Collagen degradation assessment with an in vitro rotator cuff tendinopathy model using multiparametric ultrashort-TE magnetization transfer (UTE-MT) imaging

PURPOSE

This study aims to assess ultrashort-TE magnetization transfer (UTE-MT) imaging of collagen degradation using an in vitro model of rotator cuff tendinopathy.

METHODS

Thirty-six supraspinatus tendon specimens were divided into three groups and treated with 600 U collagenase (Group 1), 150 U collagenase (Group 2), and phosphate buffer saline (Group 3). UTE-MT imaging was performed to assess changes in macromolecular fraction (MMF), macromolecule transverse relaxation time (T2m), water longitudinal relaxation rate constant (R1m), the magnetization exchange rate from the macromolecular to water pool (Rm0 w) and from water to the macromolecular pool (Rm0 m), and magnetization transfer ratio (MTR) at baseline and following digestion and their differences between groups. Biochemical and histological studies were conducted to determine the extent of collagen degradation. Correlation analyses were performed with MMF, T2m, R1m, Rm0 w, Rm0 m, and MTR, respectively. Univariate and multivariate linear regression analyses were performed to evaluate combinations of UTE-MT parameters to predict collagen degradation.

RESULTS

MMF, T2m, R1m, Rm0 m, and MTR decreased after digestion. MMF (r = -0.842, p < 0.001), MTR (r = -0.78, p < 0.001), and Rm0 m (r = -0.662, p < 0.001) were strongly negatively correlated with collagen degradation. The linear regression model of differences in MMF and Rm0 m before and after digestion explained 68.9% of collagen degradation variation in the tendon. The model of postdigestion in MMF and T2m and the model of MTR explained 54.2% and 52.3% of collagen degradation variation, respectively.

CONCLUSION

This study highlighted the potential of UTE-MT parameters for evaluation of supraspinatus tendinopathy.

Evaluation of the metabolic activity of the torn rotator cuff muscles by 18 F-2-deoxy- d -glucose PET-computed tomography scan

OBJECTIVES

Fatty atrophy and fatty infiltration have been considered as limiting factors for rotator cuff repair. The metabolic activity of the muscle can be measured noninvasively by PET. In our study, we aim to compare the metabolic activity between the shoulders with rotator cuff tears and normal shoulders.

METHODS

All the patients with unilateral full-thickness rotator cuff tears were included. The patients were divided into two groups based on fatty atrophy and the metabolic activities of the rotator cuff muscles, trapezius, and deltoid were calculated using an 18 F-2-deoxy- d -glucose PET-computed tomography scan for comparison.

RESULTS

A total of 17 patients were included. The standardized uptake values were compared between the affected shoulder and the normal shoulders. There was a significant increase in uptake in the insertion sites and musculotendinous junctions in the rotator cuff torn group. The standardized uptake values showed no significant difference between the low-grade and high-grade groups.

CONCLUSION

Our first hypothesis was also proven wrong; when we found that there was no statistically significant difference in the metabolic activity in muscle bellies of normal shoulders and those with rotator cuff tears. Our second hypothesis was proven wrong when found that there was no statistically significant difference in the metabolic activities of rotator cuff muscles between high-grade and low-grade fatty atrophy groups. The metabolic activities of the middle deltoid and trapezius are inversely related. Based on the findings of our study, fatty atrophy or fatty infiltration alone cannot be considered a limiting factor for rotator cuff repair.

Preoperative magnetic resonance imaging rotator cuff tendon stump classification correlates with the surgical outcomes following superior capsular reconstruction

HYPOTHESIS

This study aimed to investigate the correlation between rotator cuff stump classification and postoperative outcomes after superior capsular reconstruction (SCR).

METHODS

A total of 75 patients who underwent SCR between June 2013 and May 2021 were included in this study. Based on stump classification using the signal intensity ratio of the tendon rupture site to the deltoid muscle in the coronal view of preoperative T2-weighted, fat-suppressed magnetic resonance imaging scans, the patients were classified into types 1, 2, and 3 with ratios of <0.8, 0.8-1.3, and >1.3 (44, 17, and 14 patients, respectively). The American Shoulder and Elbow Surgeons (ASES), Constant, and visual analog scale (VAS) scores for pain and range of motion were evaluated at a minimum of 1 year of follow-up postoperatively. The acromiohumeral distance and rotator cuff arthropathy according to the Hamada classification were assessed on plain radiography. The graft integrity was evaluated by magnetic resonance imaging at 3 and 12 months postoperatively and annually thereafter.

RESULTS

Clinical and radiological outcomes were significantly improved after SCR. In comparison with type 2 and 3 patients, type 1 patients had significantly higher ASES scores (type 1, 2, and 3 = 84 ± 10, 75 ± 15, and 76 ± 14; all P = .014), Constant scores (type 1, 2, and 3 = 65 ± 5, 61 ± 9, and 56 ± 13; all P = .005), and forward flexion (type 1, 2, and 3 = 155 ± 10, 154 ± 15, and 145 ± 13; all P = .013). However, these statistical differences between groups were below the established minimum clinically important difference values for the ASES and Constant scores after rotator cuff repair. The graft failure rate after surgery was lower in the type 1 group than that in the other 2 groups; however, the difference was not statistically significant (P = .749).

CONCLUSION

Patients with stump classification type 1 showed significantly better functional scores (ASES and VAS scores) and forward flexion; however, the clinical importance of these differences may be limited. Stump classification may be useful for predicting postoperative clinical outcomes.

Quantitative magnetic resonance imaging vs. perioperative arthroscopy to measure stage 1 ruptures of the supraspinatus tendon for surgical planning

BACKGROUND

Accurate preoperative assessment of supraspinatus tendon tear (STT) size is important for surgical planning. Our aims were to evaluate the correlation between stage 1 STT size measured preoperatively by quantitative magnetic resonance imaging (qMRI) and size measured perioperatively by arthroscopy. The concordance between preoperative tear size and the surgical plan was also assessed.

