Tendon Elasticity Research Articles

Urinary bladder matrix does not improve tenogenesis in an in vitro equine model.

Extracellular matrix (ECM) is responsible for tendon strength and elasticity. Healed tendon ECM lacks structural integrity, leading to reinjury. Porcine urinary bladder matrix (UBM) provides a scaffold and source of bioactive proteins to improve tissue healing, but has received limited attention for treating tendon injuries. The objective of this study was to evaluate the ability of UBM to induce matrix organization and tenogenesis using a novel in vitro model. We hypothesized that addition of UBM to tendon ECM hydrogels would improve matrix organization and cell differentiation. Hydrogels seeded with bone marrow cells (n = 6 adult horses) were cast using rat tail tendon ECM ± UBM, fixed under static tension and harvested at 7 and 21 days for construct contraction, cell viability, histology, biochemistry, and gene expression. By day 7, UBM constructs contracted significantly from baseline, whereas control constructs did not. Both control and UBM constructs contracted significantly by day 21. In both groups, cells remained viable over time and changed from round and randomly oriented to elongated along lines of tension with visible compaction of the ECM. There were no differences over time or between treatments for nuclear aspect ratio, DNA, or glycosaminoglycan content. Decorin, MMP-13, and Scleraxis expression increased significantly over time, but not in response to UBM treatment. Mohawk expression was constant over time. COMP expression decreased over time in both groups. Using a novel ECM hydrogel model, substantial matrix organization and cell differentiation occurred; however, addition of UBM failed to induce greater matrix organization than tendon ECM alone. This article is protected by copyright. All rights reserved.

Training-induced increase in Achilles tendon stiffness affects tendon strain pattern during running.

BackgroundDuring the stance phase of running, the elasticity of the Achilles tendon enables the utilisation of elastic energy and allows beneficial contractile conditions for the triceps surae muscles. However, the effect of changes in tendon mechanical properties induced by chronic loading is still poorly understood. We tested the hypothesis that a training-induced increase in Achilles tendon stiffness would result in reduced tendon strain during the stance phase of running, which would reduce fascicle strains in the triceps surae muscles, particularly in the mono-articular soleus.MethodsEleven subjects were assigned to a training group performing isometric single-leg plantarflexion contractions three times per week for ten weeks, and another ten subjects formed a control group. Before and after the training period, Achilles tendon stiffness was estimated, and muscle-tendon mechanics were assessed during running at preferred speed using ultrasonography, kinematics and kinetics.ResultsAchilles tendon stiffness increased by 18% (P < 0.01) in the training group, but the associated reduction in strain seen during isometric contractions was not statistically significant. Tendon elongation during the stance phase of running was similar after training, but tendon recoil was reduced by 30% (P < 0.01), while estimated tendon force remained unchanged. Neither gastrocnemius medialis nor soleus fascicle shortening during stance was affected by training.DiscussionThese results show that a training-induced increase in Achilles tendon stiffness altered tendon behaviour during running. Despite training-induced changes in tendon mechanical properties and recoil behaviour, the data suggest that fascicle shortening patterns were preserved for the running speed that we examined. The asymmetrical changes in tendon strain patterns supports the notion that simple in-series models do not fully explain the mechanical output of the muscle-tendon unit during a complex task like running.

Acoustic Radiation Force Impulse Elastography and Ultrasonographic Findings of Achilles Tendon in Patients With and Without Diabetic Peripheral Neuropathy: A Cross-Sectional Study.

We aimed to evaluate the elastographic features of Achilles tendon with Acoustic Radiation Force Impulse in patients with and without diabetic neuropathy. According to the presence of peripheral neuropathy, 45 patients with type 2 diabetes were divided into 2 subgroups. Those with peripheral neuropathy were defined as group I (22 patients) and those without peripheral neuropathy were defined as group II (23 patients). A total of thirty age-, gender-, and body mass index-matched healthy individuals were selected as controls. All participants underwent both ultrasonographic and Acoustic Radiation Force Impulse elastographic examination in order to evaluate Achilles Tendon thickness and stiffness. Achilles tendon thicknesses were similar between groups (p=0.991). Achilles tendon thicknesses of both patient groups were significantly higher than the control group (group I vs control p=0.01; group II vs control p=0.006). Stiffness values of Achilles tendons were similar between the control group and group II (p=0.993). Shear Wave Velocity was significantly lower in group I than group IIand control group (p<0.001). Diabetic patients with neuropathy have thicker and softer Achilles tendon while the elasticity of Achilles tendon in diabetic patients without neuropathy is similar to the healthy controls. Softening of the Achilles tendon may be an early sign of diabetic foot and reveal the patients with a risk of diabetic foot.

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.

