Supraspinatus Muscle and Tendon Stiffness Changes After Arthroscopic Rotator Cuff Repair: A Shear Wave Elastography Assessment

Preoperative Increases in T2-Weighted Fat-Suppressed MRI Signal Intensities Associated with Advanced Tissue Degeneration and Mitochondrial Dysfunction in Rotator Cuff Tears

PURPOSE

The purpose of this study was to investigate the relationship between magnetic resonance imaging (MRI) signal intensities and mitochondrial function in patients undergoing arthroscopic rotator cuff repair, assessed through histological and genetic profiling of tendon tissue.

METHODS

This study, conducted between April 2022 and January 2023, included 20 patients undergoing rotator cuff repair for atraumatic/degenerative tears. Rotator cuff tendon edge samples were obtained during arthroscopic rotator cuff repair. Patients were classified based on signal intensity from preoperative T2-weighted fat suppressed MRI. Specifically, they were categorized as having either high or low signal intensity at the rotator cuff tendon edge, with the deltoid muscle serving as a reference. Comparative analyses specifically compared the histological features and genetic profiles of the tendon tissue at the rotator cuff tendon edge. Histological evaluation of harvested tendon specimens during arthroscopic rotator cuff repair employed the modified Bonar score. Real-time polymerase chain reaction was used to assess expression of various mitochondrial and apoptosis-related genes. The mitochondrial morphology of the rotator cuff torn site was examined using electron microscopy.

RESULTS

The higher signal intensity group showed significantly higher modified Bonar scores (p=0.0068), decreased mitochondrial gene expression, increased TUNEL-positive cells (p=0.032), lower SOD activity (p=0.011), reduced ATP5A (p=0.031), and increased cleaved caspase-9 activity (p=0.026) when compared to the lower signal intensity group. Electron microscopy revealed fewer mitochondrial cristae in the higher signal intensity group.

CONCLUSION

Our results suggest correlations between high MRI signal intensities and the presence of degeneration, mitochondrial dysfunction, and increased apoptosis in rotator cuff tissues. This underscores the utility of MRI signal intensity as an indicator of tissue condition.

CLINICAL RELEVANCE

Building on the established premise that elevated preoperative MRI signal intensities may indicate higher rates of postoperative rotator cuff re-tears, the current study substantiates these findings from a mitochondrial function perspective.

Prospective Evaluation of Normal Supraspinatus Muscle Using Shear Wave Elastography: Comparison With Symptomatic Tendon Tears

OBJECTIVE

This study aimed to evaluate normal supraspinatus (SS) muscle elasticity using shear wave elastography (SWE) in an asymptomatic group, analyze its correlation with demographic factors and ultrasound (US) grayscale grade, and compare the elasticity between normal SS muscles and symptomatic SS muscles with tendon tears.

METHODS

A prospective study was conducted with 101 adult patients with normal SS muscle scheduled for surgery due to a contralateral shoulder with SS tendon tear. Both shoulders underwent US examinations, including SWE. The SWE values, including mean and median elasticity, as well as the elasticity ratio, were analyzed for their correlation with demographic characteristics and grayscale grades. A comparison of SWE values was performed between the normal and symptomatic SS muscle groups.

RESULTS

The mean SWE modulus of the normal SS muscle was 27.87 kPa (±49.04), with an elasticity ratio of approximately 1.52 (±0.03). Males exhibited slightly higher elasticity ratios compared with females (1.61 vs 1.45, P = .016). The interobserver agreement for all SWE measurements was excellent (>0.8). Grayscale grade increased with age, showing a similar pattern in females (P < .001). However, no significant correlation was observed between SWE values and grayscale grade in the normal SS muscle group. SWE values in normal SS muscles were significantly lower than those with tendon tears (P < .001).

CONCLUSIONS

SWE provides objective measurements of normal SS muscle elasticity. Gender-based variations were observed, with males exhibiting slightly higher elastography ratios. SWE values were significantly lower in asymptomatic SS muscles compared with those with tendon tears.

A systematic review on sonoelastography for rotator-cuff post-repair assessment

Surgical repair of rotator cuff tears is performed routinely; however, the risks of re-tears and the associated consequences are significant. Sonoelastography, an imaging modality that evaluates the mechanical properties of tissues, can examine the dynamic transitions in rotator cuff stiffness following retear and investigate the relationship between these changes and the occurrences of retears. This systematic review aimed to summarize the role of perioperative sonoelastography in repaired rotator cuffs. A comprehensive search of the PubMed, Embase, and Cochrane databases was conducted, covering studies published until June 19, 2023. The Newcastle-Ottawa scale was used for quality assessment. The key information extracted from each study included the injury/surgery type, follow-up duration, sonoelastography mode, and main sonoelastographic findings. Eleven eligible studies comprising 355 patients were included. All studies focused on supraspinatus muscles and tendons with previous arthroscopic repairs. During the postoperative 1st - 6th months, muscle stiffness increased in the supraspinatus and decreased in the ipsilateral deltoid. Failure to recover supraspinatus muscle elasticity might be indicative of potential tendon re-tear; however, it is imperative to first establish correlations with other imaging modalities. Conflicting findings have been observed regarding stiffening or softening of the supraspinatus tendon after surgical repair. The preoperative stiffness of the supraspinatus tendon did not correlate with postoperative tendon integrity or function.

Relationship Between the Changes of Tendon Elastic Moduli With Ultrasound Shear Wave Elastography and Mechanical Compression Test

OBJECTIVE

The purpose of this study was to investigate the consistency of the changes in the elastic modulus measured with ultrasound shear wave elastography (SWE) with changes measured through mechanical testing using tendons that were artificially altered by chemical modifications.