METHODS

This prospective, nonrandomized, noncontrolled, interventional study was carried out in patients with a stable stage 1 STT. Three months before surgery, STT size was measured in the sagittal and coronal planes by a radiologist by qMRI (1.5 T). Three months later, the surgeon measured the size of the tear again on the same qMRI scans and decided on the most appropriate surgical plan. During arthroscopy, the surgeon measured the size of the tear again using a graduated sensor hook and carried out the repair. STT size measured preoperatively was compared to that measured by arthroscopy and the concordance between preoperative STT size and the surgical plan was determined.

RESULTS

Sixty-seven patients were included (mean age: 59.5 ± 8.9 years; 58.2% female). There was good concordance between STT size measured by qMRI vs. arthroscopy in the coronal plane (concordance correlation coefficient = 0.36 [95% confidence interval (CI): 0.16-0.53]; Pearson's correlation coefficient = 0.42 [95% CI: 0.2-0.6]; P = .0004) and in the sagittal plane (concordance correlation coefficient = 0.51 [95% CI: 0.33-0.65]; Pearson's correlation coefficient = 0.57 [95% CI: 0.38-0.71]; P < .0001). Preoperative STT size concurred with the surgical plan in 85% of patients.

CONCLUSION

There was good concordance between STT size measured by qMRI and that measured perioperatively by arthroscopy. However, preoperative STT size measured by qMRI did not concur with the surgical plan in 15% of patients and in these patients the surgical procedure had to be revised during surgery.

Do therapeutic exercises impact supraspinatus tendon thickness? Secondary analyses of the combined dataset from two randomized controlled trials in patients with rotator cuff-related shoulder pain

BACKGROUND

The mechanistic response of rotator cuff tendons to exercises within the context of rotator cuff-related shoulder pain (RCRSP) remains a significant gap in current research. A greater understanding of this response can shed light on why individuals exhibit varying responses to exercise interventions. It can also provide information on the influence of certain types of exercise on tendons. The primary aim of this article is to explore if changes in supraspinatus tendon thickness (SSTT) ratio differ between exercise interventions (high load vs. low load). The secondary aims are to explore if changes in SSTT ratio differ between ultrasonographic tendinopathy subgroups (reactive vs. degenerative) and if there are associations between tendinopathy subgroups, changes in tendon thickness ratio, and clinical outcomes (disability).

METHODS

This study comprises secondary analyses of the combined dataset from two randomized controlled trials that compared high and low-load exercises in patients with RCRSP. In those trials, different exercise interventions were compared: 1) progressive high-load strengthening exercises and 2) low-load strengthening with or without motor control exercises. In 1 trial, there was also a third group that was not allocated to exercises (education only). Ultrasound-assessed SSTT ratio, derived from comparing symptomatic and asymptomatic sides, served as the primary measure in categorizing participants into tendinopathy subgroups (reactive, normal and degenerative) at baseline.

RESULTS

Data from 159 participants were analyzed. Two-way repeated measures ANOVAs revealed significant Group (P < .001) and Group × Time interaction (P < .001) effects for the SSTT ratio in different tendinopathy subgroups, but no Time effect (P = .63). Following the interventions, SSTT ratio increased in the "Degenerative" subgroup (0.14 [95% confidence interval {CI}: 0.09-0.19]), decreased in the "Reactive" subgroup (-0.11 [95% CI: -0.16 to -0.06]), and remained unchanged in the "Normal" subgroup (-0.01 [95% CI: -0.04 to 0.02]). There was no Time (P = .21), Group (P = .61), or Group × Time interaction (P = .66) effect for the SSTT ratio based on intervention allocation. Results of the linear regression did not highlight any significant association between the tendinopathy subgroup (P = .25) or change in SSTT ratio (P = .40) and change in disability score.

CONCLUSION

Findings from this study suggest that, over time, SSTT in individuals with RCRSP tends to normalize, compared to the contralateral side, regardless of the exercise intervention. Different subgroups of symptomatic tendons behave differently, emphasizing the need to potentially consider tendinopathy subtypes in RCRSP research. Future adequately powered studies should investigate how those different tendinopathy subgroups may predict long-term clinical outcomes.

Dependence of Rotator Cuff Muscle Thickness and Stiffness on Low-Level Contractions: Metrology of the Contraction Level Using Shear-Wave Imaging

OBJECTIVE

The study aimed to investigate the effects of the level of contraction during isometric shoulder abduction at different abduction angles on muscle thickness and stiffness of the shoulder girdle in asymptomatic individuals.

DESIGN

Measurement properties study.

SETTING

Biomechanics and motion analysis lab.

PARTICIPANTS

Twenty individuals volunteered to participate in this study.

MAIN OUTCOME MEASURE

The subjects were tested for morphological and mechanical properties, expressed by thickness and stiffness of the supraspinatus tendon and muscle, and upper trapezius muscle. Moreover, acromiohumeral distance was also evaluated using B-mode ultrasound and shear-wave elastography.

INTERVENTION

The thickness and stiffness of the supraspinatus and upper trapezius muscle were assessed at 3 angles of abduction (0°, 60°, and 90°) and 3 levels of contraction (0%, 10%, and 20% of the maximal voluntary isometric contraction) using ultrasonography with shear-wave imaging. Moreover, the acromiohumeral distance was measured to establish the occupation ratio during passive movement.

RESULTS

The supraspinatus and upper trapezius muscle thickness and stiffness were significantly greater at 60° shoulder abduction compared with 0°, and 90° compared with 60°, as well as significantly greater at 20% maximal voluntary isometric contraction compared with 0% and 10% maximal voluntary isometric contraction. Thickness and stiffness were significantly greater in the supraspinatus compared with the upper trapezius muscle at all 3 angles of shoulder abduction for all 3 level of contractions. The acromiohumeral distance decreased significantly from 0° to 60° and from 60° to 90°.

