Real-time sonoelastography: principles and clinical applications in tendon disorders. A systematic review

Acute Effects of Running on Shear Wave Elastography Measures of the Achilles Tendon and Calf Muscles in Professional Female Handball and Volleyball Players

Shear Wave Elastography (SWE) is currently used to detect tissue pathologies, i.e., tendinopathy. For preventive medicine, it is important to examine the sensitivity of SWE and to investigate how stiffness measures are affected by methodological variables. The aim of this study is to examine shear wave elastography (SWE) measures in order to compare the pre- and post-running values and to determine the correlation between the shear wave speed values (m/s). SWE examinations of the Achilles tendon (AT), soleus muscle (MS) and gastrocnemius muscle (MG)) were performed in 24 healthy professional female athletes. Measurements of the shear wave speed (m/s) were taken before and after incremental treadmill running until exhaustion. Correlations were investigated using the Pearson correlation coefficient and were examined for significance using the Student's t-test. The pre- and post-exercise shear wave speed did not differ. The pre-exercise and post-exercise stiffness for MS (r = 0.613), MG (r = 0.609) and AT (r = 0.583) correlated strongly. The pre-exercise values and changes in stiffness showed a significant correlation (p < 0.001). In professional athletes, acute exercise induces different tissue stiffness changes in AT, MS and MG for each individual. Thus, exercise activity immediately prior to the SWE measurement needs to be factored in when evaluating tissue stiffness.

Stiffness of Muscles and Tendons of the Lower Limb of Professional and Semiprofessional Athletes Using Shear Wave Elastography

OBJECTIVE

Shear wave elastography (SWE) allows assessment of muscle and tendon stiffness and can be used to diagnose soft tissue pathologies such as tendinopathies. In sports medicine, SWE may have the potential to uncover structural changes early on before they lead to functional impairment. To systematically analyze possible differences in tendon and muscle stiffness of the lower limb between professional (PG) and semiprofessional female athletes (SG) using SWE and to compile reference values for developing preventive medicine approaches for professional athletes.

METHODS

Standardized SWE of both lower limb tendons and muscles (Achilles tendon [AT], soleus muscle insertion [SM], patellar tendon [PT], quadriceps tendon [QT], vastus medialis muscle [VM]) in the longitudinal plane was performed with the tendons in relaxed position in 24 healthy professional female athletes (PG) in comparison with 24 healthy semiprofessional female athletes (SG).

RESULTS

Median tendon and muscle stiffness was significantly higher in professional athletes (AT:PG, 11.12 m/s vs SG, 7.33 m/s, P < .001; SM: 1.77 m/s vs 1.14 m/s, P < .001; VM: 1.63 m/s vs 0.87 m/s, P < .001; QT: 3.31 m/s vs 2.61 m/s, P < .05). There was no significant difference in patellar tendon stiffness between PG and SG (PT: 2.57 m/s vs 3.21, P = .25).

CONCLUSION

Professional female athletes have higher stiffness values than semiprofessional female athletes in lower limb muscles and tendons, except for the patellar tendon. Knowledge of such differences is necessary for diagnosing tendinopathy and injuries. Musculoskeletal SWE could offer great benefits in sports medicine as well as in rehabilitation and preventive medicine.

Mid- and Long-Term Results Using 448 kHz Stimulation on the Elasticity of the Supraspinatus Tendon Measured by Quantitative Ultrasound Elastographyin Badminton Professionals: Prospective Randomized Double-Blinded Clinical Trial with Nine Months of Follow-Up

