Changes in morphological and elastic properties of patellar tendon in athletes with unilateral patellar tendinopathy and their relationships with pain and functional disability

A New Quantitative Tool for the Ultrasonographic Assessment of Tendons: A Reliability and Validity Study on the Patellar Tendon

Ultrasound is widely used for tendon assessment due to its safety, affordability, and portability, but its subjective nature poses challenges. This study aimed to develop a new quantitative analysis tool based on artificial intelligence to identify statistical patterns of healthy and pathological tendons. Furthermore, we aimed to validate this new tool by comparing it to experts' subjective assessments. A pilot database including healthy controls and patients with patellar tendinopathy was constructed, involving 14 participants with asymptomatic (n = 7) and symptomatic (n = 7) patellar tendons. Ultrasonographic images were assessed twice, utilizing both the new quantitative tool and the subjective scoring method applied by an expert across five regions of interest. The database contained 61 variables per image. The robustness of the clinical and quantitative assessments was tested via reliability analyses. Lastly, the prediction accuracy of the quantitative features was tested via cross-validated generalized linear mixed-effects logistic regressions. These analyses showed high reliability for quantitative variables related to "Bone" and "Quality", with ICCs above 0.75. The ICCs for "Edges" and "Thickness" varied but mostly exceeded 0.75. The results of this study show that certain quantitative variables are capable of predicting an expert's subjective assessment with generally high cross-validated AUC scores. A new quantitative tool for the ultrasonographic assessment of the tendon was designed. This system is shown to be a reliable and valid method for evaluating the patellar tendon structure.

Assessment of the stiffness of the upper trapezius muscle in a group of asymptomatic people with cervical spine rotation asymmetry

This study investigated the relationship between the stiffness of the upper trapezius muscle and the range of rotational movement of the cervical spine. A total of 60 right-handed asymptomatic students participated in the study. Participants (N = 22) characterised by asymmetry in rotational movements were selected for the experimental group. A difference of ≥10° between right and left rotation of the cervical spine was considered asymmetrical. The control group (N = 38) included participants whose rotation difference was < 10°. Belonging to the experimental or control group did not significantly differentiate trapezius muscle stiffness. The rotation side differentiated the stiffness of the right and left trapezius muscles only in the group of people with rotational movement asymmetry. There were high correlation coefficients between right cervical rotation and the stiffness of the muscle on the right side, and between rotation to the left and the stiffness of the muscle on the left side. There is a relationship between the stiffness of the right and left upper trapezius muscles and the range of right and left rotational motion of the cervical spine. Stiffness of the upper trapezius correlates more strongly with rotation to the side on which the muscle lies than to the opposite side. Increased stiffness of the upper trapezius muscle on the side of limited cervical spine rotation is likely to be determined by the muscle fibre stretching mechanism.

The Effects of Soft-Tissue Techniques and Exercise in the Treatment of Patellar Tendinopathy-Systematic Review and Meta-Analysis

BACKGROUND

Patellar tendinopathy is a degenerative clinical disorder that causes load-related pain in the lower pole of the patella or patellar tendon. It predominantly affects young male athletes engaged in sports involving repetitive tendon loading, particularly explosive jumping. The combination of manual techniques with therapeutic exercise is hypothesized to provide greater benefits than exercise alone.

OBJECTIVE

The aim of this study is to analyze the scientific evidence regarding the effects of soft-tissue techniques combined with therapeutic exercise versus therapeutic exercise alone on pain intensity and function in individuals with patellar tendinopathy.

METHODS

A systematic review with meta-analysis was conducted following the PRISMA guidelines. PubMed, Lilacs, IBECS, CENTRAL, WOS, SciELO, Academic Search, CINAHL, SportDiscus, PEDro, and Google Scholar databases were consulted. Randomized controlled trials and quasi-randomized trials focusing on the effects of soft-tissue techniques combined with therapeutic exercise (experimental group) versus therapeutic exercise alone (control group) on pain and function in individuals aged 16 years and older with patellar tendinopathy were selected. The Cochrane tool for risk-of-bias assessment and the PEDro scale for methodological quality were used.

RESULTS AND DISCUSSION

A total of six studies (n = 309; age range = 16-40 years), considered to have a low risk of bias and moderate-to-high methodological quality, were included. The results showed improvements in function in the experimental group (mean of 60% on the Visa-P scale) and pain in the experimental group (mean decrease of 2 points in the VAS scale). There were improvements in 50% of the studies when comparing variables between the experimental and control groups.

CONCLUSIONS

The combination of manual techniques, such as dry needling, percutaneous electrolysis, transverse friction massage, and stretching, along with a squat on a 25° inclined plane, appears to be effective in the treatment of patellar tendinopathy. Static stretching of the quadriceps before and after the squat five times per week, along with dry needling or percutaneous electrolysis sessions twice a week for 8 weeks, is recommended. However, future studies analyzing groups with passive techniques versus therapeutic exercise are needed to standardize the treatment and establish the optimal dose.

A Novel Tendon Injury Model, Induced by Collagenase Administration Combined with a Thermo-Responsive Hydrogel in Rats, Reproduces the Pathogenesis of Human Degenerative Tendinopathy

Patellar tendinopathy is a common clinical problem, but its underlying pathophysiology remains poorly understood, primarily due to the absence of a representative experimental model. The most widely used method to generate such a model is collagenase injection, although this method possesses limitations. We developed an optimized rat model of patellar tendinopathy via the ultrasound-guided injection of collagenase mixed with a thermo-responsive Pluronic hydrogel into the patellar tendon of sixty male Wistar rats. All analyses were carried out at 3, 7, 14, 30, and 60 days post-injury. We confirmed that our rat model reproduced the pathophysiology observed in human patients through analyses of ultrasonography, histology, immunofluorescence, and biomechanical parameters. Tendons that were injured by the injection of the collagenase-Pluronic mixture exhibited a significant increase in the cross-sectional area (p < 0.01), a high degree of tissue disorganization and hypercellularity, significantly strong neovascularization (p < 0.01), important changes in the levels of types I and III collagen expression, and the organization and presence of intra-tendinous calcifications. Decreases in the maximum rupture force and stiffness were also observed. These results demonstrate that our model replicates the key features observed in human patellar tendinopathy. Collagenase is evenly distributed, as the Pluronic hydrogel prevents its leakage and thus, damage to surrounding tissues. Therefore, this model is valuable for testing new treatments for patellar tendinopathy.

Diagnostic value of shear-wave elastography for patellar tendinopathy in female volleyball and basketball athletes: a cross sectional case control study

OBJECTIVES

We aim to investigate the accuracy of shear-wave elastography (SWE) in diagnosing patellar tendinopathy in female volleyball and basketball players. In addition, we compared different parts of the patellar tendon and investigated the effects of different knee angles on elastography measurements.

METHODS

This cross-sectional case-control study evaluated 63 female athletes from professional basketball and volleyball teams (NCT06199583). Patellar tendinopathy diagnoses were made using clinical and ultrasonographic criteria. SWE measurements were taken at 30-degree knee flexion and extension. Rectangular regions of interest boxes were placed in three different parts of the tendon (proximal, middle, distal). The global SWE value was calculated by taking the mean of measurements in the three parts. Receiver operating characteristic (ROC) curves were used to identify significant cutoff points for SWE, and 2 × 2 tables were generated to determine sensitivity and specificity.

RESULTS

Thirteen (20.6%) of the 63 athletes were diagnosed with patellar tendinopathy. The ROC curves have identified different cutoff scores for SWE measurements. The SWE score of 130.75 from the proximal part showed the highest sensitivity of 89% and specificity of 80% (p < 0.001) with a 4.45 likelihood ratio at the 30-degree knee flexion. The likelihood ratio is 1.5 at a 30-degree angle and 1.65 at a 0-degree angle when measuring the entire tendon, whereas other portions indicate a ratio ranging from 1.12 to 1.73.