METHODS

Thirty-six canine flexor digitorum profundus tendons were used for this experiment. To mimic tendon mechanical property changes induced by tendinopathy conditions, tendons were treated with collagenase to soften the tissue by collagen digestion or with 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride (EDC) to stiffen the tissues through chemical crosslinking. Tendons were randomly assigned to one of three groups: immersion in phosphate-buffered saline (PBS) as a control group (n = 12), collagenase treatment (n = 12) or EDC treatment (n = 12). Immediately following SWE measurement of each tendon, mechanical compression testing was performed as a gold standard to validate the SWE measurement. Both tests were conducted before and after treatment.

RESULTS

The compressive modulus and SWE shear modulus significantly decreased after collagenase treatment. Conversely, both moduli significantly increased after EDC treatment. There was no significant difference in either modulus before or after PBS treatment. As a result of a regression analysis with the percentage change of the compressive modulus as the dependent variable and SWE shear modulus as the independent variable, the best-fit regression was found to be an exponential function and the coefficient of determination was 0.687.

CONCLUSION

The changes in the compressive moduli and SWE shear moduli in tendons induced by chemical treatments were correlated by approximately 70%.

Ultrasonic shear wave elastography predicts the quality of the residual tendon before the rotator cuff repair

BACKGROUND AND PURPOSE

Effective evaluation of rotator cuff tear residual tendon quality is the key to surgical repair. However, until now, the evaluation of rotator cuff tissue by ultrasonic shear wave elasticity (SWE) has been controversial. This prospective study analyzed the association between preoperative SWE and arthroscopic residual tendon quality scores.

METHODS

The shear wave velocity (SWV) of the deltoid muscle, the supraspinatus tendon, and the supraspinatus muscle were measured in full-thickness rotator cuff tear patients. Tendon quality was scored according to tear size, tendon margin, tendon thickness, and footprint coverage during arthroscopy. The arthroscopic scores were used as the gold standard, and the SWV ratio of tendon and muscle (supraspinatus tendon/deltoid and supraspinatus muscle/deltoid) were calculated and correlated with the arthroscopic scores.

RESULT

Eighty-nine patients (129 shoulders) were enrolled, including 89 operation shoulders and 40 control shoulders. In the group of operation shoulders, both the SWV ratios of tendon (SWV-RT) and the SWV ratio of muscle (SWV-RM) were negatively correlated with arthroscopic scores (The correlation coefficient (R) ranged from -0.722 to -0.884 and -0.569 to -0.689). The SWV-RT and SWV-RM of the operation shoulders were significantly lower than that of the control shoulders (p < 0.05).

CONCLUSION

SWE could be used to predict the quality of the residual tendon before the rotator cuff repair. SWV of the supraspinatus tendon and muscle was a useful parameter to predict the quality of the residual tendon.

CRITICAL RELEVANCE STATEMENT

Measuring the shear wave velocity of the supraspinatus tendon and muscle with SWE is useful for predicting the quality of the residual tendon which is one of the key factors for a successful rotator cuff repair.

KEY POINTS

• Evaluating the quality of the residual tendon is important before surgery. • Elasticity measurements were negatively correlated with the arthroscopic score. • SWE is useful for predicting the quality of the residual tendon.

The Fate of the Shoulder Post Rotator Cuff Repair: Biomechanical Properties of the Supraspinatus Tendon and Surrounding Structures

The study aimed to describe the changes in biomechanical properties of the supraspinatus tendon, deltoid muscle, and humeral head post arthroscopic rotator cuff repair using shear wave elastography. Shear wave velocity of the tendon, deltoid, and humeral head of 48 patients was measured at predetermined sites at 1 week, 6 weeks, 12 weeks, 6 months, and 12 months post repair. One-way ANOVA with Tukey's correction and Spearman's correlation were performed. Mean±SEM healing tendon stiffness, adjacent to tendon footprint, increased from 1 week (6.2±0.2 m/s) to 6 months (7.5±0.3 m/s) and 12 months (7.8±0.3 m/s) (P<0.001). Mean±SEM deltoid muscle stiffness was higher at 12 months (4.1±0.2 m/s) compared to 1 week (3.4±0.1 m/s) and 12 weeks (3.5±0.1 m/s) (P<0.05). Humeral head stiffness did not change. Following arthroscopic rotator cuff repair, supraspinatus tendon stiffness increased in a curvilinear fashion over 6 months. From 6 months, deltoid muscle stiffness increased, corresponding to when patients were instructed to return to normal activities.

The Combined Suture Bridge With Mason-Allen Technique Is Superior to the Conventional Suture Bridge Technique for Arthroscopic Rotator Cuff Repair

PURPOSE

To compare clinical results and retear rates between the combined suture bridge with Mason-Allen (SBMA) technique and the conventional suture bridge (SB) technique in patients with full-thickness rotator cuff tears who underwent arthroscopic rotator cuff repair.

METHODS

One hundred two patients who underwent arthroscopic rotator cuff repair using the SB technique (n = 50) or SBMA technique (n = 52) for a full-thickness rotator cuff tear and had at least 2 years of follow-up were retrospectively analyzed. Magnetic resonance imaging was performed before surgery and 2 years after to determine preoperative tear size, Goutallier stage, and presence of retear after surgery. Patients were clinically evaluated using the Japanese Orthopaedic Association (JOA) score.

