for shoulder and elbow pain in child and adolescent baseball players.

METHODS

A total of 1563 players aged 7 to 12 years participated in this investigation. Subjects were asked whether they had experienced episodes of shoulder or elbow pain. We investigated the following risk factors for shoulder and elbow pain: age, position, years of baseball experience, and training hours per week. Data from the groups with and without shoulder and elbow pain were analyzed using multivariate logistic regression models.

RESULTS

Among the 1563 participants, 15.9% and 29.2% reported episodes of shoulder and elbow pain, respectively. Multivariate analysis showed that shoulder pain was associated with age 10, 11, and 12 years, and that elbow pain was associated with age 10, 11, and 12 years, playing catcher, and >2 years of baseball experience. Training hours per week were not associated with either shoulder or elbow pain.

CONCLUSION

In over 1000 baseball players aged 7 to 12 years, 15.9% reported episodes of shoulder pain, while 29.2% reported elbow pain in the throwing arm. The associated risk factors were different for each type of pain. Shoulder pain was associated with increased age while elbow pain was associated with increased age, increased years of baseball experience, and playing catcher.

Youth Baseball Pitching Stride Length: Normal Values and Correlation With Field Testing

BACKGROUND

Pitching biomechanical analysis has been recommended as an important component of performance, injury prevention, and rehabilitation. Normal values for youth pitching stride length have not been established, leading to application of normative values found among professional pitchers to youth pitchers.

HYPOTHESES

The average youth pitching stride length will be significantly less than that of college and professional pitchers. There will be a positive correlation between stride length, lower extremity power, balance, and pitching experience.

STUDY DESIGN

Prospective cohort study.

LEVEL OF EVIDENCE

Level 3.

METHODS

Ninety-two youth baseball pitchers (aged 9-14 years) met the inclusion/exclusion criteria and completed the study. Stride length was recorded using a Dartfish video system over 3 maximal effort pitches. Both intra- and interrater reliability was calculated for the assessment of stride length. Double-leg vertical jump, single-leg stance time, leg length, weight, age, and pitching experience were also recorded.

RESULTS

Mean (SD) stride length was 66.0% (7.1%) of height. Stride length was correlated ( P < 0.01) with vertical jump (0.38), pitching experience (0.36), and single-leg balance (0.28), with excellent intra- and interrater reliability (0.985 or higher). No significant correlations between stride length and body weight, leg length, or age existed.

CONCLUSIONS

There was a significant difference between youth pitching stride length and the current published norms for older and more elite throwers. There was a positive correlation between stride length and lower extremity power, pitching experience, and single-leg balance.

CLINICAL RELEVANCE

Two-dimensional analysis of stride length allows for the assessment of pitching biomechanics in a practical manner. These values can be used for return to pitching parameters after an injury and designing injury prevention and performance programs.

Shoulder Injuries in Pediatric Athletes

Shoulder injuries in pediatric athletes are typically caused by acute or overuse injuries. The developing structures of the shoulder lead to injury patterns that are distinct from those of adult athletes. Overuse injuries often affect the physeal structures of the proximal humerus and can lead to pain and loss of sports participation. Shoulder instability is common in pediatric athletes, and recurrence is also a concern in this population. Fractures of the proximal humerus and clavicle are typically treated with conservative management, but there is a trend toward surgical intervention.

Biomechanical modeling as a practical tool for predicting injury risk related to repetitive muscle lengthening during learning and training of human complex motor skills