CONCLUSION

Morphological and mechanical properties of the supraspinatus and upper trapezius muscles depended on the relative level of muscle contraction and the angle of shoulder abduction.

Activation patterns of rotator-cuff muscles from quantitative IVIM DWI after physical testing

BACKGROUND

The diagnostic value of clinical rotator cuff (RC) tests is controversial, with only sparse evidence available about their anatomical specificity. We prospectively assessed regional RC muscle activation patterns by means of intravoxel incoherent motion (IVIM) diffusion-weighted magnetic resonance imaging (MRI) after the execution of common clinical RC tests.

METHODS

Ten healthy subjects (five males, five females) underwent three sessions of diffusion-weighted 3-T shoulder MRI before and after testing the supraspinatus (SSP, Jobe test, session 1), subscapularis (SSC, lift-off test, session 2, at least 1 week later), and infraspinatus muscle (ISP, external rotation test, session 3, another week later). IVIM parameters (perfusion fraction, f; pseudo-diffusion coefficient. D*; and their product, fD*) were measured in regions of interest placed in images of the SSP, SSC, ISP, and deltoid muscle. The Wilcoxon signed-rank test was used for group comparisons; p-values were adjusted using the Bonferroni correction.

RESULTS

After all tests, fD* was significantly increased in the respective target muscles (SSP, SSC, or ISP; p ≤ 0.001). After SSP testing, an additional significant increase of fD* was observed in the deltoid, the SSC, and the ISP muscle (p < 0.001). After the SSC and ISP tests, no significant concomitant increase of any parameter was observed in the other RC muscles.

CONCLUSION

IVIM revealed varying activation patterns of RC muscles for different clinical RC tests. For SSP testing, coactivation of the deltoid and other RC muscles was observed, implying limited anatomical specificity, while the tests for the SSC and ISP specifically activated their respective target muscle.

RELEVANCE STATEMENT

Following clinical RC tests, IVIM MRI revealed that SSP testing led to shoulder muscle coactivation, while the SSC and ISP tests specifically activated the target muscles.

KEY POINTS

In this study, intravoxel incoherent motion MRI depicted muscle activation following clinical rotator cuff tests. After supraspinatus testing, coactivation of surrounding shoulder girdle muscles was observed. Subscapularis and infraspinatus tests exhibited isolated activation of their respective target muscles.

Effect of low-intensity pulsed ultrasound on postoperative rehabilitation of rotator cuff tears: Protocol for a systematic review and meta-analysis

BACKGROUND

Rotator cuff tears are a common shoulder injury that significantly impacts patients' daily lives and work abilities. Although surgical treatment methods for rotator cuff tears have been continuously improved with advances in medical technology, postoperative rehabilitation remains challenging. Therefore, finding effective rehabilitation treatments is crucial for improving patient prognosis and enhancing quality of life. This study will aim to systematically evaluate the impact of low-intensity pulsed ultrasound (LIPUS) on postoperative rehabilitation of rotator cuff tears, comprehensively assessing the efficacy and safety of LIPUS in postoperative recovery.

METHODS

This protocol will search multiple databases including PubMed/MEDLINE, Embase, Cochrane Library, CNKI, Scopus, and Web of Science to identify randomized controlled trials related to LIPUS for postoperative rehabilitation of rotator cuff tears. The search will encompass literature published from the inception of the databases up to April 2024. Methodological quality assessment and data extraction will be conducted using the Cochrane Handbook for Systematic Reviews of Interventions and PRISMA guidelines. Meta-analysis will be performed on appropriate studies using either random-effects or fixed-effects models, and subgroup analyses will be conducted to explore potential heterogeneity. Studies meeting the inclusion criteria will be included in the analysis. All analyses will be performed using Stata version 16.0.

RESULTS

The incidence of rotator cuff tear rates will be assessed by imaging techniques such as MRI or ultrasound. Pain intensity will be scored using standardized pain assessment scales, such as the Visual Analog Scale (VAS). Improved range of motion (ROM) in shoulder flexion, abduction, and rotation. Functional outcomes will be evaluated using effective measures such as Constant-Murley scores (CMS) and shoulder joint scores by American Shoulder and Elbow Surgeons (ASES). Adverse events associated with LIPUS therapy, including skin irritation, increased pain, or any other complications. Subgroup analysis will also be carried out if possible.

DISCUSSION AND CONCLUSION

Following the meta-analysis, we will assess the overall effect of LIPUS on postoperative rehabilitation of rotator cuff tears, and further explore its impact on aspects such as pain relief, functional improvement, and postoperative complications. It is anticipated that this study will provide comprehensive evidence regarding the role of LIPUS in postoperative rehabilitation of rotator cuff tears, guiding clinical practice and future research. The resultant manuscript will be submitted for publication in a peer-reviewed journal.

PROTOCOL REGISTRATION NUMBER

CRD42024530798.

Three-Dimensional Morphological Analysis of the Suprascapular Notch in Patients with Arthroscopic Rotator Cuff Repair

Background

The morphology of the suprascapular notch (SSN) and the ossification of the superior transverse suprascapular ligament (STSL) are risk factors for injury of the suprascapular nerve (SN) during arthroscopic shoulder procedures. The purpose of the current study was to compare preoperative clinical and radiologic characteristics between patients with and without STSL ossification and to evaluate SSN morphology in patients who underwent arthroscopic rotator cuff repair using a 3-dimensional (3D) reconstructed model.

