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Background: Contributing factors for arm injuries among baseball players have been described. However, no review has systematically identified risk factors with findings from prospective cohort studies. Purpose: To systematically review prospective cohort studies that investigated risk factors for arm injury among baseball players. Study Design: Systematic review; Level of evidence, 3. Methods: Electronic databases were searched for relevant English-language studies. Titles, abstracts, and full-text articles were screened by 2 blinded reviewers to identify only prospective cohort studies and randomized controlled trials. Two independent investigators screened each article for appropriate criteria. Results: Fourteen prospective articles were selected for this review. Youth, high school, and professional baseball players (N = 2426) were pooled, and 43 risk factors were assessed in relation to general arm, shoulder, and elbow injuries. All studies evaluated players for at least 1 season. Deficits in preseason shoulder range of motion and strength were significant risk factors for general arm or shoulder injury among high school and professional players. Elbow and shoulder varus torque at peak external shoulder rotation during pitching, high pitch velocity, and shoulder rotational and flexion deficits were risk factors for elbow injuries among professional pitchers. Pitching >100 innings in 1 year, being aged 9 to 11 years, being a pitcher or catcher, training >16 hours per week, and having a history of elbow pain were significant risk factors for elbow injury among youth players. Conclusion: History of elbow pain and age had a high risk of associated elbow injury among youth players. Training or pitching load also increased elbow injury risk for youth athletes. Loss of shoulder range of motion appears to increase risk for elbow injury among professional athletes. Single time-point data collections per season, studies with the same sample population, and studies with self-reported injury and risk factor data may limit the interpretation of these findings. Health care professionals should use caution when assessing injury risk during evaluation and making decisions about the training workload and playing time of baseball players.

Estimating external workload in baseball pitchers is important for training and rehabilitation. Since current methods of estimating workload through pitch counts and rest days have only been marginally successful, clubs are looking for more sophisticated methods to quantify the mechanical loads experienced by pitchers. Among these are the use of wearable systems. While wearables offer a promising solution, there remains a lack of standards or guidelines for how best to employ these devices. As a result, sensor location and workload calculation methods vary from system to system. This can influence workload estimates and blur their interpretation and utility when making decisions about training or returning to sport. The primary purpose of this study was to determine the extent to which sensor location influences workload estimate. A secondary purpose was to compare estimates using different workload calculations. Acceleration data from three sensor locations—trunk, throwing upper arm, and throwing forearm—were collected from ten collegiate pitchers as they threw a series of pitches during a single bullpen session. The effect of sensor location and pitch type was assessed in relation to four different workload estimates. Sensor location significantly influenced workload estimates. Workload estimates calculated from the forearm sensor were significantly different across pitch types. Whole-body workload measured from a trunk-mounted sensor may not adequately reflect the mechanical loads experienced at throwing arm segments. A sensor on the forearm was the most sensitive to differences in workloads across pitch types, regardless of the calculation method.

Pitching biomechanical research is highly focused on injury prevention with little attention to how biomechanical data can facilitate skill development. The overall purpose of this study was to explore how sensor-derived segment kinematics and timing relate to command and ball velocity during baseball pitching. We used a cross-sectional design to analyze a series of pitches thrown from 10 collegiate baseball pitchers. We collected biomechanical data from six inertial sensors, subjective command from the pitchers, and ball velocity from a radar device. Stepwise regression analyses were used to explore biomechanical variables associated with command for all pitches and ball velocity for fastballs only. We found that only peak forearm linear acceleration was significantly associated with command, whereas several segment kinematic measures were significantly associated with ball velocity. Our results suggest that different biomechanical variables are linked to specific pithing skills. Our findings suggest that end-effector (forearm) movement is more important for pitch command, whereas proximal-to-distal (pelvis, trunk, upper arm, forearm) segmental movement is important for ball velocity.