Previous studies have shown that muscle repetitive stress injuries (RSIs) are often related to sport trainings among young participants. As such, understanding the mechanism of RSIs is essential for injury prevention. One potential means would be to identify muscles in risk by applying biomechanical modeling. By capturing 3D movements of four typical youth sports and building the biomechanical models, the current study has identified several risk factors related to the development of RSIs. The causal factors for RSIs are the muscle over-lengthening, the impact-like (speedy increase) eccentric tension in muscles, imbalance between agonists and antagonists, muscle loading frequency and muscle strength. In general, a large range of motion of joints would lead to over-lengthening of certain small muscles; Limb’s acceleration during power generation could cause imbalance between agonists and antagonists; a quick deceleration of limbs during follow-throughs would induce an impact-like eccentric tension to muscles; and even at low speed, frequent muscle over-lengthening would cause a micro-trauma accumulation which could result in RSIs in long term. Based on the results, the following measures can be applied to reduce the risk of RSIs during learning/training in youth participants: (1) stretching training of muscles at risk in order to increase lengthening ability; (2) dynamic warming-up for minimizing possible imbalance between agonists and antagonists; (3) limiting practice times of the frequency and duration of movements requiring strength and/or large range of motion to reducing micro-trauma accumulation; and (4) allowing enough repair time for recovery from micro-traumas induced by training (individual training time). Collectively, the results show that biomechanical modeling is a practical tool for predicting injury risk and provides an effective way to establish an optimization strategy to counteract the factors leading to muscle repetitive stress injuries during motor skill learning and training.

Adaptations of the Shoulder to Overhead Throwing in Youth Athletes

CONTEXT

The high number of repetitions and high forces associated with overhead throwing lead to anatomical adaptations, such as humeral retrotorsion and posterior-capsule thickness, in elite and professional baseball athletes. However, little is known about the origin and progression of these changes that may account for the increasing trend of chronic shoulder injuries in youth baseball and precipitate subsequent pathologic conditions throughout a young athlete's lifetime.

OBJECTIVE

To investigate the relationship of age and upper extremity dominance on humeral retrotorsion, posterior-capsule thickness, and glenohumeral range of motion.

DESIGN

Cross-sectional study.

SETTING

Research laboratory, local baseball fields, and training facilities.

PATIENTS OR OTHER PARTICIPANTS

Thirty-six boys (mean age = 10.94 ± 1.34 years, height = 151.31 ± 12.17 cm, mass = 42.51 ± 10.32 kg) ranging in age from 8 to 12 years and involved in organized youth baseball.

MAIN OUTCOME MEASURE(S)

Diagnostic ultrasound was used to determine humeral retrotorsion and posterior-capsule thickness. Glenohumeral internal rotation and external rotation were measured using a handheld inclinometer. We used 2 × 2 mixed-model analyses of variance to compare the influence of limb dominance and age on the dependent variables of humeral retrotorsion, posterior-capsule thickness, internal rotation, and external rotation.

RESULTS

The dominant shoulders of youth throwers exhibited less glenohumeral internal rotation but greater humeral retrotorsion, posterior-capsule thickness, and glenohumeral external rotation than the nondominant shoulders. Dominant internal rotation was greater in the 8- to 10-year-old group than in the 11- to 12-year-old group, and results trended toward a difference (F1,33 = 4.12, P = .05). Correlations existed between humeral retrotorsion and range of motion (P < .05).

CONCLUSIONS

The structural adaptations in the dominant shoulders of younger baseball players were similar to adaptations observed in older baseball athletes, indicating that more examination is needed in younger athletes. We are the first to demonstrate greater posterior-capsule thickness in the dominant shoulders of youth baseball athletes.

Arm pain in youth baseball players: a survey of healthy players

BACKGROUND

Overuse injury in youth baseball players is increasing in prevalence, and these injuries have been correlated to pitching mechanics and pitch counts/types. Prior studies regarding arm pain in these athletes have focused simply on presence or absence of pain during the season rather than on detailed factors related to arm pain with respect to frequency, severity, and associated performance and psychosocial effect.

HYPOTHESIS/PURPOSE

The goal of this study was to investigate frequency, quality, and effect of arm pain in healthy youth baseball players. The hypothesis was that arm pain will affect a majority of healthy baseball players and will be associated with adverse psychosocial effects.

STUDY DESIGN

Descriptive epidemiological study.