Methods

Patients who underwent arthroscopic rotator cuff repair and were given a computed tomography (CT) scan from March 2018 to August 2019 were included in this study. Patients were divided into 2 groups: those without STSL ossification (group I) and those with STSL ossification (group II). Tear size of the rotator cuff and fatty infiltration of rotator cuff muscles were assessed in preoperative magnetic resonance imaging. The morphology of the SSN was classified following Rengachary's classification. The transverse and vertical diameters of the SSN and the distances from anatomical landmarks to the STSL were measured. All measurements were completed using a 3D CT reconstructed scapula model.

Results

A total of 200 patients were included in this study. One hundred seventy-eight patients (89.0%) without STSL ossification were included in group I, and 22 patients (11.0%) with STSL ossification were included in group II. Group II showed a significantly advanced age (61.0 ± 7.4 vs. 71.0 ± 7.3 years, p < 0.001) and a shorter transverse diameter of SSN (10.7 ± 3.1 mm vs. 6.1 ± 3.7 mm, p < 0.001) than group I. In the logistic regression analysis, age was an independent prognostic factor for STSL ossification (odds ratio, 1.201; 95% confidence interval, 1.112-1.296; p < 0.001). Patients in type VI showed significantly shorter transverse diameters than other types (p < 0.001). The patient with type I showed a significantly shorter distance from the articular surface of the glenoid to the SSN than those with other types (p < 0.001).

Conclusions

In the 3D morphological analysis, age was the independent factor associated with STSL ossification in patients who underwent arthroscopic rotator cuff repair. Type VI showed significantly shorter transverse diameters than other types. Type I showed a significantly shorter distance from the articular surface of the glenoid to the SSN than other types.

Three-dimensional architecture and moment arms of human rotator cuff muscles in vivo: Interindividual, intermuscular, and intramuscular variations

The human rotator cuff consists of four muscles, each with a complex, multipennate architecture. Despite the functional and clinical importance, the architecture of the human rotator cuff has yet to be clearly described in humans in vivo. The purpose of this study was to investigate the intramuscular, intermuscular, and interindividual variations in architecture and moment arms of the human rotator cuff. Muscle volumes, fascicle lengths, physiological cross-sectional areas (PCSAs), pennation angles, and moment arms of all four rotator cuff muscles were measured from mDixon and diffusion tensor imaging (DTI) scans of the right shoulders of 20 young adults. In accordance with the most detailed dissections available to date, we found substantial intramuscular variation in fascicle length (coefficients of variation (CVs) ranged from 26% to 40%) and pennation angles (CVs ranged from 56% to 62%) in all rotator cuff muscles. We also found substantial intermuscular and interindividual variations in muscle volumes, but relatively consistent mean fascicle lengths, pennation angles, and moment arms (CVs for all ≤17%). Moreover, when expressed as a proportion of total rotator cuff muscle volume, the volumes of individual rotator cuff muscles were highly consistent between individuals and sexes (CVs ≤16%), suggesting that rotator cuff muscle volumes scale uniformly, at least in a younger population without musculoskeletal problems. Together, these data indicate limited interindividual and intermuscular variability in architecture, which may simplify scaling routines for musculoskeletal models. However, the substantial intramuscular variation in architecture questions the validity of previously reported mean architectural parameters to adequately describe rotator cuff function.

The Destiny of the Subscapularis Tendon after Arthroscopic Supraspinatus Repair

Background

The purpose of this study was to identify the changes in untreated subscapularis in patients who underwent supraspinatus repair and to evaluate the factors related to the changes in the subscapularis.

Methods

A cohort of patients who underwent isolated supraspinatus repair with preservation of the subscapularis was reviewed. Changes in the subscapularis, including any newly formed lesion and aggravation of an existing lesion, were evaluated 12 months postoperatively on magnetic resonance imaging along with an examination to identify causative factors after supraspinatus repair. Clinical scores were compared between patients with and without subscapularis changes.

Results

A total of 528 patients were reviewed. Changes in the subscapularis, including newly formed lesions and aggravation of an existing lesion, were shown in 90 patients (17.0%). Upon regression analysis, changes in the subscapularis were associated with the initial existence of a subscapularis lesion (grade I: p = 0.042, grade II: p = 0.025), an accompanying biceps lesion (p = 0.038), and a retear of the repaired supraspinatus (p = 0.024). No significant differences were shown in clinical scores between patients with and without subscapularis changes after supraspinatus repair.

Conclusions

Untreated asymptomatic subscapularis may undergo morphological changes even after repair of the torn supraspinatus. Preoperative subscapularis lesions, biceps long head pathology, and retears of the repaired supraspinatus were associated with subscapularis pathology in patients who underwent supraspinatus repair.

The relationship between the duration and the retraction and atrophy grades in traumatic isolated full-thickness supraspinatus tears in young patients

BACKGROUND

The study aimed to determine the grade of retraction and atrophy according to the time elapsed in traumatic isolated full-thickness supraspinatus (SS) tears in young patients.

METHODS

One thousand twenty-six patients, who underwent arthroscopic shoulder surgery, were retrospectively reviewed. Pre-operative magnetic resonance imaging (MRI) of 69 patients aged 18 to 40 years with isolated traumatic full-thickness SS lesions remaining after exclusion criteria were evaluated for tendon retraction and atrophy grades. SS retraction was determined from a T2-weighted oblique coronal MRI slice, and the atrophy grade was determined from the T1-weighted oblique sagittal MRI slice. The patients were divided into four groups 0-1 month, 1-3 months, 3-6 months, and 6-12 months according to the time between trauma and MRI. The relationship of tendon retraction and muscle atrophy with elapsed time was evaluated, in addition, comparisons between groups were made.

