Surgically repaired massive rotator cuff tears: MRI of tendon integrity, muscle fatty degeneration, and muscle atrophy correlated with intraoperative and clinical findings

Development of a deep learning-based fully automated segmentation of rotator cuff muscles from clinical MR scans

BACKGROUND

The fatty infiltration and atrophy in the muscle after a rotator cuff (RC) tear are important in surgical decision-making and are linked to poor clinical outcomes after rotator cuff repair. An accurate and reliable quantitative method should be developed to assess the entire RC muscles.

PURPOSE

To develop a fully automated approach based on a deep neural network to segment RC muscles from clinical magnetic resonance imaging (MRI) scans.

MATERIAL AND METHODS

In total, 94 shoulder MRI scans (mean age = 62.3 years) were utilized for the training and internal validation datasets, while an additional 20 MRI scans (mean age = 62.6 years) were collected from another institution for external validation. An orthopedic surgeon and a radiologist manually segmented muscles and bones as reference masks. Segmentation performance was evaluated using the Dice score, sensitivities, precision, and percent difference in muscle volume (%). In addition, the segmentation performance was assessed based on sex, age, and the presence of a RC tendon tear.

RESULTS

The average Dice score, sensitivities, precision, and percentage difference in muscle volume of the developed algorithm were 0.920, 0.933, 0.912, and 4.58%, respectively, in external validation. There was no difference in the prediction of shoulder muscles, with the exception of teres minor, where significant prediction errors were observed (0.831, 0.854, 0.835, and 10.88%, respectively). The segmentation performance of the algorithm was generally unaffected by age, sex, and the presence of RC tears.

CONCLUSION

We developed a fully automated deep neural network for RC muscle and bone segmentation with excellent performance from clinical MRI scans.

Supraspinatus Muscle and Tendon Characteristics 1 Year After Surgical Rotator Cuff Repair Compared With Contralateral Shoulder: Data From the CUT-N-MOVE Trial

BACKGROUND

It is necessary to better understand the structural characteristics of the supraspinatus tendon and associated muscle after rotator cuff repair and in the event of retear.

PURPOSE

To study structural differences between the repaired and contralateral shoulders 1 year after rotator cuff repair in patients who received either progressive exercise therapy (PR) or usual care (UC) in a randomized controlled trial and to investigate whether there was interaction with tendon retear and limb dominance.

STUDY DESIGN

Cohort study; Level of evidence, 2.

METHODS

Patients with surgically repaired traumatic full-thickness rotator cuff tears involving the supraspinatus tendon were included. After surgery, they were randomized to PR or UC (active from postoperative week 2 or 6, respectively). The subacromial structures (acromiohumeral distance, supraspinatus tendon thickness, and vascularity) and the supraspinatus muscle thickness were examined with ultrasound at the 1-year follow-up.

RESULTS

A total of 79 patients were included. The characteristics of the 2 intervention groups (PR and UC) were comparable, including the Western Ontario Rotator Cuff Index score and number of retears. The authors found significantly thinner supraspinatus tendon (PR, P < .001; UC, P = .003) and reduced acromiohumeral distance (PR, P = .023; UC, P = .025) in the repaired versus the contralateral shoulders in both intervention groups. For neovascularization, there was no interlimb difference in either of the groups or between groups (PR vs UC). In patients with intact tendons, there was no interlimb difference in the muscle thickness, but in patients with tendon retear the muscle was significantly thinner on the repaired side (P = .024 and P < .001, respectively). When the dominant supraspinatus tendon was repaired (both groups), it was significantly thinner than the nondominant healthy tendon, but this difference was not seen when the nondominant supraspinatus tendon was repaired (P = .006).

CONCLUSION

One year after rotator cuff surgery, the repaired supraspinatus tendon was significantly thinner and the corresponding acromiohumeral distance was reduced. In patients with retear, the supraspinatus muscle was significantly thinner on the repaired side and early initiation of tendon-loading exercises did not affect these findings.

REGISTRATION

NCT02969135 (ClinicalTrials.gov identifier).

Obesity is associated with muscle atrophy in rotator cuff tear

Objective

The primary goal of this study is to evaluate the relationship between Body Mass Index (BMI) and muscle atrophy in individuals with rotator cuff tears.

Methods

This study consists of patients with rotator cuff tears identified by MRI from two independent cohorts, the Rotator Cuff Outcomes Workgroup (ROW) and the Multicenter Orthopaedic Outcomes Network (MOON). Presence of atrophy (yes/no) and severity of atrophy (as an ordinal variable) were assessed on MRI by expert physicians. We used multivariable regression models to evaluate the relationship between BMI and muscle atrophy while adjusting for age and sex in each study, conducted sensitivity analyses for full-thickness tear and combined results using inverse variance-weighted meta-analysis.

Results

A total of 539 patients (MOON=395, ROW=144) from the combined cohorts had MRI data available on muscle atrophy. Among these patients, 246 (46%) had atrophy of at least one of the muscles of the rotator cuff and 282 (52%) had full-thickness tears. In meta-analysis across both cohorts, each 5 kg/m2 increase in BMI was associated with a 21% (aOR=1.21, 95% CI=1.02, 1.43) increased odds of having muscle atrophy among individuals with any tear size, and 36% (aOR=1.36, 95% CI=1.01-1.81) increased odds among individuals with full-thickness tear.

Conclusions

Higher BMI was associated with significantly higher odds of muscle atrophy in patiens with rotator cuff tears. More study is needed to unders1tand why and how this relationship exists, as well as whether interventions to reduce BMI may help improve outcomes for these patients.

Level of Evidence

III.

Risk factors for intracellular fatty accumulation in rotator cuff muscle: a histologic analysis

BACKGROUND

Fatty accumulation in rotator cuff muscles has been associated with shoulder dysfunction, risk of repair failure, and poor postoperative outcomes. This study sought to assess risk factors associated with true fatty accumulation based on histologic analysis and determine whether preoperative function directly correlated with this fatty rotator cuff accumulation.

METHODS

Supraspinatus muscle biopsy specimens obtained prospectively from patients undergoing arthroscopic rotator cuff repair were stained with LipidTOX to quantify lipid accumulation. Two-step cluster analysis with Goutallier classification was used to define the fatty and non-fatty rotator cuff groups. We further performed a receiver operating characteristic curve analysis to confirm the group cutoff values.

RESULTS

In total, 51 patients (aged 60.1 ± 10.5 years) were included. There were 19 high-grade partial tears, 10 small tears, 7 medium tears, 10 large tears, and 5 massive tears. Both cluster and receiver operating characteristic curve analyses yielded a cutoff value of 30% LipidTOX/4',6-diamidino-2-phenylindole (DAPI) separating the fatty vs. non-fatty groups. In the univariate analysis, patients with fatty rotator cuffs were aged 63.2 years on average compared with 59.7 years in the non-fatty group (P = .038). Female patients made up 57.1% of the fatty cohort, which was statistically higher than the non-fatty group (P = .042). Massive and large tears were more likely to occur in the fatty group (P = .005). In the multivariate analysis, full tendon tears had the largest predictive status of falling into the fatty group (odds ratio, 15.4; P = .008), followed by female sex (odds ratio, 4.9; P = .036). Patients in the fatty group had significantly higher American Shoulder and Elbow Surgeons scores (P = .048) and lower visual analog scale scores (P = .002).

DISCUSSION AND CONCLUSION

This prospective histologic assessment revealed that full-thickness rotator cuff tears and female sex were the largest risk factors for intracellular lipid accumulation. Although tear size correlated with fatty accumulation, the sex disparity is a noteworthy finding that warrants further research.

Aging-Related Rotator Cuff Tears: Molecular Mechanisms and Implications for Clinical Management

Shoulder pain and disabilities are prevalent issues among the elderly population, with rotator cuff tear (RCT) being one of the leading causes. Although surgical treatment has shown some success, high postoperative retear rates remain a great challenge, particularly in elderly patients. Aging-related degeneration of muscle, tendon, tendon-to-bone enthesis, and bone plays a critical role in the development and prognosis of RCT. Studies have demonstrated that aging worsens muscle atrophy and fatty infiltration, alters tendon structure and biomechanical properties, exacerbates enthesis degeneration, and reduces bone density. Although recent researches have contributed to understanding the pathophysiological mechanisms of aging-related RCT, a comprehensive systematic review of this topic is still lacking. Therefore, this article aims to present a review of the pathophysiological changes and their clinical significance, as well as the molecular mechanisms underlying aging-related RCT, with the goal of shedding light on new therapeutic approaches to reduce the occurrence of aging-related RCT and improve postoperative prognosis in elderly patients.

Automatic MRI-based rotator cuff muscle segmentation using U-Nets

BACKGROUND

The rotator cuff (RC) is a crucial anatomical element within the shoulder joint, facilitating an extensive array of motions while maintaining joint stability. Comprised of the subscapularis, infraspinatus, supraspinatus, and teres minor muscles, the RC plays an integral role in shoulder functionality. RC injuries represent prevalent, incapacitating conditions that impose a substantial impact on approximately 8% of the adult population in the USA. Segmentation of these muscles provides valuable anatomical information for evaluating muscle quality and allows for better treatment planning.

MATERIALS AND METHODS

We developed a model based on residual deep convolutional encoder-decoder U-net to segment RC muscles on oblique sagittal T1-weighted images MRI. Our data consisted of shoulder MRIs from a cohort of 157 individuals, consisting of individuals without RC tendon tear (N=79) and patients with partial RC tendon tear (N=78). We evaluated different modeling approaches. The performance of the models was evaluated by calculating the Dice coefficient on the hold out test set.

RESULTS

The best-performing model's median Dice coefficient was measured to be 89% (Q1:85%, Q3:96%) for the supraspinatus, 86% (Q1:82%, Q3:88%) for the subscapularis, 86% (Q1:82%, Q3:90%) for the infraspinatus, and 78% (Q1:70%, Q3:81%) for the teres minor muscle, indicating a satisfactory level of accuracy in the model's predictions.

CONCLUSION

Our computational models demonstrated the capability to delineate RC muscles with a level of precision akin to that of experienced radiologists. As hypothesized, the proposed algorithm exhibited superior performance when segmenting muscles with well-defined boundaries, including the supraspinatus, subscapularis, and infraspinatus muscles.

Reliability of Magnetic Resonance Imaging Criteria for the Preoperative Assessment of Rotator Cuff Tears: A Systematic Review

BACKGROUND

Magnetic resonance (MR) imaging is the most common modality for assessment of the rotator cuff before and after surgery. Several classifications have been described aiming to define main tear characteristics. However, there is still confusion when it comes to the reliability of those classifications.

PURPOSE

(1) To identify all MR classifications available in the literature for preoperative assessment of rotator cuff tears, (2) to summarize available data on the reliability of identified classifications, and (3) to assess the methodological quality of reliability studies.

STUDY DESIGN

Systematic review; Level of evidence, 4.

