Youth Pitcher Fatigue: Medial Elbow Laxity, Ultrasonographic Assessment of Flexor-Pronator Mass Energy Depletion, and Association With Pitch Count.

Background: Ulnar collateral ligament (UCL) injuries in youth pitchers continue to be concerning despite the institution of pitch count limits. Flexor-pronator mass fatigue can lead to diminished dynamic stability, resulting in greater stress on the UCL. Purpose/Hypothesis: To evaluate fatigue of the flexor-pronator mass by assessing changes in medial elbow laxity; noninvasively characterizing alterations in muscle glycogen; and identifying changes in subjective fatigue, strength, range of motion (ROM), pitching velocity, and accuracy with increasing pitches thrown by youth pitchers to their recommended 75-pitch count limit. It was hypothesized that, with increased pitches, medial elbow laxity would increase and that the glycogen content of the flexor-pronator mass would decrease. Study Design: Descriptive laboratory study. Methods: Healthy male pitchers aged 10 years (n = 22) threw 3 sets of 25 pitches with 12 minutes between sets (3 timepoints). Bilateral ulnohumeral joint gapping was measured by applying a standardized valgus force and utilizing ultrasound imaging. Relative changes in muscle glycogen in the bilateral flexor carpi radialis (FCR), and the flexor digitorum superficialis/flexor carpi ulnaris (FDS/FCU) muscles were measured with ultrasound software and recorded as fuel percentiles. Additional measures obtained included subjective fatigue, strength, ROM, velocity, and accuracy. Results: There were no differences in medial elbow joint-line gapping between the throwing and nonthrowing arms or between timepoints. The throwing arm demonstrated a significant decline in fuel percentile of the FCR from baseline to after 75 pitches (P = .05). There were no differences across timepoints for FDS/FCU fuel percentile values. Fatigue measurements for both arms were significantly higher at all timepoints compared with baseline (P≤ .03). Grip strength of the dominant arm after 75 pitches was decreased significantly compared with after 25 pitches (P = .02). Conclusion: Although an increase in medial elbow joint gapping was not demonstrated within the recommended 75 pitch count limit in 10-year-olds, a relative decrease in glycogen stores of the flexor-pronator mass did occur, as well as a decrease in grip strength, with increasing subjective fatigue. Clinical Relevance: This study provides a foundation for further objective testing of physiologic changes that occur with pitching to better guide pitch count limits and improve the safety of young athletes.

High variability among surgeons in evaluation, treatment, and rehabilitation of medial ulnar collateral ligament injuries.

Hypothesis and/or Background: The incidence of elbow medial ulnar collateral ligament (MUCL) injuries has been increasing, leading to advances in surgical treatments. However, it is not clear that there is consensus among surgeons regarding diagnostic imaging, the indications for acute surgery and postoperative rehabilitation. The purpose of this study is evaluate surgeon variability in the presurgical, surgical, and postsurgical treatment of MUCL injuries regarding the imaging modalities used for diagnosis, indications for acute surgical treatment, and postoperative treatment recommendations for rehabilitation and return to play (RTP). Our hypothesis is that indications for acute surgical treatment will be highly variable based on MUCL tear patterns and that agreement on the time to RTP will be consistent for throwing athletes and inconsistent for nonthrowing athletes. Methods: A survey developed by 6 orthopedic surgeons with expertise in throwing athlete elbow injuries was distributed to 31 orthopedic surgeons who routinely treat MUCL injuries. The survey evaluated diagnostic and treatment topics related to MUCL injuries, and responses reaching 75% agreement were considered as high-level agreement. Results: Twenty-four surgeons responded to the survey, resulting in a 77% response rate. There is 75% or better agreement among surveyed surgeons regarding acute surgical treatment for distal full thickness tears, ulnar nerve transposition in symptomatic patients or with ulnar nerve subluxation, postoperative splinting for 1-2 weeks with initiation of rehabilitation within 2 weeks, the use of bracing after surgery and the initiation of a throwing program at 3 months after MUCL repair with internal brace by surgeons performing 20 or more MUCL surgeries per year. There were a considerable number of survey topics without high-level agreement, particularly regarding the indications for acute surgical treatment, the time to return to throwing and time RTP in both throwing and nonthrowing athletes. Discussion and/or Conclusion: The study reveals that there is agreement for the indication of acute surgical treatment of distal MUCL tears, duration of bracing after surgery, and the time to initiate physical therapy after surgery. There is not clear agreement on indications for surgical treatment for every MUCL tear pattern, RTP time for throwing, hitting and participation in nonthrowing sports.