CONCLUSIONS

Shear-wave elastography is a reliable evaluation method for diagnosing patellar tendinopathy. It has more accuracy when applied to the proximal part and at 30-degree knee flexion compared to measurements taken at knee extension and other parts of the tendon.

Relationship between Muscle-Tendon Stiffness and Drop Jump Performance in Young Male Basketball Players during Developmental Stages

BACKGROUND

The relationship between stiffness and drop jump performance in athletes in various stages of development has yet to be fully investigated. The first aim of this study was to investigate the association between the stiffness of the patellar and quadriceps tendon (PT, QT), gastrocnemius-Achilles tendon unit (GAT), and rectus femoris (RF) using drop jump (DJ) performance in young basketball players. The second aim was to investigate possible variations in the stiffness levels of those tissues in different developmental stages.

METHODS

The stiffness levels of the GAT, PT, QT, and RF were measured in both limbs in 73 male basketball players aged 12 to 18 years. The reactive strength index (RSI), contact time (CT) and jump height (JH) during 30 and 40 cm DJs were also measured.

RESULTS

Pearson correlation coefficients showed a significant association between DJ performance and PT, QT, GAT, and RF dynamic stiffness. Moreover, the youngest subjects were found to have lower stiffness values than the older ones.

CONCLUSIONS

Tissue stiffness can affect athletic performance by modifying the stretch-shortening cycle in young basketball players. Stiffness of muscles and tendons increases during the maturation process. Further investigations could shed light on the effect of training on the stiffness of muscles and tendons.

Relationships between tendon structure and clinical impairments in patients with patellar tendinopathy

The clinical relevance of altered tendon structure in patellar tendinopathy is contested since structural change persists after symptom resolution. The purpose of this study was to explore the relationships between tendon structure and clinical impairments in patellar tendinopathy. In this retrospective, secondary analysis of individuals with patellar tendinopathy (n = 41), tendon structure (thickness, cross-sectional area [CSA], shear modulus, and viscosity), symptom severity, lower extremity function (counter-movement jump [CMJ] height), and quadriceps muscle performance (knee extension force and central activation ratio [CAR]) were recorded for the symptomatic limb. Relationships among structure, symptom severity, lower extremity function, and quadriceps muscle performance were examined using sequential regression models. Adjusting for age, sex, body mass index, and pain levels, there were significant positive relationships for thickness (p < 0.001, β = 0.718) and viscosity (p = 0.006, β = 0.496) with CMJ height. There were significant negative relationships between CSA with both CMJ height (p = 0.001, β = -0.538) and CAR (p = 0.04, β = -0.517). This is the first study to demonstrate relationships between tendon structure and lower extremity function or quadriceps muscle performance in patients with patellar tendinopathy. Clinical significance: Since structural changes persist after symptom resolution, addressing these changes may assist in restoring lower extremity function and quadriceps muscle performance.

Shear-Wave Elastography of Patellar Ligament and Achilles Tendon in Semiprofessional Athletes: Comparing With Nonexercising Individuals

OBJECTIVES

To compare semiprofessional athletes and nonexercising individuals in terms of p-SWE properties of the patellar ligament and the Achilles tendon.

METHODS

This case-control study was conducted in University of Health Sciences, Haseki Education and Research Hospital. A total of 58 individuals, with 29 in each group (according to power analysis), were included in the study. All relevant findings, including demographic characteristics, body mass index (BMI), and exercise (km run per week, km/w) were recorded. The MyLab 9 (Esaote, Genova, Italy) device was used for SWE. The QElaXto-p-SWE software was utilized for P-SWE interpretation and analyses.

RESULTS

The mean age was 47.21 ± 12.16 years (range 22-70). Weight (P = .001) and BMI (P < .001) values were significantly higher in the nonathlete group than in the athlete group. There were no significant differences between groups in terms of age, gender, and height. Median SWE values of bilateral patellar ligaments (P < .001 and P < .001) and bilateral Achilles tendons (P < .001 and P < .001) were significantly higher in the athlete group than in the nonathlete group.

CONCLUSIONS

We revealed normal p-SWE characteristics for the patellar ligament and Achilles tendon, which are frequently injured in athletes. These scores are important in early detection and follow-up of injuries in athletes.

The Effects of Eccentric Contraction Execution Time on the Properties of the Patellar Tendon

The purpose of this study was to assess the effects of eccentric contraction execution time on the morphological and elastic properties of the patellar tendon (PT) in a six-week, single-leg decline squat (SLDS) exercise training program. In addition, the effects of a six-week detraining period on the same variables were evaluated. Fifty participants were randomized into the control group (CG; n = 15), experimental group 1 (EG6s; n = 17; eccentric contraction execution time = 6 s) and experimental group 2 (EG3s; n = 18; eccentric contraction execution time = 3 s). The thickness and elastographic index (EI) in different regions of interest (ROIs) in the PT were measured after 6 weeks of eccentric training using the single-leg decline squat exercise (three sessions per week, 80% of the eccentric one-repetition maximum) and after 6 weeks of detraining. There was an increase in the thickness of the PT in the different ROIs analyzed in both experimental groups at the end of the training period. Especially worth noting was the increase in the thickness of the PT at the proximal level in EG3s (p = 0.001), and the increase at the distal level in EG6s (p = 0.001). On the other hand, there was a reduction in EI in EG6S at the end of the intervention program (p = 0.021), and both experimental groups increased EI in the three regions of interest analyzed after the detraining period (p < 0.01). In conclusion, the execution time of the eccentric contraction in the SLDS exercise determines the anatomical level of the morphological adaptations in the PT. These morphological adaptations are lost after 6 weeks of detraining, producing an increase in tendon stiffness.

Ultrasound imaging of patellar tendon thickness in elite sprint track cyclists and elite soccer players: An intra-rater and inter-rater reliability study

The goal of our study was to investigate the relative and absolute intra-rater and inter-rater reliability of ultrasound assessment of patellar tendon (PT) thickness assessed over four locations, in track cyclists and soccer players. Fifteen male elite track cyclists and 15 male elite soccer players participated. Tendon thickness was measured over 4 locations placed at 5-10-15-20 mm inferior to the apex of the patella by two experienced examiners. Each examiner took two US images for the test measurements with a 10-min rest period. After a 30-min period, the subjects underwent a retest measurements that were also repeated 1-week after. A two-way analysis of variance revealed a significant group x location interaction on PT thickness for Examiner 1 (p = .001, η² = .81) and Examiner 2 (p = 0.001, η² = 0.78). Intra-rater reliability ranged from good to excellent (ICC_2,k ≥ 0.75), whereas inter-rater reliability was good (ICC_2,k ≥ 0.75) in both groups. Ultrasonographic assessment of PT was found to be a reliable method to assess tendon thickness. The middle location of the PT (corresponding to 15 and 20 mm) can be considered the most reliable spot to measure PT thickness. The PT thickness was larger among track cyclists than soccer players, with larger differences over the distal location (15 mm). Ultrasonographic assessment of PT was found to be a reliable method to assess tendon thickness. The middle location of the PT corresponding to 15 mm and 20 mm can be considered the most reliable area to measure PT thickness.

Quantifying the stiffness of lumbar erector spinae during different positions among participants with chronic low back pain

Objective

The purposes of this study were to (1) detect the intra- and inter-reliabilities of the lumbar erector spinae stiffness by MyotonPRO among participants with chronic lower back pain (CLBP); (2) compare the muscle stiffness between pain and non-pain sides during different positions; (3) explore the correlation between intensity of pain and muscle stiffness.