METHODS

This systematic review was conducted following the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines. All studies reporting MR assessment in patients with a superior or posterosuperior rotator cuff tear were included. After identification of the available MR criteria, reliability studies were analyzed. Descriptive statistics were used to summarize findings. Methodological quality was assessed using the Quality Appraisal of Reliability Studies checklist.

RESULTS

A total of 75 studies were included in this review. Eight categories of outcomes could be identified. Of the total, 62 studies reported interobserver reliability whereas 32 reported intraobserver reliability of some of the identified criteria. Each category reflected a variety of reliability, ranging from poor to excellent agreement. MR proved to be a reliable imaging modality to detect the structural integrity of the posterosuperior cuff, especially in cases of full-thickness tear; it was also reliable in terms of tear width and length and muscle atrophy based on a tangent sign or Thomazeau classification. All other classifications did not prove acceptable reliability. Methodological quality was high for 23 articles and moderate for 14.

CONCLUSION

Preoperative MR is a reliable imaging modality to identify full-thickness tears, measure tear size and morphology, and identify muscle atrophy with tangent sign or Thomazeau classification. All other outcomes and classifications did not show acceptable reliability; therefore, caution is needed when using them for preoperative evaluation of a rotator cuff tear.

Rotator cuff tear patterns: MRI appearance and its surgical relevance

A new perspective on rotator cuff anatomy has allowed a better understanding of the patterns of the different rotator cuff tears. It is essential for radiologists to be aware of these different patterns of tears and to understand how they might influence treatment and surgical approach. Our objective is to review the arthroscopy correlated magnetic resonance imaging appearance of the different types of rotator cuff tears based on current anatomical concepts.Critical relevance statement Knowledge of the characteristics of rotator cuff tears improves our communication with the surgeon and can also make it easier for the radiologist to prepare a report that guides therapeutic conduct and serves as a prognosis for the patient.Key points• There is no universally accepted classification for RC tears.• New patterns such as delamination or myotendinous junction tears have been defined.• The most difficult feature to assess in full thickness tears on MRI is the pattern.• Fatty infiltration of the RC tendons is crucial in the prognosis and outcome.• The radiological report is an effective way of communication with the surgeon.

Top 50 most impactful publications on massive rotator cuff tears

Background

Bibliometric analysis is a useful tool for measuring the scholarly impact of a topic and its more and less heavily studied aspects. The purpose of this study is to use bibliometric analysis to comprehensively analyze the 50 articles with the highest citation indices in studies evaluating the treatment and outcomes of massive rotator cuff tears (mRCTs).

Methods

This cross-sectional study identified articles within the Scopus database published through December 2022. Keywords used were "massive rotator cuff tear." Articles were sorted in chronological order. The year published and number of citations were recorded. A citation index (CI) was calculated for each article by dividing the number of citations by number of years published [1 citation/1 year published (2021) = CI of 1]. Of these, the 50 articles with the highest CIs were carried forward for evaluation. Frequencies and distributions were assessed for data of each variable collected.

Results

These search methods produced 625 articles regarding mRCT research (ranging from January 1986 to December 2022). Four of the top 10 most impactful articles were published in the 2010s. The level of evidence (LOE) published with the greatest frequency was level of evidence 4 (41%). The journal Arthroscopy published the highest number within the top 50 (26%) followed by the Journal of Bone and Joint Surgery and the American Journal of Sports Medicine (20% each). Clinical studies composed 88% of the top 50. Case series (38%) predominated, while systematic reviews (20%) and randomized control trials (8%) were less prevalent. The majority of studies concentrated on the clinical outcomes of certain interventions (62%), mainly comparing multiple interventions.

Conclusion

Despite the relatively high prevalence of mRCTs (40% of all tears), this topic comprises only a small proportion of all rotator cuff research. This analysis has identified gaps within and limitations of the findings concerning mRCTs for researchers to propose research questions targeting understudied topics and influence the future treatment and outcomes of this clinically difficult diagnosis.

Influence of Vitamin D Deficiency on the Expression of Genes and Proteins in Patients With Medium Rotator Cuff Tears

BACKGROUND

Whether vitamin D deficiency is related to rotator cuff muscle and tendon physiology is controversial.

PURPOSE

To assess the relationship between vitamin D deficiency and various gene expression patterns in patients with rotator cuff tears.

STUDY DESIGN

Controlled laboratory study.

METHODS

During arthroscopic surgery, samples from the supraspinatus muscle, deltoid muscle, and supraspinatus tendon were acquired from 12 patients with vitamin D deficiency (serum 25-hydroxyvitamin D concentration <20 ng/dL) and 12 patients with sufficient vitamin D levels (control group, serum 25-hydroxyvitamin D concentration ≥30 ng/dL) who were matched for age, sex, and tear size. Alterations in the expression of genes and proteins associated with myogenesis, muscle atrophy, adipogenesis, inflammation, and apoptosis, as well as in vitamin D receptor expression, were assessed using quantitative reverse transcription polymerase chain reaction, Western blotting, and immunohistochemistry and were compared between the 2 groups.

RESULTS

Vitamin D receptor gene expression in the deltoid muscle was significantly lower in the vitamin D deficiency group than in the control group (P = .043). Additionally, in the deltoid muscle, myoDgene expression levels were lower and atrogin levels were higher in the vitamin D deficiency group than in the control group (P = .034 and P = .011, respectively). However, in the supraspinatus muscle, no differences were observed between groups in the expression of myogenesis- or atrophy-related genes (all P > .05). The expression of inflammation-related genes (interleukin (IL)-1β and IL-6) was significantly higher in the vitamin D deficiency group, in both the deltoid and supraspinatus muscles (all P < .05). The supraspinatus tendon tissue did not show any significant differences in any gene expression evaluated (all P > .05). A correlation between gene and protein expression was observed for atrogin and IL-1β in the deltoid muscle (P = .019 and P = .037, respectively) and for IL-6 in the supraspinatus muscle (P = .044).

CONCLUSION

Vitamin D deficiency was not associated with the expression of myogenesis-related or muscle atrophy-related genes in the supraspinatus muscle of patients with rotator cuff tears, unlike in the deltoid muscle; rather, vitamin D deficiency was associated with increased proinflammatory cytokine expression.

CLINICAL RELEVANCE

In patients with rotator cuff tears, vitamin D deficiency was observed to be associated with increased levels of proinflammatory cytokines in the rotator cuff muscles, without significant changes in gene expression related to myogenesis or muscle atrophy.

Rotator Cuff Injury and Repair

Rotator cuff pathology is a commonly encountered clinical and radiologic entity that can manifest as tendinopathy or tearing. Magnetic resonance imaging (MRI) and ultrasonography offer similar sensitivity and specificity for the evaluation of the native rotator cuff, and the chosen modality may vary, depending on local practice and accessibility. MR arthrography is frequently used in the postoperative setting as a problem-solving tool. Key findings to include in the preoperative MRI report include the size and location of the tear, thickness of the tendon involved (partial versus full thickness), and overall tendon quality. The report should also address features associated with poor surgical outcomes, such as fatty atrophy, a decreased acromiohumeral interval, and evidence of rotator cuff arthropathy. Musculoskeletal radiologists should be familiar with the various surgical techniques and expected postoperative imaging appearance of rotator cuff repairs. Imaging also plays a role in identifying recurrent tearing, graft failure, hardware loosening, infection, and other complications.

Clinical outcomes of reverse shoulder arthroplasty and rotator cuff repair in patients with massive rotator cuff tears without osteoarthritis: comparison using propensity score matching

BACKGROUND

The optimal management for massive rotator cuff tears (MRCTs) without osteoarthritis (OA) remains controversial. The purpose of this study was to evaluate and compare the clinical outcomes of reverse shoulder arthroplasty (RSA) vs. rotator cuff repair (RCR) in patients with MRCTs without OA.

METHODS

We conducted a retrospective data analysis of 68 patients treated for MRCTs via RSA and 215 patients treated for MRCTs via arthroscopic RCR between January 2014 and April 2019. Through propensity score matching, patients were matched for sex, age, tear size, and global fatty degeneration index. Thirty-nine patients in each group were included, and all patients had completed minimal 2-year follow-up. Postoperative radiologic evaluations of healing failure were performed. The visual analog scale score for pain, range of motion, and functional outcome measures including the American Shoulder and Elbow Surgeons score, QuickDASH (short version of Disabilities of the Arm, Shoulder and Hand questionnaire) score, Simple Shoulder Test score, and Constant score were assessed and compared between the 2 groups.

RESULTS

Healing failure was observed in 10 patients in the RCR group (32.3%). No statistically significant differences in preoperative range of motion and functional scores were found between the RCR and RSA groups. Both groups showed significant pain relief and functional improvement at final follow-up. Patients in the RCR group showed significantly greater forward elevation (156.4° ± 23.8° vs. 139.7° ± 22.4°, P < .001) and internal rotation (thoracic vertebra, T8.2 ± 1.2 vs. T9.7 ± 2.6, P = .001). The average American Shoulder and Elbow Surgeons score was 88.3 ± 12.2 in the RCR group and 81.8 ± 16.1 in the RSA group (P = .045). The QuickDASH score was significantly higher in the RCR group (P = .019). A significantly higher Simple Shoulder Test score (9.7 ± 2.8 vs. 8.1 ± 3.0, P = .01) and a significantly higher Constant score (67.2 ± 6.5 vs. 63.2 ± 7.1, P = .011) were seen in the RCR group.

CONCLUSION

Both RSA and RCR are effective and reliable treatment options for MRCTs without OA. However, the RCR group showed better shoulder function improvement than the RSA group. Considering the possible implications of RSA, RCR should be referred to as a first-line treatment option for patients with MRCTs without OA with proper indications.

The correlation between types of posterior upper rotator cuff tears and intramuscular fat infiltration based on magnetic resonance imaging: A retrospective observational study

Objective: This study investigated the correlation between types of posterior upper rotator cuff tears (RCTs) and intramuscular fat infiltration (FI) in magnetic resonance imaging (MRI).

Methods: The shoulder joints of 50 adults with a full-thickness posterior upper RCT diagnosed by MRI, from January 2019 to December 2021, were retrospectively analyzed. The patients were divided into three groups according to tear type: 1) an L-shaped tear group; 2) a crescent/U-shaped tear group; 3) a complete tear group. The correlation among age, gender, tear range, trauma history, and the duration of clinical symptoms was analyzed. The MRI images were used by two musculoskeletal imaging physicians to evaluate the type and range of tears, the Goutallier grade of the supraspinatus and infraspinatus, and the correlations and reliability were analyzed.