Background: Ulnar collateral ligament (UCL) reconstruction (UCLR) is commonly performed in Major League Baseball (MLB) pitchers, and there remain limited data on off-speed pitch performance in those that return to play after reconstruction. Purpose/Hypothesis: The purpose of this study was to evaluate the effect of primary UCLR on curveball (CB) and change-up (CU) pitch performance in terms of velocity along with novel pitching metrics including spin rate, hard-hit rate, and whiff rate. It was hypothesized that post-UCLR off-speed pitch spin rates, velocity, and whiff rate would decrease significantly compared with pre-UCLR levels, while hard-hit rates would increase. Study Design: Cohort study; Level of evidence, 3. Methods: Pitchers who underwent UCLR and returned to MLB level of play were identified from public records from 2016 to 2019. The Statcast system was used to collect spin rate, velocity, hard-hit, and whiff rate data for CB and CU pitches for preinjury seasons, as well as the first 2 seasons after return from UCLR. A matched-pair analysis was performed by matching each pitcher to an uninjured healthy pitcher from the same draft class and round. Results: A total of 29 pitchers met inclusion criteria and threw the pitches of interest. There were no statistically significant changes in CB or CU mean spin rate, pitch velocity, hard-hit rate, or whiff rate when comparing preinjury levels with the first and second seasons played after reconstruction. There were no significant differences in any pitching metrics when comparing the UCLR cohort with the healthy matched-pair cohort. The mean total number of CU pitches significantly decreased in the first season after UCLR (154.0 vs 67.9; P = .04) and compared with the matched-pair cohort at 1 year (67.9 vs 233.2; P = .001). Pitchers also threw fewer total pitches in the first season after returning from UCLR compared with preinjury baselines and healthy matched pairs. Conclusion: The results of this study demonstrate that pitchers who undergo UCLR and return to the MLB level can expect similar off-speed pitch performance in comparison with their preinjury levels and with pitchers without UCL injury.

Background: Portable ultrasound machines are now common, used for point-of-care applications and needle guidance for percutaneous procedures; however, the effectiveness of portable ultrasound in evaluation of the musculoskeletal system has not been fully assessed. Purpose: To prospectively evaluate the use of portable hand-held ultrasound in comparison with conventional cart-based ultrasound in evaluation of the musculoskeletal system. Study Design: Cohort study (diagnosis); Level of evidence, 2. Methods: In this institutional review board–approved, prospective study, 100 consecutive patients with informed consent were imaged through use of both portable and cart-based ultrasound equipment using 12-5 MHz linear transducers. Agreement in ultrasound diagnosis was documented along with expected clinical changes in management if there was disagreement (definitely no, probably no, uncertain, probably yes, definitely yes). Imaging details of disagreement cases were recorded, and descriptive statistics were calculated. Results: There were 42 male and 58 female patients (mean ± SD age, 53 ± 13 years) imaged over a time period of 20 months. Anatomic areas scanned were the shoulder (n = 30), elbow (n = 11), hand and wrist (n = 15), hip (n = 10), knee (n = 11), foot and ankle (n = 12), and others (n = 11). Scanning with conventional ultrasound revealed abnormality in 92% of patients. Agreement in diagnosis made between portable versus cart-based ultrasound was found in 65% of patients. In the 35% of patients with discordant results, the change in diagnosis resulted in no change in clinical management in 46%, probably no change in 29%, uncertain change in 14%, probable change in 11%, and definite change in 0%. The diagnoses changing management (4%; 4/100) included nondetection of a satellite nodule (n = 1), ganglion cyst (n = 1), hernia (n = 1), and underestimated tendon tear (n = 1). Conclusion: When compared with conventional cart-based ultrasound, a musculoskeletal diagnosis using portable hand-held ultrasound was concordant or was discordant without clinical relevance in 96% (96/100) of patients. Knowledge of benefits and limitations of portable hand-held ultrasound will help determine areas where specific types of ultrasound equipment can be used.