RESULTS

The groups did not significantly differ in terms of follow-up period, age, sex, tear size, Goutallier stage, or number of suture anchors. The retear rate was significantly lower in the SBMA group (7.7% vs 28.0%; P < .01). The JOA score was significantly higher at last follow-up than before surgery in both groups (P <.01). The JOA score at last follow-up was significantly higher in the SBMA group (P = .02).

CONCLUSIONS

Arthroscopic rotator cuff repair using the SBMA technique may provide better clinical and anatomical outcomes than the conventional SB technique.

LEVEL OF EVIDENCE

Level III, retrospective cohort design; treatment study).

Compensation strategy of shoulder synergist muscles is not stereotypical in patients with rotator cuff repair

Rotator cuff tear is a common shoulder injury that causes shoulder dysfunction and pain. Although surgical repair is the primary treatment for rotator cuff tear, it is well recognized that impaired force exertion of muscles connecting to the involved tendon and subsequent complemental change in the force exertion of synergist muscles persist even after repair. This study aimed to identify the compensation strategy of shoulder abductors by examining how synergist muscles respond to supraspinatus (SSP) muscle force deficit in patients with rotator cuff repair. Muscle shear modulus, an index of muscle force, was assessed for SSP, infraspinatus, upper trapezius, and middle deltoid muscles in repaired and contralateral control shoulders of 15 patients with unilateral tendon repair of the SSP muscle using ultrasound shear wave elastography while the patients passively or actively held their arm in shoulder abduction. In the repaired shoulder, the shear modulus of the SSP muscle declined, whereas that of other synergist muscles did not differ relative to that of the control. To find the association between the affected SSP and each of the synergist muscles, a regression analysis was used to assess the shear moduli at the population level. However, no association was observed between them. At the individual level, there was a tendency of variation among patients with regard to a specific muscle whose shear modulus complementarily increased. These results suggest that the compensation strategy for SSP muscle force deficit varies among individuals, being nonstereotypical in patients with rotator cuff injury.

Mechanical characteristic of supraspinatus muscle changes independent of its size and intramuscular fat in patient with rotator cuff repair

PURPOSE

This study aimed i) to investigate the mechanical, morphological, and compositional characteristics of the supraspinatus muscle after rotator cuff repair by using ultrasound shear wave elastography (SWE) and B-mode imaging, and ii) to determine whether the morphological or compositional characteristics are associated with the mechanical characteristic of the supraspinatus during contraction.

METHODS

Using SWE and B-mode imaging, active and passive shear moduli, muscle thickness, and echo intensity of the supraspinatus were measured from the repaired and contralateral control shoulders of 22 patients with rotator cuff repair. The shear modulus, muscle thickness, and echo intensity were compared between the repaired and control shoulders. The association between the active shear modulus and the other variables was determined.

RESULTS

While the active and passive shear moduli were lower in the repaired shoulder compared to the control, the muscle thickness and echo intensity did not vary between them. Interestingly, the passive shear modulus was positively correlated with the active shear modulus only in the control shoulder.

CONCLUSION

The mechanical characteristic of supraspinatus remains impaired, even without degenerative changes in the morphological and compositional characteristics after rotator cuff repair. Furthermore, the association between contractile and elastic characteristics in the supraspinatus was deteriorated in control shoulder.

Providing safe and effective rehabilitation by assessing supraspinatus muscle elasticity using ultrasound real-time tissue elastography after rotator cuff repair: A case series

INTRODUCTION

Although surgical techniques have advanced to avoid a postoperative re-tear after rotator cuff surgery, it remains unclear how to directly evaluate the risk of a re-tear.

OBJECTIVE

To describe how muscle elasticity with real-time tissue elastography could be used to avoid re-tear in individual cases after rotator cuff repair.

CASE DESCRIPTION

This case series included four patients, two per tear size (small and large/massive), with contrasting changes in muscle elasticity of the supraspinatus muscle. All patients underwent primary arthroscopic or open rotator cuff repair. The elasticity of the supraspinatus muscle was evaluated at relaxed and elongated positions of 0° and 60° shoulder abduction angles, respectively. The change in muscle elasticity at 1 month after surgery was characteristically different, and we predicted that a greater elasticity in the elongated position indicated a higher risk of re-tear. The cases with high risk underwent careful rehabilitation to avoid re-tear, and no re-tears were recorded in this report.

CONCLUSION

Our findings suggested that evaluation of muscle elasticity using real-time tissue elastography, which provides an indication of the risk of re-tear, in the clinical setting might be useful for therapists, who could adjust the intensity of rehabilitation, and for patients.

Adduction Manipulation of the Glenohumeral Joint versus Physiotherapy for Atraumatic Rotator Cuff Tears: A Randomized Controlled Trial

BACKGROUND

Atraumatic rotator cuff tears (ARCTs) are frequently concomitant with adduction restriction of the glenohumeral joint (GHJ). Adduction manipulation (AM) removes the restriction and relieves pain. The present study aimed to investigate the clinical efficacy of AM versus physiotherapy (PT) in ARCTs.

METHODS

Eighty-eight patients with adduction restriction were allocated to the AM and PT groups (n = 44 per group). The glenohumeral adduction angle (GAA) was calculated using X-rays at the first and last follow-up appointments. We recorded pain severity (visual analog scale, VAS), flexion, abduction, external rotation (ER), internal rotation (IR), and American Shoulder and Elbow Society (ASES) and Constant scores at baseline and at 1-, 3-, 6-, and 12- month follow-ups.