Results: Differences in the tear range (p < 0.001) and the Goutallier grade of the infraspinatus muscle (p = 0.036) among the L-shaped, crescent/U-shaped, and complete tear groups were statistically significant; however, differences in the Goutallier grade of the supraspinatus muscle was not statistically significant (p = 0.356). In the crescent/U-shaped tear group, age was significantly correlated with the Goutallier grade of the supraspinatus muscle (RS = 0.720, p = 0.029) and the infraspinatus muscle (RS = 0.713, p = 0.032). In the complete tear group, tear range was significantly correlated with the Goutallier grade of the supraspinatus muscle (RS = 0.801, p = 0.001) and the infraspinatus muscle (RS = 0.802, p = 0.001). The Goutallier grades of the supraspinatus muscle (kappa, 0.489) and the infraspinatus muscle (kappa, 0.424) presented with interobserver consistency.

Conclusion: The type of posterior upper RCT correlates with the degree of FI. There is a positive correlation between the FI of crescent/U-shaped full-thickness RCTs and age. Additionally, the range of complete tears in the posterior upper RC has a positive correlation with FI.

MRI-based 3-dimensional volumetric assessment of fatty infiltration and muscle atrophy in rotator cuff tears

BACKGROUND

The Goutallier and Warner Classification systems are useful in determining rotator cuff reparability. Data are limited on how accurately the scapular-Y view used in both systems reflects the 3-dimensional (3-D) changes in fatty infiltration (FI) and muscle atrophy (MA). Tendon retraction in the setting of a cuff tear may also influence the perception of these changes. This study's objectives were to (1) measure the 3-D volume of the supraspinatus muscle in intact rotator cuffs, and with varying magnitudes of retraction; (2) measure the 3-D volume of FI in the supraspinatus muscle in these conditions; and (3) determine the influence of tendon retraction on measured FI and MA using the Goutallier and Warner Classification Systems.

METHODS

Between August 2015 and February 2016, all shoulder magnetic resonance images (MRIs) at the Portland VA Medical Center were standardized to include the medial scapular border. MRIs and charts were reviewed for inclusion/exclusion criteria. Included MRIs were categorized into 4 groups based on rotator cuff retraction. Supraspinatus muscle and fossa were traced to create 3-D volumes. FI and MA were measured within the supraspinatus. The supraspinatus muscle was graded among 6 physicians using the Goutallier and Warner classification systems. These grades were compared to 3-D measured FI and MA. The influence of tendon retraction on the measured grades were also evaluated.

RESULTS

One hundred nine patients met inclusion/exclusion criteria. Ten MRIs for each group (N = 40) were included for image analysis. Supraspinatus volume tracings were highly reproducible and consistent between tracers. Supraspinatus muscle volumes decreased while global FI and MA increased with greater degrees of tendon retraction. In muscles with less than 10% global fat, fat concentrated in the lateral third of the muscle. In muscle with more than 10% global fat content, it distributed more diffusely throughout the muscle from medial to lateral. In comparing the scapular-Y to a medial cut, there was no consistent trend in FI whereas MA was more accurate at the medial cut.

CONCLUSION

Parasagittal imaging location did not significantly influence the Goutallier score; however, assessment of MA using the Warner score leads readers to perceive less MA medially regardless of the magnitude of tendon retraction. The pattern of FI within the supraspinatus muscle changes from a laterally based location around the muscle-tendon junction to a more diffuse, global infiltration pattern when the whole muscle fat content exceeds 10%.

Biomechanically and biochemically functional scaffold for recruitment of endogenous stem cells to promote tendon regeneration

Tendon regeneration highly relies on biomechanical and biochemical cues in the repair microenvironment. Herein, we combined the decellularized bovine tendon sheet (DBTS) with extracellular matrix (ECM) from tendon-derived stem cells (TDSCs) to fabricate a biomechanically and biochemically functional scaffold (tECM-DBTS), to provide a functional and stem cell ECM-based microenvironment for tendon regeneration. Our prior study showed that DBTS was biomechanically suitable to tendon repair. In this study, the biological function of tECM-DBTS was examined in vitro, and the efficiency of the scaffold for Achilles tendon repair was evaluated using immunofluorescence staining, histological staining, stem cell tracking, biomechanical and functional analyses. It was found that tECM-DBTS increased the content of bioactive factors and had a better performance for the proliferation, migration and tenogenic differentiation of bone marrow-derived stem cells (BMSCs) than DBTS. Furthermore, our results demonstrated that tECM-DBTS promoted tendon regeneration and improved the biomechanical properties of regenerated Achilles tendons in rats by recruiting endogenous stem cells and participating in the functionalization of these stem cells. As a whole, the results of this study demonstrated that the tECM-DBTS can provide a bionic microenvironment for recruiting endogenous stem cells and facilitating in situ regeneration of tendons.

Automatic MRI segmentation of pectoralis major muscle using deep learning

To develop and validate a deep convolutional neural network (CNN) method capable of selecting the greatest Pectoralis Major Cross-Sectional Area (PMM-CSA) and automatically segmenting PMM on an axial Magnetic Resonance Imaging (MRI). We hypothesized a CNN technique can accurately perform both tasks compared with manual reference standards. Our method is based on two steps: (A) segmentation model, (B) PMM-CSA selection. In step A, we manually segmented the PMM on 134 axial T1-weighted PM MRIs. The segmentation model was trained from scratch (MONAI/Pytorch SegResNet, 4 mini-batch, 1000 epochs, dropout 0.20, Adam, learning rate 0.0005, cosine annealing, softmax). Mean-dice score determined the segmentation score on 8 internal axial T1-weighted PM MRIs. In step B, we used the OpenCV2 (version 4.5.1, https://opencv.org) framework to calculate the PMM-CSA of the model predictions and ground truth. Then, we selected the top-3 slices with the largest cross-sectional area and compared them with the ground truth. If one of the selected was in the top-3 from the ground truth, then we considered it to be a success. A top-3 accuracy evaluated this method on 8 axial T1-weighted PM MRIs internal test cases. The segmentation model (Step A) produced an accurate pectoralis muscle segmentation with a Mean Dice score of 0.94 ± 0.01. The results of Step B showed top-3 accuracy > 98% to select an appropriate axial image with the greatest PMM-CSA. Our results show an overall accurate selection of PMM-CSA and automated PM muscle segmentation using a combination of deep CNN algorithms.

Effects of Hydroxylated Lecithin on Growth Performance, Serum Enzyme Activity, Hormone Levels Related to Lipid Metabolism and Meat Quality in Jiangnan White Goslings

The objective of the present study was to evaluate the effects of hydroxylated lecithin on growth performance, serum enzyme activity, hormone levels related to lipid metabolism and meat quality in Jiangnan White goslings. Six hundred 1-day-old goslings were randomly divided into five treatments with six replicates and 20 for each replicate. The control group (CG) was fed the basal diet, while the experimental group was fed the basal diet with 50, 100, 200 mg/kg hydroxylated lecithin and 100 mg/kg soy lecithin (HLG50, HLG100, HLG200, and LG100, respectively) in the form of powder. Feed and water were provided ad libitum for 32 days. Compared with the CG, (a) the average daily feed intake was higher (P &lt; 0.05) in HLG100, the final body weight and average daily gain were higher (P &lt; 0.05), and the feed conversion ratio was lower in the HLG200; (b) the alanine aminotransferase, malate dehydrogenase, leptin, glucagon, thyroid hormone, Triiodothyronine contents in the HLG200 were lower (P &lt; 0.05); (c) The breast muscle water holding capacity was higher (P &lt; 0.05) in groups with hydroxylated lecithin, the breast muscle shear force and fiber diameter were lower (P &lt; 0.05) in the HLG100; (d) the inositic acid, intramuscular fat, phospholipid contents were higher (P &lt; 0.05), the triglyceride content was lower (P &lt; 0.05) in HLG100 of the breast muscle; (e) the relative expression of sterol regulatory element-binding protein-1 genes were higher (P &lt; 0.05) in the treated groups of muscles, the phosphorylase kinase gamma subunit 1 gene expression was shown an opposite trend. In comparison with LG100, (a) the feed conversion ratio was lower (P &lt; 0.05) in HLG200; (b) the alanine aminotransferase and adiponectin contents were higher (P &lt; 0.05), the malondialdehyde and free fatty acid contents were lower (P &lt; 0.05) in HLG200; (c) the water holding capacity and intramuscular fat contents in the breast and leg muscles were higher (P &lt; 0.05) in HLG200. The hydroxylated lecithin concentration of 200 mg/kg improved the growth performance, serum enzyme activity, hormone levels related to lipid metabolism, and the meat quality of Jiangnan White goslings.

Effect of human dermal allograft thickness on glenohumeral stability for superior capsular reconstruction in irreparable supraspinatus tears: A biomechanical analysis of the superior capsular reconstruction - A cadaveric study

PURPOSE

The objective of this study was to compare the biomechanics of using a double layered human dermal allograft to a single layered human dermal allograft in superior capsular reconstruction.

METHODS

Five cadaveric shoulders were tested. The superior translation of the humerus and the subacromial contact pressure were measured at 0°, 30° and 60° of glenohumeral abduction in the following six conditions: (1) intact rotator cuff, (2) irreparable supraspinatus tear, (3) superior capsular reconstruction using a double layered human dermal allograft with and (4) without posterior suturing, (5) superior capsular reconstruction using a single human dermal allograft with and (6) without posterior suturing.

RESULTS

There was a significant increase in superior translation of the humerus and subacromial contact pressure when comparing torn supraspinatus to intact shoulder. All superior capsular reconstruction repairs lead to a reduction in superior translation and subacromial contact pressures compared to after the supraspinatus tear except for single layered superior capsular reconstruction repair without posterior suturing. There was no difference in superior translation and subacromial contact pressures comparing the intact shoulder to any of the superior capsular reconstruction constructs.

CONCLUSION

Superior capsular reconstruction using a single or double layered human dermal allograft improves superior translation after supraspinatus repair. There is some biomechanical benefit of a double layered human dermal allograft technique over a single layered graft technique in superior capsular reconstruction.

LEVEL OF EVIDENCE

IV.

Long-Term Outcomes of Massive Rotator Cuff Tear Repair: A Systematic Review

BACKGROUND

With an increase in the treatment options available for massive rotator cuff tears, understanding the long-term outcomes of the chosen modality is important.

QUESTIONS/PURPOSE

The purpose of this study was to systematically review the available literature on repair of massive rotator cuff repairs and learn the longevity of outcomes, the failure rate, outcomes after failure, and any contributing factors to poor outcomes or failure.

METHODS

We conducted a systematic review of the MEDLINE, Cochrane, and Embase databases to find studies that investigated the long-term results of repair of massive rotator cuff repairs. Studies were excluded if they did not stratify results of massive tears, provide a definition for a massive rotator cuff tear, or report isolate patients with long-term follow-up.

RESULTS

Six studies met the inclusion criteria, for a total of 472 shoulders; average patient age was 57.6 years. Follow-up ranged from 119 to 240 months. Outcome scores improved significantly following repair and were maintained throughout follow-up. The repair failure rate across studies was 39.2%. Patients who suffered retear had significantly worse outcome scores than patients with intact tendons at long-term follow-up.