Design

Twenty participants with CLBP were recruited and the stiffness measurements were carried out by two experienced physiotherapists (operators Ⅰ and Ⅱ). Each participant was evaluated by the operatorⅠ in different postures (static prone and sitting). After a 5-day interval, the same participant was reassessed by the operatorⅠ in the static prone posture. For the inter-rater reliability test, each participant was quantified by both operators once, with 30 minutes between the measurements on the same day. The intensity of pain was evaluated using a 0–10 visual analog scale (VAS).

Results

The intra- and inter-rater reliabilities were excellent (ICC = 0.88–0.99). The MDC values ranged from 25.03 to 86.26 N/m. Examples of Bland-Altman plots showed good agreement. The erector spinae stiffness on the painful sides was higher with a marked increase in the sitting position (P < .05) when compared with the non-painful side. However, there was no significant difference in the prone position (P > .05). The intensity of pain among adults with CLBP was not associated with muscle stiffness of the lumbar erector spinae muscle.

Conclusions

Our findings indicated that the MyotonPRO is a feasible device in quantifying the stiffness of the lumbar erector spinae muscle in patients with CLBP. Meanwhile, the erector spinae stiffness on the painful sides was higher in the sitting when compared with the non-painful side.

Altered regional 3D shear wave velocity patterns in youth competitive alpine skiers suffering from patellar tendon complaints - A prospective case-control study

AbstractPatellar tendon (PT) complaints are frequent throughout the population, with increased occurrence in athletes and, particularly, in youth competitive alpine skiers. Timely detection and treatment might improve prospects of recovery. Diagnostic modalities in clinical use to date rely on pain symptoms, manual palpation, and potentially, magnetic resonance imaging (MRI); however, MRI-based imaging yields limited sensitivity. Quantitatively measuring the morphological and mechanical properties of PTs by means of B-mode ultrasound and shear wave elastography (SWE), instead, may allow improved diagnosis or even early detection. We performed B-mode scans and three-dimensional ultrasound shear wave velocity (SWV) mapping and MRI of the PT in 106 youth skiers. A prospective one-year survey on health problems combined with clinical assessments served to categorize symptomatic and asymptomatic youth skiers. Skiers suffering from distal or proximal tendon complaints showed lower SWV in the respective tendon region than asymptomatic skiers (p = 0.035 and p = 0.019, respectively). Youth skiers with distal tendon complaints additionally exhibited decreased SWV in the proximal region compared to asymptomatic counterparts (p = 0.020). Cross-validated analysis of retrospective prediction indicated sensitivity and specificity in detecting tendon complaints in the range of 0.606-0.621 and 0.536-0.650, respectively. MRI detected distal tendon complaints with a sensitivity of 0.410 (12/29) but failed to detect any proximal cases. This study agrees with the most recent literature in that SWE holds promise as a valuable adjunct modality for the diagnosis of PT complaints or even the detection of subclinical prestages. However, to evaluate its prospective predictive value, long-term studies are warranted.

Reliability of shear wave elastography for the assessment of gastrocnemius fascia elasticity in healthy individual

The mechanical properties of the deep fascia, particularly their stiffness, strongly affect the development of muscle pathologies (such as compartment syndrome) and the action of the muscles. However, the mechanical characteristics of the deep muscular fascia are still not clearly understood. The present study focuses on examining the reliability of ultrasonic shear wave elastography (USWE) devices in quantifying the shear modulus of the gastrocnemius fascia in healthy individuals, particularly their ability to measure the shear modulus of the deep fascia of the gastrocnemius during ankle dorsiflexion. Twenty-one healthy males (age: 21.48 ± 1.17 years) participated in the study. Using USWE, the shear moduli of the medial gastrocnemius fascia (MGF) and lateral gastrocnemius fascia (LGF) were quantified at different angles during passive lengthening. The two operators took turns measuring each subject's MGF and LGF over a 1-h period, and operator B took an additional measurement 2 h later. For the intra-operator test, the same subjects were measured again at the same time of day 5 days later. Both the intrarater [intraclass correlation coefficient (ICC) = 0.846-0.965)] and interrater (ICC = 0.877-0.961) reliability values for measuring the shear moduli of the MGF and LGF were rated as excellent; the standard error of the mean (SEM) was 3.49 kPa, and the minimal detectable change (MDC) was 9.68 kPa. Regardless of the ankle angle, the shear moduli of the LGF were significantly greater than that of the MGF (p < 0.001). Significant increases in the shear moduli of both the MGF and the LGF were observed in the neutral position compared to the relaxed position. These results indicate that USWE is a reliable technique to assess the shear modulus of the gastrocnemius fascia and detect its dynamic changes during ankle dorsiflexion. USWE can be used for biomechanical studies and intervention experiments concerning the deep fascia.

Feasibility Trial to Evaluate Tendon Stiffness Obtained from Shear Wave Elastography Imaging as a Biomarker of Aromatase Inhibitor-Induced Arthralgias

Aromatase inhibitor-induced arthralgia (AIA) comprises significant, activity-limiting musculoskeletal symptoms, including joint pain, myalgia, and joint stiffness. We conducted a prospective feasibility study in postmenopausal women diagnosed with early-stage (0–3) hormone receptor positive (HR+) breast cancer who were candidates for treatment with adjuvant AI therapy (n = 16). Tendons of the hands and wrists and the median nerve were imaged using gray-scale and power Doppler ultrasound (US) and US SWE. Arthralgia symptoms were evaluated using the Breast Cancer Prevention Trial (BCPT) Symptom Checklist musculoskeletal subscale (MS) and the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) pain and stiffness subscales. At baseline, there were significant differences in the SW velocities of tendons between dominant and nondominant hands. Increased velocity in 2 of 6 tendons and the median nerve was associated with greater pain at baseline, whereas slower velocity of the extensor digitorum tendon (suggesting decreased stiffness) was associated with a higher WOMAC stiffness score. Increased SW velocity (suggestive of increased stiffness) at baseline in the abductor pollicis longus tendon was associated with a worsening of all three pain and stiffness measures by 6 months. Future studies should evaluate SWE scores related to AIA outcomes in a larger sample size.

Modulation in the Stiffness of Specific Muscles of the Quadriceps in Patients With Knee Osteoarthritis and Their Relationship With Functional Ability

Deficits in the flexibility of the quadriceps are one of the risk factors for developing knee joint disorders. No studies have investigated the changes in the stiffness of the quadriceps muscle among patients with knee osteoarthritis (OA). Therefore, the purpose of this study was to investigate changes in the stiffness of specific-muscle of the quadriceps in patients with knee OA and their relationship with functional ability. Twenty-five patients with knee OA and 25 healthy, asymptomatic subjects were recruited in this study. The stiffness of the vastus lateralis (VL), vastus medialis (VM) and rectus femoris (RF) in all participants was evaluated using MyotonPRO at 60° and 90° flexion of the knee joint. The results of this study showed a greater VL stiffness in patients with knee OA than in healthy subjects at both 60° and 90° of knee flexion (p &lt; 0.05). Significant differences in VL, VM and RF stiffness were obtained at different knee joint angles in individuals with and without knee OA (p &lt; 0.05). In addition, there was a positive correlation between VL stiffness and the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) scores in patients with Knee OA (60° of knee flexion: r = 0.508, p = 0.010; 90° of knee flexion: r = 0.456, p = 0.022). These results indicate that there is an increase in VL stiffness in patients with knee OA compared with healthy, asymptomatic subjects, and the quadriceps stiffness was increased with knee flexion in both healthy subjects and patients with knee OA. VL stiffness is associated with WOMAC scores in patients with knee OA.

