Arm Injury in Youth Baseball Players: A 10-Year Cohort Study

BACKGROUND

Arm injuries are commonly encountered in baseball as young athletes play into adulthood. The purpose of this study was to examine the incidence of arm injury and risk for surgery in adolescent baseball players followed over a 10-year period from scholastic, age-group, and travel baseball leagues through their highest level of competition.

METHODS

A prospective study was conducted enrolling middle and high school baseball players in 2010-2012, then followed for 10 years or until retirement from competitive baseball. Players were included if fully participating in team activities at the time of pre-season study enrollment. Players with prior arm (shoulder or elbow) surgery or those diagnosed with time loss arm injury within the past year were excluded. Only shoulder and elbow overuse problems resulting in time-loss from sport and medical attention from a sports medicine physician or orthopedic surgeon were documented as injuries in this study. Musculoskeletal overuse injuries were classified based on the orchard injury classification system. Incidence proportion (IP) and risk ratio (RR) and 95% confidence intervals (CI) for initial injury and injuries requiring surgery were calculated.

RESULTS

A total of 261 pitchers (Age: 14.2 ± 2.6; Follow-up: 4.2 ± 2.7 years) were enrolled. Twenty percent of the cohort was followed for 7 or more years. The overall injury incidence was 25.6/100 athletes (95% CI=21-31) with a cumulative surgical incidence of 5.4/100 athletes (95% CI= 3.2-8.8). The risk of experiencing shoulder injury (n=25) and elbow injury (n= 38) were similar (n= 38) (RR= 0.7; 95% CI= 0.4- 1.1). The athletes also presented with a similar frequency of requiring surgery regardless of the injured body part. However, the risk of surgery in those playing beyond the high school level was 4.3 times greater (95% CI, 1.2-15.0) than those only playing high school.

CONCLUSION

This is the first study to follow a large cohort of youth baseball players as they progress, showing a relatively high arm injury incidence. Shoulder and elbow injury incidence was similar but surgical risk increased playing beyond high school, specifically for the elbow. The high injury frequency and burden of care required by young baseball players as reported in this study is concerning and strategies to reduce injury should be investigated.

Development of an Injury Burden Prediction Model in Professional Baseball Pitchers

Background

Baseball injuries are a significant problem and have increased in incidence over the last decade. Reporting injury incidence only gives context to rate but not in relation to severity or injury time loss.

Hypothesis/Purpose

The purpose of this study was to 1) incorporate both modifiable and non-modifiable factors to develop an arm injury burden prediction model in Minor League Baseball (MiLB) pitchers; and 2) understand how the model performs separately on elbow and shoulder injury burden.

Study Design

Prospective longitudinal study.

Methods

The study was conducted from 2013 to 2019 on MiLB pitchers. Pitchers were evaluated in spring training arm for shoulder range of motion and injuries were followed throughout the season. A model to predict arm injury burden was produced using zero inflated negative binomial regression. Internal validation was performed using ten-fold cross validation. Subgroup analyses were performed for elbow and shoulder separately. Model performance was assessed with root mean square error (RMSE), model fit (R2), and calibration with 95% confidence intervals (95% CI).

Results

Two-hundred, ninety-seven pitchers (94 injuries) were included with an injury incidence of 1.15 arm injuries per 1000 athletic exposures. Median days lost to an arm injury was 58 (11, 106). The final model demonstrated good prediction ability (RMSE: 11.9 days, R2: 0.80) and a calibration slope of 0.98 (95% CI: 0.92, 1.04). A separate elbow model demonstrated weaker predictive performance (RMSE: 21.3; R2: 0.42; calibration: 1.25 [1.16, 1.34]), as did a separate shoulder model (RMSE: 17.9; R2: 0.57; calibration: 1.01 [0.92, 1.10]).

Conclusions

The injury burden prediction model demonstrated excellent performance. Caution should be advised with predictions between one to 14 days lost to arm injury. Separate elbow and shoulder prediction models demonstrated decreased performance. The inclusion of both modifiable and non-modifiable factors into a comprehensive injury burden model provides the most accurate prediction of days lost in professional pitchers.