Utilizing the Pronated Forearm Technique for Measuring Glenohumeral External Rotation in Baseball Players.

BACKGROUND: Alterations in glenohumeral internal rotation (GIR), glenohumeral external rotation (GER), and total range of motion (TROM) have been linked with increased injury risk. GER capacity has been measured routinely with the forearm in neutral rotation (GERN), but a recent study reported GERN was greater than GER with the forearm in pronation (GERP) in Minor League pitchers. This work has not yet been replicated or extended to other groups. HYPOTHESIS: GERP would be significantly less than GERN in Independent League baseball pitchers, and there would be no difference in GERP or GERN measurements between this new group and the previous group of Minor League pitchers. STUDY DESIGN: Cross-sectional study. LEVEL OF EVIDENCE: Level 3. METHODS: Goniometric measurements were recorded for bilateral GIR, GERN, and GERP, and resulting TROM for 37 Independent League baseball pitchers. These data were compared with the previous study. All motions were compared individually between groups, between throwing and nonthrowing arm, and both within and between techniques (forearm neutral or pronated). RESULTS: GERP was significantly less than GERN for both arms within each group tested (P < 0.01). Independent League pitchers had greater between arm differences for GIR (-16.9° vs -6.9°), GERN (+15.1° vs -0.6°), and GERP (+13.1° vs -5.9°) compared with Minor League pitchers. TROM for the Independent League pitchers was not statistically different for either measurement technique, while TROM for the throwing arm of the Minor League pitchers was statistically reduced with varying effect sizes (d = 0.35-0.99) compared with the nonthrowing arm (P < 0.01). CONCLUSION: This study confirmed earlier findings that the pronated forearm resulted in decreased GER capacity, illustrating the adaptive response to throwing and the need to evaluate for this variable. CLINICAL RELEVANCE: GERP should be evaluated in all groups of pitchers, but there may be variations within tested groups.

Interval Throwing Programs for Baseball Players: Methodological Assessment of the Quality and Construct of Publicly Available Programs.

CONTEXT: The quality and interprogram variability of publicly available throwing programs have not been assessed. OBJECTIVE: To (1) identify publicly available interval throwing programs, (2) describe their components and structure, and (3) evaluate their quality, variability, and completeness. DATA SOURCES: Google, Bing, Yahoo; keyword: "interval throwing program." STUDY SELECTION: Baseball-specific publicly available programs. STUDY DESIGN: Systematic review. LEVEL OF EVIDENCE: Level 4. DATA EXTRACTION: Independent evaluation by 2 authors using a novel 21-item Quality Assessment Rubric (QAR). RESULTS: Of the 99 included programs, 54% were designed for return from injury/surgery; 42% explicitly stated no expected timeline for completion, and approximately 40% did not provide criteria to initiate the program. Program construction was highly variable. There were broad-ranging shortest (mean: 40±8 ft, range: 20-45 ft) and longest (mean: 150±33 ft, range: 90-250 ft) long toss distances, and variable maximum numbers of mound pitches thrown before returning to game play (range: 40-120, mean: 85). Only 63% of programs provided guidelines for handling setbacks, and standardized warm-ups, arm care, and concomitant training were absent in 32%, 63%, and 47% of programs, respectively. Mean QAR completion rate and QAR item response rate were low (62 ± 4% [range, 24-91%], 62 ± 24% [range, 7-99%], respectively). Finally, only 20 (20%) programs provided at least 1 peer-reviewed reference, most of which were published >10 years ago. CONCLUSION: Publicly available interval throwing programs are readily available but demonstrate significant interprogram heterogeneity across multiple areas including target audience, program construction, progression, and execution. The quality and consistency of publicly available interval throwing programs is poor at this time, which may limit their utility and effectiveness for baseball players attempting to return to competition. This work identifies a multitude of deficiencies in currently available throwing programs that should be targets of future improvement efforts.