CONCLUSIONS

The existing literature on long-term follow-up after massive rotator cuff repair is scarce and not of high level of evidence. This review found repair of massive rotator cuff tears leads to long-term maintained improvements in outcome measures. Failure of repair is quite common, but results following failure are superior to preoperative outcomes.

Supraspinatus fatty infiltration on MRI among older adults receiving physical therapy as initial management for clinically suspected rotator cuff tear: A pilot study

Objectives

Rotator cuff (RC) tear is common among adults ≥60 years, with supraspinatus tear most common. Intramuscular fatty infiltration (FI) on imaging is predictive of long-term outcomes following RC tear. Physical therapists routinely diagnose RC tear only by clinical examination since most do not order imaging studies. Thus, there is limited knowledge about FI in older populations receiving physical therapy (PT) for initial management of RC tear. The primary objective of our pilot study is to determine longitudinal differences in supraspinatus FI over time among older adults receiving PT (PT cohort) for initial management of RC tear relative to older adult volunteers (control cohort), and with secondary objective to evaluate longitudinal self-reported shoulder function over time.

Material and Methods

This was a prospective longitudinal cohort study. Forty adults, 60-85 years, were enrolled at baseline; one follow-up visit at ≥6 months. Shoulder magnetic resonance imaging and clinical screening for Charlson comorbidity index (CCI), body mass index (BMI), and American Shoulder and Elbow Surgeon (ASES) score were completed at baseline and follow-up visits. Supraspinatus FI was evaluated by 6-point Dixon fat fraction and Goutallier grade. PT (n = 15) and control (n = 25) cohorts were stratified by supraspinatus status: Intact (no tear), partial-thickness tear (PTT), and full-thickness tear (FTT). Comparisons within cohort were performed by Kruskal-Wallis test and between cohorts by Mann-Whitney U-test. Interobserver reliability was performed for Dixon fat fraction and Goutallier grade.

Results

PT cohort at baseline showed no difference for age, BMI, CCI, and ASES score; supraspinatus FI was highest for FTT by Goutallier grade (no tear, 0.5 ± 0.5; PTT, 1.1 ± 0.2; and FTT, 1.5 ± 0.5; P = 0.033) and by Dixon fat fraction (no tear, 4.6% ± 1.4%; PTT, 6.1% ± 1.9%; and FTT, 6.7% ± 2.5%; P = 0.430). Control cohort at baseline showed no difference for age, BMI, CCI, and ASES score; supraspinatus FI was highest for supraspinatus FTT by Dixon fat fraction (no tear, 5.8% ± 1.2%; PTT, 7.1% ± 6.3%; and FTT, 21.4% ± 10.4%; P = 0.034) and by Goutallier grade (no tear, 0.8 ± 0.5; PTT, 1.0 ± 0.6; and FTT, 2.4 ± 1.7; P = 0.141). No difference between similar PT and control cohort subgroups at baseline except no tear groups for ASES score (PT cohort, 58.9 ± 8.2; control cohort, 84.0 ± 21.9; P = 0.049). No differences were identified for Δ-Dixon fat fraction and Δ-Goutallier grade over time in the PT and control cohorts. PT cohort no tear subgroup showed significant improvement (P = 0.042) for Δ-ASES score over time relative to PTT and FTT subgroups; no difference for Δ-ASES score over time in the control cohort.

Conclusion

Full-thickness RC tear showed higher levels of FI relative to PTT or no tear at baseline. Our pilot study's trend suggested that older adults receiving PT for initial management of RC tear have full-thickness RC tear for shorter duration based on relative lower levels of FI at baseline as compared to older adult volunteers with full-thickness RC tear. Our pilot study also found that older adults in the PT cohort with no tear had superior shoulder functional recovery by ASES score over time relative to full-thickness and PTTs.

Relationship between preoperative size of rotator cuff tears measured using radial-slice magnetic resonance images and postoperative rotator cuff integrity: a prospective case-control study

Background

Magnetic resonance imaging (MRI) is useful for diagnosing shoulder diseases preoperatively. However, preoperative risk factors for retears have not been previously reported using a radial-slice MRI. Here, we investigated the relationship between the preoperative tear area of the rotator cuff evaluated using radial-slice MRI and the postoperative rotator cuff integrity. Our hypothesis is that larger tear area of the rotator cuff measured using radial-slice MRI would be associated with increased retear rates.

Methods

From June 2010 to October 2015, we treated 102 consecutive patients who underwent shoulder arthroscopy for reparable rotator cuff tears. The patient demographics, medical comorbidities, radiologic factors, tear size, fatty infiltration, muscle atrophy measured using oblique coronal and oblique sagittal MRI, and the tear area calculated using radial-slice MRI were assessed to compare the intact and retear groups in univariate and multivariate logistic regression analyses. The cutoff values of the independent factors were obtained using the receiver operating characteristic curve.

Results

Retears occurred in 15 of 102 (14.7%) patients. In the univariate analysis, significant differences were found between the two groups for tear size, fatty infiltration of the supraspinatus and infraspinatus, muscle atrophy, and tear area. In the multivariate analysis, the tear area was the independent factor that significantly affected the rate of retear. A tear area of 6.3 cm² was the strongest predictor of retear with an area under the curve of 0.965, sensitivity of 86.7%, and specificity of 96.6%.

Conclusion

The tear area was the independent factor that most significantly affected the rate of retear and showed excellent accuracy with a cutoff value of 6.3 cm². Radial-slice MRI may be a valuable diagnostic tool for assessing the postoperative rotator cuff integrity.

Editorial Commentary: Repairing Retracted Rotator Cuff Tears: Histologically Different, but Success Still Achievable With "Failure in Continuity"

Failure after rotator cuff repair continues to occur despite advances in our understanding of the native tendon enthesis. Recurrent postoperative tendon defects are common, and the impact of nonhealing on postoperative outcomes remains controversial. Rotator cuff tears (RCT) of all patterns commonly present with some degree of retraction, and it is, therefore, critical to understand and examine the biology and biomechanics of the retracted RCT to address why a repaired tendon may fail. An article in this issue reports on retracted tears forming more disorganized fibrous tissue with similar biomechanical properties compared to nonretracted tear tissue. It provides insight into what lies "beneath the surface" after retracted rotator cuff repair, but it is unclear whether the fibrous tissue formed after their acute partial tendon excision adequately reflects the tissue found in more chronic, retracted human rotator cuff tears, particularly with varying degrees of retraction. Facilitating a more favorable "scar-forming" environment and optimizing this postoperative fibrous tissue may be crucial to improving rotator cuff repairs in the future.

Fatty degeneration of the rotator cuff: pathogenesis, clinical implications, and future treatment

Chronic rotator cuff pathology is often complicated by fatty degeneration of the rotator cuff (FDRC) muscles, an insidious process associated with poor prognosis with or without surgical intervention. Currently there is no treatment for FDRC, and many studies have described a natural course for this disease almost always resulting in further degeneration and morbidity. Recapitulating FDRC using animal injury models, and using imaging-based studies of human FDRC, the pathophysiology of this disease continues to be further characterized. Researchers studying mesenchymal stem cell-derived progenitor cells and known fibrogenic and adipogenic signaling pathways implicated in FDRC seek to clarify the underlying processes driving these changes. While new cell- and molecular-based therapies are being developed, currently the strongest available avenue for improved management of FDRC is the use of novel imaging techniques which allow for more accurate and personalized staging of fatty degeneration. This narrative review summarizes the evidence on the molecular and pathophysiologic mechanisms of FDRC and provides a clinical update on the diagnosis and management of this condition based on the existing knowledge. We also sought to examine the role of newer biologic therapies in the management of RC fatty degeneration and to identify areas of future research.

Tendon midsubstance trauma as a means for the development of translatable chronic rotator cuff degeneration in an ovine model

BACKGROUND

Chronic degeneration of rotator cuff tendons is a major contributing factor to the unacceptably high prevalence of rotator cuff repair surgery failures. The etiology of chronic rotator cuff degeneration is not well understood, and current therapies are not effective, necessitating preclinical research to fill this knowledge gap. Unfortunately, current large animal models rely on enthesis disruption as a means of model generation, which is not representative of human patients with chronic rotator cuff degeneration prior to full-thickness tears. Following, the goal of this study was to develop and characterize a translational large-animal model of chronic rotator cuff degeneration without enthesis release.

METHODS

A midsubstance damage model [i.e., "combed fenestration" (CF)] in adult sheep was generated by creating 16 longitudinal cuts within the top third of the infraspinatus tendon thickness. Tendon integrity was characterized through exhaustive non-destructive biomechanical stress relaxation testing [peak stress, peak load, percent relaxation, and cross-sectional area (CSA)], followed by histopathological degeneration scoring and analysis (Bonar score), histomorphological analysis of collagen organization and fatty atrophy (percent adipose area), and gene expression analyses.

RESULTS

The CF model tendons exhibited significantly decreased mechanical properties as evidenced by decreased peak stress (P<0.025) and increased percent relaxation (18-week vs. Control, P<0.035) at multiple strain magnitudes and across all timepoints. At all timepoints, the CF tendons exhibited pathological changes aligned with tendon degeneration, as evidenced by increased Bonar scoring (P<0.001) and decreased collagen organization (6-week vs. Control, P=0.013). Increases in intramuscular adipose content were also documented through histomorphology analysis (6- and 18-week vs. Control, P<0.077). Significant changes in gene expression were noted at all timepoints.

CONCLUSIONS

These data reveal that this new ovine CF model of chronic rotator cuff degeneration results in tendons with decreased mechanical properties, degenerative pathology characteristics, and gene expression profiles that aligned with the degenerative changes that have been noted in humans with tendinopathy. For these reasons, we believe this novel large animal model of chronic rotator cuff degeneration is a translational platform in which to test devices, therapies, and/or technologies aimed at repairing damage to the shoulder.

Diagnostic Ultrasound Shows Reversal of Supraspinatus Muscle Atrophy Following Arthroscopic Rotator Cuff Repair

PURPOSE

Prospective study to assess ultrasonography (US) utility as an imaging tool for supraspinatus muscle atrophy diagnosis, establishing if there is any relationship between repairing supraspinatus tears and its eventual muscular recovery.

METHODS

Observational study.

SELECTION CRITERIA

adults with a full-thickness reparable supraspinatus tear confirmed arthroscopically. Clinical and imaging data pre- and postoperatively with 12 months of follow-up were recorded, including demographic data, Constant scale, Patte classification, repair type, and supraspinatus muscle belly US images in both shoulders, recording height, diameter, echogenicity (mean number of pixels between 0-black and 255-white), and central tendon pennate angle (PA).