RESULTS

Forty-three patients (23 males, average age 71.3 years) in the AM group and 41 (16 males, average age 70.7 years) in the PT group were consequently analyzed. At the 1-month follow-up, VAS, shoulder motion except ER, ASES and Constant scores were much better in the AM group than in the PT group, whereas those in the PT group improved gradually up to 12 months. At the final follow-up, flexion, abduction, and Constant score were significantly better in the AM group than in the PT group. The GAA at the initial and final examinations was -21.6° and -3.2°, respectively, in the AM group, and -21.1° and -14.4°, respectively, in the PT group.

CONCLUSIONS

The AM procedure, which had better clinical efficacy than PT, is recommended as the first conservative treatment option for ARCTs.

Determination of the reference range for semi-quantified elasticity of healthy supraspinatus muscles using real-time tissue elastography and its clinical use in patients after rotator cuff repair

BACKGROUND

The quantitative assessment of healthy supraspinatus muscle elasticity may provide clinically useful preliminary information after rotator cuff repairs. We aimed to determine the reference range for supraspinatus muscle semi-quantified elasticity and describe how it can be used clinically after rotator cuff repair.

METHODS

The elasticity of healthy bilateral supraspinatus muscles in 43 participants aged between 24 and 75 years (categorized into two subgroups: <50 and ≥ 50 years) was measured as a strain ratio at 0° and 60° of shoulder abduction using real-time tissue elastography. The reference and modified reference ranges calculated by excluding outliers for elasticity were determined using normal distribution methods for logarithmically transformed data. The modified reference range was applied to eight cases of rotator cuff repair.

FINDINGS

Strain ratios under and over 50 years of age were 1.63 vs. 2.21 at 0° of shoulder abduction (P = 0.028) and 0.92 vs. 1.29 at 60° of shoulder abduction (P = 0.002), respectively. Modified reference ranges for under and over 50 years of age were 0.72-4.17 and 0.98-4.50 at 0° of shoulder abduction and 0.38-1.95 and 0.56-2.76 at 60° of shoulder abduction, respectively. Among eight cases, two showed strain ratios above the reference range at 1 month postoperatively, and rehabilitation protocols were adjusted.

INTERPRETATION

A strain ratio above the reference range, especially above the upper limit at 0° of shoulder abduction, may indicate increased passive stiffness of the musculotendinous unit. Clinically, the reference range has the potential to be used as a baseline after rotator cuff repairs.

Sonographic and elastographic findings after arthroscopic rotator cuff repair: a comparison with clinical results

OBJECTIVE

We assessed the relationship between early postoperative clinical outcomes of arthroscopic rotator cuff repair (ARCR) and observations obtained by postsurgical ultrasound (US) and strain elastography (SE) of repaired supraspinatus tendons (SSTs).

METHODS

This retrospective study included 42 cases in which the patient underwent ARCR followed by postoperative US and SE. The Korean Shoulder Scoring (KSS) system was used to assess preoperative and postoperative conditions. The thickness of the repaired SST and subdeltoid fluid was measured by US. SE scores were classified into four grades (1 to 4) according to elasticity of repaired SST. In addition, SE scores were divided into two groups: soft (SE scores of 1 and 2) and hard (SE scores of 3 and 4). The relationship between clinical outcomes and US parameters and SE scores was determined by KSS.

RESULTS

Postoperative SE scores observed by two readers correlated significantly with function (p = 0.021 and p = 0.021, respectively) and muscle strength (p = 0.008 and p = 0.015, respectively). SE scores were significantly correlated with a difference value of muscle strength of KSS scores (p = 0.002 and p = 0.014). In a comparison of hard and soft groups of repaired SSTs, function (p = 0.008 and p = 0.010, respectively) and muscle strength (p = 0.002 and p = 0.014, respectively) in postoperative KSS scores were statistically higher in the hard SE scores than the soft SE scores. The difference value of function (p = 0.021 and p = 0.021,) and muscle strength (p = 0.008 and p = 0.015) of KSS scores was significantly higher in the hard SE scores.

CONCLUSIONS

Postoperative SE scores of repaired tendons correlated significantly with muscle strength and function after ARCR. Postoperative US images including thickness of repaired tendon and subdeltoid fluid did not correlate with clinical outcome.

ADVANCES IN KNOWLEDGE

SE evaluations of repaired SST may provide important information about postoperative muscle strength and function.

A Systematic Temporal Assessment of Changes in Tendon Stiffness Following Rotator Cuff Repair

OBJECTIVES

How the material properties of the human supraspinatus tendon change following arthroscopic rotator cuff repair is undetermined. Shear wave elastography ultrasound is a relatively new, noninvasive measure of tissue stiffness. We aimed to evaluate any temporal changes in stiffness and/or thickness of supraspinatus tendons in humans following primary arthroscopic rotator cuff repair.

METHODS

Shear wave elastography was performed at three predetermined regions by a single sonographer at 1-, 6-, 12-, 24-, and 52 weeks postoperatively in 50 consecutive single-row inverted mattress primary arthroscopic rotator cuff repairs. One-way ANOVA with Tukey's correction and Spearman's correlation tests was performed.

RESULTS

Of 50 patients, two retore by 1-week and were excluded. Two patients retore at 6 weeks, two at 12 weeks, and one at 24 weeks. The mean tendon stiffness in 48 patients at the tendon footprint increased by 21% (1.32 m/s) at 6 months (P < .001), with the lateral tendon stiffening before the medial tendon. Tendon thickness decreased by 11% (0.6 mm) at 6 weeks (P = .008), then stabilized to 24 weeks. Tendons that were less elastographically stiff at 1 week were more likely to be thinner at 6-weeks (r = .38, P = .010).