RESULTS

Thirty-one (45%) of the patients were female and their mean age was 30 ± 7.3 (18-40) years. The mean age of men was 30.5 ± 6.9 (18-39) years (p = 0.880). The time between rupture and MRI was moderately correlated with retraction and strongly correlated with atrophy grades (r = 0.599, 0.751, respectively). It was observed that there was a statistically significant difference between the 1st (0-1 month) and 2nd (1-3 months) groups (p = 0.003, 0.001, respectively), and between the 2nd and 3rd (3-6 months) groups (p = 0.032, 0.002, respectively), but there was no significant difference between the 3rd and 4th (6-12 months) groups (p = 0.118, 0.057, respectively). In addition, there was a moderate correlation between tendon retraction and atrophy grades (r = 0.668). Power (1- b) in post hoc analysis was calculated as 0.826.

CONCLUSIONS

The current study, supported by arthroscopy, showed that there is a moderate and strong positive correlation between the time elapsed after trauma and the level of retraction and degree of atrophy in traumatic full-thickness SS tears, and demonstrated the importance of early surgical intervention in young patients.

Retrospective analysis of the subscapularis-sparing approach for reverse total shoulder arthroplasty

PURPOSE

The influence of the subscapularis tendon on reverse total shoulder arthroplasty (RTSA) has been discussed controversially. The aim of the study was to investigate the subscapularis-sparing approach for RTSA and the effect of the intact subscapularis tendon.

METHODS

This retrospective comparative study included 93 patients. Among these, 55 underwent the deltopectoral subscapularis-sparing approach, and in 38 cases, the standard deltopectoral approach with subscapularis tenotomy was applied. At the final follow-up, representative shoulder scores were measured, radiographs were taken in two planes, and shoulder sonography was performed.

RESULTS

The subscapularis-sparing group showed a significantly higher Constant score (71.8 vs. 65.9 points) and adapted Constant score if the subscapularis tendon was shown to be intact in the postoperative sonography (85.2% vs. 78.6%) (p = 0.005; p = 0.041). Furthermore, these patients had improved abduction (128.2 vs. 116.8, p = 0.009) and external rotation (34.6 vs. 27.1, p = 0.047). However, no significant differences were found for the degree of internal rotation and internal rotation strength. No dislocation or infection was observed. The degree of scapular notching was not significantly different between the two groups (p = 0.082). However, independently from the integrity of the subscapularis the subscapularis-sparing approach showed no difference in clinical and radiographic outcome (Constant score scapularis-sparing 70.0 points vs. tenotomy 66.8 points; p = 0.27).

CONCLUSION

The subscapularis-sparing approach RTSA showed improved clinical outcome, abduction, and external rotation, if the subscapularis was shown to be intact at time of follow-up. Both groups showed no difference in internal rotation.

Effects of Quality of Integrity on Clinical and Structural Outcomes of Rotator Cuff Repair: A Retrospective Cohort Study of 504 Cases

BACKGROUND

The clinical implications of structural integrity have been a subject of long debate. The oversimplified binary categorization of structural integrity into either healing or retear, along with faulty preoperative baselines for comparison, may contribute to the controversy.

PURPOSE

To determine how the quality of structural integrity in a repaired cuff tendon affects both clinical and structural outcomes by dividing the patients into groups based on integrity and using the immediate postoperative baseline (time zero).

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

A total of 504 patients with a full-thickness rotator cuff tear who underwent arthroscopic rotator cuff repair and were followed up for at least a year with magnetic resonance imaging (MRI) were included. The quality of structural integrity was graded using the Sugaya classification. To evaluate clinical outcomes, pain, range of motion, strength, functional scores, and overall satisfaction and function were used for within- and between-group analyses at the last follow-up. For the assessment of structural outcomes, the Goutallier classification for fatty infiltration (FI) and the tangent sign, occupation ratio, and normalized cross-sectional area for muscle atrophy (MA) were used. The baselines for these structural measurements were both the preoperative and the time-zero MRI scans.

RESULTS

The mean clinical follow-up period was 31.8 ± 27.5 months, and the MRI follow-up period was 10.9 ± 5.3 months. There were 178 (35.3%), 228 (45.2%), 58 (11.5%), 14 (2.8%), and 26 (5.2%) shoulders with Sugaya grades 1, 2, 3, 4, and 5, respectively. Regardless of structural integrity, all clinical outcomes at a mean follow-up of 31.8 months after repair significantly improved compared with those before repair. Only in shoulders with Sugaya grade 1 did the FI of the supraspinatus muscle improve significantly from baseline. FI of the infraspinatus muscle did not change significantly in those with grades 1 and 2 but worsened in those with grades 3 and 5. MA measured using the occupation ratio improved significantly in shoulders with Sugaya grades 1 and 2 but declined in those with grade 5.

CONCLUSION

This study established a correlation between improved structural integrity of the repaired cuff tendon and enhanced structural outcomes in rotator cuff muscles. Furthermore, the findings revealed that both FI and MA could be reversed in patients exhibiting high-quality structural integrity. However, these structural improvements were not mirrored in the clinical outcomes.

Are glenoid retroversion, humeral subluxation, and Walch classification associated with a muscle imbalance?

BACKGROUND

The etiology of humeral posterior subluxation remains unknown, and it has been hypothesized that horizontal muscle imbalance could cause this condition. The objective of this study was to compare the ratio of anterior-to-posterior rotator cuff and deltoid muscle volume as a function of humeral subluxation and glenoid morphology when analyzed as a continuous variable in arthritic shoulders.

METHODS

In total, 333 computed tomography scans of shoulders (273 arthritic shoulders and 60 healthy controls) were included in this study and were segmented automatically. For each muscle, the volume of muscle fibers without intramuscular fat was measured. The ratio between the volume of the subscapularis and the volume of the infraspinatus plus teres minor (AP ratio) and the ratio between the anterior and posterior deltoids (APdeltoid) were calculated. Statistical analyses were performed to determine whether a correlation could be found between these ratios and glenoid version, humeral subluxation, and/or glenoid type per the Walch classification.