METHODS

A novel survey focusing on arm pain in youth baseball players was developed for the purpose of this study. Survey questions were formulated by a consortium of trainers, clinicians, and coaches. Surveys were administered to healthy youth baseball players throughout the states of New Jersey and New York.

RESULTS

A total of 203 healthy players completed the survey; 23% of players (n=47) reported a prior overuse injury. Only 26% and 20% of players reported that their arm never hurt when throwing or the day after throwing, respectively; 30% of players reported that arm pain at least sometimes caused them to have less fun playing; and 46% of players reported at least once being encouraged to keep playing despite having arm pain. Pitchers were more likely to report arm pain while throwing and the day after throwing and to indicate that arm pain held them back from being a better player (all P<.05). Those with prior overuse injury were more likely to have arm pain while throwing, to have arm fatigue during a game or practice, and to be encouraged to keep playing despite having pain (all P<.05).

CONCLUSION

A majority of healthy (actively competing) youth baseball players report at least some baseline arm pain and fatigue, and many players suffer adverse psychosocial effects from this pain.

Common overuse injuries in the young athlete

Pediatric overuse injury is a common complaint presenting to pediatricians. Overuse injury can affect the soft tissues or bone, and results from an imbalance between training and load to the tissues and recovery time. In the skeletally immature athlete, physeal and apophyseal tissue is particularly vulnerable to overuse resulting in different patterns of injury compared to adults. Awareness of age-dependent patterns of overuse is necessary for proper recognition, treatment, and prevention of injury. This article reviews the most common pediatric overuse injuries with emphasis on risk factors, diagnosis, and treatment. Guidelines for prevention are included, as this is the key component for successful management of overuse injury in pediatric athletes.

Risk Factors for Shoulder and Elbow Injuries in High School Baseball Pitchers: The Role of Preseason Strength and Range of Motion

BACKGROUND

Shoulder strength and motion deficits in high school baseball pitchers have been implicated in injury risk.

PURPOSE/HYPOTHESIS

To prospectively determine if preseason strength and range of motion (ROM) are predictive of injury in high school baseball pitchers. It was hypothesized that ROM asymmetries and weakness would be predictive of injury.

STUDY DESIGN

Case-control study; Level of evidence, 3.

METHODS

Preseason strength and ROM measurements were made on 101 pitchers from 4 different high schools over 4 seasons (total 166 pitcher-seasons: 25 freshman, 46 junior varsity, and 95 varsity player-seasons). Glenohumeral internal rotation (IR), glenohumeral external rotation, and posterior shoulder ROM were measured bilaterally. Strength in IR, external rotation, supraspinatus (empty-can test), and scapular retraction was measured bilaterally (handheld dynamometer). Injury incidence (injuries per 1000 pitches) was computed for players categorized as above normal (≥1 SD above the mean), normal (within 1 standard deviation of the mean), and below normal (≤1 SD below the mean) for each potential risk factor. Injury was defined as a missed game or practice because of shoulder or elbow problem.

RESULTS

There were 28 upper extremity injuries (19 shoulder, 9 elbow; incidence, 0.58 injuries/1000 pitches). There was a trend for supraspinatus weakness to be associated with increased injury risk (relative risk [RR], 3.60; 95% CI, 0.75-17.32; P = .09). When analyzing major injuries only (>3 missed games), preseason supraspinatus weakness was significantly associated with increased injury risk (RR, 4.58; 95% CI, 1.40-15.01; P = .02). Paradoxically, pitchers with no IR loss were at increased risk compared with pitchers with ≥20° loss (RR, 4.85; 95% CI, 1.01-23.29; P = .04). Other ROM and strength measures were unrelated to injury risk.

CONCLUSION

Although excessive loss of IR ROM is thought to be a risk factor for injury, the opposite was the case in this study. The absence of IR ROM loss in high school pitchers may indicate inadequate prior exposure to pitching, resulting in increased injury risk. Preseason supraspinatus weakness was associated with increased risk for a major injury, and preventative supraspinatus strengthening may be beneficial.

