Time-course changes in active stiffness of the supraspinatus muscle after arthroscopic rotator cuff repair

Ultrasound elastography of back muscle biomechanical properties: a systematic review and meta-analysis of current methods

OBJECTIVES

To report the current elastography methods used to quantify back muscles' biomechanical characteristics in patients with musculoskeletal disorders (MSKd) and inform on their reliability, validity, and responsiveness.

METHODS

MEDLINE, Embase, CINAHL, Cochrane library and grey literature were consulted. Predefined criteria allowed for study selection and data extraction. The quality of evidence was rated using the COSMIN tool. Data were meta-analyzed in terms of pooled intraclass correlation coefficient (pICC) for reliability and pooled standardized mean difference (pSMD) for validity and responsiveness. Heterogeneity was assessed.

RESULTS

Seventy-nine studies were included in the meta-analysis (total number of participants N = 3178). Three elastography methods were identified: strain imaging (SI; number of cohorts M = 26), shear wave imaging (SWI; M = 50), and vibration sonoelastography (VSE; M = 3). Strain imaging and SWI studies reported good reliability measurement properties (pICC > 0.70) and a medium pSMD (0.58 for SI and 0.60 for SWI; p ≤ 0.020) in discriminating MSKd from controls' condition (validity). Strain imaging studies reported a medium pSMD (0.64; p = 0.005) in detecting within-group changes over time, whereas SWI pSMD was very high (1.24; p = 0.005). Only SWI reported significant but small pSMD (0.30; p = 0.003) in detecting between-group changes over time. The small number of VSE studies could not be meta-analyzed. Heterogeneity was high (I-squared > 90%; p < 0.001).

CONCLUSIONS

Elastography presents good reliability results and a medium pSMD in discriminating MSKd from control conditions. Responsiveness data suggest detectable changes within groups over time using SI and SWI, calling for long-term longitudinal studies. Assessing changes between groups over time using elastography still needs to be proven. Highly significant heterogeneity limits meta-analytic results.

CRITICAL RELEVANCE STATEMENT

While still in its early-stage exploration phase, musculoskeletal ultrasound elastography may reliably quantify back muscles' biomechanics in asymptomatic individuals, moderately discriminate back musculoskeletal disorders and detect biomechanical changes over time in these conditions, calling for long-term longitudinal studies.

KEY POINTS

Ultrasound elastography is reviewed for back pain and related musculoskeletal disorder assessments. Growing literature supports good reproducibility, some validity and responsiveness. Back muscle elastography considers assumptions calling for standardized protocols.

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.

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.

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.

The application of shear wave elastography with ultrasound for rotator cuff tears: a systematic review

Background

Shear wave elastography (SWE) is an emerging ultrasound-based technology that provides a quantitative assessment of musculoskeletal tissue integrity. This systematic review investigates the use of SWE in the evaluation of rotator cuff tears.

Methods

PubMed, Embase, Web of Science, Google Scholar, and the Cochrane Library databases were searched for relevant studies from 1901 up to June 2022. Articles utilizing SWE in rotator cuff tears were selected based on inclusion and exclusion criteria. The studies included involved the assessment of shear wave velocity, tendon thickness and stiffness after healing, and fatty infiltrates evaluation using SWE. The Newcastle-Ottawa Scale was used to evaluate the risk of bias in included observational studies. Double-sided P value < .05 was considered statistically significant.

Results

Sixteen studies comprising 520 patients were included in the systematic review. SWE demonstrated that shear wave velocities in torn supraspinatus tendons were lower than in healthy supraspinatus tendons. A decrease in tendon SWE modulus elasticity was observed in tendinopathic tendons. Shear wave velocity decreased with increasing fat content and muscle atrophy. The velocity of SWE in muscle in re-tear groups was greater than in the healed group at 1 month after surgery (P < .05).

Conclusion

SWE ultrasound of the supraspinatus tendon can be a useful diagnostic tool for orthopedic surgeons that provide quantitative information on tendinopathic stiffness, velocity, fatty infiltrate, and elasticity characteristics. Decreased tendon velocity of SWE may predict recurrent rotator cuff tears and be useful in postoperative evaluations for muscle healing to plan for future management.