Rehabilitation of the painful elbow.

Although lateral elbow pain and medial ulnar collateral ligament injury are common musculoskeletal pathologies in overhead athletes, the evidence supporting specific interventions for managing these conditions is scarce. Management of these conditions has been guided mostly by expert opinion rather than empirical evidence, yet the lack of comparative data in the literature has not negatively affected return-to-play rates following surgery. However, an understanding of what is known regarding unimodal and multimodal treatments for lateral elbow pain and medial ulnar collateral ligament injury is needed for clinicians to select evidence-based treatment pathways and highlight what is not known to develop future high-quality investigations.

Rehabilitation of the painful shoulder.

Managing the painful shoulder in overhead athletes can be difficult because of a lack of time-loss injuries in overhead sports and focusing primarily on either pathoanatomic causes or movement impairments. Although managing the painful shoulder can be challenging, the combination of identifying pathoanatomic causes with movement impairments can provide a more focused rehabilitation approach directed at the causes of shoulder pain. Understanding the potential influence of scapular positioning as well as mobility and/or strength impairments on shoulder pain can help clinicians develop more directed rehabilitation programs. Furthermore, sports-specific methods such as long toss or the use of weighted balls for achieving physiological or performance-based gains have limited empirical evidence regarding their clinical and performance-based benefits, which may impede the rehabilitation process. Applying a comprehensive evaluation approach prior to and throughout the treatment process can assist clinicians with selecting the most appropriate treatment based on patient need. Reconsidering traditional treatments based on existing evidence may help refine the treatment process for overhead athletes with shoulder pain.

The shoulder joint complex in the throwing motion.

The shoulder joint complex in the overhead athlete is organized to effectively transfer the proximally generated forces distally into the arm. The organization also protects the joints and anatomic structures against the repetitive high velocities, large ranges of motions, and compressive, shear, translational, and distraction loads in the overhead motion while placing the hand in the "launch window." Coupling of the movements of the scapula, clavicle, and humerus results in scapulohumeral rhythm (SHR). Effective SHR requires the clavicle and scapula-and, at times, the mechanically linked claviscapular segment-to move the arm into the task-specific position and motion and requires the humerus to move through the ranges of motion to achieve the specific task in the throwing motion. Alterations in SHR can negatively affect effective shoulder joint complex function in the overhead throwing motion and increase injury risk. There are 4 phases of clavicular, scapular, and claviscapular motion that are coupled with arm motion in SHR. The first 3 phases occur in arm elevation motions from 0°-90° and result in the claviscapula and humerus being placed in task-specific positions. The fourth phase is coupling of claviscapular motion with humeral motion to maintain ball-and-socket kinematics throughout the throwing motion. Alterations in this composite motion are termed "scapular dyskinesis." The dyskinesis is considered an impairment of the efficient mobility of the claviscapular segment of the shoulder complex. The most prevalent problem with scapular dyskinesis is the association of scapular protraction and consequent glenoid antetilt with alterations in humeral rotation and posterior humeral head translation to produce shoulder joint internal impingement. Task effectiveness in overhead throwing is also based on and determined by humeral range of motion, precision of humeral motion, and velocity of humeral motion, as well as humeral and arm position in 3-dimensional space. This activity requires maximum ball-and-socket kinematics to create the highest amount of concavity-compression that creates stability for the joint. There are bony and soft-tissue contributions to this stability. Injuries to the glenoid labrum are among the most common deficits that alter concavity-compression. Clinical evaluation of the shoulder joint complex in the injured throwing athlete should be comprehensive and systematic, following an evaluation pathway for proximal and distal causative factors and including observation of humeral motion. This type of evaluation can result in intervention protocols that address the pathoanatomic, pathophysiological, and pathomechanical deficits identified.

Case-Based Understanding of the Role of the Scapula in Common Shoulder Pathologies.