The thrower's shoulder

Throwers, or athletes who engage in repetitive overhead motions, are a unique subset of athletes that experience distinct shoulder injuries. Athletes engaged in baseball comprise the majority of patients seeking orthopedic care for throwing related injuries. Injuries specific to throwers most commonly involve the labrum and the undersurface of the rotator cuff. In addition, tissue changes in both the anterior and posterior glenohumeral capsule are common with repetitive overhead motions. These capsular changes alter. This article will examine the pathomechanics of injuries to throwers, elaborate means of diagnoses of cuff and labral injury and discuss recent advances in both non-operative and operative interventions, including preventative principles.

Risk-Prone Pitching Activities and Injuries in Youth Baseball: Findings From a National Sample

BACKGROUND

There are relatively few published epidemiological studies that have correlated pitching-related risk factors with increased pitching-related arm problems as well as injuries.

HYPOTHESIS

High pitching volume and limited recovery will lead to arm fatigue, thus placing young pitchers at a greater risk for elbow and shoulder problems and, subsequently, an increased risk for arm injuries.

STUDY DESIGN

Cross-sectional study; Level of evidence, 3.

METHODS

A national survey was conducted among 754 youth pitchers (ages 9 to 18 years) who had pitched in organized baseball leagues during the 12 months before the survey. Self-reported risk-prone pitching activities were identified and compared with recommendations by the American Sports Medicine Institute. Relationships between self-reported pitching activities, shoulder and elbow problems, and injuries were assessed using multivariable logistic regression.

RESULTS

Of the 754 participating pitchers, 43.4% pitched on consecutive days, 30.7% pitched on multiple teams with overlapping seasons, and 19.0% pitched multiple games a day during the 12 months before the study. Pitchers who engaged in these activities had increased risk of pitching-related arm pain (odds ratio [OR] = 2.53, 95% confidence interval [CI] = 1.14-5.60; OR = 1.85, 95% CI = 1.02-3.38; OR = 1.89, 95% CI = 1.03-3.49, respectively). Nearly 70% of the sample reported throwing curveballs, which was associated with 1.66 (95% CI = 1.09-2.53) greater odds of experiencing arm pain while throwing. Pitching-related arm tiredness and arm pain were associated with increased risk of pitching-related injuries. Specifically, those who often pitched with arm tiredness and arm pain had 7.88 (95% CI = 3.88-15.99) and 7.50 (95% CI = 3.47-16.21) greater odds of pitching-related injury, respectively. However, pitching on a travel baseball club, playing baseball exclusively, or playing catcher were not associated with arm problems.

CONCLUSION

The results of this study, along with those of others, reinforce the importance of avoiding risk-prone pitching activities to prevent pitching-related injuries among youth pitchers.

Comparison of the morphology of the rotator cuff muscles across age groups

We aimed at investigating the morphological difference of the rotator cuff (RC) muscles among age groups from elementary school students to college students. The subjects included 10 college (22.6 ± 1.8 years), 10 high school (16.8 ± 0.6 years), 10 junior high school (13.9 ± 0.6 years), and 10 elementary school (10.4 ± 0.5 years) students. Consecutive oblique sagittal magnetic resonance T1 -weighted images of the dominant shoulder were acquired for each participant. Muscle length, maximal anatomical cross-sectional area (ACSA), the position of the maximal ACSA at full muscle length, muscle volume, and the individual-to-total RC muscle volume ratio for the supraspinatus, external rotators (infraspinatus and teres minor), and subscapularis were evaluated. The muscle length, maximal ACSA, and muscle volume in the RC muscles significantly increased with increasing age (P < 0.01), but there was no significant difference between college and high school students except in regard to the volume of the external rotators. There was no difference in the position of the maximal ACSA or the individual-to-total RC muscle volume ratio among the groups. The findings of this study show that the size of each RC muscle increases with increasing age, but the position of maximal ACSA and the proportion of each muscle to the total RC muscle volume are similar among age groups from elementary school students to college students.