CONCLUSIONS

The data supports the hypothesis that rotator cuff tendons repaired using the single-row inverted-mattress technique take 6 weeks to heal to bone. Unlike in other tendons, there was no hypertrophic healing response. Prior to 6 weeks, the tendon may stretch/thin-out, particularly if its material properties, as assessed by shear wave elastography, are inferior. The material properties of the tendon improved at the tendon insertion site first, then medially out to 12 months post-repair.

All-inside technique versus in situ transtendon repair for Ellman Ⅲ partial articular supraspinatus tendon avulsion

BACKGROUND

The current surgical techniques for repairing Ellman Ⅲ partial articular supraspinatus tendon avulsion (PASTA) is mainly tear completion followed by repair and in situ transtendon repair, and both techniques have been proven to have good clinical effects. In situ transtendon repair is more widely used because of its high performance in preserving the integrity of the bursal side supraspinatus tendon. However, there is still some scope for improvement. Our purpose was to compare the clinical outcomes of the all-inside repair technique and in situ transtendon repair for Ellman III PASTA.

METHODS

A retrospective comparative study was conducted on 56 patients who suffered from Ellman Ⅲ PASTA and underwent rotator cuff repair; 28 patients were treated with the all-inside technique (group A), and 28 patients were treated with the transtendinous technique (group B). All patients were followed up for at least 2 years. The visual analog scale (VAS), Constant, and American Shoulder and Elbow Surgeons (ASES) scores were used to evaluate the patient's shoulder joint function before surgery, 1 month and 3 months after surgery, and at the last time of follow-up.

RESULTS

Group A showed superiority in pain and functional improvement 1 month after the operation: the VAS score, 2.8 ± 0.3 in group A vs. 4.7 ± 0.4 in group B (P = .042); Constant score, 73 ± 5 in group A vs. 60 ± 6 in group B (P = .038); and ASES score, 75 ± 5 in group A vs. 58 ± 7 in group B (P = .043), whereas there was no statistical difference in group B. However, 3 months after surgery and at the last follow-up, the VAS, Constant, and ASES scores in both groups were significantly improved (P < .01), and there was no significant statistical difference between the groups (P > .05). Magnetic resonance imaging showed that the repaired rotator cuff tendon-bone healed well; at the last follow-up, all patients were in good function, the pain was completely relieved, and no revision was performed in both groups.

CONCLUSION

Arthroscopic repair of Ellman Ⅲ PASTA provided satisfactory functional improvements and pain relief regardless of the all-inside and in situ transtendon repair techniques. However, the all-inside repair technique is more beneficial due to its dual function in preserving the intact bursa and avoidance of uneven tension of the articular side, which is advantageous to early postoperative rehabilitation.

[Evaluation methods of postoperative healing of supraspinatus tendon tear]

Objective

To summarize the evaluation methods of postoperative healing of supraspinatus tendon tear in recent years, in order to provide reference for clinic.

Methods

CNKI, Wanfang, PubMed, and Foreign Medical Literature Retrieval Service (FMRS) databases were used to search the literatures between 2005 and 2022. The literature related to the diagnosis and postoperative healing of supraspinatus tendon tear was included. Finally, 50 articles were reviewed.

Results

Supraspinatus tendon tear is a common shoulder disease. Physical examination, clinical score, and imaging examination are used to predict and evaluate the postoperative healing. Among them, physical examination and clinical score are non-invasive and the most economical methods, but their accuracy and sensitivity are lower than imaging examination, so they can only be used as auxiliary methods. The acromio-humeral distance (AHD) and upward migration index (UMI) measured by X-ray films can directly reflect the change of supraspinatus tendon thickness, but they are impossible to distinguish whether there is tear or not. Ultrasound and MRI are the main methods for the clinical diagnosis of supraspinatus tendon tear, but the commonly used MRI sequence can not accurately judge the internal healing of the tendon. Shear wave elastrography (SWE) and ultrashort-echo-time (UTE) techniques are the latest research directions in recent years, but different studies have shown opposite conclusions on the application of SWE technique. This conclusion shows that the principle of SWE technique and its relationship with tendons need to be further studied. UTE technique has good clinical effect, and the T2* value obtained by UTE technique is more accurate than that of traditional Sugaya typing, but there are still few research samples.

Conclusion

AHD and UMI measured by X-ray film and T2* value measured by UTE technique can be used as effective methods for evaluating the healing of supraspinatus tendon tear after repairing, and can be used as a follow-up evaluation method combined with physical examination and clinical score for patients with supraspinatus tendon tear.

Dyslipidemia is associated with risk for rotator cuff repair failure: a systematic review and meta-analysis

Background

Lipid deposition secondary to dyslipidemia (DLD) is shown to have a significant impact on tendon pathology, including tendon elasticity, fatty infiltration, and healing properties. Rotator cuff repair is a common procedure, susceptible to influence from many tear-related and patient-related characteristics. The purpose of this study was to determine the relationship between DLD and rotator cuff repair outcomes with analysis of retear risk and function.

Methods

PubMed, Embase, and SPORTDiscus were searched for all English-language, peer-reviewed studies between 2000 and the present, which analyzed relationships between patient-related factors and outcomes of rotator cuff repair. Studies that explicitly examined the effect of DLD on rotator cuff repair outcomes were chosen for inclusion. Included studies were assessed for methodological quality, and data were extracted for meta-analysis.

