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Background: Baseball is one of the most popular sports among youth athletes in the United States, and among these players, pitchers are at a particularly high risk of sustaining an injury. Overuse of the arm from repetitive pitching is a common mechanism for injury. Despite the attention that overuse injury has received, little is known regarding the mechanism that leads to elbow injury. This study aims to determine the effect of increasing pitch count on elbow flexion at ball release in a youth pitching cohort. The authors hypothesize that elbow flexion would increase as pitch count increases., Methods: Study subjects included volunteers from youth baseball players from local teams and public advertisements. Retroreflective markers attached to bony landmarks were placed on the players according to International Shoulder Group recommendations. Pitchers threw an indoor simulated game. Three-dimensional marker trajectories were collected using a 12-camera optical motion capture system, and ball velocity was captured using a radar gun. Voluntary maximal isometric strength of the internal and external rotators was evaluated before and after pitching. Paired 2-tailed t tests were performed to determine if a significant change occurred between the fresh and fatigued sets., Results: Twelve adolescent male pitchers were recruited. Eleven of 12 pitchers completed the prescribed 6 sets of 15 pitches, culminating in a 90-pitch simulated game. The ball speed in the second set was found to be the highest in all pitchers and was considered the "peak set" (P = .021), whereas ball speed was the slowest in the sixth set of pitches and was therefore considered the "fatigue set" (P = .001). There was a moderate but statistically significant inverse correlation between elbow flexion at ball release and maximum internal rotation velocity (P = .005). Elbow flexion at ball release was also significantly positively correlated with shoulder abduction at ball release (P = .004). Elbow flexion at ball release was not significantly correlated with ball velocity (P = .108)., Conclusions: In a simulated game laboratory setting, increasing pitch count was associated with increasing elbow flexion angle at ball release in youth baseball pitchers. These findings demonstrate that pitching with fatigue may cause biomechanical changes that have been associated with increased rates of elbow injury in the adult throwing population. Further investigation on the association between elbow flexion angle and elbow injury in the youth baseball population is needed., (Copyright © 2024 Journal of Shoulder and Elbow Surgery Board of Trustees. Published by Elsevier Inc. All rights reserved.)

Background: Prior to the Major League Baseball (MLB) draft, some pitchers undergo predraft magnetic resonance imaging (MRI). This study aimed to evaluate pre-draft elbow MRI on baseball pitchers who were entering the MLB draft to determine the presence or absence of pathology, the associations between these pathologies and ulnar collateral ligament (UCL) tears, and interobserver reliability regarding common MRI pathology., Methods: Predraft elbow MRI performed on prospective MLB pitchers between 2011 and 2017 were deidentified and then reviewed by two separate authors. The authors graded the MRI on several factors including presence or absence of: UCL ossification, UCL appearance (heterogeneous or not), UCL thickening (and location), UCL tear (partial vs. full thickness and location), muscle strain, flexor tendon tear, posteromedial osteophyte, sublime tubercle enthesophyte, and osseous stress reactions., Results: Overall, 245 predraft elbow MRI were reviewed. MRI abnormalities were found in 70% (171/245) of pitchers. UCL thickening was found in 20% (50/245) of pitchers. Regarding UCL tears, 3% had a full thickness tear and 24% had a partial thickness tear. Of full thickness tears, 86% were distal and 1 was midsubstance. Of partial thickness tears, 41% (24/58) were distal, 12% (7/58) were midsubstance, and 47% (27/58) were proximal. Periligamentous edema was present in 36% of pitchers while 14% had a flexor pronator muscle strain., Conclusion: The majority (70%) of pitchers entering the MLB draft had abnormal findings on their MRI, most commonly involving changes to the UCL. Interobserver reliability was acceptable following the definition of pathology when reading predraft elbow MRI on MLB prospects., (Copyright © 2024 Journal of Shoulder and Elbow Surgery Board of Trustees. Published by Elsevier Inc. All rights reserved.)