Scapular dyskinesis is an extremely common component of shoulder pathology, especially in the overhead athlete; despite its prevalence, proper diagnosis and management of scapular disorders remains an enigma for many clinicians. An understanding of the contribution of the scapula to pathomechanics and clinical symptoms is necessary to optimize both surgical and nonsurgical treatment of shoulder disorders. Without correction of scapular dysfunction, even effective management of the pathoanatomy is unlikely to produce optimal results. It is important to examine the role of the scapula in common shoulder pathologies and elucidate a case-based treatment strategy for both surgical and nonsurgical shoulder disorders.

Accuracy of measuring scapular position and motion with a novel motion capture system.

Background: Scapula kinematics is recognized to be a crucial variable in shoulder dysfunction. Nevertheless, quantitative scapula tracking and measurement are not part of the current clinical evaluation. The main concern is measurement accuracy. Methods: To assess the accuracy of the wearable sensor technology Showmotion a cadaver experiment was designed, allowing a direct comparison between sensors directly pinned to the scapula and superficial sensors. A measurement protocol was adopted to evaluate errors in measurement, mimicking the suggested in vivo evaluation. Sensors were simultaneously placed above (supraspinal) and below (infraspinal) the scapular spine to determine if one placement resulted in fewer errors compared to the other. Results: Mean and standard deviations of the supraspinal sensor root mean square error (RMSE) in flexion-extension movements resulted in 3.59° ± 2.36°, 4.73° ± 2.98°, and 6.26° ± 3.62° for upward-downward rotation (up-down), anterior-posterior tilt and internal-external (intra-extra) rotation, respectively, while 2.16° ± 1.21°, 2.20° ± 1.02°, and 4.46° ± 2.16° for the infraspinal sensor. In abduction-adduction movements, mean and standard deviations of the supraspinal sensor RMSE resulted in 4.26° ± 2.98°, 5.68° ± 4.22°, and 7.04° ± 4.36° for up-down rotation, anterior-posterior tilt, and intra-extra rotation, respectively, while 2.38° ± 1.63°, 2.47° ± 1.77°, and 4.92° ± 3.14° for the infraspinal sensor. The same behavior was confirmed in shrug movements, where 4.35° ± 3.24°, 4.63° ± 3.09°, and 5.34° ± 6.67° are mean and standard deviations of the supraspinal sensor RMSE for up-down rotation, anterior-posterior tilt, and intra-extra rotation, respectively, while 2.76° ± 1.87°, 2.83° ± 2.53°, and 4.68° ± 5.22° for the infraspinal sensor. Conclusion: This method of quantitative assessment of scapular motion is shown to have good accuracy and low error between the sensor measurements and actual bone movement in multiple planes of scapular motion, both over the entire range of motion and in its individual segment intervals. The decreased amount of error with the infraspinal sensor placement suggests that placement is ideal for clinical quantitative assessment of scapular motion.

Reliability Analysis of In-person and Virtual Goniometric Measurements of the Upper Extremity.

Background: Virtual healthcare has forced clinicians to modify or eliminate parts of the musculoskeletal evaluation such as motion assessment. Although acceptable to excellent levels of in-person goniometric reliability is achievable, reliability of virtual assessments is unknown. Purpose: To determine if similar upper extremity goniometric measurements could be obtained in-person and virtually. Study Design: Reliability study; classroom setting. Methods: Publicly recruited sample over 18 years of age with no upper extremity injuries. Each subject was tested in a standing position with dominant arm facing the clinicians to visualize the landmarks for goniometer placement. Flexion and extension of the shoulder, elbow and wrist were measured. Prior to performing in-person goniometric measurements for each joint, an image was captured of each pre-determined joint position using a mobile device with a camera. This image represented the screenshot on a virtual platform. Four clinicians performed in-person measurements twice during the same session on each subject. The following week clinicians measured virtual images using the same techniques. Inter-rater and intra-rater reliability were determined via intraclass correlation coefficients (ICC). Results: Inter-rater reliability for five of the six in-person (ICC≥0.81) and virtual measurements (ICC≥0.78 ) were classified as excellent. In-person wrist extension (ICC=0.60) and virtual wrist flexion (ICC=0.65) were classified as good. Intra-rater reliability for individual clinicians were between good and excellent for the in-person measurements (ICC:0.61-0.96) and virtual measurements (ICC:0.72-0.97). There were a greater number of excellent ICC values for the virtual measurements (90%) compared to in-person measurements (70%). There were statistically significant differences between in-person and virtual sessions for five of six measurements (p≤0.006). Only elbow extension did not differ between sessions (p=0.966). Conclusion: Virtual assessment compared to goniometric measurements showed good to excellent inter- and intra-rater reliabilities (ICC > 0.60), which suggests clinicians can utilize goniometry either in person or on a virtual platform. Level of Evidence: 3b©The Author(s).