Quantifying Region-Specific Elastic Properties of Distal Femoral Articular Cartilage: A Shear-Wave Elastography Study

Knee osteoarthritis is a disease with the degeneration of articular cartilage as its main feature. Cartilage thickness cannot become a single index to evaluate cartilage degeneration, so it is essential to also evaluate the stiffness. The purposes were as follows: (1) to examine test-retest reliabilities of the elastic modulus measurement in distal femoral articular cartilage (FAC) and compare the changes in specific-regional of distal FAC, (2) to explore the difference in distal FAC stiffness and thickness between the dominant and nondominant sides, and (3) to examine the correlation between the elastic properties of cartilage and the thickness of cartilage. Twenty healthy participants were recruited. The stiffness of distal FAC at the lateral femoral condyle (LFC), medial femoral condyle (MFC), and intercondylar notch (IN) was quantified using shear-wave elastography (SWE). Intra- and interrater reliabilities were excellent for measuring the stiffness of distal FAC (ICC: 0.83-0.98). About a 50% increase in the stiffness of LFC (40.78 kPa) was found when compared with IN (21.82 kPa) and MFC (18.34 kPa). No significant difference was found between the dominant and nondominant sides in distal FAC stiffness and thickness. There was no correlation between the stiffness and thickness of the distal FAC. In conclusion, SWE can quantify the stiffness of the distal FAC.

Resistance training induces similar adaptations of upper and lower-body muscles between sexes

The purpose of the study was to compare sex adaptations in hypertrophy, strength and contractile properties of upper and lower-body muscles induced by resistance training (RT). Eighteen RT untrained male (MG) and female (FG) students (aged 24.1 ± 1.7 years, height: 1.75 ± 0.08 m, weight: 70.4 ± 12.3 kg) undervent 7 weeks of biceps curl and squat training (2 days/week, 60–70% repetition maximum, 3–4 sets, 120 s rest intervals, reps until muscular failure). At baseline and final measurement, thickness and cross-section area, one-repetition maximum and tensiomyography parameters (contraction time − Tc and radial displacement − Dm) of elbow flexors (biceps brachii) and knee extensors (4 quadriceps muscles) were evaluated. Although MG tends to display greater absolute strength gains for upper- (p = 0.055) and lower-body (p = 0.098), for relative changes ANCOVA revealed no sex-specific differences for either of the tested variables. Significant hypertrophy was observed for all tested muscles, except for vastus intermedius in FG (p = 0.076). The Dm significantly decreased for biceps brachii (MG by 12%, p < 0.01 and FG by 13.1%, p < 0.01) and rectus femoris (MG by19.2%, p < 0.01 and FG by 12.3%, p < 0.05), while Tc values remain unchanged. These results indicate that initial morphological, functional and contractile alterations following RT are similar for males and females, and that there are no specific sex adaptations either for the upper- or lower-body muscles. The study was registered with ClinicalTrials.gov (NCT04845295).

Morphology of the Patellar Tendon and the Contractility Response of the Quadriceps: Symmetry and Gender Analysis

The purpose of the study was to describe the differences between the dominant and non-dominant leg regarding contractility response and quadriceps strength and the morphology and stiffness of the patellar tendon (PT) in a group of physically active men and women. Fifty physically active subjects (36 men and 14 women) were evaluated for morphology and stiffness of the PT, contractility response of the rectus femoris of the quadriceps, isometric strength of the quadriceps and hamstrings, and isokinetic strength (concentric and eccentric) at 60°/s of the knee extensors. The measurements were made on the subject's dominant and non-dominant leg. The men showed a greater thickness of the PT in both legs compared to the women. Regarding the contractility response, the women recorded a 10.1 ± 16.2% (p = 0.038) greater contraction time (ct) in the dominant versus the non-dominant leg and the men recorded 11.9% (p = 0.040) higher values in the dominant leg compared to the women. In all the absolute strength measurements the men recorded higher values (p < 0.05) than the women, however, when the values were normalised with respect to the muscle mass of the leg these differences disappeared. The dominant leg showed values of isometric strength and eccentric strength at 60°/s (p < 0.05) greater than the non-dominant leg. The reference values provided in this study of the knee extensors and PT may be useful for detecting possible muscular or tendinous anomalies.

Anterior knee pain after total knee arthroplasty: A multifactorial analysis

PURPOSE

Dissatisfaction and an impaired quality of life after total knee arthroplasty (TKA) is often associated with postsurgical anterior knee pain (AKP). The underlying pathological mechanisms are not yet fully understood. Therefore, a multifactorial approach encompassing clinical and radiological parameters seemed reasonable and promising to investigate postsurgical AKP.

METHODS

In this cross-sectional study, 25 patients without and 25 patients with postsurgical AKP after unilateral TKA were randomly recruited from a larger cohort of patients. Multiple clinical and radiological parameters-including real-time shear wave elastography (SWE) to measure the patellar and quadriceps tendon elasticity-were acquired and subsequently associated with AKP. For statistical analysis, SPSS (IBM, version 25) was used.

RESULTS

In total 50 participants (58.0% men, mean age 63.42 years, mean body mass index 29.75 kg/m²), having different prosthetic designs implanted, were included. Independently of key covariates, the strength of the quadriceps muscle (p = 0.021), a thinner inlay (p = 0.041), and a lower position of the patella (p = 0.041) were associated with AKP. Although no correlation with AKP was found (p = 0.346, resp. p = 0.154), we observed significantly decreased Young's modulus of the patellar and quadriceps tendons for the involved knee compared to the uninvolved knee (p < 0.001).

CONCLUSION

In conclusion, quadriceps muscle strength, inlay thickness, and the patella position might be of particular relevance in avoiding postsurgical AKP. Future studies with larger sample sizes are needed to clarify the impact of quadriceps muscle strength and the postoperative patella position as well as the role of SWE as a personalized modifiable prediction marker.

Sonographic and radiographic evaluation of the extensor tendons in early postoperative period after total knee arthroplasty

OBJECTIVE

To prospectively assess the early changes in the quadriceps and patellar tendons before and after total knee arthroplasty using ultrasound, shear wave elastography, and X-rays.

MATERIALS AND METHODS

Radiographs, ultrasound, and shear wave elastography were performed on 23 patients (16 women; aged 51-85, mean 66 ± 9 years) before and after surgery at 6 weeks and on 11 patients at 3 months. Patellar position and patellar tendon lengths were evaluated by radiography; joint effusion or synovitis, quadriceps and patellar tendon lengths, and thicknesses, echogenicity, vascularity, and stiffness were assessed with ultrasound and shear wave elastography.

RESULTS

In the early postoperative period, 87% of the patients had joint effusion, and 43% had signs of synovitis. There was a significant thickening of the quadriceps tendon in 51.5% (p < .0001) and of the patellar tendon in 93.8% (p < .0001) of patients with a significant shortening of the patellar tendon in 7.8% (p < .0001). A hypoechoic defect on the medial aspect of the quadriceps tendon was found in 87% of the patients. There was a significant increase in Young's modulus in the quadriceps tendon (p = .0006) but not in the patellar tendon.

CONCLUSION

The following should not be considered to be pathological findings at early postoperative imaging: joint effusion, synovitis, increasing of stiffness and thickening of quadriceps tendons by more than 50%, thickening of patellar tendon by more than 90%, focal defect through the medial aspect of the quadriceps tendon, and shortening of the patellar tendon by 8%.