RESULTS

In total, 110 supraspinatus tears underwent arthroscopic repair (2015-2018). Mean age was 61 ± 8 years (46-77). We detected a correlation between atrophy and age in terms of echogenicity and PA (P = .01). Echogenicity improved from 54.5 to 51.0 (P = .365) and slightly deteriorated on the contralateral side from 51.6 to 52.9 (P = .351). Supraspinatus echogenicity compared to trapezius muscle reduced from 0.43 to 0.36 (P < .001). PA augmented from 5.8 to 8.6 (P < .001). Mean PA on the contralateral side was 8.6 preoperatively. Patte II cases showed the most significant improvement in terms of imaging evaluation of atrophy. Although Patte III cases almost did not improve in terms of atrophy, they improved clinically. We observed improvement after surgery in Constant score from 35 to 85 (P < .001). Minimal clinically important differences for Constant and visual analog scale were 44.45 ± 12.87 and 6.54 ± 1.41, respectively. Recurrence of symptoms was 13%, related to worse results of PA and echogenicity compared to nonrecurrences.

CONCLUSIONS

Supraspinatus atrophic muscle changes after repair can be reversed. It can be quantified using US imaging (histogram, histogram ratio and echogenicity reduction, pennate pattern, and PA augmentation). Patte II cases showed the best results after repair, demonstrated by US. The faster the repair, the better the results without being influenced by repair type. The bigger the tear and retraction, the more echogenicity and less PA, with worse clinical and US results.

LEVEL OF EVIDENCE

Level III, prospective therapeutic study.

Bridging Allograft Reconstruction Is Superior to Maximal Repair for the Treatment of Chronic, Massive Rotator Cuff Tears: Results of a Prospective, Randomized Controlled Trial

BACKGROUND

Despite advances in surgical techniques, the use of maximal repair to treat large or massive rotator cuff tears results in a high retear rate postoperatively. Currently, no randomized controlled trials have compared the outcomes of maximal repair with interposition dermal allograft bridging reconstruction.

HYPOTHESIS

We hypothesized that large or massive rotator cuff tendon tears reconstructed using bridging dermal allograft would have better clinical outcomes 2 years postoperatively, as measured using the Western Ontario Rotator Cuff (WORC) index, than would those receiving the current gold standard treatment of debridement and maximal repair alone. We also expected that patients treated via bridging reconstruction using dermal allograft would have fewer postoperative failures as assessed using postoperative magnetic resonance imaging scans.

STUDY DESIGN

Randomized controlled trial; Level of evidence 1.

METHODS

A sample size of 30 patients (determined using a priori sample size calculation) with massive, retracted rotator cuff tears were randomly allocated to 1 of 2 groups: maximal repair or bridging reconstruction using dermal allograft. All patients completed questionnaires (WORC and Disabilities of the Arm, Shoulder and Hand [DASH]) preoperatively and postoperatively at 3 months, 6 months, 1 year, and 2 years. The primary outcome of this study was the WORC index at 2 years. Secondary outcomes included healing rate, progression of rotator cuff arthropathy, and postoperative acromiohumeral distance in both groups.

RESULTS

Patients treated via bridging reconstruction using dermal allograft had better postoperative WORC and DASH scores (23.93 ± 24.55 and 15.77 ± 19.27, respectively) compared with patients who received maximal repair alone (53.36 ± 31.93 and 34.32 ± 23.31, respectively). We also noted increased progression to rotator cuff arthropathy in the maximal repair group with an increased retear rate when compared with the reconstruction group (87% and 21%, respectively; P < .001). The acromiohumeral distance was maintained in the reconstruction group but significantly decreased in the maximal repair group.

CONCLUSION

Rotator cuff bridging reconstruction using a dermal allograft demonstrated improved patient-reported outcomes as measured using the WORC index 2 years postoperatively. This technique also showed favorable structural healing rates and decreased progression to arthropathy compared with maximal repair.

TRIAL REGISTRATION

ClinicalTrials.gov (NCT01987973).

Decreased Colony-Forming Ability of Subacromial Bursa-Derived Cells During Revision Arthroscopic Rotator Cuff Repair

Purpose

To compare the cellular viability and differentiation potential of subacromial bursa-derived cells (SBDCs) located over the rotator cuff muscle and tendon of patients undergoing primary versus revision arthroscopic rotator cuff repair (ARCR).

Methods

Subacromial bursa was harvested from 18 primary (57.1 ± 4.6 years) and 12 revision ARCRs (57.3 ± 6.7 years). Bursa was collected from 2 sites (over rotator cuff tendon and muscle), digested with collagenase, and grown in culture. The number of nucleated cells, colony-forming units (CFUs), differentiation potential, and mesenchymal stem cell surface markers were compared in primary and revision cases.

Results

There was no difference in the number of nucleated cells between primary and revision ARCR harvested from the subacromial bursa overlying the tendon (3019.3 ± 1420.6 cells/mg and 3541.7 ± 2244.2 cells/mg, respectively; P = .912) or muscle (2753.5 ± 1547.1 cells/mg and 2989.0 ± 2231.4 cells/mg, respectively; P = .777). There was no difference in the number of CFUs between primary and revision ARCR over the rotator cuff tendon (81.5 ± 49.5 CFUs and 53.0 ± 36.9 CFUs, respectively; P = .138), but there were significantly fewer CFUs over the muscle in revision cases (28.1 ± 22.7 CFUs) compared with primary cases (55.7 ± 34.5 CFUs) (P = .031). SBDCs from revision ARCR expressed characteristic mesenchymal stem cell surface epitopes and had multidifferentiation potentials for chondrogenesis, osteogenesis, and adipogenesis.

Conclusions

SBDCs harvested over the rotator cuff muscle demonstrated significantly decreased colony-forming abilities in revision arthroscopic rotator cuff repairs compared with primary repairs. However, the subacromial bursa retains its pluripotent differentiation potential for chondrogenic, osteogenic, and adipogenic lineages in the revision setting.

Clinical Relevance

The subacromial bursa may play a role in the healing response of the repaired rotator cuff. This capacity is not necessarily diminished in the revision setting and may be harnessed as an orthobiologic.

Muscle stem cells and rotator cuff injury

The incidence of reinjury after treatment of rotator cuff tears (RCTs) remains very high despite the variety of nonoperative treatments and the high volume of surgical interventions performed. Muscle stem cells (MuSCs), also known as satellite cells, have risen to the forefront of rotator cuff tear research as a potential adjuvant therapy to aid unsatisfactory surgical outcomes. MuSCs are adult stem cells exhibiting the capacity to proliferate and self-renew, both symmetrically and asymmetrically. As part of this niche, they have been shown to adopt an activated phenotype in response to musculoskeletal injury and decrease their cellular populations during aging, implicating them as key players in both pathologic and normal physiological processes. While commonly connected to the regenerative phase of muscle healing, MuSCs also have the potential to differentiate into adverse morphologies. For instance, if MuSCs differentiate into adipocytes, the ensuing fatty infiltration serves as an obstacle to proper muscle healing and has been associated with the failure of surgical management of RCTs. With the potential to both harm and heal, we have identified MuSCs as a key player in RCT repair. To better understand this dichotomy, the following review will identify key studies regarding the morphology, function, and behavior of MuSCs with respect to RCTs and healing.

CT-based volumetric assessment of rotator cuff muscle in shoulder arthroplasty preoperative planning

Aims

The aim of this study was to describe a quantitative 3D CT method to measure rotator cuff muscle volume, atrophy, and balance in healthy controls and in three pathological shoulder cohorts.

Methods

In all, 102 CT scans were included in the analysis: 46 healthy, 21 cuff tear arthropathy (CTA), 18 irreparable rotator cuff tear (IRCT), and 17 primary osteoarthritis (OA). The four rotator cuff muscles were manually segmented and their volume, including intramuscular fat, was calculated. The normalized volume (NV) of each muscle was calculated by dividing muscle volume to the patient’s scapular bone volume. Muscle volume and percentage of muscle atrophy were compared between muscles and between cohorts.

Results

Rotator cuff muscle volume was significantly decreased in patients with OA, CTA, and IRCT compared to healthy patients (p < 0.0001). Atrophy was comparable for all muscles between CTA, IRCT, and OA patients, except for the supraspinatus, which was significantly more atrophied in CTA and IRCT (p = 0.002). In healthy shoulders, the anterior cuff represented 45% of the entire cuff, while the posterior cuff represented 40%. A similar partition between anterior and posterior cuff was also found in both CTA and IRCT patients. However, in OA patients, the relative volume of the anterior (42%) and posterior cuff (45%) were similar.

Conclusion

This study shows that rotator cuff muscle volume is significantly decreased in patients with OA, CTA, or IRCT compared to healthy patients, but that only minimal differences can be observed between the different pathological groups. This suggests that the influence of rotator cuff muscle volume and atrophy (including intramuscular fat) as an independent factor of outcome may be overestimated.

Cite this article: Bone Jt Open 2021;2(7):552–561.

Primary arthroscopic repair of massive rotator cuff tears results in significant improvements with low rate of re-tear

PURPOSE

To conduct a systematic review of outcomes following primary arthroscopic repair of chronic massive rotator cuff tears (RCTs) and to assess clinical outcomes and rates of repair failure. The authors' preferred treatment algorithm is also provided.

METHODS

Medline, Embase and PubMed were searched identifying articles pertaining to primary arthroscopic repair of chronic massive RCTs without the use of augmentation. Primary outcomes were patient-reported outcomes and the secondary outcome was the rate of repair failure. Outcome data were pooled and presented as well as assessment of study methodological quality. Data from studies reporting similar outcome measures were pooled when possible, and mean differences alongside confidence intervals and p values were reported, where appropriate.

RESULTS

Twenty-six studies (1405 participants) were included, with mean age of 62 years (range 52-69). The mean duration of symptoms pre-operatively was 31 months (range 6-40), and the mean follow-up time was 39 months (range 12-111). Complete repair was performed in 78% of patients and partial repair was performed in 22%. Both complete and partial repairs resulted in significant improvements with respect to pain, range of motion and functional outcome scores. The rate of repair failure for the total cohort was 36% at a mean follow-up of 31 months, and for the complete and partial repair subgroups the failure rate was 35% and 40%, respectively.

CONCLUSIONS

Arthroscopic repairs of chronic, massive RCTs, whether complete or partial, are associated with significant improvements in pain, function and objective outcome scores. The rate of repair failure is lower than previously reported, however, still high at 36%. The present paper finds that arthroscopic repair is still a viable treatment option for massive RCTs.

LEVEL OF EVIDENCE

IV.

Deep learning method for segmentation of rotator cuff muscles on MR images

OBJECTIVE

To develop and validate a deep convolutional neural network (CNN) method capable of (1) selecting a specific shoulder sagittal MR image (Y-view) and (2) automatically segmenting rotator cuff (RC) muscles on a Y-view. We hypothesized a CNN approach can accurately perform both tasks compared with manual reference standards.