Level of Evidence

2.

Assessing the ability of an instrumental variable causal forest algorithm to personalize treatment evidence using observational data: the case of early surgery for shoulder fracture

Background

Comparative effectiveness research (CER) using observational databases has been suggested to obtain personalized evidence of treatment effectiveness. Inferential difficulties remain using traditional CER approaches especially related to designating patients to reference classes a priori. A novel Instrumental Variable Causal Forest Algorithm (IV-CFA) has the potential to provide personalized evidence using observational data without designating reference classes a priori, but the consistency of the evidence when varying key algorithm parameters remains unclear. We investigated the consistency of IV-CFA estimates through application to a database of Medicare beneficiaries with proximal humerus fractures (PHFs) that previously revealed heterogeneity in the effects of early surgery using instrumental variable estimators.

Methods

IV-CFA was used to estimate patient-specific early surgery effects on both beneficial and detrimental outcomes using different combinations of algorithm parameters and estimate variation was assessed for a population of 72,751 fee-for-service Medicare beneficiaries with PHFs in 2011. Classification and regression trees (CART) were applied to these estimates to create ex-post reference classes and the consistency of these classes were assessed. Two-stage least squares (2SLS) estimators were applied to representative ex-post reference classes to scrutinize the estimates relative to known 2SLS properties.

Results

IV-CFA uncovered substantial early surgery effect heterogeneity across PHF patients, but estimates for individual patients varied with algorithm parameters. CART applied to these estimates revealed ex-post reference classes consistent across algorithm parameters. 2SLS estimates showed that ex-post reference classes containing older, frailer patients with more comorbidities, and lower utilizers of healthcare were less likely to benefit and more likely to have detriments from higher rates of early surgery.

Conclusions

IV-CFA provides an illuminating method to uncover ex-post reference classes of patients based on treatment effects using observational data with a strong instrumental variable. Interpretation of treatment effect estimates within each ex-post reference class using traditional CER methods remains conditional on the extent of measured information in the data.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12874-022-01663-0.

Heads Up Football Training Decreases Concussion Rates in High School Football Players

OBJECTIVE

The objective of this study was to determine whether football players receiving heads up (HU) training would display a lower rate of sport-related concussion (SRC) compared to those without HU training.

DESIGN

Prospective cohort.

SETTING

Scholastic football fields.

PATIENTS

Two thousand five hundred fourteen scholastic football players during the 2015 to 2016 football season were monitored throughout the football season.

INTERVENTIONS

Before the preseason, 1 coach from 14 schools received HU training from US football. These schools were matched with 10 control schools performing standard football training [non-heads up (NHU)]. Random monitoring for proper coaching instruction was performed during the season. School athletic trainers monitored injuries and return to sport over the season for all schools.

MAIN OUTCOME MEASURES

The outcome measures of concussions and associated time loss were determined before data collection began. Injury incidence and rate ratios were calculated to determine program effectiveness.

RESULTS

During the season, football players sustained 117 concussions (HU = 75; NHU = 42). The HU players displayed a significantly lower concussion rate (4.1 vs 6.0/100 players) compared with NHU teams [rate ratio = 1.5; 95% confidence interval (CI), 1.1-5.4]. The HU group returned to full participation 27% faster than athletes in the NHU group [time loss: 18.2 days (95% CI, 15.8-20.6) vs 24.8 days (95% CI, 19.9-29.7)], respectively.

CONCLUSIONS

This is the first study to evaluate the impact of the HU program on the incidence of SRC in high school football players. Our data demonstrated that the HU program reduced SRC rates by 33% supporting the use of US HU football training as an effective method to decrease the rate of SRCs in scholastic football.

CLINICAL RELEVANCE

This study is the first to prospectively explore the effect of HU training on the incidence and recovery from SRC in high school football players.