Quantification of the Masseter Muscle Hardness of Stroke Patients Using the MyotonPRO Apparatus: Intra- and Inter-Rater Reliability and Its Correlation with Masticatory Performance

BACKGROUND Chewing dysfunction is one of the most common serious complications after a stroke. It may be influenced by the hardness of the masseter muscle and masticatory performance; however, the association between these 2 factors is not explicit. Thus, it is meaningful to explore the functional status of the masseter muscle among stroke patients. The main objectives of this study were to examine the intra- and inter-rater reliability of the MyotonPRO apparatus in measuring masseter muscle hardness in stroke patients and to investigate the correlation between the bilateral masseter muscle hardness and masticatory performance in these patients. MATERIAL AND METHODS A total of 20 stroke patients participated in our study. The hardness of the masseter muscle was measured by 2 physiotherapists using the MyotonPRO apparatus. Overall, each patient masticated 2 pieces of red-blue bicolor chewing gum for 20 chewing cycles each. The chewing pieces were analyzed using ViewGum software for masticatory performance. RESULTS The intra- and inter-rater reliability of the MyotonPRO apparatus for measuring bilateral masseter hardness of stroke patients was excellent. The correlation analysis showed that the hardness index of the masseter muscle on the affected side was moderately correlated with the masticatory performance of the same side. CONCLUSIONS The MyotonPRO device can be used for measuring the masseter muscle hardness of stroke patients, with excellent reliability. This study established the construct validity between the stiffness of the masseter muscle and masticatory performance.

Quadriceps and Patellar Tendon Thickness and Stiffness in Elite Track Cyclists: An Ultrasonographic and Myotonometric Evaluation

Track cyclists are required to perform short- and long-term efforts during sprint and endurance race events, respectively. The 200 m flying sprint races require maximal power output and anaerobic capacity, while the 4,000 m pursuit cyclists demand a high level of aerobic capacity. Our goal was to investigate spatial changes in morphological and mechanical properties displayed using 3D topographical maps of the quadriceps muscle and tendons after 200 m flying start and 4,000 m individual pursuit race in elite track cyclists. We hypothesized a non-uniform distribution of the changes in the quadriceps muscle stiffness (QM_stiff), and acute alterations in quadriceps tendon (QT_thick) and patellar tendon (PT_thick) thickness. Fifteen men elite sprint and 15 elite men endurance track cyclists participated. Sprint track cyclists participated in a 200 m flying start, while endurance track cyclists in 4,000 m individual pursuit. Outcomes including QT_thick (5–10–15 mm proximal to the upper edge of the patella), PT_thick (5–10–15–20 mm inferior to the apex of the patella)—using ultrasonography evaluation, QM_stiff, and quadriceps tendon stiffness (QT_stiff) were measured according to anatomically defined locations (point 1–8) and patellar tendon stiffness (PT_stiff)—using myotonometry, measured in a midway point between the patella distal and the tuberosity of tibial. All parameters were assessed before and after (up to 5 min) the 200 m or 4,000 m events. Sprint track cyclists had significantly larger QT_thick and PT_thick than endurance track cyclists. Post-hoc analysis showed significant spatial differences in QM_stiff between rectus femoris, vastus lateralis, and vastus medialis in sprint track cyclists. At before race, sprint track cyclists presented significantly higher mean QT_thick and PT_thick, and higher QM_stiff and the QT_stiff, as compared with the endurance track cyclists. The observed changes in PT_Thick and QT_Thick were mostly related to adaptation-based vascularity and hypertrophy processes. The current study suggests that assessments using both ultrasonography and myotonometry provides crucial information about tendons and muscles properties and their acute adaptation to exercise. Higher stiffness in sprint compared with endurance track cyclists at baseline seems to highlight alterations in mechanical properties of the tendon and muscle that could lead to overuse injuries.

Shear Wave Elastographic Study of the Myotendinous Junction of the Medial Gastrocnemius: Normal Patterns and Dynamic Evaluation

OBJECTIVES

The myotendinous junction (MTJ) represents a specialized anatomic region through which the contractile strength is transmitted from the muscle to the tendon. The integrity of this region is essential to permit force transmission and to optimize energy expenditure during walking, running, and globally for human movement. We evaluated the MTJ with shear wave elastography to assess its elasticity variation during a functional test.

METHODS

Forty professional soccer players were enrolled in the study. Shear wave elastography was performed at the level of the medial gastrocnemius MTJ both in a resting position and during a standing calf rise position to assess functional contraction.

RESULTS

All 40 participants were male, aged between 18 and 38 years (mean age, 25 years). The results of the elastographic study showed mean stiffness values ± SD of 4.19 ± 0.86 m/s for the right medial gastrocnemius and 4.20 ± 0.87 m/s for the left medial gastrocnemius with the muscle relaxed. During contraction, the stiffness values were 8.33 ± 0.5 m/s for the right medial gastrocnemius and 8.30 ± 0.48 m/s for the left medial gastrocnemius.

CONCLUSIONS

Our study showed an increase of stiffness at the level of the MTJ during muscle contraction. This result is in line with the physiologic stiffening of the MTJ to resist the high level of force applied during muscle contraction. Shear wave elastography could be a useful method to assess the characteristics of the MTJ under both physiologic and pathologic conditions.

Objective Assessment of Regional Stiffness in Achilles Tendon in Different Ankle Joint Positions Using the MyotonPRO

BACKGROUND Achilles tendinopathy commonly occurs in specific regions of the tendon, and Achilles tendon stiffness can be related to local pathological changes in the tendon. The MyotonPRO is a new handheld device that conveniently assesses stiffness of muscles and tendons. This study aimed to 1) evaluate the intra- and inter-rater reliability of stiffness measurements of the Achilles tendon at different ankle positions, 2) investigate the modulation of stiffness at different ankle joint angles, and 3) examine the differences between 2 regions of Achilles tendon stiffness. MATERIAL AND METHODS Thirty healthy young adults (15 men and 15 women) participated in this study. The regional Achilles tendon stiffness at 0 cm (AT-0) and 6 cm (AT-6) above the tendon insertion were evaluated by the MyotonPRO in the neutral position and 10° dorsiflexion of the ankle joint. Measurements of stiffness were taken by 2 raters on the first day and 5 days later. The stiffness data were compared by repeated measures analysis of variance (ANOVA). RESULTS The intra- and inter-rater reliability of stiffness measurements at AT-0 and AT-6 for each ankle position were good (all intraclass correlation coefficients >0.84). A significant modulation of Achilles tendon stiffness was obtained at different ankle joint angles (P<0.05). Stiffness at AT-0 was higher than at AT-6 (P<0.05) in both positions. CONCLUSIONS These results suggest the MyotonPRO reliably assessed Achilles tendon stiffness and monitors its modulation, and tendon stiffness increased with ankle dorsiflexion. Stiffness was also nonuniform along the length of the tendon.

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.

Evaluation of patellar tendon with shear wave elastography after anterior cruciate ligament reconstruction using hamstring tendons

Objectives

This study aims to evaluate the characteristics of patellar tendons (PTs) of patients who underwent anterior cruciate ligament reconstruction (ACLR) with hamstring tendon autograft using shear wave elastography (SWE).

Patients and methods

This prospective study was conducted between August 2017 and February 2018. We performed brightness mode (B-mode) ultrasound and SWE on 21 patients (20 males, 1 female; mean age 32 years; range, 19 to 42 years) who underwent ACLR with a single-bundle transtibial technique using quadruple hamstring autografts and 14 healthy controls (13 males, 1 female; mean age 35 years; range, 25 to 47 years). Length and thickness of the PT were evaluated with B-mode ultrasound, while elasticity values were evaluated with SWE in the patient and control groups.