MATERIAL AND METHODS

We created 2 models: model A for Y-view selection and model B for muscle segmentation. For model A, we manually selected shoulder sagittal T1 Y-views from 258 cases as ground truth to train a classification CNN (Keras/Tensorflow, Inception v3, 16 batch, 100 epochs, dropout 0.2, learning rate 0.001, RMSprop). A top-3 success rate evaluated model A on 100 internal and 50 external test cases. For model B, we manually segmented subscapularis, supraspinatus, and infraspinatus/teres minor on 1048 sagittal T1 Y-views. After histogram equalization and data augmentation, the model was trained from scratch (U-Net, 8 batch, 50 epochs, dropout 0.25, learning rate 0.0001, softmax). Dice (F1) score determined segmentation accuracy on 105 internal and 50 external test images.

RESULTS

Model A showed top-3 accuracy > 98% to select an appropriate Y-view. Model B produced accurate RC muscle segmentations with mean Dice scores > 0.93. Individual muscle Dice scores on internal/external datasets were as follows: subscapularis 0.96/0.93, supraspinatus 0.97/0.96, and infraspinatus/teres minor 0.97/0.95.

CONCLUSIONS

Our results show overall accurate Y-view selection and automated RC muscle segmentation using a combination of deep CNN algorithms.

Preoperative Fatty Infiltration of the Teres Minor Negatively Affects Postoperative Outcomes in Patients With Rotator Cuff Pathology

Background

The teres minor is a critical component of the rotator cuff and serves as one of the few external rotators of the humerus. Information is lacking regarding the effect of teres minor atrophy in isolation and in the setting of concomitant full-thickness rotator cuff tears on outcomes in patients undergoing rotator cuff surgery.

Purpose

To investigate the effect of preoperative teres minor fatty infiltration on postoperative clinical outcomes in patients with and without full-thickness rotator cuff pathology.

Study Design

Cohort study; Level of evidence, 3.

Methods

A retrospective review of patients undergoing primary arthroscopic shoulder surgery between 2014 and 2016 was performed. Preoperative magnetic resonance imaging was used to determine fatty infiltration for each rotator cuff muscle using the modified Goutallier classification. American Shoulder and Elbow Surgeons (ASES) as well as the shortened version of Disabilities of the Arm, Shoulder and Hand (QuickDASH) scores were obtained preoperatively and during follow-up. Exclusion criteria included prior surgery on the ipsilateral shoulder or a diagnosis of inflammatory arthropathy. For analysis, patients were dichotomized to grade 0 or grade 1-4 atrophy of the teres minor as well as to full-thickness or partial-thickness rotator cuff pathology.

Results

A total of 36 of 47 (76.6%) patients (mean age, 63 years; range, 45-76 years) were available for postoperative follow-up at a mean of 40 months (range, 30-48 months). Postoperative ASES score was significantly higher and QuickDASH score was significantly lower among all patients in the grade 0 group compared with the grade 1-4 group. Postoperative ASES and QuickDASH scores were not significantly different in patients with partial-thickness rotator cuff tears at any time point. However, the postoperative ASES score was significantly higher and QuickDASH score was significantly lower in the grade 0 versus grade 1-4 group for patients with full-thickness rotator cuff pathology.

Conclusion

Preoperative teres minor atrophy in patients undergoing surgery for rotator cuff pathology may impair postoperative clinical outcomes, especially in patients with full-thickness tears.

Rotator cuff tear degeneration and the role of fibro-adipogenic progenitors

The high prevalence of rotator cuff tears poses challenges to individual patients and the healthcare system at large. This orthopedic injury is complicated further by high rates of retear after surgical repair. Outcomes following repair are highly dependent upon the quality of the injured rotator cuff muscles, and it is, therefore, crucial that the pathophysiology of rotator cuff degeneration continues to be explored. Fibro-adipogenic progenitors, a major population of resident muscle stem cells, have emerged as the main source of intramuscular fibrosis and fatty infiltration, both of which are key features of rotator cuff muscle degeneration. Improvements to rotator cuff repair outcomes will likely require addressing the muscle pathology produced by these cells. The aim of this review is to summarize the current rotator cuff degeneration assessment tools, the effects of poor muscle quality on patient outcomes, the role of fibro-adipogenic progenitors in mediating muscle pathology, and how these cells could be leveraged for potential therapeutics to augment current rotator cuff surgical and rehabilitative strategies.

Correlation of Quantitative Versus Semiquantitative Measures of Supraspinatus Intramuscular Fatty Infiltration to Shoulder Range of Motion and Strength: A Pilot Study

PURPOSE

The relationship of magnetic resonance imaging (MRI) measures of rotator cuff intramuscular fatty infiltration (FI) to shoulder range of motion (ROM) and strength are not well understood. Our purpose was to determine if supraspinatus quantitative Dixon fat fraction has superior correlation to shoulder ROM and strength as compared to semiquantitative Goutallier grade.

METHODS

Thirty-seven study subjects received shoulder MRI; and measurement of ipsilateral shoulder forward flexion ROM, abduction ROM and abduction strength. Supraspinatus Dixon fat fraction was measured on 6-point Dixon MRI by 2 diagnostic radiology residents. Supraspinatus Goutallier grade was assessed on T1-weighted MRI by 2 musculoskeletal radiologists. Questionnaires recorded demographics. Based on characteristics, study subjects were divided into 3 groups: Group 1, neither shoulder pain nor full-thickness supraspinatus tendon (SST) tear (n = 17; mean age, 63.0 ± 10.1 years); Group 2, positive complaint of shoulder pain but without full-thickness SST tear (n = 7; mean age, 57.4 ± 9.9 years); Group 3, positive complaint of shoulder pain and full-thickness SST tear (n = 13; mean age, 63.6 ± 8.1 years). One-way analysis of variance compared groups. Spearman (rho) rank order correlation was performed to determine correlation of supraspinatus Dixon fat fraction, or Goutallier grade, with measures of ROM and strength for the study population. Reliability analyses were performed for Dixon fat fraction and Goutallier grade.

RESULTS

No significant differences were present among groups for age. Significant differences existed among groups for forward flexion ROM (P= 0.001), abduction ROM (P < 0.001), Dixon fat fraction (P = 0.004) and Goutallier grade (P = 0.012). Dixon fat fraction showed statistically significant inverse correlations with forward flexion ROM (rho = -0.47; P = 0.005), abduction ROM (rho = -0.35, P = 0.041), and abduction strength (rho = -0.42; P = 0.013). Goutallier grade demonstrated weak inverse correlation that lacked statistical significance (P > 0.05) for the same measures. Dixon fat fraction showed strong interobserver and intraobserver reliability with intraclass correlation coefficients of 0.956 and 0.999, respectively. Goutallier grade showed poor interobserver (kappa, 0.188) and moderate intraobserver (kappa, 0.608) reliability.

CONCLUSION

Supraspinatus Dixon fat fraction has superior correlation to shoulder ROM and strength relative to Goutallier grade on MRI.

Use sonoelastography to predict the reparability of large-to-massive rotator cuff tears

INTRODUCTION

Most symptomatic large-to-massive rotator cuff tears (RCTs) should be operated, but the surgical reparability depended on the degree of rotator cuff muscle atrophy or fatty infiltration. The orthopedic surgeons will decide whether the teared stump is reparable during the surgery, but preoperative evaluation can be done by some assessment tools. Magnetic resonance imaging (MRI) was used in recent studies to predict the reparability of large-to-massive RCTs, but the clinical availability was not as good as ultrasound. We hypothesize that the ultrasound elastography can predict the reparability of large-to-massive RCTs.

METHODS

This is a prospective observational study and participants with large-to-massive RCTs who are going to have surgeries will be included. Out investigators will evaluate the shoulder passive range of motion (ROM) and strength of all participants. Participants' degree of shoulder pain and activities of daily living (ADLs) will be assessed by American Shoulder and Elbow Surgeons (ASES) score. The ultrasound elastography will be used to evaluate the tissue quality of supraspinatus muscle and infraspinatus muscle. To test the reliability of the ultrasound elastography, two physicians will perform the ultrasound elastography independently and twenty participants will be selected for the reliability test. Besides, MRI will be used to evaluate the size of tear, the degree of tendon retraction, fatty infiltration of rotator cuff muscles, and muscle atrophy. Finally, the orthopedic surgeons will perform surgeries and decide whether the teared stump can be completely repaired intraoperatively. The primary analysis is the predictive validity of ultrasound elastography for the reparability of large-to-massive RCTs. Before the predictive validity of ultrasound elastography is measured, our investigators will assess the reliability of ultrasound elastography when administered to cases with large-to-massive RCTs, and we will check the correlations between the findings of ultrasound elastography and MRI.

DISCUSSION

The outcome will provide the evidence of ultrasound elastography for preoperative evaluation of large-to-massive RCTs. The relationships between the findings of ultrasound elastography and MRI will also be examined for further analysis.

TRIAL REGISTRATION

Clinicaltrials.gov NCT03682679. Date of Registration: 25 September 2018, https://clinicaltrials.gov/ct2/show/NCT03682679?cond=rotator+cuff&cntry=TW&draw=2&rank=1.

Inconsistencies in the MRI Evaluation of Supraspinatus Volume After Repair

Background:

Reversibility of rotator cuff atrophy after surgical repair is controversial. Traditionally, the cross-sectional area (CSA) of the rotator cuff was measured in conventional Y-view (CYV) via magnetic resonance imaging (MRI) to evaluate reversibility. However, it has been suggested that scanning axis inconsistency in CYV was overlooked and that the CSA in CYV reflects not only atrophy but also rotator cuff retraction.

Hypothesis:

Discrepancies between scanning axes in CYV cause significant errors when one is evaluating changes in the CSA of the supraspinatus (SS) using preoperative and postoperative MRI scans. A more medial section than the Y-view is not influenced as much by retraction recovery after repair.

Study Design:

Cohort study (diagnosis); Level of evidence, 3.

Methods:

The study included 36 patients with full-thickness SS tear and retraction who underwent arthroscopic complete repair with preoperative MRI and immediate postoperative MRI (within 5 days after rotator cuff repair). Angles between CYV planes in the preoperative and immediate postoperative MRI scans were measured. MRI scans were reconstructed perpendicular to the scapular axes by multiplanar reconstruction. Differences between the CSAs of the SS in preoperative and postoperative Y-view on the original and reconstructed MRI scans were compared, and changes in CSAs of the SS muscles after repair in 2 sections medial to the reconstructed Y-view (RYV) were compared.

Results:

The mean angle between CYV planes in preoperative and postoperative MRI scans was 13.1° ± 7.1°. Mean pre- to postoperative increase in the CSA of the SS was greater in CYV than in RYV (95 ± 72 vs 75 ± 62 mm²; P = .024). Furthermore, pre- to postoperative CSA differences in the 2 medial sections were less than in RYV. For the most medial section, crossing the omohyoid origin, the CSA differences were not significant (434 ± 98 vs 448 ± 98 mm²; P = .061).

Conclusion:

Scanning axes inconsistencies in CYV cause unacceptable errors in CSA measurements of the SS after repair. We recommend reconstruction along a consistent axis by multiplanar reconstruction when evaluating postoperative changes in SS atrophy and the use of sections more medial than the scapular Y-view to reduce errors caused by tendon retraction.