Reliability of ulnar collateral ligament findings in magnetic resonance imaging.

BACKGROUND: Ulnar collateral ligament (UCL) tears are common in baseball players. Although magnetic resonance imaging (MRI) is the most used imaging modality for UCL injuries, the inter-rater reliability of MRI analyzing specific characteristics of UCL pathology has not been defined. The purpose of this study was to define the inter-rater reliability of MRI for evaluating UCL characteristics. METHODS: Three surgeons analyzed 45 noncontrast MRIs: 15 without UCL tears, 15 with intraoperatively confirmed partial-thickness tears, and 15 with intraoperatively confirmed full-thickness tears. Findings evaluated included ligament characteristics (periligamentous or osseous edema, ligament hypertrophy, calcifications, and partial- or full-thickness tearing) and location of the pathology (proximal, midsubstance, or distal). Fleiss' κ coefficients were used to assess interobserver reliability. RESULTS: There were high rates of agreement for midsubstance (κ: 0.50) and distal (κ: 0.69) ligament edema and proximal osseous edema (κ: 0.48). There were low rates of agreement for proximal ligament edema (κ: 0.08), ligament thickening (κ: -0.02 to 0.20), and proximal to midsubstance calcifications (κ: -0.04 to 0.10). Midsubstance (κ: 0.55) and distal full-thickness tears (κ: 0.63) demonstrated higher agreement than proximal (κ: 0.29). Proximal partial-thickness tears (κ: 0.45) had higher agreement than midsubstance (κ: -0.02) or distal (κ: -0.02). CONCLUSIONS: In our study, there was high inter-rater reliability regarding proximal osseous edema, midsubstance, and distal ligament edema and full-thickness tears. There was no agreement for midsubstance and distal partial-thickness UCL tears, but fair agreement for proximal tears. UCL tissue characteristics including ligament thickening and calcifications demonstrated low agreement. Challenges remain in effectively evaluating UCL tissue characteristics on noncontrast MRIs.

Managing Scapular Dyskinesis.

Scapular dyskinesis, the impairment of optimal scapular position and motion, is common in association with shoulder injury. A comprehensive evaluation process can show the causative factors and lead to effective treatment protocols. The complexity of scapular motion and the integrated relationship between the scapula, humerus, trunk, and legs suggest a need to develop rehabilitation programs that involve all segments working as a unit rather than isolated components. This is best accomplished with an integrated rehabilitation approach that includes rectifying deficits in mobility, strength, and motor control but not overtly focusing on any one area.

Kinetic chain revisited: consensus expert opinion on terminology, clinical reasoning, examination, and treatment in people with shoulder pain.