Lower Extremity Musculoskeletal Injury Is Associated with Increased Risk of Concussion in High School Athletes

Objectives:

Previous research indicates that concussion increases the risk of lower extremity injuries (LE) after return to sport. However, no study has examined the risk of precedent lower extremity injuries and their relationship to the development of a sport related concussion (SRC). To determine if the risk of combined injuries (LE injury-SRC) is elevated in high school athletes accounting for athlete sport and gender.

Methods:

33,386 high school athletes were monitored over 4 seasons. 4223 LE injuries and 1132 concussions were reported. Injured athletes were identified by their school athletic trainer (AT) time-loss injury during a team-sponsored practice or game. ATs documented the date, mechanism, and sport of injury. Injured athletes were referred to a board-certified sports medicine physician for diagnoses and follow up care. Cumulative injury rates were calculated with 95% confidence intervals. Rate ratios were used to compare frequency of SRC after RTS following a LE injury. Comparisons were made overall cohort between those participating athletes with and without isolated and combined injuries as well as by gender. (α=0.05).

Results:

A cumulative incidence for athletes sustaining an isolated SRC was 2.3/100 athletes (95% CI= 2.1-2.5) and for isolated LE injury was 11.5/100 (95% CI=11.2-11.9) athletes. Athletes presenting with a LE injury had an increased risk (RR= 4.7; 95% CI = 4.2-5.2) of sustaining a subsequent SRC within 1 year when compared to athletes that did not suffer precedent LE injuries. Male athletes presenting with a LE injury had an increased risk (RR= 4.9; 95% CI = 4.2-5.7) of sustaining a subsequent SRC within 1 year when compared to male athletes that did not suffer precedent LE injuries. Female athletes presenting with a LE injury had an increased risk (RR= 4.4; 95% CI = 3.6-5.2) of sustaining a subsequent SRC within 1 year when compared to female athletes that did not suffer precedent LE injuries. In football, presenting with a LE injury had an increased risk (RR= 5.8; 95% CI = 4.5-7.4) of sustaining a subsequent SRC within 1 year when compared to football athletes that did not suffer precedent LE injuries.

Conclusion:

Our results are the first to show that high school athletes who suffer a time-loss LE injury are at 4.4-5.8 times increased risk to suffer a sports related concussion within the next year. Additional studies are warranted to confirm these findings.

Is residual tendon a predictor of outcome following arthroscopic rotator cuff repair? A preliminary outlook at short-term follow-up

BACKGROUND

Multiple factors including muscle atrophy, fatty infiltration, smoking, advanced patient age, and increasing tear size have been identified as risk factors for retear after rotator cuff repair. However, little is known about what effect the length of the residual rotator cuff tendon has on the success of repair and patient outcomes.

METHODS

This study included 64 patients. Patients were stratified based on a residual tendon length of greater than 15 mm (group 1, residual tendon) or 15 mm or less (group 2, no residual tendon). Rotator cuff tendon integrity was then evaluated using ultrasound imaging at 6 months. Outcome measures included the Single Assessment Numeric Evaluation score, visual analog scale score, EQ5D Index score, Global Rating of Change score, and Penn Shoulder Score.

RESULTS

No differences were found between groups regarding demographic data or repair configuration. Assessment of tendon healing demonstrated an increased rate of tendons that had "not healed" in group 2 (19.3% [n = 5] vs. 13.2% [n = 5]), but this difference was not statistically significant (P = .55). Functional outcome scores improved significantly from preoperatively to final follow-up in both groups and displayed no differences at 6-month follow-up.

CONCLUSION

A smaller residual tendon length was not a negative predictor of clinical outcomes following arthroscopic rotator cuff repair in patients with short-term follow-up. Although there was a trend toward a decreased rate of healing in patients with smaller residual tendons, this was not significant.

Association of Surgical Treatment With Adverse Events and Mortality Among Medicare Beneficiaries With Proximal Humerus Fracture

IMPORTANCE

Meta-analyses of randomized clinical trials suggest that the advantages and risks of surgery compared with conservative management as the initial treatment for proximal humerus fracture (PHF) vary, or are heterogeneous across patients. Substantial geographic variation in surgery rates for PHF suggests that the optimal rate of surgery across the population of patients with PHF is unknown.