RESULTS

Within the arthritic cohort, no statistically significant difference in the AP ratio was found between type A glenoids (1.09 ± 0.22) and type B glenoids (1.03 ± 0.16, P = .09), type D glenoids (1.12 ± 0.27, P = .77), or type C glenoids (1.10 ± 0.19, P > .999). No correlation was found between the AP ratio and glenoid version (ρ = -0.0360, P = .55) or humeral subluxation (ρ = 0.076, P = .21). The APdeltoid ratio of type A glenoids (0.48 ± 0.15) was significantly greater than that of type B glenoids (0.35 ± 0.16, P < .01) and type C glenoids (0.21 ± 0.10, P < .01) but was not significantly different from that of type D glenoids (0.64 ± 0.34, P > .999). When evaluating both healthy control and arthritic shoulders, moderate correlations were found between the APdeltoid ratio and both glenoid version (ρ = 0.55, P < .01) and humeral subluxation (ρ = -0.61, P < .01).

CONCLUSION

This in vitro study supports the use of software for fully automated 3-dimensional reconstruction of the 4 rotator cuff muscles and the deltoid. Compared with previous 2-dimensional computed tomography scan studies, our study did not find any correlation between the anteroposterior muscle volume ratio and glenoid parameters in arthritic shoulders. However, once deformity occurred, the observed APdeltoid ratio was lower with type B and C glenoids. These findings suggest that rotator cuff muscle imbalance may not be the precipitating etiology for the posterior humeral subluxation and secondary posterior glenoid erosion characteristic of Walch type B glenoids.

Maximum in-vivo joint contact forces double during active compared to assisted motion in the glenohumeral joint and decline long-term due to rotator cuff pathologies

Rehabilitation programs advocate early passive and assisted motion after rotator cuff repair to induce healing und maintaining range of motion while avoiding excessive strain on the repaired tendons. In-vivo glenohumeral joint contact forces reflect the compressive forces generated by the rotator muscles. In the present study, maximum in-vivo joint contact forces (FresMax) were determined to compare active and assisted execution of a single movement and the long-term development of joint compression forces. FresMax were measured in six patients who received instrumented, telemetric modified anatomical hemi endoprostheses of the shoulder joint between 2006 and 2008. Data were gathered 23 months postoperatively (2006-2010), were analysed and compared with measurements 133 months postoperatively. Additional imaging was obtained as x-rays and ultrasound examination. Data analysis was conducted by synchronizing video tapes and measured force curves. New imaging showed a rupture of the M. supraspinatus and progressive joint degeneration. FresMax nearly doubled during active compared to assisted execution of each of the four chosen movements. Over the course of 133 months post-surgery, the studied movements showed a decrease of active compression force, probably due to a ruptured supraspinatus, resulting in a lower active/assisted ratio. A long term follow up after eleven years, eight out of ten measured movements showed a decrease of FresMax. These results support current rehabilitation protocols recommending early passive and assisted motion to limit activation of the rotator muscles generating compressive forces. Following degeneration of the rotator cuff, active joint contact forces decrease over time.Level of evidence: III.

Wearable Ultrasound Imaging Device for Dynamic Dual-Direction Shear Wave Elastography of Shoulder Muscle

The shoulder is the most mobile joint in the human body, thus requiring intricate coordination of adjacent muscles. Patients suffered from rotator cuff muscle injuries have several typical symptoms including shoulder pain and difficulty raising the arm, thus reducing work efficiency and compromising the quality of life. Ultrasound has been used widely for shoulder soft tissue imaging as well as ultrasound elastography was introduced in shoulder examination for the dilemma of treating degenerative rotator cuff tears. However, most of the ultrasound examination was performed under a static condition. Providing dynamic information from shoulder muscle is important in clinical applications because the pains sometimes come from various positions of the shoulder during moving. In this study, a customized wearable T-shaped ultrasound transducer (128 + 128 elements) was proposed for shoulder dual-direction shear wave elastography (DDSWE), which provides the SWE for both longitudinal (SW along the muscle fiber) and transverse (SW cross the muscle fiber) directions dynamically. An optical tracking system was synchronized with an ultrasound imaging system to capture shoulder movements in 3-D space with their corresponding ultrasound images. The performance of DDSWE and the accuracy of optical tracking were verified by phantom experiments. Human studies were carried out by volunteers as they are moving their arms. The experimental results show that the bias and precision for the proposed DDSWE in elastic phantom were about 6% and 1.2% for both directions, respectively. A high accuracy of optical tracking was observed using a 3-D motor stage experimental setup. Human experiments show that the shear wave velocities (SWVs) were increased with the angles of shoulder abduction, and the average transverse and longitudinal SWVs were increased from 2.24 to 3.35 m/s and 2.95 to 5.95 m/s with abduction angle from 0° to 60°, respectively, which they are anisotropic-dependent. All the experimental results indicate that the proposed wearable ultrasound DDSWE can quantify the mechanical properties of shoulder muscles dynamically, thereby helping surgeons and physical therapists determine whether the intensity of rehabilitation shoulder be tuned down or escalated in the future.

The correlation of the spinoglenoid ganglion cyst size with the electrophysiological alterations of suprascapular nerve and the rotator cuff muscle power

BACKGROUND

Although various treatment options are available for spinoglenoid cyst, including conservative and surgical methods, there is no standard guideline for its surgical decompression. Thus, the purpose of the study was to correlate the size of the spinoglenoid notch ganglion cyst (GC) as revealed by magnetic resonance imaging (MRI) with electrophysiological alterations, muscle power, and pain severity, and to estimate a cut-off value of cyst size to perform a decompression.

METHODS

Between January 2010 and January 2018, the patients with a GC at the spinoglenoid notch diagnosed on MRI, and who had a minimum follow-up of 2 years after the decompression were included. Maximum cyst diameter as measured on MRI was used for comparison. Electromyography (EMG) and nerve conduction velocity (NCV) studies were performed before the surgery. Peak torque deficit (PTD) percentage compared to opposite shoulder was calculated preoperatively and at 1 year after surgery. Pain severity was estimated using visual analogue scale (VAS) preoperatively.