BACKGROUND: The purpose of this study was to reach consensus on the most appropriate terminology and issues related to clinical reasoning, examination, and treatment of the kinetic chain (KC) in people with shoulder pain among an international panel of experts. METHODS: A 3-round Delphi study that involved an international panel of experts with extensive clinical, teaching, and research experience in the study topic was conducted. A search equation of terms related to the KC in Web of Science and a manual search were used to find the experts. Participants were asked to rate items across 5 different domains (terminology, clinical reasoning, subjective examination, physical examination, and treatment) using a 5-point Likert-type scale. An Aiken coefficient of validity (V) ≥0.7 was considered indicative of group consensus. RESULTS: The participation rate was 30.2% (n = 16), whereas the retention rate was high throughout the 3 rounds (100%, 93.8%, and 100%). A total of 15 experts from different fields and countries completed the study. After the 3 rounds, consensus was reached on 102 items: 3 items were included in the "terminology" domain; 17 items, in the "rationale and clinical reasoning" domain; 11 items, in the "subjective examination" domain; 44 items, in the "physical examination" domain; and 27 items, in the "treatment" domain. Terminology was the domain with the highest level of agreement, with 2 items achieving an Aiken V of 0.93, whereas the domains of physical examination and treatment of the KC were the 2 areas with less consensus. Together with the terminology items, 1 item from the treatment domain and 2 items from the rationale and clinical reasoning domain reached the highest level of agreement (V = 0.93 and V = 0.92, respectively). CONCLUSION: This study defined a list of 102 items across 5 different domains (terminology, rationale and clinical reasoning, subjective examination, physical examination, and treatment) regarding the KC in people with shoulder pain. The term "KC" was preferred and a agreement on a definition of this concept was reached. Dysfunction of a segment in the chain (ie, weak link) was agreed to result in altered performance or injury to distal segments. Experts considered it important to assess and treat the KC in particular in throwing or overhead athletes and agreed that no one-size-fits-all approach exists when implementing shoulder KC exercises within the rehabilitation process. Further research is now required to determine the validity of the identified items.

What are the indications for medial ulnar collateral ligament surgery in baseball players? An MRI case-based study.

BACKGROUND: Ulnar collateral ligament (UCL) tears are common in baseball players. When nonoperative management fails; reconstruction or repair may be necessary to restore physical function. There is no clear consensus regarding the indications for surgery based on magnetic resonance imaging (MRI) tear characteristics or the indications for selecting repair over reconstruction. The purpose of this study was to define the indications for UCL surgery based on MRI and to elucidate indications for UCL repair vs. reconstruction. METHODS: Twenty-six orthopedic surgeons who treat baseball players were surveyed. Forty-five MRIs were reviewed: 15 without UCL tears, 15 with intraoperatively confirmed partial-thickness tears, and 15 with full-thickness tears. Factors investigated included ligament characteristics (periligamentous or osseous edema, ligament hypertrophy, calcification, partial or full-thickness tearing) and location (proximal, midsubstance, or distal). Surgeons were given a clinical scenario and asked whether 1) surgery was indicated and 2) whether repair or reconstruction was recommended. Odds ratios (OR) and 95% confidence intervals (95% CI) helped identify significant predictors for both queries. RESULTS: The odds of recommending surgical treatment compared to nonoperative treatment were 2.4× more likely for a proximal partial-thickness tear, 3.2× for distal partial-thickness tear, 5.1× for distal full-thickness tear, and 7.0× for proximal full-thickness tear (P < .001). Significant indications for repair included distal partial (OR = 1.6, 95% CI 1.0, 2.1, P < .001) and full-thickness tears (OR = 1.7, 95% CI 1.1, 2.3, P < .001). Repair was 3× less likely recommended for midsubstance full-thickness tears (OR = 3.0, 95% CI -5.0, -1.0, P = .004). Ultrasound stress testing was requested in 78% of partial tears. CONCLUSIONS: Among surgeons surveyed, the highest odds for recommending operative treatment were proximal full-thickness tears, then distal full-thickness, distal partial-thickness, and proximal partial-thickness tears. Repair was most appropriate for partial and full-thickness distal tears, but relatively contraindicated for complete midsubstance UCL tears. Ultrasound stress testing was frequently requested for partial tears. Given the lack of consensus among surgeons, future prospective registries are necessary to determine whether these factors associate with clinical outcomes.

A Plague of Their Own: Injury Incidence Remains Elevated in the 2021 Major League Baseball Season Compared to Pre-COVID-19 Seasons.