Results

The mean SWE value of the patient group on the operated side was 25.30 (min-max=16.60-46.20) and on the non-operated side 23.20 (min-max=12.40-44). There were no statistically significant differences regarding PT elasticity, thickness, or length between the groups (p>0.05).

Conclusion

There were no differences regarding elasticity, length, or thickness between the operated and healthy knees detected with SWE. Upcoming research should focus on tendon biopsy and biochemical analyses for the identification of possible intrastructural changes of the tendon due to collagen synthesis after ACLR with hamstring autograft.

The association between patellar tendon stiffness measured with shear-wave elastography and patellar tendinopathy-a case-control study

OBJECTIVES

(1) To determine the association between patellar tendon stiffness and the presence of patellar tendinopathy (PT). (2) To evaluate the reliability of shear-wave elastography (SWE).

METHODS

Participants were consecutively enrolled between January 2017 and June 2019. PT was diagnosed clinically and confirmed by either grayscale US or power Doppler US, or both. Controls had no history of anterior knee pain and no clinical signs of PT. Patellar tendon stiffness (kilopascal, kPa) was assessed using SWE. Logistic regression was used to estimate adjusted odds ratios (ORs) and 95% confidence intervals (CIs). Reliability analyses included coefficients-of-variation (CV), coefficients-of-repeatability (CR), intraclass correlation coefficient (ICC) for intraobserver and interobserver reliability, and Bland-Altman analysis.

RESULTS

In total, 76 participants with PT (58 men, mean age 24.4 ± 3.8 years) and 35 asymptomatic controls (16 men, mean age 21.5 ± 3.8 years) were included. Univariate analyses (OR 1.094, 95% CI 1.061-1.128, p < .001) and adjusted multivariate analyses (OR 1.294, 95% CI 1.044-1.605, p = .018) showed that athletes with PT had significantly increased patellar tendon stiffness. ICC for intraobserver reliability was 0.95 (95% CI 0.92-0.97), CR (CV) 12 kPa (10%) and 0.79 (95% CI 0.65-0.88), CR (CV) 18 kPa (21%) for interobserver reliability. Mean differences from Bland-Altman analysis were 5.6 kPa (95% CI 3.1-8.1, p < .001) for intraobserver reliability and 4.6 kPa (95% CI 1.9-7.2, p < .001) for interobserver reliability.

CONCLUSIONS

PT is associated with significantly higher patellar tendon stiffness. SWE measurements demonstrate excellent intraobserver reliability and good interobserver reliability. Therefore, SWE is a promising tool to implement in longitudinal studies and future studies should evaluate its prognostic value and utility as a monitoring tool in athletes with PT.

KEY POINTS

• Patellar tendon stiffness measured with shear-wave elastography (SWE) is higher in athletes with patellar tendinopathy than in healthy controls, also after adjusting for potential confounders. • Excellent intraobserver reliability and good interobserver reliability were found for the quantitative assessment of patellar tendon stiffness using SWE.

One Session of Extracorporeal Shockwave Therapy-Induced Modulation on Tendon Shear Modulus is Associated with Reduction in Pain

The aim of the study was to examine the immediate effect of 1 session of extracorporeal shockwave therapy (ESWT) on patellar tendon stiffness and to explore the relationship between the change in tendon stiffness and the pain intensity. Thirty-four male athletes aged 22.2 ± 3.8 with patellar tendinopathy were recruited. The participants were randomized into ESWT and sham groups. The ESWT group received 1500 impulses of ESWT at 4 Hz with maximal tolerable pain intensity and the sham group received intensities below 0.08 mJ/mm². Supersonic Shearwave Imaging (SSI) was used to measure tendon shear modulus (an index of tissue stiffness), and a visual analogue scale was used to quantify the pain intensity during compression with 10 lb (4.535 kg) pressure directed on the most tender part and then during a single-leg declined-squat test. A significant reduction in tendon shear modulus (from 57.4 ± 25.5 kPa to 40.6 ± 17.6kPa, p = 0.001) was detected in the ESWT receiving ESWT with an intensity from 0.13-0.33 mJ/mm² but not the sham group (from 47.7 ± 17.1 kPa to 41.0 ± 12.7 kPa; p = 0.06). In the ESWT group, the change in tendon shear modulus was associated with the change in the intensity of pain during single-legged declined-squat test (ρ = 0.55; p = 0.023) but not pressure pain (p > 0.05). These findings suggest that one session of ESWT induces reduction of tendon stiffness in volleyball and basketball players with patellar tendinopathy. The reduction in tendon stiffness is associated with reduction in pain during single-legged declined-squat test.

Evaluation of Periarticular Soft Tissues in Patients With Juvenile Idiopathic Arthritis by Superb Microvascular Imaging and Shear Wave Elastography

OBJECTIVES

This study aims to compare the vascularity and elasticity of periarticular soft tissues by superb microvascular imaging (SMI) and power Doppler (PD) ultrasound along with shear wave elastography (SWE) between children with juvenile idiopathic arthritis (JIA) and healthy children.

PATIENTS AND METHODS

This prospective single center study, conducted between March 2018 and May 2018, included 22 children with JIA (14 males, 8 females; mean age 11.27±5 years; range, 5 to 17 years) and 24 healthy pediatric volunteers (12 males, 12 females; mean age 13±5.5 years; range, 7 to 17 years). Quadriceps tendon (QT), patellar tendon (PT), infraarticular and supraarticular soft tissue elasticities were calculated via SWE. Supraarticular and infraarticular soft tissue vascularity index (VI) were evaluated via SMI and PD.

RESULTS

No significant difference was found among the mean ages of the participants in study and control groups. Mean VI of both supraarticular (8.15%) and infraarticular soft tissues (7.9%) by SMI were significantly higher in study group compared to control group (2.88% vs. 2.57%, respectively). Mean VI of both supraarticular (9.1%) and infraarticular soft tissues (8.12%) by PD were significantly higher in study group compared to control group (3.4% vs. 3.1%, respectively). Highly significant good positive correlation was found between VI values obtained with PD and SMI (r=0.9, p=0.001). There was a significant moderate positive correlation between the mean elasticity of the QT with VI of the supraarticular soft tissues by SMI (r=0.4, p=0.003). There was a significant moderate positive correlation of VI of infraarticular soft tissues by SMI with mean elasiticity of PT (r=0.42, p=0.002).

CONCLUSION

Vascularity index by SMI and PD could differentiate patients with JIA from healthy subjects. The SWE examination of tendons and soft tissues did not show any significant difference among patients with JIA and healthy subjects.

Non-uniform Stiffness within Gastrocnemius-Achilles tendon Complex Observed after Static Stretching

Higher stiffness of the Achilles tendon (AT) and gastrocnemius have been found to be risk factors associated with Achilles tendinitis. Static stretching (SS) is one intervention that has been investigated to improve the flexibility and therefore reduce injury risk. Previous studies have investigated the acute effect of SS on one region for AT and gastrocnemius morphology and stiffness; however, there is a lack of knowledge about the effect of SS on other regions of the AT and gastrocnemius (e.g., proximal vs. distal, within gastrocnemius). The aims of the present study were: (1) to investigate the acute effects of SS on the shear modulus of the medial gastrocnemius muscles (MG) and lateral gastrocnemius muscles (LG) and AT for different regions; (2) to examine the differences in range of motion (ROM) before and after SS; and (3) to investigate the change of thickness of AT and fascicle length of MG and LG before and after SS. The stiffness of AT and the gastrocnemius, fascicle length of the muscles, thickness of the AT, and maximal ankle joint dorsiflexion angle were measured in thirty healthy subjects (15 males, 15 females) before(pre) and immediately after (post) 5-minute SS. Stretching effects are not homogeneous among different regions. After SS administration, the proximal, middle, and distal regions of MG stiffness decreased by 34.12%, 22.45%, and 25.27%, respectively (p = 0.000), and LG stiffness decreased by 37.71%, 30.47%, and 22.13%, respectively (p = 0.000), whereas AT stiffness increased by 25.73%, 17.01%, and 19.53%, respectively (p= 0.000). ROM of ankle joint increased by 8.02% (p=0.00). Nevertheless, there were no changes in the thickness of AT and fascicle length of the gastrocnemius. These results suggest that non-uniform behaviour is consistently present within the gastrocnemius and AT, and the gastrocnemius heterogeneity is reduced after SS. The stretching maneuver could be effective to increase the flexibility.