Results

Of the 3087 titles, 424 were screened by abstract, and 67 were reviewed in full. Inclusion criteria were met by 11 studies. Of these studies, 5 studies assessed retear, 2 studies measured function, 3 studies reported both retear and function, and 1 study evaluated the risk of retear necessitating a revision surgery. The studies report no significant difference in functional outcomes. Meta-analysis revealed that DLD patients had a significantly higher risk of retear after primary rotator cuff repair (odds ratio 1.32, 95% confidence interval 1.06-1.64).

Conclusion

DLD leads to an increased risk of retear after rotator cuff repair, although function appears to be unimpaired. DLD should be considered among other risk factors when counseling patients regarding expected rotator cuff repair outcomes.

Ultrasound shear wave elastography-derived tissue stiffness is positively correlated with rotator cuff tear size and muscular degeneration

PURPOSE

The purpose of this study is to describe rotator cuff muscle stiffness in patients with different degrees of rotator cuff tear (RCT) severity and to assess its predictive ability for RCT reparability.

METHODS

One hundred and thirty-three consecutive patients who were scheduled to undergo arthroscopic shoulder surgery were prospectively enrolled. Tendon retraction, fatty infiltration, and muscle atrophy were evaluated using magnetic resonance imaging. Shear modulus of supraspinatus (SSP) and infraspinatus (ISP) muscles were measured by ultrasound shear wave elastography (SWE). The tear size and reparability were determined intraoperatively.

RESULTS

There were 97 patients in RCT group and 36 patients in control group. Bilateral shear modulus discrepancy (Δshear modulus) was used to represent rotator cuff stiffness. Severely fatty-infiltrated rotator cuff muscles possessed a significantly higher stiffness compared with their counterparts (SSP: CI 27.8-31.8 vs. 13.5-15.6 kPa, ISP: CI 33.2-38.1 vs. 8.8-11.2 kPa, p < 0.001). The same trend applied to muscles with distinct tendon retraction (SSP: CI 27.7-32.3 vs. 10.9-14.9 kPa, ISP: CI 33.2-38.6 vs. 6.5-11.0 kPa, p < 0.001) and obvious muscle atrophy (SSP: CI 27.9-32.1 vs. 13.6-15.8 kPa, ISP: CI 32.9-38.2 vs. 9.0-11.7 kPa, p < 0.001). Irreparable massive RCT (MRCT) patients had significantly stiffer SSP (CI 27.7-31.9 vs. 13.5-16.5 kPa, p < 0.001) and ISP (CI 33.5-37.8 vs. 10.3-14.8 kPa, p < 0.001) than reparable MRCT. The Δshear modulus of the ISP was a highly accurate predictor of RCT reparability. A cutoff value of 18.0 kPa had a sensitivity of 100% and specificity of 98.8% for irreparable MRCT.

CONCLUSION

Ultrasound SWE-derived rotator cuff muscle stiffness is closely correlated with RCT size and severity.

LEVEL OF EVIDENCE

I.

Posterior shoulder stiffness was associated with shoulder pain during throwing in college baseball players: assessment of shear wave elastography

PURPOSE

To investigate shoulder stiffness on the throwing and non-throwing sides in college baseball players using ultrasound shear wave elastography (SWE), and investigate the relationship between stiffness and shoulder pain during throwing.

METHODS

Forty-nine college baseball players (98 shoulders) were recruited. Shoulder range of motion was evaluated. SWE was used to measure stiffness of the bilateral supraspinatus tendons, infraspinatus tendons, subscapularis tendons, supraspinatus muscles, infraspinatus muscles (ISPM), and posterior capsules. Participants were divided into pain and no pain groups based on the presence or absence of shoulder pain during throwing within 1 month before measurements on the throwing side. Items were compared between the throwing and non-throwing sides, and between the pain and no pain groups. Factors affecting shoulder pain during throwing were also investigated via multiple logistic regression analysis.

RESULTS

Compared with the non-throwing side, the throwing side had significantly greater external rotation at 90° abduction, significantly lesser internal rotation at 0° abduction and internal rotation at 90° abduction (AbdIR), significantly higher SWE values of the infraspinatus tendon, ISPM, and posterior capsule, and significantly lower SWE values of the subscapularis tendon. Compared with the no pain group, the pain group had a significantly higher SWE value of the ISPM, and significantly lesser AbdIR. Increased ISPM SWE values and decreased AbdIR were significantly correlated with shoulder pain during throwing.

CONCLUSIONS

The posterior tissue was stiffer than the anterior tissue on the throwing side. Decreased AbdIR and increased ISPM stiffness may be correlated with shoulder pain during throwing.

Utility of Preoperative Shear-Wave Elastography of the Supraspinatus Muscle for Predicting Successful Rotator Cuff Repair: A Prospective Observational Study With MRI Correlation