Background: There is currently no consensus on immobilization protocols following shoulder surgery. The aim of this study was to establish patterns and types of sling use for various surgical procedures in the United States (US) and Europe, and to identify factors associated with the variations. Methods: An online survey was sent to all members of the American Shoulder and Elbow Society (ASES) and European Society for Surgery of the Shoulder and Elbow (ESSSE). The survey gathered member data, including practice location and years in practice. It also obtained preferences for the type and duration of sling use after the following surgical procedures: arthroscopic Bankart repair, Latarjet, arthroscopic superior/posterosuperior rotator cuff repair (ARCR) of tears <3 cm and >3 cm, anatomic total shoulder arthroplasty (aTSA) and reverse TSA (rTSA), and isolated biceps tenodesis (BT). Relationships between physician location and sling type for each procedure were analyzed using Fisher’s exact tests and post-hoc tests using Bonferroni-adjusted p-values. Relationships looking at years in practice and sling duration preferred were analyzed using Spearman’s correlation tests. Results: In total, 499 surgeons with a median of 15 years of experience (IQR = 9–25) responded, with 54.7% from the US and 45.3% from Europe. US respondents reported higher abduction pillow sling use than European respondents for the following: Bankart repair (62% vs. 15%, p < 0.0001), Latarjet (53% vs. 12%, p < 0.001), ARCR < 3 cm (80% vs. 42%, p < 0.001) and >3 cm (84% vs. 61%, p < 0.001), aTSA (50% vs. 21%, p < 0.001) and rTSA with subscapularis repair (61% vs. 22%, p < 0.001) and without subscapularis repair (57% vs. 17%, p < 0.001), and isolated BT (18% vs. 7%, p = 0.006). European respondents reported higher simple sling use than US respondents for the following: Bankart repair (74% vs. 31%, p < 0.001), Latarjet (78% vs. 44%, p < 0.001), ARCR < 3 cm (50% vs. 17%, p < 0.001) and >3 cm (34% vs. 13%, p < 0.001), and aTSA (69% vs. 41%, p < 0.001) and rTSA with subscapularis repair (70% vs. 35%, p < 0.001) and without subscapularis repair (73% vs. 39%, p < 0.001). Increasing years of experience demonstrated a negative correlation with the duration of sling use after Bankart repair (r = −0.20, p < 0.001), Latarjet (r = −0.25, p < 0.001), ARCR < 3 cm (r = −0.14, p = 0.014) and >3 cm (r = −0.20, p < 0.002), and aTSA (r = −0.37, p < 0.001), and rTSA with subscapularis repair (r = −0.10, p = 0.049) and without subscapularis repair (r = −0.19, p = 0.022. Thus, the more experienced surgeons tended to recommend shorter durations of post-operative sling use. US surgeons reported longer post-operative sling durations for Bankart repair (4.8 vs. 4.1 weeks, p < 0.001), Latarjet (4.6 vs. 3.6 weeks, p < 0.001), ARCR < 3 cm (5.2 vs. 4.5 weeks p < 0.001) and >3 cm (5.9 vs. 5.1 weeks, p < 0.001), aTSA (4.9 vs. 4.3 weeks, p < 0.001), rTSR without subscapularis repair (4.0 vs. 3.6 weeks, p = 0.031), and isolated BT (3.7 vs. 3.3 weeks, p = 0.012) than Europe respondents. No significant differences between regions within the US and Europe were demonstrated. Conclusions: There is considerable variation in the immobilization advocated by surgeons, with geographic location and years of clinical experience influencing patterns of sling use. Future work is required to establish the most clinically beneficial protocols for immobilization following shoulder surgery. Level of Evidence: Level IV.