The aim of this study is to analyse the changes that occur in the elasticity of the supraspinatus tendon after the application of a 448 kHz capacitive resistive monopolar radiofrequency (CRMR) at 3, 6 and 9 months in professional badminton players. A randomized double-blinded clinical trial that included 9 months of follow-up was used. A private care practice was used to recruit the participants of this study. They were randomly assigned either the CRMR treatment (n = 19) or the placebo treatment (n = 19). The experimental group received a total of nine treatments of 448 kHz CRMR divided into three treatments per week. The control group received the same regimen but with no radiofrequency. Quantitative ultrasound strain elastography was used to report the main values for three areas of the supraspinatus tendon. These were measured at the start (T1) and directly after (T2), one week after, (T3), three months after (T4), six months after (T5) and nine months after (T6) the completion of the intervention program. There were statistically significant differences in the supraspinatus tendon elasticity immediately after (p ≤ 0.001), one week after (p ≤ 0.001) and three months after (p = 0.01) the intervention program. No significant changes were found six or nine months after the intervention program. A three-week intervention program using 448 kHz produced significant changes in the elasticity of the supraspinatus tendon, with the changes lasting up to approximately three months when compared to the control group.

A Systematic Review of Systematic Reviews on the Epidemiology, Evaluation, and Treatment of Plantar Fasciitis

The number of systematic review and meta-analyses on plantar fasciitis is expanding. The purpose of this review was to provide a comprehensive summary of reviews on the topic pertaining to plantar fasciitis, identify any conflicting and inconsistent results, and propose future research direction. A qualitative review of all systematic reviews and meta-analyses related to plantar fasciitis up to February 2021 was performed using PubMed, Embase, Web of Science, and the Cochrane Database. A total of 1052 articles were initially identified and 96 met the inclusion criteria. Included articles were summarized and divided into the following topics: epidemiology, diagnosis, and treatment. While the majority of reviews had high level of heterogeneity and included a small number of studies, there was general consensus on certain topics, such as BMI as a risk factor for plantar fasciitis and extracorporeal shockwave therapy as an effective mode of therapy. A qualitative summary of systematic reviews and meta-analyses published on plantar fasciitis provides a single source of updated information for clinicians. Evidence on topics such as the epidemiology, exercise therapy, or cost-effectiveness of treatment options for plantar fasciitis are lacking and warrant future research.

Influence of Bias in the Assessment of Patellar Tendon Stiffness: A Systematic Review and Meta-analysis

The aim of the present study was to provide a systematic review and meta-analysis of the main biases in practical applications of the different types of elastography in assessment of the stiffness of healthy patellar tendons. A literature search on four databases (Scopus, Web of Science, Pubmed and SportDiscus) was conducted on March 25, 2020. After analysis of 1,052 resultant articles, studies were included if they met two inclusion criteria: (1) studies were observational or randomized controlled trials; (2) studies included outcomes of patellar tendon stiffness. Twenty-one studies met the inclusion criteria and were included in this meta-analysis. Four meta-analyses were performed with respect to assessment procedure and participant characteristics. This meta-analysis found a low effect of examined portion of patellar tendon (standardized mean difference [SMD] = 0.27, 95% confidence interval [CI]: 0.01-0.54, n = 379, Z = 2.01, p = 0.04) and a high effect of knee flexion angle during assessment (SMD = -2.12; 95% CI: -2.67 to -1.58, n = 97, Z = 7.68, p < 0.01) in stiffness outcomes. The risk of bias was generally low, but the heterogenicity of the results downgraded the level of evidence. There is evidence in the elastography assessment of patellar tendon suggesting that the knee position and patellar tendon portion evaluated influence stiffness outcomes for patellar tendon in healthy volunteers.

Serial Ultrasonographic and Real-Time Elastosonographic Assessment of the Ovine Common Calcaneal Tendon, after an Experimentally Induced Tendinopathy