Distinguishing Quadriceps Tendinopathy and Patellar Tendinopathy: Semantics or Significant?

Jumper's knee is not synonymous with patellar tendinopathy. The term includes patellar tendinopathy and quadriceps tendinopathy. Although the patellar and quadriceps tendons work in tandem as part of the extensor mechanism of the knee, they have distinct anatomy and functional roles. As a result, there are probable differences in risk factors, etiology, and response to treatment. It is time to clinically separate patellar tendinopathy and quadriceps tendinopathy and design more specific rehabilitation programs. In this Viewpoint, the authors will (1) provide a rationale for distinguishing the 2 clinical entities-patellar tendinopathy and quadriceps tendinopathy-for treatment decision making, and (2) identify areas of research priority in quadriceps tendinopathy. J Orthop Sports Phys Ther 2019;49(9):627-630. doi:10.2519/jospt.2019.0611.

Cheiroarthropathy and tendinopathy in diabetes

Joint problems commonly occur in people with diabetes. Cheiroarthropathy affects the hands and results in painless limited finger joint extension, appearing to be associated with longer diabetes duration and the presence of microvascular complications. The prevalence of cheiroarthropathy seems to be falling, perhaps as a result of improvements in glycaemic management. Non-enzymatic glycation of collagen results in abnormally crosslinked protein resistant to degradation with subsequent increased build-up of collagen in joints. The management of cheiroarthropathy is predominantly conservative, with occupational and hand therapy at the forefront. Tendinopathy is more common in people with diabetes than those without, and is associated with obesity and insulin resistance. As with cheiroarthropathy, the exact causative mechanism of tendinopathy in diabetes is not known, but may be linked to inflammation, apoptosis and increased vascularity of affected tendons, driven by hyperinsulinaemia. Local fat pads have also been suggested to play a role in the pathogenesis of tendinopathy.

Investigating the Effect of Aging on the Viscosity of Tendon Fascicles and Fibers

In the current work, we investigate the effect of aging on the viscosity of tendon subunits. To that scope, we make use of experimental relaxation curves of healthy and aged tendon fascicles and fibers, upon which we identify the viscosity parameters characterizing the time-dependent behavior of each tendon subunit. We subsequently combine the obtained results with analytical viscoelastic homogenization analysis methods to extract information on the effective viscous contribution of the embedding matrix substance at the fiber scale. The results suggest that the matrix substance plays a significant role in the relaxation process of the upper tendon subunits both for aged and healthy specimens. What is more, the viscosity coefficients computed for the fibrillar components indicate that aging leads to a viscosity reduction that is statistically significant for both fascicles and fibers. Its impact is more prominent for the lower hierarchical scale of fibers. As such, the reduced stress relaxation capability at the tendon macroscale is to be primarily attributed to the modified viscosity of its inner fibrillar subunits rather than to the matrix substance.

Exploiting Viscoelastic Experimental Observations and Numerical Simulations to Infer Biomimetic Artificial Tendon Fiber Designs

Designing biomimetic artificial tendons requires a thorough, data-based understanding of the tendon's inner material properties. The current work exploits viscoelastic experimental observations at the tendon fascicle scale, making use of mechanical and data analysis methods. More specifically, based on reported elastic, volumetric and relaxation fascicle scale properties, we infer most probable, mechanically compatible material attributes at the fiber scale. In particular, the work provides pairs of elastic and viscous fiber-scale moduli, which can reproduce the upper scale tendon mechanics. The computed range of values for the fiber-scale tendon viscosity attest to the substantial stress relaxation capabilities of tendons. More importantly, the reported mechanical parameters constitute a basis for the design of tendon-specific restoration materials, such as fiber-based, engineering scaffolds.

An 8-week resistance training protocol is effective in adapting quadriceps but not patellar tendon shear modulus measured by Shear Wave Elastography

Habitual loading and resistance training (RT) can lead to changes in muscle and tendon morphology as well as in its mechanical properties which can be measured by Shear Wave Elastography (SWE) technique. The objective of this study was to analyze the Vastus Lateralis (VL) and patellar tendon (PT) mechanical properties adaptations to an 8-week RT protocol using SWE. We submitted 15 untrained health young men to an 8-week RT directed for knee extensor mechanism. VL and PT shear modulus (μ) were assessed pre and post intervention with SWE. PT thickness (PTT), VL muscle thickness (VL MT) and knee extension torque (KT) were also measure pre and post intervention to ensure the RT efficiency. Significant increases were observed in VL MT and KT (pre = 2.40 ± 0.40 cm and post = 2.63 ± 0.35 cm, p = 0.0111, and pre = 294.66 ± 73.98 Nm and post = 338.93 ± 76.39 Nm, p = 0.005, respectively). The 8-week RT was also effective in promoting VL μ adaptations (pre = 4.87 ± 1.38 kPa and post = 9.08.12 ± 1.86 kPa, p = 0.0105), but not in significantly affecting PT μ (pre = 78.85 ± 7.37 kPa and post = 66.41 ± 7.25 kPa, p = 0.1287) nor PTT (baseline = 0.364 ± 0.053 cm and post = 0.368 ± 0.046 cm, p = 0.71). The present study showed that an 8-week resistance training protocol was effective in adapting VL μ but not PT μ. Further investigation should be conducted with special attention to longer interventions, to possible PT differential individual responsiveness and to the muscle-tendon resting state tension environment.

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.

Assessing the elastic properties of skeletal muscle and tendon using shearwave ultrasound elastography and MyotonPRO

The purposes of this study were to compare Young’s modulus values determined by shear wave ultrasound elastography (SWUE) with stiffness index obtained using a hand-held MyotonPRO device on the resting stiffness of gastrocnemius muscle belly and Achilles tendon; and to examine the test-retest reliability of those stiffness measurement using hand-held MyotonPRO. Twenty healthy volunteers participated in the study. The measurement values of muscle and tendon was determined in dominant legs. Each marker point was assessed using MyotonPRO and SWUE, respectively. Intra-operator reliability of MyotonPRO was established in 10 of the subjects. The correlation coefficients between the values of muscle and tendon stiffness indices determined by MyotonPRO and SWUE were calculated. Significant correlations were found for muscle and tendon stiffness and Young’s modulus ranged from 0.463 to 0.544 (all P < 0.05). The intra-operator reliability ranged from good to excellent (ICC_(3,1) = 0.787~0.928). These results suggest that the resting stiffness of gastrocnemius muscle belly and Achilles tendon measured by MyotonPRO is related to the Young’s modulus of those quantified by SWUE. The MyotonPRO shows good intra-operator repeatability. Therefore, the present study shows that MyotonPRO can be used to assess mechanical properties of gastrocnemius muscle belly and Achilles tendon with a resting condition.

Virtual touch IQ elastography in evaluation of Achilles tendon in patients with chronic renal failure

PURPOSE

To evaluate the sonoelastographic changes in the Achilles tendon in patients with chronic renal failure (CRF) using virtual touch imaging quantification (VTIQ) elastography.