Glenoid superior biceps-labral pathology diagnosis, treatment, and outcomes are an evolving area of shoulder surgery. Historically, described as superior labrum anterior posterior (SLAP) tears, these lesions were identified as a source of pain in throwing athletes. Diagnosis and treatments applied to these SLAP lesions resulted in less than optimal outcomes in some patients and a prevailing sense of confusion. The purpose of this paper is to perform a reappraisal of the anatomy, examination, imaging, and diagnosis by the American Shoulder and Elbow Surgeons/SLAP biceps study group. We sought to capture emerging concepts and suggest a more unified approach to evaluation and identify specific needs for future research., (Copyright © 2023 Journal of Shoulder and Elbow Surgery Board of Trustees. Published by Elsevier Inc. All rights reserved.)

Background: The objectives of this study were to characterize and compare the vascularity of arthroscopically repaired rotator cuff tendons at short-term and intermediate-term follow-up., Materials and Methods: Nineteen patients who underwent arthroscopic rotator cuff repair were prospectively monitored for an average of 21.2 months. Initial baseline, grayscale ultrasound images of the operated-on shoulder were obtained on all patients at 3 months and at a minimum of 10 months postoperatively. Perflutren-lipid microsphere contrast (DEFINITY, Lantheus Medical Imaging, North Billerica, MA, USA) was injected after baseline grayscale images and after exercise to obtain contrast-enhanced images of the repair. Three regions of interest--supraspinatus tendon, peribursal tissue, and bone anchor site--were evaluated before and after rotator cuff-specific exercises., Results: The peribursal tissue demonstrated the greatest blood flow, followed by the bone anchor site and tendon, in pre-exercise and postexercise states. Significantly less blood flow was observed in all regions of interest before exercise (P < .05) and only at the bone anchor site after exercise (P < .001) at latest follow-up compared with the 3-month values. Intratendinous blood flow remained relatively low at both evaluation points after surgical repair., Conclusion: Preliminary findings suggest that the peribursal tissue and bone anchor site are the main conduits of blood flow for the rotator cuff tendon after arthroscopic repair, with the supraspinatus tendon being relatively avascular. Blood flow of the repaired rotator cuff tendon decreases with time. Furthermore, exercise significantly enhances blood flow to the repaired rotator cuff., (Copyright © 2012. Published by Mosby, Inc.)

Background: There has been limited in-vivo assessment of rotator cuff vascularity following repair. This study aims to characterize the vascularity of the shoulder 3 months following supraspinatus tendon repair., Methods: Twenty-nine patients (average age, 61.4 years) underwent Perflutren lipid microsphere contrast-enhanced shoulder ultrasound examinations 3 months after arthroscopic rotator cuff repair. Each shoulder was scanned at rest and following exercise using linear phased array 9-MHz transducer optimized to detect the contrast agent. Blood flow was quantified off-line using ultrasound imaging quantification and analysis software (QLAB, Philips, Andover, MA). Peak enhancement (vascular volume) and rate of rise (perfusion) were determined for 3 regions of interest: peribursal area, supraspinatus tendon, and anchor site., Results: Peak enhancement and rate of rise were greatest in the peribursal soft tissue and anchor site. Resting peak enhancement and rate of rise were significantly lower within the tendon compared to the other 2 regions (P < .001). Exercise resulted in increased enhancement and rate-of-rise to all 3 regions, but had a significant predilection towards increasing vascular volume within the peri-bursal region (P = .026)., Conclusion: At 3 months following repair, the majority of blood flow to the repair is derived from the peribursal soft tissues and the anchor site. The tendon, particularly those with a defect at 3 months, is relatively avascular. Though limited by inclusion of only a single time point, this study introduces a new technique to quantify vascularity following supraspinatus repairs and suggests that the surrounding vascular milieu may play a role in tendon healing., Level of Evidence: Basic Science.