Supraspinatus muscle shear wave elastography (SWE): detection of biomechanical differences with varying tendon quality prior to gray-scale morphologic changes

OBJECTIVE

The purpose of this study was to determine whether SWE can detect biomechanical changes in the supraspinatus muscle that occur with increasing supraspinatus tendon abnormality prior to morphologic gray-scale changes.

MATERIALS AND METHODS

An IRB approved, HIPAA compliant retrospective study of shoulder ultrasounds from 2013-2018 was performed. The cohort consisted of 88 patients (mean age 55 ± 15 years old) with 110 ultrasounds. Images were acquired in longitudinal orientation to the supraspinatus muscle with shear wave velocity (SWV) point quantification. The tendon and muscle were graded in order of increasing tendinosis/tear (1-4 scale) and increasing fatty infiltration (0-3 scale). Mixed model analysis of variance, analysis of covariance, and Spearman rank correlation were used for statistical analysis.

RESULTS

There was no statistically significant age or sex dependence for supraspinatus muscle SWV (p = 0.314, 0.118, respectively). There was no significant correlation between muscle SWV and muscle or tendon grade (p = 0.317, 0.691, respectively). In patients with morphologically normal muscle on gray-scale ultrasound, there were significant differences in muscle SWV when comparing tendon grade 3 with grades 1, 2, and 4 (p = 0.018, 0.025, 0.014, respectively), even when adjusting for gender and age (p = 0.044, 0.028, 0.018, respectively). Pairwise comparison of tendon grades other than those mentioned did not achieve statistical significance (p > 0.05).

CONCLUSION

SWE can detect biomechanical differences within the supraspinatus muscle that are not morphologically evident on gray-scale ultrasound. Specifically, supraspinatus tendon partial tears with moderate to severe tendinosis may correspond to biomechanically distinct muscle properties compared to both lower grades of tendon abnormality and full-thickness tears.

Does pre-operative multifidus morphology on MRI predict clinical outcomes in adults following surgical treatment for degenerative lumbar spine disease? A systematic review

Aim

Low back pain (LBP) resulting from degenerative lumbar spine disease is a leading contributor to global disability. Changes in the morphology of the lumbar multifidus muscle on magnetic-resonance imaging (MRI) are associated with worse LBP and disability, but the association between multifidus morphology and post-operative outcomes is not known. The purpose of this systematic review is to examine the relationship between pre-operative multifidus morphology and post-operative changes in pain and disability.

Methods

We performed a systematic search using the Cochrane Library, EMBASE, MEDLINE, CINAHL and Scopus databases covering the period from January 1946 to January 2018. The literature was searched and assessed by independent reviewers according to the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) statement. All relevant papers were assessed for risk of bias according to the Quality in Prognosis Studies tool.

Results

The initial search yielded 436 studies, of which 6 studies were included in the analysis. Four studies were at a low risk of bias. These studies included a total of 873 patients undergoing spinal surgery. An association between low fat infiltration and greater improvement in LBP and disability following surgery was identified. There was insufficient evidence to identify a relationship between cross-sectional area (CSA) and LBP or disability.

Conclusions

This systematic review found evidence for an association between low multifidus fat infiltration on MRI at baseline and greater reductions in measures of LBP and disability following surgical treatment. There is also limited evidence for an association between larger pre-operative multifidus CSA and improvements in disability, but not pain. The findings of this review should be interpreted with caution due to the small quantity of the available literature.

The Postoperative Rotator Cuff

MR imaging interpretation following rotator cuff repair can be challenging and requires familiarity with various types of rotator cuff tear, their surgical treatments, normal postoperative MR imaging appearance, and complications. This article reviews the common surgical procedures for the reparable and nonreparable massive rotator cuff tears, their expected postoperative MR imaging findings, and imaging appearance of a range of complications.

A prospective study comparing tendon-to-bone interface healing using an interposition bioresorbable scaffold with a vented anchor for primary rotator cuff repair in sheep

BACKGROUND

The purpose of this study was to evaluate the biomechanical and histologic properties of rotator cuff repairs using a vented anchor attached to a bioresorbable interpositional scaffold composed of aligned PLGA (poly(l-lactide-co-glycoside)) microfibers in an animal model compared to standard anchors in an ovine model.

METHODS

Fifty-six (n = 56) skeletally mature sheep were randomly assigned to a repair of an acute infraspinatus tendon detachment using a innovative anchor-PLGA scaffold device (Treatment) or a similar anchor without the scaffold (Control). Animals were humanely euthanized at 7 and 12 weeks post repair. Histologic and biomechanical properties of the repairs were evaluated and compared.

RESULTS

The Treatment group had a significantly higher fibroblast count at 7 weeks compared to the Control group. The tendon bone repair distance, percentage perpendicular fibers, new bone formation at the tendon-bone interface, and collagen type III deposition was significantly greater for the Treatment group compared with the Control group at 12 weeks (P ≤ .05). A positive correlation was identified in the Treatment group between increased failure loads at 12 weeks and the following parameters: tendon-bone integration, new bone formation, and collagen type III. No statistically significant differences in biomechanical properties were identified between Treatment and Control Groups (P > .05).

CONCLUSIONS

Use of a vented anchor attached to a bioresorbable interpositional scaffold composed of aligned PLGA microfibers improves the histologic properties of rotator cuff repairs in a sheep model. Improved histology was correlated with improved final construct strength at the 12-week time point.

Does the Use of Injectable Atelocollagen during Arthroscopic Rotator Cuff Repair Improve Clinical and Structural Outcomes?

Background

Since the establishment of biological augmentation to improve the treatment of rotator cuff tears, it is imperative to explore newer techniques to reduce the retear rate and improve long-term shoulder function after rotator cuff repair. This study was undertaken to determine the consequences of a gel-type atelocollagen injection during arthroscopic rotator cuff repair on clinical outcomes, and evaluate its effect on structural integrity.

Methods

Between January 2014 and June 2015, 121 patients with full thickness rotator cuff tears underwent arthroscopic rotator cuff repair. Of these, 61 patients were subjected to arthroscopic rotator cuff repair in combination with an atelocollagen injection (group I), and 60 patients underwent arthroscopic rotator cuff repair alone (group II). The visual analogue scale (VAS) for pain and the Korean Shoulder Society (KSS) scores were evaluated preoperatively and postoperatively. Magnetic resonance imaging (MRI) was performed at 6 months postoperatively, to assess the integrity of the repair.

Results

VAS scores were significantly lower in group I than in group II at 3, 7, and 14 days after surgery. KSS scores showed no significant difference between groups in the 24 months period of follow-up. No significant difference was obtained in the healing rate of the rotator cuff tear at 6 months postoperatively (p=0.529).

Conclusions

Although a gel-type atelocollagen injection results in reduced pain in patients at 2 weeks after surgery, our study does not substantiate the administration of atelocollagen during rotator cuff repair to improve the clinical outcomes and healing of the rotator cuff.

Exploring the Business Case for Improving Quality of Care for Patients With Chronic Rotator Cuff Tears

BACKGROUND AND OBJECTIVES

Currently, management of patients presenting with chronic rotator cuff tears in Alberta is in need of quality improvements. This article explores the potential impact of a proposed care pathway whereby all patients presenting with chronic rotator cuff tears in Alberta would adopt an early, conservative management plan as the first stage of care; ultrasound investigation would be the preferred tool for diagnosing a rotator cuff tear; and only patients are referred for surgery once conservative measures have been exhausted.

METHODS

We evaluate evidence in support of surgery and conservative management, compare care in the current state with the proposed care pathway, and identify potential solutions in moving toward optimal care.

RESULTS

A literature search resulted in an absence of indications for either surgical or conservative management. Conservative management has the potential to reduce utilization of public health care resources and may be preferable to surgery. The proposed care pathway has the potential to avoid nearly Can $87 000 in public health care costs in the current system for every 100 patients treated successfully with conservative management.

CONCLUSION

The proposed care pathway is a low-cost, first-stage treatment that is cost-effective and has the potential to reduce unnecessary, costly surgical procedures.

Association of Patient Self-Reported Shoulder Scores to Quantitative and Semiquantitative MRI Measures of Rotator Cuff Intramuscular Fatty Infiltration: A Pilot Study

OBJECTIVE. The purpose of this study was to determine the relationship of supraspinatus fat fraction and Goutallier grade to the American Shoulder and Elbow Surgeons (ASES) score in cohorts of older adults with painful full-thickness supraspinatus tendon (SST) tear and control subjects. SUBJECTS AND METHODS. Seventeen control subjects and 15 study participants with painful full-thickness SST tear were prospectively recruited (mean age ± SD, 63.0 ± 10.1 years and 62.6 ± 9.0 years, respectively). Study participants received shoulder MRI and completed ASES questionnaires at one time. Goutallier grade was assessed on T1-weighted MRI. Fat fraction was measured on 6-point Dixon MRI. Body mass index (BMI) was determined. Descriptive, correlation, reliability, and regression analyses were performed. RESULTS. The control and painful full-thickness SST tear cohorts differed in mean supraspinatus fat fraction (3.3% ± 1.4% and 7.3 ± 5.9%, respectively; p = 0.024) and Goutallier grade (0.4 ± 0.5 and 0.9 ± 0.7, respectively; p = 0.022). Fat fraction (p = 0.014) and Goutallier grade (p = 0.017) showed a significant inverse association with ASES score only in the SST tear cohort. The association of BMI to ASES score was significant only in the control group (p = 0.036). The correlation between BMI and fat fraction were different for the two groups (control cohort, r = 0.676 and p = 0.003; SST tear cohort, r = 0.124 and p = 0.687). Fat fraction showed strong interobserver reliability (intraclass correlation coefficient, 0.903); Goutallier grade showed poor interobserver reliability (κ = 0.178). CONCLUSION. The association of ASES score and supraspinatus fat fraction or Goutallier grade differs between patients with painful full-thickness SST tear and control subjects without symptoms. Although fat fraction shows strong reliability, Goutallier grade should be regarded cautiously because of suboptimal reproducibility. Our results also suggest that painful full-thickness SST tear alters the correlation between supraspinatus fat fraction and BMI as compared with control subjects.

Association of Rotator Cuff Tear Patterns and Intramuscular Fatty Infiltration on Magnetic Resonance Imaging

Objective

The impact of rotator cuff (RC) tear pattern on intramuscular fatty infiltration (FI) is not well understood. The purpose of our study is to determine if differing RC tear patterns are associated with discordant presentations of intramuscular FI.

Methods

Fifty-one adults with full-thickness tear of the posterosuperior RC on shoulder magnetic resonance imaging (MRI) were identified retrospectively. The study subjects were stratified by RC tear pattern: (1) L-shaped tear cohort, (2) crescent-/U-shaped tear cohort, and (3) complete tear cohort. Clinical information pertaining to age, sex, tear size, trauma history, and length of clinical symptoms was recorded from the institution's picture archiving and communication system. Goutallier grade was assessed on oblique sagittal T1-weighted MRI by two orthopedic surgeons and one orthopedic resident. A musculoskeletal radiologist recorded the shape and size of full-thickness RC tears. Descriptive, correlation, and reliability analyses were performed.