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

Rotator cuff tears (RCT) in older individuals may compound age-associated physiological changes and impact their ability to perform daily functional tasks. Our objective was to quantify thoracohumeral kinematics for functional tasks in 18 older adults (mean age=63.3±2.2), and compare findings from nine with a RCT to nine matched controls. Motion capture was used to record kinematics for 7 tasks (axilla wash, forward reach, functional pull, hair comb, perineal care, upward reach to 90°, upward reach to 105°) spanning the upper limb workspace. Maximum and minimum joint angles and motion excursion for the three thoracohumeral degrees of freedom (elevation plane, elevation, axial rotation) were identified for each task and compared between groups. The RCT group used greater minimum elevation angles for axilla wash and functional pull (p≤0.0124) and a smaller motion excursion for functional pull (p=0.0032) compared to the control group. The RCT group also used a more internally rotated maximum axial rotation angle than controls for functional reach, functional pull, hair comb, and upward reach to 105° (p≤0.0494). The most differences between groups were observed for axial rotation, with the RCT group using greater internal rotation to complete functional tasks, and significant differences between groups were identified for all three thoracohumeral degrees of freedom for functional pull. We conclude that older adults with RCT used more internal rotation to perform functional tasks than controls. The kinematic differences identified in this study may have consequences for progression of shoulder damage and further functional impairment in older adults with RCT.

Background: Pitch count recommendations are used to reduce injury risk in youth baseball pitchers and are based chiefly on expert opinion, with limited scientific support. Furthermore, they only account for pitches thrown against a hitter and do not include the total number of throws on the day a player pitched. Currently, counts are recorded manually. Purpose: To provide a method using a wearable sensor to quantify total throws per game that is compliant with Little League Baseball rules and regulations. Study Design: Descriptive laboratory study. Methods: Eleven male baseball players (age, 10-11 years) from an 11U (players 11 years and younger) competitive travel team were evaluated over a single summer season. An inertial sensor was placed above the midhumerus of the throwing arm and was worn during baseball games across the season. A throw identification algorithm capturing all throws and reporting linear acceleration and peak linear acceleration was used to quantify throwing intensity. Pitching charts were collected and used to verify actual pitches thrown against a hitter in a game versus all other throws identified. Results: A total of 2748 pitches and 13,429 throws were captured. On the day a player pitched, he averaged 36 ± 18 pitches (23%) and 158 ± 106 total throws (pitches in game as well as all warm-up pitches and other throws during game). In comparison, on a day a player did not pitch, he averaged 119 ± 102 throws. Across all pitchers, 32% of all throws were low intensity, 54% were medium intensity, and 15% were high intensity. The player with one of the highest percentages of high-intensity throws did not pitch as their primary position, while the 2 players who pitched most often had the lowest percentages. Conclusion: Total throw count can be successfully quantified using a single inertial sensor. Total throws tended to be higher on days a player pitched compared with regular game days without pitching. Clinical Relevance: This study provides a fast, feasible, and reliable method to obtain pitch and throw counts so that more rigorous research on contributing factors to arm injury in the youth athlete can be achieved.

Background The rate, complexity, and cost of total shoulder arthroplasty (TSA) continues to grow. Technology has advanced pre-operative templating. Reducing cost of TSA has positive impact for the patient, manufacturer, and hospital. The aim of this study was to evaluate the accuracy of implant size selection based on 3-D templating. Our hypothesis was that pre-operative templating would enable accurate implant prediction within one size. Methods Multicenter retrospective study of anatomic TSAs templated utilizing 3-D virtual planning technology. This program uses computed tomography (CT) scans allowing the surgeon to predict component sizes of the glenoid and humeral head and stem. Pre-operative templated implant size were compared to actual implant size at the time of surgery. Primary data analysis utilized unweighted Cohen's Kappa test. Results 111 TSAs were analyzed from five surgeons. Pre-operative templated glenoid sizes were within one size of actual implant in 99% and exactly matched in 89%. For patients requiring a posterior glenoid augment (n = 14), 100% of implants were within one size of the template and 93% matched exactly. For stemless humeral components (n = 87) implanted, 98% matched the pre-operative template within one size with 79% exactly matched. For stemmed components (n = 24), 88% of cases were within one size of the preoperative plan and exactly matching in 83%. Humeral head diameter matched within one size of the pre-operative template in 84% of cases and exactly matched in 72%. Conclusion Pre-operative 3-D templating for TSAs can accurately predict glenoid and humeral component size. This study sets the groundwork for utilization of pre-operative 3-D templating as a potential method to reduce overall TSA costs by managing cost of implants, reducing inventory needs, and improving surgical efficiency.