OBJECTIVE

To use geographic variation in treatment rates to assess the outcomes associated with higher rates of surgery for patients with PHF.

DESIGN, SETTING, AND PARTICIPANTS

This comparative effectiveness research study analyzed all fee-for-service Medicare beneficiaries with proximal humerus fracture in 2011 who were continuously enrolled in Medicare Parts A and B for the 365-day period before and immediately after their index fracture. Data analysis was performed January through June 2019.

EXPOSURE

Undergoing 1 of the commonly used surgical procedures in the 60 days after an index fracture diagnosis.

MAIN OUTCOMES AND MEASURES

Risk-adjusted area surgery ratios were created for each hospital referral region as a measure of local area practice styles. Instrumental variable approaches were used to assess the association between higher surgery rates and adverse events, mortality risk, and cost at 1 year from Medicare's perspective for patients with PHF in 2011. Instrumental variable models were stratified by age, comorbidities, and frailty. Instrumental variable estimates were compared with estimates from risk-adjusted regression models.

RESULTS

The final cohort included 72 823 patients (mean [SD] age, 80.0 [7.9] years; 13 958 [19.2%] men). The proportion of patients treated surgically ranged from 1.8% to 33.3% across hospital referral regions in the United States. Compared with conservatively managed patients, surgical patients were younger (mean [SD] age, 80.4 [8.1] years vs 78.0 [7.2] years; P < .001) and healthier (Charlson Comorbidity Index score of 0, 14 863 [24.4%] patients vs 3468 [29.1%] patients; Function-Related Indicator score of 0, 20 720 [34.0%] patients vs 4980 [41.8%] patients; P < .001 for both), and a larger proportion were women (49 030 [80.5%] patients vs 9835 [82.5%] patients; P < .001). Instrumental variable analysis showed that higher rates of surgery were associated with increased total costs ($8913) during the treatment period, increased adverse event rates (a 1-percentage point increase in the surgery rate was associated with a 0.19-percentage point increase in the 1-year adverse event rate; β = 0.19; 95% CI, 0.09-0.27; P < .001), and increased mortality risk (a 1-percentage point increase in the surgery rate was associated with a 0.09-percentage point increase in the 1-year mortality rate; β = 0.09; 95% CI, 0.04-0.15; P < .01). Instrumental variable mortality results were even more striking for older patients and those with higher comorbidity burdens and greater frailty. Risk-adjusted estimates suggested that surgical patients had higher costs (increase of $17 278) and more adverse events (a 1-percentage point increase in the surgery rate was associated with a 0.12-percentage point increase in the 1-year adverse event rate; β = 0.12; 95% CI, 0.11 to 0.13; P < .001) but lower risk of mortality after PHF (a 1-percentage point increase in the surgery rate was associated with a 0.01-percentage point decrease in the 1-year mortality rate; β = -0.01; 95% CI, -0.015 to -0.005; P < .001).

CONCLUSIONS AND RELEVANCE

This study found that higher rates of surgery for treatment of patients with PHF were associated with increased costs, adverse event rates, and risk of mortality. Orthopedic surgeons should be aware of the harms of extending the use of surgery to more clinically vulnerable patient subgroups.

Humeral Torsion as a Risk Factor for Shoulder and Elbow Injury in Professional Baseball Pitchers

BACKGROUND

Numerous studies have demonstrated that humeral retrotorsion is increased in the dominant arms of throwing athletes. No study has clearly defined the relationship between humeral retrotorsion and shoulder and elbow injury.

HYPOTHESIS

Uninjured professional pitchers will display more dominant humeral torsion (HT) than professional pitchers who sustain shoulder injuries but less than pitchers who sustain elbow injuries.

STUDY DESIGN

Case-control study; Level of evidence, 3.