RESULTS

Ten (50%) of 20 patients with GC > 2.2 cm and 1 (5.9%) of 17 patients with GC < 2.2 cm showed EMG/NCV abnormalities (p = 0.019). There was a correlation between the cyst size and the positive EMG/NCV findings (Correlation coefficient (CC) = 0.535, p < 0.001). The preoperative peak torque deficit on the external rotation was correlated with the positive EMG/NCV findings (CC = 0.373, p = 0.021). The PTD was improved significantly at 1 year postoperatively in patients with a GC size >2.2 cm (p = 0.029). The cyst size was not related to the preoperative pain VAS and muscle power.

CONCLUSIONS

The spinoglenoid cyst size >2.2 cm, but not pain severity or muscle power, correlates with the positive finding of EMG for compressive suprascapular neuropathy. The GC size >2.2 cm can be a reference to decide the need of decompression surgery.

LEVEL OF EVIDENCE

IV, case series.

Preliminary results of clinical, biochemical, and radiological investigation into the oxidative status in patients with rotator cuff tendinopathy

We investigated oxidative status in patients with rotator cuff tendinopathy (RCT) and evaluated their relationship with radiological and clinical parameters. In this cross-section study, 88 patients with RCT (59 males and 29 females) and 86 healthy controls (66 males, 20 females) were enrolled. The sample consisted of nontraumatic patients who are suffering from shoulder pain because of rotator cuff disease, which was established by clinical tests and MRI scanning. Oxidative stress in patients with RCT was analyzed via the dynamic thiol/disulfide homeostasis (TDH). Thiol/disulfide homeostasis was measured by a new colorimetric method. Furthermore, oxidative stress was indirectly measured by serum total oxidant status (TOS), oxidative stress index (OSI), and total antioxidant capacity (TAC). Serum disulfide levels and the other oxidative stress parameters of the RCT group were significantly greater than those of the control group (P < .001 for all), whereas the anti-oxidative stress parameters remained unchanged (P > .05 for all). The lowest and highest serum disulfide levels were detected in patients with grades 1 and 3, respectively (P < .001). Furthermore, in a multiple regression analysis, the disulfide/natural thiol ratio (β=-4.886, P = .004) and the MRI grading (β=0.314, P=.001) were independently associated with the Western Ontario Rotator Cuff Index WORC score. We found an association between the levels of various serum markers of oxidative injury, especially serum disulfide levels, and the increasing severity of RCT. Thiol/disulfide homeostasis seems to play a critical role in RCT, both in the beginning and during the progression of disease.

Relationship between scapular body morphology and rotator cuff tears: a threedimensional computed tomography study

The purpose of this study was to identify the relationship between scapula morphology and rotator cuff tears (RCT). Hundred seventeen shoulders with and 87 shoulders without RCTs were included in this retrospective study. The critical shoulder angle (CSA) and lateral acromion angle in the coronal view, and the acromial coverage angle (ACA) and coracoid and scapular spine angle (CSSA) in the sagittal view were evaluated using 3-dimensional computed tomography. The glenoid anterior tilt, anterior acromial projection angle (AAPA), coracoid process angle, scapular spine angle (SSA), and inferior angle angle (IAA) with respect to the scapular plane were measured in the sagittal view. In univariate logistic regression analysis, CSA, ACA, AAPA, SSA, and IAA were significantly greater in shoulders with RCTs, whereas CSSA was greater in shoulders without RCTs. In multivariate logistic regression analysis, CSA and IAA were greater in shoulders with RCT and were significantly associated with this condition (P=.00073, P=.0032). This study has shown us that RCTs were associated with a greater curvature of the scapular body and greater CSA and IAA.

Association of calcific rotator cuff tendinopathy with nephrolithiasis and/or cholelithiasis: A case-control study

This study aimed to examine the association between calcific rotator cuff tendinopathy (RCT) and nephrolithiasis and/or cholelithiasis. A case-control study was conducted on patients diagnosed with RCT between June 2016 and June 2022. RCT was confirmed by ultrasound, and patients were divided into 2 groups: calcific RCT (case) and non-calcific RCT (control). Data were collected retrospectively from electronic medical records and completed by phone calls, looking for a history of nephrolithiasis and/or cholelithiasis; based on clinical features or incidental findings on abdominal and pelvic imaging. A total of 210 patients with RCT were included. Among the 95 cases of calcific RCT, 43 had a history of lithiasis (45.3%) against 23 (20%) from the non-calcific RCT group (P < .001); 21 patients suffered from nephrolithiasis (22.1%) and 26 had cholelithiasis (27.4%) versus 10 (8.7%) (P = .006) and 16 (13.9%) (P = .015) in the non-calcific RCT group, respectively. Logistic regression showed that the independent predictors of calcific RCT included a history of nephrolithiasis (OR, 4.38; 95% CI: 1.61-11.92, P = .004) and a history of cholelithiasis (OR, 3.83; 95% CI: 1.64-8.94, P = .002). In patients with calcific RCT, the occurrence of lithiasis was significantly associated in the bivariate analysis with higher age, body mass index, fasting blood sugar, and HbA1c (all with P < .05), but only with the presence of another site of calcific tendinopathy than the shoulder (OR, 3.11; 95% CI: 1.12-8.65, P = .03) in the multivariate analysis. Nephrolithiasis and/or cholelithiasis are associated with calcific RCT, and their presence predicts calcific RCT at least 3 times. Further research is required to determine the common risk factors and preventive measures against lithogenesis in patients with calcific RCT, nephrolithiasis, and cholelithiasis.