Real-time elastosonography (RTE) is a recently described, non-invasive, ultrasonographic technique developed to assess tissue elasticity. The main aim of this study was to investigate the ultrasonographic and elastosonographic appearance of the common calcaneal tendon (CCT) in an ovine model, and to monitor the progression of tendon healing after an experimentally-induced tendinopathy. Sound tendons were initially evaluated (T₀) with a caliper and by a single operator with ultrasound. Ultrasonographic and elastosonographic images were then acquired. Subsequently, ultrasound-guided tendon lesions were induced by injecting 500 IU of Type IA collagenases proximally to the calcaneal tuberosity. Caliper measurement, ultrasonography and elastosonography were then repeated at 15 (T₁), 30 (T₂) and 60 (T₃) days. Clinically measured width of the tendon, ultrasonographic thickness and width and percentage of hard (Elx-t%hrd) and soft (Elx-t%sft) tissue were recorded. Statistical analysis was performed on the data collected; statistical significance was set at p < 0.05. Intra-class correlation coefficient (ICC) revealed good (0.68) repeatability of elastosonographic evaluation of the CCT. The tendon width was significantly increased when comparing T₀ with T_1–2 and decreased when comparing T_1–2 with T₃. Ultrasound-assessed thickness was significantly increased between T₀–T₁ and decreased between T₁-T_2–3. Elx-t%hrd was significantly decreased at T_1–2–3 and Elx-t%sft was significantly increased at T_1–2–3. In conclusion, the ovine CCT is a highly stiff structure that undergoes a severe loss of stiffness during the healing process. Thickness and width of the tendon increased during the first 30 days and then reduced progressively along the subsequent 30 days. Ultrasonographic appearance of the tendon remained severely abnormal and the tendon showed severely reduced elastic proprieties 60 days after lesion induction.

Strain Elastography of Injured Equine Superficial Digital Flexor Tendons: A Reliability Study of Manual Measurements

Simple Summary

Strain elastography is an ultrasound-based technique that assesses the mechanical properties of tissues and gives a relative representation of elasticity. Early diagnosis of tendon injuries and long-term monitoring of the healing process are key to equine practice; thus, an accurate method is needed for analyzing and interpreting the images obtained with strain elastography. The first aim of the study was to demonstrate the intraoperator repeatability and interoperator reproducibility of manual measurements of elastograms obtained from injured superficial digital flexor tendons of horses; the second aim was to perform a standardization of the manual measurement method by comparing it with external software. Despite their subjectivity, manual measurements proved to be repeatable and reproducible. In addition, the results obtained with the manual method matched those obtained with the external software.

Abstract

Early diagnosis of tendon injuries and accurate long-term monitoring of the healing process are key for equine veterinarians that use conventional ultrasonography. The development of strain elastography could improve the management of clinical cases. The aim of the study was to assess the intraobserver repeatability and interobserver reproducibility of manual measurements of the colored areas of the tendons within elastograms and to standardize this manual modality by comparing the analysis of the images with ImageJ. Twenty elastograms of the injured superficial digital flexor tendons (SDFTs) of horses were analyzed by two different operators after an acute injury was diagnosed with ultrasonography. Statistical analysis demonstrated excellent intraobserver repeatability (intraclass correlation coefficient, ICC = 0.949) and good interobserver reproducibility (ICC = 0.855) for manual measurements performed with tools available on the ultrasound unit. A good agreement between manual measurements and measurements performed with ImageJ (ICC = 0.849) was then demonstrated. Despite its subjectivity, the manual modality proved to be a valid method for analyzing images obtained with strain elastography.

Short-term effects of 448 kilohertz radiofrequency stimulation on supraspinatus tendon elasticity measured by quantitative ultrasound elastography in professional badminton players: a double-blinded randomized clinical trial

OBJECTIVE

To study changes in supraspinatus tendon elasticity after a 448 kHz capacitive resistive monopolar radiofrequency (CRMR) intervention in professional badminton players.

DESIGN

Double-blinded randomized clinical trial.

SETTING

All participants were recruited in a private care practice. Participants were randomized to receive either a CRMR treatment (n = 19) or placebo (n = 19).

SUBJECTS

Professional badminton players (n = 38).

INTERVENTION

A total of nine intervention (three per week) with CRMR at 448 kHz were carried out in the experimental group. The same intervention without an active CRMR current was carried out in the control group.

MAIN MEASURES

Mean values of three different regions of the supraspinatus tendon were reported at baseline (T1), immediately after the intervention (T2) and one week after the end of the whole intervention program (T3) using quantitative ultrasound strain elastography (SEL).