Results

The L-shaped, crescent-/U-shaped, and compete tear cohorts demonstrated significant differences pertaining to tear size (P < 0.001) and infraspinatus Goutallier grade (P = 0.024), but not supraspinatus Goutallier grade (P = 0.370). Age had strong correlation to supraspinatus Goutallier grade (rs = 0.712, P = 0.031) and infraspinatus Goutallier grade (rs = 0.712, P = 0.029) in the crescent-/U-shaped tear cohort. Tear size had strong correlation to supraspinatus Goutallier grade (rs = 0.796, P = 0.001) and infraspinatus Goutallier grade (rs = 0.793, P = 0.001) in the complete tear cohort. Moderate interobserver agreement was present for supraspinatus (kappa, 0.484) and infraspinatus (kappa, 0.427) Goutallier grade.

Conclusion

RC tear pattern is associated with different presentations of intramuscular FI at the posterosuperior RC. Full-thickness tears involving the crescent region of the RC cuff are associated with age. Intramuscular FI is associated with RC tear size.

Preoperative MRI Shoulder Findings Associated with Clinical Outcome 1 Year after Rotator Cuff Repair

Background Investigation of the use of preoperative MRI for providing prognostic information regarding clinical outcome following rotator cuff repair has been limited. Purpose To determine whether patients with more severe rotator cuff tears of the shoulder at preoperative MRI have a greater degree of residual pain and disability after rotator cuff repair. Materials and Methods This retrospective study included a cohort of 141 patients who underwent surgical repair of a full-thickness rotator cuff tear at a single institution between April 16, 2012, and September 3, 2015. The mean patient age was 56.8 years, and there were 100 men (mean age, 56.1 years) and 41 women (mean age, 56.3 years). Patients completed the Disabilities of the Arm, Shoulder, and Hand (DASH) survey (lower score indicates less pain and disability) before and 1 year after surgery. One musculoskeletal radiologist blinded to the DASH scores measured the maximal anterior-posterior width and medial-lateral retraction of the rotator cuff tear on the preoperative MRI and assessed tendon degeneration and composite muscle atrophy and fatty infiltration using categorical grading scales (grade 0 indicates no tendon degeneration or muscle atrophy and fatty infiltration, and higher grades indicate incrementally more severe tendon degeneration or muscle atrophy and fatty infiltration). Generalized estimating equation models were used to determine the association between preoperative MRI findings and the postoperative DASH score. Results There was a significant positive association (P < .05) between the measured tear width (estimate, 2.05), measured tear retraction (estimate, 3.52), and tendon degeneration grade (estimate, 1.59) and the postoperative DASH score. There was no significant association (P = .49) between the composite muscle atrophy and fatty infiltration grade (estimate, 0.31) and the postoperative DASH score. Conclusion Patients with larger rotator cuff tears, more tendon retraction, and more severe tendon degeneration have worse clinical outcome scores 1 year after rotator cuff repair. © RSNA, 2019.

How Long Should We Wait to Create the Goutallier Stage 2 Fatty Infiltrations in the Rabbit Shoulder for Repairable Rotator Cuff Tear Model?

Background

Significant proportion of rotator cuff tears (RCTs) in clinical field are of a kind of repairable tear wherein the degree of fatty infiltration is of Goutallier stage 1 or stage 2. Therefore, the animal model, showing similar fatty infiltration, seems preferable for researches. The purpose of this study is to find out the proper time frame in which there is Goutallier stage 1 or stage 2 fatty infiltration in the rabbit RCT model for the research of repairable RCT in humans.

Methods

Supraspinatus tendon tears were created in forty male New Zealand white rabbits at their right shoulder (n= 8 for each group), and a sham operation on the left shoulder. Rabbits were divided into five groups (2nd, 4th, 6th, 8th, and 12th weeks). Specimens were harvested from the central portion of the supraspinatus muscle for haematoxylin and eosin (H &E) staining, followed by histological and Goutallier grading evaluation. Results are expressed as mean ± standard deviation by Sigma Plot software (version 7.0).

Results

At two weeks, mainly lipoblasts were observed around the muscle fibers, and at four weeks these lipoblasts were replaced by mature adipocytes with fatty infiltration amount (2.13 ± 0.35). The degree of muscle atrophy was (1.50 ± 0.53) at four weeks compared to sham group (0.88 ± 0.64) with significant difference (p < 0.05). The inflammatory process appeared as two phases. At two weeks, it was increased with grading value (1.88 ± 0.35). However, in the four-week group, it showed a sharp decrease (0.50 ± 0.53). At six weeks, inflammation reappeared to increase (1.13 ± 0.83). Then, a gradual decline appeared at eight weeks (0.88 ± 0.83) and at 12 weeks (0.50 ± 0.92).

Conclusions

At two and four weeks, both fat distribution in rabbit supraspinatus muscles and Goutallier grading scale mostly appeared as grade 2. Therefore, we can consider four weeks to be a suitable period for making a repairable RCT animal model for the human research, considering the early acute tissue reaction at 2 weeks after the tendon tears.

Quantification of shoulder muscle intramuscular fatty infiltration on T1-weighted MRI: a viable alternative to the Goutallier classification system

BACKGROUND

Quantification of rotator cuff intramuscular fatty infiltration is important for clinical decision-making in patients with rotator cuff tear. The semi-quantitative Goutallier classification system is the most commonly used method, but has limited reliability. Therefore, we sought to test a freely available fuzzy C-means segmentation software program for reliability of the quantification of shoulder intramuscular fatty infiltration on T1-weighted MR images and for correlation with fat fraction by six-point Dixon MRI.

MATERIALS AND METHODS

We performed a prospective cross-sectional study to measure visible intramuscular fat area percentage on oblique sagittal T1 MR images by fuzzy C-means segmentation and fat fraction maps by six-point Dixon MRI for 42 shoulder muscles. Intra- and inter-observer reliability were determined. Correlative analysis for fuzzy C-means and six-point Dixon intramuscular fatty infiltration measures was also performed.

RESULTS

We found that inter-observer reliability for the quantification of visible intramuscular fat area percentage by fuzzy C-means segmentation and fat fraction by six-point Dixon MRI was 0.947 and 0.951 respectively. The intra-observer reliability for the quantification of visible intramuscular fat area percentage by fuzzy C-means segmentation and fat fraction by six-point Dixon MRI was 0.871 and 0.979 respectively. We found a strong correlation between fuzzy C-means segmentation and six-point Dixon techniques; r = 0.850, p < 0.001 by individual muscle; and r = 0.977, p < 0.002 by study subject.

CONCLUSION

Quantification of intramuscular fatty infiltration by fuzzy C-means segmentation on T1-weighted sequences demonstrates excellent reliability and strong correlation with fat fraction by six-point Dixon MRI. Quantitative fuzzy C-means segmentation is a viable alternative to the semi-quantitative Goutallier classification system.

Pre-operative factors correlated with arthroscopic reparability of large-to-massive rotator cuff tears

Background

The purpose of this study is to determine the pre-operative factors that are associated with reparability of the large-sized and massive rotator cuff tears.

Methods

Sixty-six patients were included in this prognostic study. Demographic data, radiographic and MRI parameters were collected. Arthroscopic rotator cuff repair was performed for all included patient. Complete rotator cuff repair was achieved when the tendon covered up at least 50% of the anatomical footprint. The receiver operating characteristic (ROC) curve was analysed to define the cut-off level of each significant factor.

Results

Eleven large-sized rotator cuff tears and fifty-five massive rotator cuff tears were defined from MRI. Fifty-four patients were in the complete repair group, and twelve patients were in the partial repair group. The mean duration between MRI and surgery of 5.5 weeks. Reparability was correlated with age, mediolateral (ML) and anteroposterior (AP) tear size, rotator cuff arthropathy, superior migration of humeral head, fatty infiltration and atrophy of the supraspinatus muscle, and fatty infiltration of infraspinatus muscle (p < 0.05). The ROC curve defined a cut-off level of each predicting factor which included age of ≥65 years, mediolateral tear size of ≥36 mm, anteroposterior tear size of ≥22 mm, Hamada’s rotator cuff arthropathy of ≥class2, acromiohumeral interval of ≥6 mm, ≥stage3 supraspinatus fatty infiltration, the presence of supraspinatus muscle atrophy, and ≥ stage1 infraspinatus fatty infiltration. In multivariated regression analysis, age, acromiohumeral interval, and anteroposterior tear size were statistically associated with the reparability. The intra- and inter-observer reliabilities were moderate to excellent.

Conclusion

Age, ML tear size, AP tear size, rotator cuff arthropathy, superior migration of humeral head, fatty infiltration of supraspinatus and infraspinatus muscles and supraspinatus muscle atrophy all correlate with reparability of large to massive rotator cuff tear.

Allogenic Myocytes and Mesenchymal Stem Cells Partially Improve Fatty Rotator Cuff Degeneration in a Rat Model

PURPOSE

Rotator cuff (RC) tears result not only in functional impairment but also in RC muscle atrophy, muscle fattening and eventually to muscle fibrosis. We hypothesized that allogenic bone marrow derived mesenchymal stem cells (MSC) and myocytes can be utilized to improve the rotator cuff muscle fattening and increase the atrophied muscle mass in a rat model.

METHODS

The right supraspinatus (SSP) tendons of 105 inbred rats were detached and muscle fattening was provoked over 4 weeks; the left side remained untouched (control group). The animals (n = 25) of the output group were euthanized after 4 weeks for reference purposes. The SSP-tendon of one group (n = 16) was left unoperated to heal spontaneously. The SSP-tendons of the remaining 64 rats (4 groups with n = 16) were repaired with transosseous sutures. One group received a saline solution injection in the SSP muscle belly, two other groups received 5 × 10⁶ allogenic myocytes and 5 × 10⁶ allogenic MSC injections from donor rats, respectively, and one group received no additional treatment. After 4 weeks of healing, the supraspinatus muscle mass was compared quantitatively and histologically to all the treated groups and to the untreated contralateral side.

RESULTS

In the end of the experiments at week 8, the myocyte and MCS treated groups showed a significantly higher muscle mass with 0.2322 g and 0.2257 g, respectively, in comparison to the output group (0.1911 g) at week 4 with p < 0.05. There was no statistical difference between the repaired, treated, or spontaneous healing groups at week 8. Supraspinatus muscle mass of all experimental groups of the right side was significantly lower compared to the untreated contralateral muscle mass.

CONCLUSION

This defect model shows that the injection of allogenic mycocytes and MSC in fatty infiltrated SSP muscles is better than no treatment and can partially improve the SSP muscle belly fattening. Nevertheless, a full restoration of the degenerated and fattened rotator cuff muscle to its original condition is not possible using myocytes and MSC in this model.