METHODS

Pitchers from the Colorado Rockies professional baseball organization were recruited for participation for this prospective injury study from 2009 to 2013. HT was assessed using indirect ultrasonographic techniques and was measured prospectively in 255 pitchers before each spring training (average of 2 trials). From the beginning of the preseason to the end of the postseason, overuse upper extremity injuries (shoulder or elbow) were tracked for each participating athlete. All athletes who reported pain or injury to their coach were referred to the organization's athletic trainer for evaluation and classification of each injury. The difference in HT was calculated by subtracting measurement of the dominant arm from the nondominant arm, and 3 separate mixed-model analyses of variance (side × injury group) were used to compare the dominant and nondominant HT between all pitchers who developed an arm injury (shoulder and elbow combined), as well as comparing pitchers who developed a shoulder or elbow injury to those who did not miss games due to shoulder or elbow injury (α = .05).

RESULTS

During the course of the study, 60 arm (30 shoulder; 30 elbow) injuries were observed; 195 pitchers did not suffer an injury. There were no differences when HT was compared between all injured (shoulder and elbow injuries combined) and uninjured pitchers (P = .13; effect size 0.14). There was a significant interaction effect showing that pitchers who suffered a shoulder injury displayed 4° less dominant humeral retrotorsion compared with pitchers without injury (P = .04) and that pitchers with elbow injury displayed 5° greater humeral retrotorsion (P = .04). In addition, those who suffered an ulnar collateral ligament injury requiring reconstruction (n = 17) also displayed 4(o) greater dominant retrotorsion and 5° less nondominant humeral retrotorsion compared with pitchers who did not suffer an injury (n = 195; P = .05). There was not a significant difference between nondominant HT among pitchers who sustained shoulder and elbow injuries and pitchers without injury.

CONCLUSION

The results of this study show a contrast in dominant humeral retrotorsion between pitchers who suffered shoulder and elbow injuries compared with those without an injury. Pitchers who sustained shoulder injuries had less dominant humeral retrotorsion compared with noninjured pitchers. In contrast, pitchers who sustained time-loss elbow injuries displayed increased humeral retrotorsion compared with noninjured pitchers. Together, these results suggest that increased adaptive humeral retrotorsion is protective against shoulder injuries but a harmful contributor for elbow injuries in professional pitchers. This is the first study to show differing injury risk profiles for shoulder and elbow injury.

Positive outcomes with intra-articular glenohumeral injections are independent of accuracy

BACKGROUND

Shoulder pain is a common, costly, and recalcitrant affliction. One treatment for shoulder pain is intra-articular injection of corticosteroid. Clinical opinion is that injection guided by palpation is accurate and effective, and there is some evidence to support a positive effect of injection on pain. However, great controversy exists as to the accuracy of injection by palpation, whether or not accuracy is important, and what the effect is of accuracy on pain.

METHODS

We used a blinded, longitudinal observational design of effectiveness in an effort to determine the accuracy of intra-articular injections and the effect of that accuracy on pain and functional outcomes in patients with various shoulder pathologies.

RESULTS

Injection accuracy data were captured on 103 patients. Of the 103 blinded injections, 54 received injections that were identified by fluoroscopy as "in" the capsule, whereas 49 were identified as "outside" the capsule; an accuracy rate of 52.4%. In the 4-week follow up, regardless of group assignment or accuracy of the injection, patients improved significantly (P < .01) from pre- to post-injection. Improvement was typically over by 2.5 points in the Numeric Pain Rating Scale (NPRS) categories, over 8 points on the Short-Form McGill Pain Questionnaire (SFMPQ), and over by 13 points on the Disabilities of the Arm, Shoulder, and Hand questionnaire (DASH).

DISCUSSION

Our accuracy rate was within the range reported in the literature. Improvements in all subjects with regard to pain and self-reported function occurred even in light of a wide variance in subject duration of symptoms, multiple injectors with varied training, a blinded approach to injection, and multiple injection approaches.

CONCLUSIONS

The accuracy of the injection does not appear to depend on the experience of the physician and may be irrelevant in treating shoulder pain of multiple origins.