METHODS

Twenty-six patients undergoing three hemodialysis sessions per week and 26 subjects admitted to our institution between January 2016 and April 2016 were included in this prospective study. The characteristics and body mass index of the patients were noted. Ultrasonography was performed parallel to the long axis of the bilateral Achilles tendons during relaxation of the legs using the Siemens Acuson S3000™ ultrasound device (Siemens HealthCare, Erlangen, Germany). Tendon thickness was reviewed, and tissue stiffness was quantitatively assessed using VTIQ elastography. Independent samples t test and Mann-Whitney U test were used for statistical analyses.

RESULTS

The median values of shear wave velocities of the Achilles tendon in patients with CRF were 7.19 m/s (4.23-9.77 m/s) on the right and 6.98 m/s (4.00-9.82 m/s) on the left, while they were 5.11 m/s (4.09-8.82 m/s) on the right and 5.36 m/s (4.05-8.80 m/s) on the left in controls. The stiffness of the Achilles tendons in patients with CRF was found to be higher than that in controls (right: P < 0.001, left: P = 0.004). There was no statistically significant difference in tendon thickness between the CRF and control groups (P > 0.05).

CONCLUSION

The thickness and stiffness of tendon can be effectively evaluated with sonoelastography. The thickness of the Achilles tendon did not significantly differ between the patients with CRF and healthy subjects. However, the stiffness of the Achilles tendon measured with VTIQ elastography was demonstrated to be increased in the patients with CRF.

Ultrasound elastography: compression elastography and shear-wave elastography in the assessment of tendon injury

Ultrasound elastography (USE) is a recent technology that has experienced major developments in the past two decades. The assessment of the main mechanical properties of tissues can be made with this technology by characterisation of their response to stress. This article reviews the two major techniques used in musculoskeletal elastography, compression elastography (CE) and shear-wave elastography (SWE), and evaluates the studies published on major electronic databases that use both techniques in the context of tendon pathology. CE accounts for more studies than SWE. The mechanical properties of tendons, particularly their stiffness, may be altered in the presence of tendon injury. CE and SWE have already been used for the assessment of Achilles tendons, patellar tendon, quadriceps tendon, epicondylar tendons and rotator cuff tendons and muscles. Achilles tendinopathy is the most studied tendon injury with USE, including the postoperative period after surgical repair of Achilles rupture tendon. In relation to conventional ultrasound (US), USE potentially increases the sensitivity and diagnostic accuracy in tendinopathy, and can detect pathological changes before they are visible in conventional US imaging. Several technical limitations are recognised, and standardisation is necessary to ensure repeatability and comparability of the results when using these techniques. Still, USE is a promising technique under development and may be used not only to promote an early diagnosis, but also to identify the risk of injury and to support the evaluation of rehabilitation interventions. KEY POINTS: • USE is used for the assessment of the mechanical properties of tissues, including the tendons. • USE increases diagnostic performance when coupled to conventional US imaging modalities. • USE will be useful in early diagnosis, tracking outcomes and monitoring treatments of tendon injury. • Technical issues and lack of standardisation limits USE use in the assessment of tendon injury.

Quantifying the Stiffness of Achilles Tendon: Intra- and Inter-Operator Reliability and the Effect of Ankle Joint Motion

Background

The objectives of the present study were to examine the intra- and inter-operator reliability of the MyotonPRO device in quantifying the stiffness of the Achilles tendon and the device’s ability to examine the modulation in stiffness of the Achilles tendon during ankle joint flexion.

Material/Methods

Twenty asymptomatic participants (10 males and 10 females; mean age: 25.0±3.1 years) were recruited for this study. The stiffness of the Achilles tendon was quantified using the MyotonPRO device.

Results

The results revealed excellent intra- and inter-operator reliability for quantifying Achilles tendon stiffness with the ankle joint in a neutral position and detected a 13.9% increase in stiffness of the Achilles tendon between 0° and 30° of ankle joint flexion. The minimal detectable change (MDC) in tendon stiffness was 45 Newton/meter (N/m).

Conclusions

Our findings indicated that the MyotonPRO device is a feasible method to quantify the stiffness of the Achilles tendon and monitor its changes. Thus, it is an essential tool to use to examine the modulation in the stiffness of the Achilles tendon due to pathology or interventions for future studies.

Ultrasound elastography and ultrasound tissue characterisation for tendon evaluation

Ultrasound elastography (UE) and ultrasound tissue characterisation (UTC) are two newer modes of ultrasound (US) which have begun to attract scientific interests as ways to improve tendon characterisation. These modes of US show early promise in improved diagnostic accuracy, prediction of at-risk tendons and prognostication capability beyond conventional grey-scale US. Here, we provide a review of the literature on UE and UTC for Achilles, patellar and rotator cuff tendons.

The translational potential of this article: The present literature indicates that UE and UTC could potentially increase the clinician's ability to accurately diagnose the extent of tendon pathology, including preclinical injury.

Machine learning for medical ultrasound: status, methods, and future opportunities

Ultrasound (US) imaging is the most commonly performed cross-sectional diagnostic imaging modality in the practice of medicine. It is low-cost, non-ionizing, portable, and capable of real-time image acquisition and display. US is a rapidly evolving technology with significant challenges and opportunities. Challenges include high inter- and intra-operator variability and limited image quality control. Tremendous opportunities have arisen in the last decade as a result of exponential growth in available computational power coupled with progressive miniaturization of US devices. As US devices become smaller, enhanced computational capability can contribute significantly to decreasing variability through advanced image processing. In this paper, we review leading machine learning (ML) approaches and research directions in US, with an emphasis on recent ML advances. We also present our outlook on future opportunities for ML techniques to further improve clinical workflow and US-based disease diagnosis and characterization.

Ultrasound elastography in tendon pathology: state of the art

Elastography assesses the biomechanical and structural properties of tissues by measuring their stiffness. Despite promising results, elastography has not yet earned its place in the daily practice of musculoskeletal radiologists. The purpose of this article is to present and examine the data available to date on ultrasound elastography of the tendons through a review of the literature to provide musculoskeletal radiologists with an overview that may help them better understand and use elastography routinely. The most common techniques in ultrasound elastography are described. Then, the aspects of the physiologic and pathologic tendon are presented and discussed. One must make this technique one's own to better apprehend its contribution to the musculoskeletal imaging field, while bearing in mind that further research will be required before admitting elastography as a reliable and validated tool able to optimize our daily clinical practice.

Shear-Wave Elastography: Basic Physics and Musculoskeletal Applications

In the past 2 decades, sonoelastography has been progressively used as a tool to help evaluate soft-tissue elasticity and add to information obtained with conventional gray-scale and Doppler ultrasonographic techniques. Recently introduced on clinical scanners, shear-wave elastography (SWE) is considered to be more objective, quantitative, and reproducible than compression sonoelastography with increasing applications to the musculoskeletal system. SWE uses an acoustic radiation force pulse sequence to generate shear waves, which propagate perpendicular to the ultrasound beam, causing transient displacements. The distribution of shear-wave velocities at each pixel is directly related to the shear modulus, an absolute measure of the tissue's elastic properties. Shear-wave images are automatically coregistered with standard B-mode images to provide quantitative color elastograms with anatomic specificity. Shear waves propagate faster through stiffer contracted tissue, as well as along the long axis of tendon and muscle. SWE has a promising role in determining the severity of disease and treatment follow-up of various musculoskeletal tissues including tendons, muscles, nerves, and ligaments. This article describes the basic ultrasound physics of SWE and its applications in the evaluation of various traumatic and pathologic conditions of the musculoskeletal system. ^©RSNA, 2017.