BACKGROUND. After rotator cuff tear, properties of the torn muscle predict failed surgical repair. OBJECTIVE. The purpose of our study was to explore the utility of preoperative shear-wave elastography (SWE) measurements of the supraspinatus muscle to predict successful rotator cuff repair, including comparison with MRI-based measures. METHODS. This prospective study included 74 patients (37 men, 37 women; mean age, 63.9 ± 10.0 [SD] years) who underwent rotator cuff repair between May 2019 and January 2021. Patients underwent preoperative clinical shoulder MRI and investigational shoulder ultrasound including SWE using shear modulus. The mean elasticity values of the supraspinatus and trapezius muscles were measured, and the elasticity ratio (i.e., ratio of mean elasticity of supraspinatus muscle to mean elasticity of trapezius muscle) was calculated. The muscular fatty infiltration score (1-3 scale) was recorded on gray-scale ultrasound. On MRI, muscular fatty infiltration was assessed by Goutallier grade (0-4 scale), and muscular atrophy was assessed by the occupation ratio (ratio of cross-sectional areas of supraspinatus muscle and supraspinatus fossa) and by the muscle atrophy grade (0-3 scale). After rotator cuff repair, the surgeon classified procedures as achieving sufficient (n = 60) or insufficient (n = 14) repair. RESULTS. Patients with insufficient repair, versus those with sufficient repair, more commonly exhibited a large (3-5 cm) tear (100.0% vs 50.0%). Patients with insufficient, versus sufficient, repair exhibited higher mean Goutallier grade (3.8 ± 0.4 vs 1.9 ± 1.1), mean muscle atrophy grade (2.0 ± 0.8 vs 0.5 ± 0.7), mean supraspinatus elasticity (44.15 ± 8.06 vs 30.84 ± 7.89 kPa), mean elasticity ratio (3.66 ± 0.66 vs 1.83 ± 0.58), and mean gray-scale fatty infiltration grade (2.86 ± 0.36 vs 1.63 ± 0.66) and showed lower mean occupation ratio (0.3 ± 0.1 vs 0.6 ± 0.1) (all, p < .001). AUC for predicting insufficient repair was 0.945 for Goutallier grade, 0.961 for occupation ratio, 0.900 for muscle atrophy grade, 0.874 for mean elasticity, 0.971 for elasticity ratio, and 0.912 for gray-scale fatty infiltration grade. Elasticity ratio (cutoff ≥ 2.51) achieved sensitivity of 100.0% and specificity of 90.0% for insufficient repair. At multivariable analysis including tear size, the three MRI measures, elasticity ratio, and gray-scale fatty infiltration grade, the only independent predictors of insufficient repair were muscle atrophy grade of 2-3 (odds ratio [OR] = 9.3) and elasticity ratio (OR = 15.7). CONCLUSION. SWE-derived elasticity is higher in patients with insufficient rotator cuff repair; the elasticity ratio predicts insufficient repair independent of tear size and muscle characteristics. CLINICAL IMPACT. Preoperative SWE may serve as a prognostic marker in patients with rotator cuff tear.

Presurgical tear characteristics and estimated shear modulus as predictors of repair integrity and shoulder function one year after rotator cuff repair

Background

Rotator cuff repair provides pain relief for many patients; however, retears are relatively common and affect approximately 20%-70% of patients after repair. Although magnetic resonance imaging (MRI) offers the ability to assess tissue characteristics such as tear size, retraction, and fatty infiltration, it provides little insight into the quality of the musculotendinous tissues the surgeon will encounter during surgery. However, shear wave elastography (SWE) could provide an indirect assessment of quality (ie, stiffness) by measuring the speed of shear waves propagating through tissue. The objective of this study was to determine the extent to which estimated shear modulus predicts repair integrity and functional outcomes 1 year after rotator cuff repair.

Methods

Thirty-three individuals scheduled to undergo arthroscopic rotator cuff repair were enrolled in this study. Before surgery, shear modulus of the supraspinatus tendon and muscle was estimated using ultrasound SWE. MRIs were obtained before and 1 year after surgery to assess tear characteristics and repair integrity, respectively. Shoulder strength, range of motion, and patient-reported pain and function were assessed before and after surgery. Functional outcomes were compared between groups and across time using a two-factor mixed model analysis of variance. Stepwise regression with model comparison was used to investigate the extent to which MRI and shear modulus predicted repair integrity and function at 1 year after surgery.

Results

At 1 year after surgery, 56.5% of patients had an intact repair. No significant differences were found in any demographic variable, presurgical tear characteristic, or shear modulus between patients with an intact repair and those with a recurrent tear. Compared with presurgical measures, patients in both groups demonstrated significant improvements at 1 year after surgery in pain (P < .01), self-reported function (P < .01), range of motion (P < .01), and shoulder strength (P < .01). In addition, neither presurgical MRI variables (P > .16) nor shear modulus (P > .52) was significantly different between groups at 1 year after surgery. Finally, presurgical shear modulus generally did not improve the prediction of functional outcomes above and beyond that provided by MRI variables alone (P > .22).

Conclusion

Although SWE remains a promising modality for many clinical applications, this study found that SWE-estimated shear modulus did not predict repair integrity or functional outcomes at 1 year after surgery, nor did it add to the prediction of outcomes above and beyond that provided by traditional presurgical MRI measures of tear characteristics. Therefore, it appears that further research is needed to fully understand the clinical utility of SWE for musculoskeletal tissue and its potential use for predicting outcomes after surgical rotator cuff repair.

Sonoelastography of the Shoulder: A Narrative Review

Sonoelastography is a relatively new non-invasive imaging tool to assess the in vivo qualitative and quantitative biomechanical properties of various tissues. Two types of sonoelastography (SE) are commonly explored: strain and shear wave. Sonoelastography can be used in multiple medical subspecialties to assess pathological tissular changes by obtaining mechanical properties, shear wave speed, and strain ratio data. Although there are various radiological imaging methods, such as MRI or CT scan, to assess musculoskeletal structures (muscles, tendons, joint capsules), SE is more accessible since this approach is of low cost and does not involve radiation. As of 2018, SE has garnered promising data in multiple studies. Preliminary clinico-radiological correlations have been established to bridge tissue biomechanical findings with their respective clinical pathologies. Specifically, concerning the shoulder complex, recent findings have described mechanical tissue changes in shoulder capsulitis. The long head of the biceps and supraspinatus SE were among the recently studied structures with conditions regarding impingement, tendinosis, and tears. Since ultrasonography has established itself as an important tool in shoulder evaluation, it completes the history and physical examination skills of the clinicians. This study will provide an update on the most recent findings on SE of shoulder structures.