Human shoulder anatomy: new ultrasound, anatomical, and microscopic perspectives

This study aimed to describe the shoulder anatomy, together with the anatomical relationships in adults and early stages of development. The shoulder muscles were studied from ultrasound, anatomical, and microscopic perspectives in a sample of 34 human shoulders. Thickness measurements were taken of the tendons and fasciae of the subscapularis, long head tendon of the biceps brachii, supraspinatus, infraspinatus, and teres minor. Ultrasound and dissection techniques are strongly correlated. However, the measurements obtained from the dissection technique were superior to those obtained from the ultrasound in all cases, except for the thickness of the long head tendon of the biceps brachii, the teres minor tendon, and the fascia thickness of the infraspinatus. In addition, the study of shoulder anatomy revealed no differences between females and males. Relevant findings from dissection included a clear overlap between the infraspinatus and supraspinatus, which shared tendon fibers, and a similar connection between the transverse ligament of the long head tendon of the biceps brachii and the subscapularis, which created a more interconnected shoulder function. The study of the anatomical measurements shows an underestimation of the shoulder measurements in the ultrasound compared with the dissection technique, but a high correlation between the measurements made by the two techniques. We present reference values for the tendon and fascia thicknesses of the rotator cuff, with no differences observed by gender. The relationships between shoulder structures described in the anatomical study imply as well that, in the event of an injury, adjacent tissues may be affected. This extended information may facilitate future optimal clinical explorations.

Biomechanical, Histologic, and Micro-Computed Tomography Characterization of Partial-Width Full-Thickness Supraspinatus Tendon Injury in Rats

PURPOSE

Partial rotator cuff tears can cause shoulder pain and dysfunction and are more common than complete tears. However, few studies examine partial injuries in small animals and, therefore a robust, clinically relevant model may be lacking. This study aimed to fully characterize the established rat model of partial rotator cuff injury over time and determine if it models human partial rotator cuff tears.

METHODS

We created a full-thickness, partial-width injury at the supraspinatus tendon-bone interface bilaterally in 31 Sprague-Dawley rats. Rats were euthanized immediately, and at 2-, 3-, 4-, and 8-weeks after surgery. Fourteen intact shoulders were used as controls. Samples were assessed biomechanically, histologically, and morphologically.

RESULTS

Biomechanically, load to failure in controls and 8 weeks after injury was significantly greater than immediately and 3 weeks after injury. Load to failure at 8 weeks was comparable to control. However, the locations of failure were different between intact shoulders and partially injured samples. Bone mineral density at 8 weeks was significantly greater than that at 2 and 3 weeks. Although no animals demonstrated propagation to complete tear and the injury site remodeled histologically, the appearance at 8 weeks was not identical to that in the controls.

CONCLUSIONS

The biomechanical properties and bone quality decreased after the injury and was restored gradually over time with full restoration by 8 weeks after injury. However, the findings were not equivalent to the intact shoulder. This study demonstrated the limitations of the current model in its application to long-term outcome studies, and the need for better models that can be used to assess chronic partial rotator cuff injuries.

CLINICAL RELEVANCE

There is no small animal model that mimics human chronic partial rotator cuff tears, which limits our ability to improve care for this common condition.

Subscapularis impairment on magnetic resonance imaging is correlated with functional limitations in neonatal brachial plexus palsy

PURPOSE

The relationship between functional shoulder deficits in children with neonatal brachial plexus palsy (NBPP) and magnetic resonance imaging (MRI) shoulder abnormalities was evaluated.

METHODS

Shoulder function was assessed in 16 children (mean age: 5.8 years; range: 3-12 years) with NBPP based on shoulder rotator muscle strength, as measured using an isokinetic dynamometer and the modified Mallet score. The thickness and fatty infiltration of the subscapularis and infraspinatus muscles, and the morphology of the glenoid on MRI, were also determined.

RESULTS

The highest subscapularis fatty infiltration subgroup of NBPP patients promoted the highest alteration muscle thickness and modified Mallet score.

CONCLUSIONS

In NBPP children, subscapularis impairments play a major role in the functional limitations. This study of pediatric NBPP patients highlighted the value of adding an examination of the muscles to routine MRI assessment of bone parameters in the shoulders of NBPP children.

TRIAL REGISTRATION

NCT03440658.

Clinical and Structural Outcomes of Arthroscopic Rotator Cuff Repair in Patients Over 75 Years Are Comparable to Those in Younger Patients: A Propensity Score-Matched Comparative Study

PURPOSE

To compare clinical and structural outcomes of arthroscopic rotator cuff repair (ARCR) in patients over 75 years and those under 75 years and to analyze the factors associated with retear and clinical outcomes after ARCR.

METHODS

This retrospective study reviewed patients who underwent ARCR between 2011 and 2021 with at least 2 years of follow-up. Using propensity score matching for sex, tear size, subscapularis involvement, and follow-up time, this study included 54 patients older than 75 years (group A) and 54 patients younger than 75 years (group B). Cuff integrity was evaluated using magnetic resonance imaging (MRI). Structural and clinical outcomes were compared between the 2 groups.

RESULTS

The mean improvements in external rotation (P = .030) and the American Shoulder and Elbow Surgeons (ASES) score (P = .043) were significantly higher in group A. Visual analog scales for pain and function, ASES score, and Constant score were significantly improved in both groups (all P = .001). On routine postoperative MRI at 6 months, the retear rate was 20.4% (11/54) in group A and 18.5% (10/54) in group B with no statistical difference between the 2 groups (P = .808). Factor analysis in group A showed that follow-up duration (P = .019), tear size in mediolateral dimension (P = .037), occupation ratio (P = .036), and incomplete repair (P = .034) were associated with retear, and mild glenohumeral arthritis (P = .003) and subscapularis involvement (P = .018) were associated with inferior Constant score.

CONCLUSIONS

Clinical and structural outcomes after ARCR in patients aged 75 years or older are comparable to those in patients younger than 75 years.

LEVEL OF EVIDENCE

Level III, retrospective case-control study.