RESULTS

There were statistically significant differences in the supraspinatus tendon elasticity immediately after the intervention (p= <.001) and one week after the end of the whole intervention program (p=.001).

CONCLUSION

CRMR at 448 kHz produces significant changes in supraspinatus tendon elasticity after an intervention program of three weeks and those changes last for a week when compared to control group. Clinical trial registration: NCT04273633 (ClinicalTrials.gov).

Effects of Ultrasound-Guided Peritendinous and Intrabursal Corticosteroid Injections on Shoulder Tendon Elasticity: A Post Hoc Analysis of a Randomized Controlled Trial

OBJECTIVES

The study aimed to investigate whether the shoulder tendons changed their elasticity after ultrasound-guided peritendinous or intrabursal corticosteroid injections.

DESIGN

Post hoc secondary analysis of a double-blinded, randomized controlled study with 3 months of follow-up.

SETTING

Outpatient rehabilitation clinic.

PARTICIPANTS

Patients with subacromial impingement syndrome (N=60).

INTERVENTIONS

Patients with unilateral shoulder pain were randomly assigned to receive standard ultrasound-guided subacromial or dual-target corticosteroid injections. The supraspinatus tendons were exposed to 40 mg triamcinolone acetonide in the formal group, whereas the long head of the biceps brachii tendons (LHBT) and supraspinatus tendons were individually infiltrated by 20 mg triamcinolone acetonide in the latter group. Patients' bilateral shoulders were divided into group 1 (n=30, receiving standard subacromial injections), group 2 (n=30, receiving dual-target injections), and group 3 (n=60, without injections).

MAIN OUTCOME MEASURES

Strain ratio of LHBT and supraspinatus tendons using ultrasound elastography.

RESULTS

The repeated-measures analysis of variance revealed no intragroup difference of the strain ratio of the LHBT (P=.412 for group 1, P=.936 for group 2, P=.131 for group 3) and supraspinatus tendon (P=.309 for group 1, P=.067 for group 2, P=.860 for group 3) across the 3 time points. Treating group 3 as the reference, the linear mixed model revealed no significant changes in tendon elasticity after either the standard subacromial injection (P=.205 for the LHBT and P=.529 for the supraspinatus tendon) or the dual-target injection (P=.961 for the LHBT and P=.831 for the supraspinatus tendon).

CONCLUSIONS

Elasticity of the LHBT and supraspinatus tendons is unlikely to change after a single dose of peritendinous or intrabursal corticosteroid injections. Future studies with a shorter follow-up interval are needed to validate whether corticosteroid injections can cause transient changes of the tendon's elasticity.

Effect of Stifle Flexion Angle on the Repeatability of Real-Time Elastosonography of the Patellar Ligament in Medium- to Large-Breed Dogs

OBJECTIVE

 The aims of this study were to describe the elastosonographic findings of the patellar ligament in healthy dogs >15 kg in different positions and determine the most appropriate stifle angle to perform elastosonography of the patellar ligament.

STUDY DESIGN

 Eighteen clinically healthy dogs, weighing >15 kg, were prospectively recruited. B-mode ultrasound and real-time elastosonography of both patellar ligaments were performed on days 0 and 14. Elastosonography examinations were performed with the stifle in four positions: standing position, lateral recumbency with the stifle positioned at 135 degrees extension and in full passive flexion and extension.

RESULTS

 The percentage hardness of the patellar ligament was significantly lower when the elastosonographic examination was performed with the dog standing, compared with the other positions (p < 0.005). The variability in the elastosonography readings for each stifle position was lowest when the dog was standing (89.32%).

CONCLUSION

 Elastosonography is a feasible technique for evaluating the elasticity of the normal canine patellar ligament in dogs >15 kg and would be a useful technique for investigating the mechanical changes within the patellar ligament following stifle surgery. Elastosonography of the patellar ligament should be performed with the dog standing to provide the most accurate elastosonograms with lowest variability between readings.