This clinical study was performed to document the prevalence of deep vein thrombosis (DVT) after prosthetic shoulder replacement surgery. We prospectively followed 100 consecutive shoulder arthroplasty procedures (total shoulder replacement in 73 and hemiarthroplasty in 27) in 44 male and 56 female patients for 12 weeks (mean age, 67 years; range, 17-88 years). Risk factors for venous thromboembolic disease were assessed preoperatively and postoperatively. A 4-limb surveillance color flow Doppler ultrasound was performed at 2 days (100 patients) and 12 weeks (50 patients randomly selected) after surgery, and the presence and location of DVT were recorded. Postoperative symptomatic or fatal pulmonary emboli (PE) were also recorded. The overall prevalence of DVT was 13.0%, consisting of 13 DVTs in 12 patients. These included 6 ipsilateral and no contralateral upper extremity DVTs and 5 ipsilateral and 2 contralateral lower extremity DVTs. The prevalence of DVT was 10.0% (10/100) at day 2 after surgery and 6.0% (3/50) at week 12 after surgery. The incidence of symptomatic nonfatal PE was 2.0% (2/100), and that of fatal PE was 1.0% (1/100). Risk factors associated with venous thromboembolic disease did not reach statistical significance because of the small study population sample size. At our institution, the prevalence of DVT after reconstructive shoulder arthroplasty was 13.0%, a rate comparable to that after hip arthroplasty (10.3%) but lower than that after knee arthroplasty (27.2%). Shoulder arthroplasty surgeons should be aware of the potential risk of perioperative thromboembolic complications in both the acute and subacute postoperative periods.

The purpose of this study was to review the outcome of patients with osteonecrosis of the humeral head, based on etiology and treatment with either hemiarthroplasty or total shoulder arthroplasty (TSA). Sixty-four shoulders, with an average age of 57 years, were evaluated at a mean of 4.8 years. Outcomes included L'Insalata and American Shoulder and Elbow Surgeons (ASES) scores, as well as range of motion (ROM). The overall ASES score was 67, average flexion was 127 degrees, and external rotation was 49 degrees. Outcomes did not differ based on etiology, but ROM was decreased with post-traumatic osteonecrosis. There was no difference in outcome or ROM between hemiarthroplasty and TSA. The complication rate was significantly higher with TSA (22%) than with hemiarthroplasty (8%). Achieving ROM in patients with post-traumatic osteonecrosis remains difficult. TSA was associated with a higher complication rate and decreased mobility and should be reserved for patients with stage V osteonecrosis.

The natural history of the blood supply to the rotator cuff and its role in the etiology of rotator cuff disease has not been definitively established. To date, there has not been an in-vivo dynamic assessment of the baseline vascularity of the asymptomatic rotator cuff. This study was designed to test the hypothesis that regional variations in supraspinatus tendon vascularity exist with an age-dependent decrease in asymptomatic individuals with intact rotator cuffs. Lipid microsphere, contrast-enhanced ultrasound shoulder examinations were done in 31 patients with a mean age of 41.5 years (range, 22-65 years). Images were obtained at baseline, after contrast administration at rest, and after contrast administration following exercise to visualize the intratendinous blood flow to the supraspinatus tendon. Qualitative and quantitative analysis was performed by determining 4 regions of interest (bursal medial, articular medial, bursal lateral, and articular lateral) with quantification and analysis software (QLAB Philips, Andover, MA) to examine each region of interest and normalize data for interpretation of the mean intensity per pixel. A statistically significant decrease in blood flow to the supraspinatus tendon with age was observed in a comparative analysis of patients aged younger than 40 and older than 40, (P < .05 for all 4 zones after exercise and for the bursal medial, articular medial, and bursal lateral zones after exercise; P = .07 for the articular lateral zone after exercise). A statistically significant increase in blood flow with exercise was observed in an analysis of all patients (P < .001). The age-related decrease in the vascular supply of the tendon observed in this study is consistent with published reports demonstrating an increasing prevalence of rotator cuff pathology with age and may predispose to the development of rotator cuff tendinopathy and, ultimately, attritional tears.