Background: Significant increases in injuries were observed in the 2020 Major League Baseball (MLB) season; these were attributed to an increased acute to chronic workload due to the interrupted preseason and compressed season during the coronavirus disease of 2019 (COVID-19) pandemic. In 2021, the MLB resumed its regular schedule. Hypothesis/Purpose: The purpose of this study was to determine the injury incidence and epidemiology of the 2021 MLB season compared to the injury incidence in the 2020 season and pre-COVID-19 seasons. The hypothesis was that, with the return to normal preseason training, injury incidence in 2021 would return to pre-COVID-19 rates. Additionally, it was hypothesized that injury list (IL) placements at midseason 2021 would be decreased relative to 2020 due to the uninterrupted preseason yet increased at full season 2021 due to increased overall workload from 2020. Study Design: Descriptive epidemiology study. Methods: The MLB transactions database was searched for players placed on the IL between 2018 and 2021. Injuries were categorized by body part and player position. Incidence per 1000 athlete-exposures was calculated for the pre-COVID-19 (2018-2019), 2020, and 2021 seasons. The z test for proportions was used to determine significant differences between injury incidences. Results: The injury incidence rate by midseason 2021 (9.32) compared to 2020 (8.66) was not significantly different (p=0.234). At full season 2021, injury incidence rate (8.69) was significantly higher than pre-COVID-19 seasons (5.13, p<0.001), but not 2020 (p=0.952). When comparing full season 2021 to 2020, increased foot/ankle (0.50 vs 0.14, respectively, p<0.001) and miscellaneous (1.92 vs 0.68, respectively, p<0.001) injuries were observed. Conclusion: The overall injury incidence in 2021 was significantly higher than pre-COVID-19 seasons, and no significant difference was observed between both mid- and full season 2021 and 2020, refuting the hypotheses. This signifies that injury incidence remained elevated in the 2021 season despite resumption of preseason training and a regular season. Level of Evidence: 3.

Acromioclavicular joint injuries revisited: Pathoanatomy, pathomechanics, and clinical presentation.

Multiple papers have described aspects of treatment of acromioclavicular (AC) joint injuries. Most have emphasized aspects of surgical treatment, and some papers have addressed non-operative treatment. Few papers have highlighted the specific pathoanatomy of an AC joint injury or have described methods of evaluating the 3-dimensional pathomechanics resulting from the pathoanatomical injury. This paper is based on 3 observations: (1) AC joint injuries exist and present on a spectrum of pathoanatomy; (2) The effect of the pathoanatomy on normal AC joint mechanics to produce pathomechanics is dependent on the extent of the pathoanatomy; and (3) Treatment protocols should be developed to address the specific pathoanatomy to optimize the mechanics. A comprehensive clinical approach emphasizing the evaluation of the extent of the anatomic injury and understanding its mechanical consequences regarding shoulder and arm function is a key in the development of guidelines for developing operative or non-operative treatment protocols and for establishing outcomes of the treatment protocols.

Biomechanical Comparison of a Novel Multiplanar, Perpendicular Whipstitch With the Krackow Stitch and Standard Commercial Whipstitch.

Background: Using alternating orthogonal suture throws with the looped whipstitch technique may allow enhanced suture fixation. Hypothesis: It was hypothesized that this novel multiplanar, perpendicular looped whipstitch (MP) technique would have improved biomechanical properties compared with the standard looped whipstitch (WS) and Krackow stitch (KS). Study Design: Controlled laboratory study. Methods: A total of 30 cadaveric tibialis anterior tendons were randomly assigned into 3 groups of 10. Tendons were secured to a custom clamp, and the other end was sutured using 1 of 3 techniques: the KS, WS, or novel MP. The MP was performed with alternating orthogonal throws starting right to left, then front to back, left to right, and back to front. Each technique used 4 passes of No. 2 FiberWire spaced 5 mm apart and ending 10 mm from the tendon end. Tendons were preloaded to 5 N, pretensioned to 50 N at 100 mm/min for 3 cycles, returned to 5 N for 1 minute, cycled from 5 to 100 N at 200 mm/min for 100 cycles, and then loaded to failure at 20 mm/min. Elongation was recorded after pretensioning and cycling and was measured both across the suture-tendon interface and from the base of the suture-tendon interface to markings on the suture limbs (construct elongation). One-way analyses of variance were performed, with Bonferroni post hoc analysis when appropriate. Results: There were no differences in cross-sectional area or stiffness among the 3 techniques. The ultimate load for WS (183.33 ± 57.44 N) was less compared with both MP (270.76 ± 39.36 N) and KS (298.90 ± 25.94 N) (P ≤ .001 for both). There was less construct elongation for KS compared with WS and MP for total displacement, measured from pretensioning to the end of cycling (P < .001). All 3 techniques saw a decrease in length (shortening) at the suture-tendon interface during testing. There was more shortening at the suture-tendon interface for WS compared with KS (P = .006). Conclusion: The KS appears superior, as it maximized strength while minimizing construct elongation or graft shortening. The ultimate load of the MP technique was greater than that of the standard technique but not significantly different from that of the KS technique. Clinical Relevance: The KS is preferred. If using a WS, multiplanar, perpendicular passes should be considered.