Advanced diagnostic imaging and intervention in tendon diseases

Degenerative tendon pathology represents one of the most frequent and disabling musculoskeletal disorders. Diagnostic radiology plays a fundamental role in the clinical evaluation of tendon pathologies. Moreover, several minimally invasive treatments can be performed under imaging guidance to treat tendon disorders, maximizing the efficacy and reducing procedural complications. In this review article we describe the most relevant diagnostic features of conventional and advanced US and MRI imaging in tendon disorders, along with the main options for image-guided intervention. (www.actabiomedica.it)

Shear Wave Elastography (SWE) for the Evaluation of Patients with Plantar Fasciitis

RATIONALE AND OBJECTIVES

The current imaging standard for diagnosing plantar fasciitis is B-Mode ultrasound (B-US). The aim of this study was to determine the diagnostic potential of Shear Wave Elastography (SWE) and the correlation of clinical scores to elastographic parameters.

MATERIALS AND METHODS

Diagnostic case-control study with n = 82 plantar fascia (PF). PF were divided into three subgroups: (1) symptomatic PF (n = 39); (2) control group of unilateral asymptomatic PF (n = 23); (3) bilateral asymptomatic PF (n = 20). Reference standard for positive findings in B-US was a PF thickness greater than 4 mm. For SWE tissue elasticity (Young's modulus kPa; shear wave speed m/s) was measured at Location 1: directly at the calcaneus; Location 2: +1 cm distal of the calcaneus and Location 3: central part of the calcaneus. Sensitivity, specificity, and diagnostic accuracy as well as correlation to American Orthopaedic Foot and Ankle Score (AOFAS) and Food Functional Index (FFI) were determined.

RESULTS

Symptomatic PF are thicker (4.2 mm, n = 39) than asymptomatic (3.0 mm, n = 43) (p < 0.001). Thickness of the PF (n = 82) correlated poorly to clinical scores (p = 0.001): FFI-pain (r = 0.349); FFI-function (r = 0.381); AOFAS (r = -0.387). Cut-off point for positive SWE finding was 51.5 kPa (4.14 m/s). Symptomatic PF (31.9 kPa, 3.26 m/s, n = 39) differ significantly from asymptomatic PF (93.3 kPa, 5.58 m/s, n = 43) with significant differences at L1 between all groups (p < 0.001). Correlation between Young's modulus (n = 82) and clinical scores was strong (p < 0.001): FFI-pain (r = -0.595); FFI-function (r = -0.567); AOFAS (r = 0.623,). B-US: sensitivity (61%), specificity (95%); SWE sensitivity (85%), specificity (83%). The combination of SWE and B-US increases the sensitivity (100%) with a diagnostic accuracy of 90%.

CONCLUSION

Based on our results, we could show that SWE can improve the diagnostic accuracy in patients with plantar fasciitis compared to B-US.

LEVEL OF EVIDENCE

II.

Ultrasonic strain elastography for detecting abnormalities in the supraspinatus tendon: an intra- and inter-rater reliability study

OBJECTIVES

The reliability of ultrasonic strain elastography (SEL) used to detect abnormalities in the supraspinatus tendon is unclear. Thus, the aim of this study was to investigate the reliability of SEL in the supraspinatus tendon.

DESIGN

An intra-rater and inter-rater reliability study.

SETTING

A single-centre study conducted at the University of Southern Denmark.

PARTICIPANTS

Twenty participants with shoulder pain and MRI-verified supraspinatus tendinosis and 20 asymptomatic participants (no MRI).

PRIMARY AND SECONDARY OUTCOME MEASURES

Raw values (RAW) and ratios (deltoid muscle (DELT) and gel pad (GEL) as reference tissues) were calculated and mean values of measurements from three regions of the supraspinatus tendon were reported. Colour scale ratings and number of yellow/red lesions from the three areas were also included.