Association of Recurrent Tear After Arthroscopic Rotator Cuff Repair and Superoxide-Induced Oxidative Stress

BACKGROUND

Recurrent tears after arthroscopic rotator cuff repair (ARCR) remain a significant clinical problem. Oxidative stress contributes to the degeneration of the rotator cuff, and a degenerative rotator cuff can lead to recurrent tear after ARCR. However, the correlation between oxidative stress and retear after ARCR is unclear.

PURPOSE

To investigate the correlation between superoxide-induced oxidative stress and recurrent tear after ARCR.

STUDY DESIGN

Case-control study; Level of evidence, 3.

METHODS

A total of 68 patients who underwent ARCR using a suture-bridge technique participated in this study. Specimens were collected from the edge of the torn tendon during surgery. The modified Bonar score was used to evaluate degeneration of the rotator cuff on histological specimens, and fluorescence intensity on dihydroethidium (DHE) staining was used to detect oxidative stress. Superoxide dismutase (SOD) enzyme activity was also measured. The following were used for clinical evaluation: age, tear size on magnetic resonance imaging (MRI) before surgery, Goutallier classification on MRI before surgery, and Japanese Orthopaedic Association score before and 6 months after surgery. After the repaired rotator cuffs were evaluated on MRI 6 months after surgery, the patients were divided into groups: those with a healed rotator cuff (healed group; n = 46) and those with a recurrent tear (retear group; n = 22). The significant differences between the groups were determined with regard to clinical evaluation, modified Bonar score, DHE intensity, and SOD activity. In addition, multivariate logistic regression analysis was performed to investigate risk factors for recurrent tear.

RESULTS

Age, tear size, Goutallier classification, modified Bonar score, DHE intensity, and SOD activity were significantly greater in the retear group than in the healed group, although the Japanese Orthopaedic Association score was not significantly different. Multiple logistic regression analysis demonstrated that age, tear size, and SOD activity were significantly correlated with recurrent tear.

CONCLUSION

In addition to tear size and age, superoxide-induced oxidative stress may be an exacerbating factor for retear after ARCR.

Stiffness change of the supraspinatus muscle can be detected by magnetic resonance elastography

Magnetic resonance elastography (MRE) and ultrasound shear wave elastography (SWE) are imaging techniques to measure stiffness of the soft tissue using magnetic resonance imaging (MRI) and ultrasound images, respectively. The purpose of this study was to explore the feasibility of the MRE measurement to evaluate the change in supraspinatus (SSP) muscle stiffness before and after rotator cuff tear, and to compare the result with those of SWE. Six swine shoulders were used. The skin and subcutaneous fat were removed, and the stiffness value of the SSP muscle was measured by MRE and SWE. The MRE measurement was performed with 0.3 T open MRI and the vibration from a pneumatic driver system with active driver to a passive driver to create the shear wave in the tissue. The passive driver was placed on the center of the SSP muscle. The stiffness was estimated from the wave images using local frequency estimation methods. In the SWE measurement, the probe of the ultrasound was placed on the center of the SSP muscle. The shear wave propagation speed was measured at a depth of 1 cm from the surface, and the stiffness was calculated. After those measurements, the rotator cuff tendon was detached from the greater tuberosity, and MRE and SWE measurements were then performed in the same manner again. The differences in the stiffness values were compared between before and after the rotator cuff tendon tear on both the MRE and SWE measurements. The results indicated that stiffness values on MRE and SWE were 9.3 ± 1.8 and 10.0 ± 1.2 kPa respectively before the rotator cuff tear, and 7.3 ± 1.3 and 8.0 ± 0.8 kPa respectively after the tendon detachment. Stiffness values were significantly lower after the tendon detachment on both the MRE and SWE measurements (p < 0.05). Our results demonstrated that stiffness values of the SSP muscle on MRE and SWE were lower after rotator cuff detachment. From this result, MRE may be a feasible method for quantification of the change in rotator cuff muscle stiffness.

Effect of localized tendon remodeling on supraspinatus tear propagation

Rotator cuff tear propagation is multifactorial and may be due to localized changes in mechanical properties from tendon remodeling based on the inhomogeneous stresses experienced by a tendon with a tear. The objective of this study was to investigate the effect of localized tendon remodeling on tear propagation for simulated supraspinatus tendon tears. A validated computational model of a supraspinatus tendon using subject-specific geometry and material properties with a 1 cm wide anterior tear was used. The medial edge of the supraspinatus tendon was displaced 5 mm to induce tear propagation and cohesive elements were used to model tear propagation. Four remodeling scenarios were investigated: (1) Baseline (no remodeling), (2) Positive remodeling (increased fiber stiffness) and (3) Negative remodeling (decreased fiber stiffness) at tear tips, and (4) Negative remodeling along the medial-lateral tear edge. Output parameters included the amount of tear propagation, critical load to propagate the tear, and maximum principal stress at the tear tips. Positive remodeling at the tear tips resulted in the largest amount of tear propagation (18.4 mm), highest peak maximum principal stress (25.2 MPa), and lowest critical load to propagate the tear (249N). Conversely, negative remodeling at the tear tips resulted in the least amount of tear propagation (16 mm), lowest peak maximum principal stress (17.6 MPa) and highest critical load to propagate the tear (278N). Overall, remodeling at the tear tips has the greatest effect on tear propagation. Therefore, a better method for clinicians to measure tendon stiffness at the tear tips would be helpful to improve outcome of patients.