More Elevated Fastballs Associated With Placement on the Injured List due to Shoulder Injury.

Purpose: To evaluate whether impending shoulder injury was associated with changes in pitch location or velocity immediately preceding injury. Methods: Pitchers placed on the injured list (IL) due to a shoulder injury between 2015 and 2020 were identified in the Major League Baseball transactions database. Four-seam fastball velocity and frequency of pitch location for each pitch type was collected for each player in the season before placement on the IL and within 1 month of placement on the IL with a minimum of 55 pitches thrown of 1 type. Pitch locations were collected as identified by Baseball Savant's Game-Day Zones. Game-Day Zones were consolidated into high (above the strike zone midpoint) versus low, arm side (closer to the pitcher's arm side of the plate) versus opposite side, and within the strike zone versus out of zone. Repeated measures analysis of variance determined differences in four-seam velocity and the location distribution of 4-seam fastballs, change-ups, and breaking balls among each group. Results: In total, 267 pitchers were placed on the IL for a shoulder injury with the majority diagnosed with inflammation (89/267) followed by strain or sprain (69/267). Four-seam fastball locations significantly increased above the mid-point of the zone (45.9% vs 42.4%, P = .008) and out of the strike zone (48.5% vs 46.5%, P = .011) within a month before IL placement. There was no significant change in 4-seam fastball velocity immediately before IL placement. Conclusions: Pitchers threw more elevated 4-seam fastballs and out-of-zone 4-seam fastballs in the month before IL placement for shoulder injury. These findings suggest that a loss of 4-seam fastball command decreases with impending shoulder injury. Level of Evidence: IV, prognostic case series.

Glenoid Labral Injuries Are More Common Posteriorly Than Superiorly and Are Combined Across Multiple Areas of the Glenoid.

Purpose: To categorize arthroscopically observed labral injuries to include location on the glenoid and frequency of the injuries in each location. Methods: Patients undergoing arthroscopic labral surgery between January 2018 and June 2020 were reviewed. Inclusion criteria for labral injury were consistently applied and included history, clinical examination and imaging findings, and failure of rehabilitation. Exclusion criteria included arthritis, adhesive capsulitis, and previous surgery. Injury locations were categorized into superior, anterior, and/or posterior areas on the glenoid and as isolated in one area or combined in more than one area. Injury patterns also were evaluated. Interrater and intrarater agreement was assessed between 2 raters for injury location and tear pattern for 22 randomly assigned cases. Results: In total, 167 cases met the inclusion criteria. Injuries were found in all areas. Combined injuries were found almost twice as often as isolated injuries (63.5% vs 37.5%). Isolated posterior injuries had the greatest frequency of all specific injury types (26.3%). Isolated superior injuries (SLAP 2-4) had a frequency of 7.2%. Tear patterns included peel back, separation/split, insubstance injury, peripheral rim flattening, and extension into the posterior inferior glenohumeral ligament. Interrater was excellent for all tear locations (intraclass correlation coefficient ≥0.85) whereas intrarater agreement was good to excellent (intraclass correlation coefficient ≥0.63). Conclusions: Labral injuries that are associated with clinical symptoms can occur as isolated or combined types in the superior, anterior, and posterior glenoid areas and can display multiple injury patterns. Combined types of injuries are almost twice as common as those that are isolated in one area. Posterior injuries, isolated or combined, are frequent but superior injuries are less common. Level of Evidence: Level IV, therapeutic case series.