RESULTS

Intra-rater reliability showed intraclass correlation coefficients (ICCs) for RAW, DELT and GEL: 0.97 (minimal detectable change (MDC): 0.28 (6.36% of the mean)), 0.89 (MDC: 2.91 (20.37%)) and 0.73 (MDC: 1.61 (58.82%)), respectively. The ICCs for inter-rater reliability were 0.89 (MDC: 0.47 (10.53%)), 0.78 (MDC: 3.69 (25.51%)) and 0.70 (MDC: 1.75 (62.63%)), respectively.For colour scale ratings, intra-rater reliability (linear weighted kappa) ranged from 0.76 to 0.79, with the inter-rater reliability from 0.71 to 0.81. For the number of lesions, intra-rater reliability ranged from 0.40 to 0.82 and inter-rater reliability from 0.24 to 0.67.

CONCLUSIONS

Intra-rater and inter-rater reliability were excellent for raw values and for ratios with deltoid muscle as the reference tissue, and good for ratios with gel pad as the reference tissue. The reliability of colour scale ratings was substantial-to-almost perfect, and for the number of lesions fair-to-almost perfect.Although high reliability was found, validity and responsiveness of these elastographic methods needs further investigation.

ETHICS APPROVAL

The study protocol was approved by the Ethics Committee for the Region of South Denmark (S-20160115) and reported to the Danish Data Protection Agency (2014-41-3266).

Relationships between Quadriceps Tendon Elasticity and Knee Flexion Angle in Young Healthy Adults

Background and objectives: Although tendon elasticity by elastography is useful for diagnosing tendon disorders and planning rehabilitation regimens of the tendon, there are few reports on the quadriceps tendon. Moreover, relationships between the quadriceps tendon elasticity and knee angle have not been investigated. The purpose of this study was to clarify the relationship between quadriceps tendon elasticity and knee flexion angle in young healthy adults using elastography, and to investigate the difference in elasticity by sex and leg dominance. Materials and Methods: A total of 40 knees in 20 young healthy adults were included in this study (age: 25.5 (23.3⁻27.5) years). At knee flexion of 30°, 60°, and 90°, quadriceps tendon elasticity was measured using ShearWave™ Elastography during the ultrasound examination. Results: There were significant differences in the elasticity between all angles (p < 0.001). Elasticity was increased more at 60° than at 30° and at 90° than at 60°. Elasticity in men was higher than that in women at 60° (p = 0.029). There were no differences (p = 0.798) in elasticity at each angle between the dominant and non-dominant legs. Conclusions: The quadriceps tendon elasticity increased according to the knee flexion angle in young healthy adults. Moreover, elasticity was affected by sex, but not by leg dominance. Clinically, in a rehabilitation regimen, attention should be paid to exercises that could increase stiffness accompanying flexion of the knee to avoid further tendon damage as risk management in the acute phase.

Interobserver variability and stiffness measurements of normal common extensor tendon in healthy volunteers using shear wave elastography

OBJECTIVES

The purposes of our study are to determine the quantitative elasticity values of normal common extensor tendon (CET) and to assess the interobserver variability of stiffness measurements using shear wave elastography (SWE).

MATERIALS AND METHODS

A total of 60 CETs of 30 (15 female, 15 male, mean age 30.2 years) healthy volunteers without any symptoms of lateral epicondylitis were examined by two radiologists. Age, sex, height, weight, body mass index (BMI), and dominant hand of all participants were noted. The first observer performed B-mode and SWE imaging, and the second observer performed only SWE imaging. Tendon thickness and stiffness values in kPa were measured.

RESULTS

The mean thickness of CETs was 3.57 ± 0.36 mm. The mean stiffness values of CETs for two observers were 45.28 ± 9.82 kPa and 45.80 ± 9.72 kPa respectively. Tendon thickness had a weak correlation with weight (r = 0.281, p = 0.03), and moderate correlation with stiffness values (r = 0.429, p < 0.001). The mean interobserver difference of CET stiffness measurements was -0.5% of the mean CET stiffness values. Range of measurement error, defined as 95% limits of agreement, was ±23.5%. There was no significant difference between absolute values of interobserver measurements (p = 0.741).

CONCLUSION

Shear wave elastography is a reproducible imaging technique for the evaluation of CET elasticity and the standard stiffness values of normal CET can be used as reference data to differentiate normal from pathological tissues.