A bioresorbable patch used for augmentation of rotator cuff repair was evaluated to determine if it would increase strength of cuff repairs associated with tendon defects and also show histologic incorporation over time. Forty goats underwent rotator cuff repairs of the infraspinatus tendon bilaterally. Tendons were detached and a defect was created prior to repair. One side was repaired and augmented with a 4 cm2 polylactic acid patch in each animal. On the other side, the same size defect was repaired in the same manner but without the patch to serve as a control. Animals were sacrificed at 3, 6, 12, and 24 weeks. Ultimate load to failure and histology were reported. No significant difference in load to failure was found between groups. A cellular fibrous tissue occupied the patch at 6 weeks, which over time matured into a dense, homogeneous fibrous tissue with alignment of collagen between the scaffold bundles.

The coracoacromial ligament (CAL), normally a superior restraint against humeral translation, is frequently involved in rotator cuff impingement pathology. However, surgical excision of the CAL is not always clinically successful. Little anatomic information exists about the morphology and function of this ligament. The CAL and glenohumeral joint in 56 cadaveric shoulders were examined in 31 cadavers. Nineteen dimensional parameters were obtained by direct measurement. In 16 shoulders, specific attention was directed at the anterior band of the CAL. Variation exists in the morphology of the CAL. The most common configuration of the CAL was two distinct ligamentous bands that could be classified anatomically as an anterolateral band (ALB) and posteromedial band (PMB). The ALB commonly extended to the posterolateral aspect of the acromion. Furthermore, it frequently extended anterolaterally to the acromion, ending in a coracoacromial falx. Spur formation had occurred in 10 of 16 shoulders evaluated and always appeared in the ALB. Spur formation in the ALB correlated with a focal CAL that was narrower, less divergent, shorter, and thicker than a diffuse CAL that did not have a spur. The mean angle of diversion between the ALB and PMB, when a spur was present, was 31 degrees compared with 45 degrees when no spur was present. CAL band thickness varied, with the ALB being thicker at the acromion than at the coracoid and the PMB being thicker at the coracoid than at the acromion. During arthroscopic subacromial decompression, failure to visualize the anterolateral corner of the acromion adequately may result in incomplete resection of the CAL, especially if the PMB is mistaken to be the entire ligament. Incomplete removal of the CAL may be a factor in clinical failures of arthroscopic subacromial decompression. The preferential location of spurs in the ALB suggests that it is a major load-bearing structure. Furthermore, the ALB is thicker at the acromion, suggesting increased strain. Our data suggest that a possible function of the CAL is to dampen stress on the acromion from muscle activity.

The embryologic development of the capsular ligaments, synovial lining, rotator cuff, and bony structures of the shoulder is incompletely understood. The purpose of this study is to report the gross and microscopic anatomy of the developing glenohumeral joint on the basis of dissections of fetal shoulder specimens. After Institutional Review Board approval from our hospital, 51 shoulders in 37 fetal specimens were obtained from cases of fetal demise. The gestation time of these specimens ranged from 9 to 40 weeks. The morphology of the capsule, labrum, and associated ligaments were studied by dissection under a dissecting microscope. High-resolution radiographs were made, and sections were processed for routine histology. There was noted to be minimal variation in the shape and slope of the acromion. The coracoid was much larger in relation to the shoulder than in the mature shoulder. The coracoacromial ligament was grossly evident at this stage of development, with distinct anterolateral and posteromedial bands in this ligament. The inferior glenohumeral ligament was seen as a prominent thickening in the capsule, whereas the middle and superior glenohumeral ligaments were thinner and more difficult to identify as distinct structures. Upon histologic examination, the inferior glenohumeral ligament was seen to consist of several layers of organized collagen fibers. The inferior glenohumeral ligament inserted into the labrum and margin of the glenoid. The capsule was much thinner in the region superior to the inferior glenohumeral ligament. A rotator interval capsular defect was often present, and the coracohumeral ligament was seen as a distinct structure as early as 15 weeks. A bare spot in the glenoid was not observed. This study indicates that some of the important functional elements of the structure of the mature human shoulder are present early in development, including the glenohumeral and coracohumeral ligaments. The coracoacromial ligament plays a significant role in the formation of the coracoacromial arch in the neonatal shoulder. The presence of a capsular rotator interval indicates that this aspect of capsular anatomy is congenital.