Shear Wave Elastography (SWE) of Asymptomatic Achilles Tendons: A Comparison Between Semiprofessional Athletes and the Nonathletic General Population

It has been shown that Shear Wave Elastography (SWE) is a useful tool to evaluate tendon stiffness, e.g. in diagnosing tendinopathies, as diseased or injured tendons are intra-individually softer than healthy ones. But reference values between different population groups are still missing. The purpose of this prospective clinical study was two-fold: First, to comparatively analyse Achilles tendon stiffness between asymptomatic semiprofessional athletes and an asymptomatic nonathletic control group. Second, to evaluate specificity, with which SWE is able to predict absence of clinical symptoms in asymptomatic individuals, compared to B-mode-Ultrasound (B-US) and Power Doppler-Ultrasound (PD-US). Prospective clinical study in 68 asymptomatic healthy participants, 33 (48.5%) of them semiprofessional athletes with at least five training units of running per week and 35 (51.5 %) normal nonathletic persons, asymptomatic respectively. A consecutive of 136 Achilles tendons underwent standardized multi-modal ultrasound, consisting of B-US, PD-US, and SWE (Aixplorer, Supersonic). Pathologic structural changes at B-US, increased Doppler signal PD-US and quantitative ROI-based-analysis of tendon elasticity in kilopascal (kPa) were performed in all participants. Tendon stiffness was compared intra-individually between right and left side in each participant. SWE values between athletes and nonathletes were compared by using student's t test (p < 0.05). To evaluate the ability of different sonographic modalities in predicting "absence of clinical symptoms", specificities of B-US, PD-US, and SWE were calculated and compared among each other. Mean SWE-value for Achilles tendon was 183.8 kPa (± 98 kPa) in athletes and 103.6 kPa (± 30.5 kPa) in the nonathletic control group. The difference between athletes and non-athletes was statistically significant (p < 0.001). No significant differences were found intra-individually between right and left side: athlete mean: right: 187.2 kPa (SD ± 45.2 kPa)/left: 180.4 kPa (SD 39.7 kPa); nonathlete mean: right: 105.4 kPa (SD 34.9 kPa)/left: 101.8 kPa (SD 28.9 kPa). Specificity with which asymptomatic tendons were rated as "inconspicuous" was 60.6% for B-US, 93.9% for PD-US and 96.3% for SWE. Healthy athletes exhibit significantly higher SWE-values in Achilles tendons than healthy nonathletic participants, which means that they have significantly stiffer tendons, possibly caused by repeated training. SWE is able to measure and display these effects. These interindividual differences should be taken into consideration, especially when rating a tendon as "healthy" or "diseased", because a "softer" tendon does not necessarily mean to be affected.

A novel application of strain sonoelastography can detect changes in Achilles tendon elasticity during isometric contractions of increasing intensity

BackgroundMechanical and morphological properties of the Achilles tendon are altered in disease and in response to changes in mechanical loading. In the last few years different ultrasound based technologies have been used to detect tendon mechanical properties changes mainly in resting condition. Therefore the aim of this study was to evaluate if strain sonoelastography can identify changes in Achilles tendon elasticity during isometric contractions of increasing intensity.MethodsThis cross-sectional study enrolled 37 healthy volunteers (19 women) with mean (±SD) age of 27.1 (±7.0) years between January and June 2017. Strain sonoelastography images of the Achilles tendon were acquired during an isometric ramp force (0 kg, 0.5 kg, 1 kg, 2 kg, 5 kg and, 10 kg). An external reference material was used to provide a comparison between the examined tissue and a material of constant elasticity. Friedman test with post hoc pairwise comparison were used to determine the correlation between the difference contraction levels.ResultsThe median and interquartile range (IQR) values for the strain ratio were 1.61 (1.5–2.9) in a relaxed state and 1.30 (1.07–2.02), 1.00 (0.76–1.66), 0.81 (0.70–1.19), 0.47 (0.39–0.73) and 0.33 (0.28–0.40) for 0.5 kg, 1 kg, 2 kg, 5 kg and 10 kg, respectively revealing increased tendon hardness with increasing contraction intensities. Friedman test revealed significant differences (p < 0.05) in the strain ratio between all contractions except between 0.5 kg – 1 kg (p = 0.41); 1 kg – 2 kg (p = 0.12) and 5 kg – 10 kg (p = 0.12).ConclusionStrain sonoelastography can detect changes in Achilles tendon elasticity between different contraction intensities. The results provide an original force-elasticity curve for the Achilles tendon in a healthy, asymptomatic population.Trial registrationThe study was approved by the Ethics Committee of Canton Ticino.

Utilizing the Nonlinearity of Tendon Elasticity for Compensation of Unknown Gravity of Payload

This paper discusses the positioning control of an elastic tendon-driven robot arm under gravity. The robot is driven by rubber string tendons and winding drums attached on the outside frames. Low-cost rubber strings that are available commercially are used as tendons. The goal is to utilize the nonlinear nature of the rubber materials to control a low-cost and soft robot arm. Theoretically, a mathematical model with accurate parameters and accurate measurement of the payload weight is necessary for rigorous gravity compensation. However, the necessity for the information of the robot parameters is hindering easy adaptability, versatility, and cost-efficiency. This paper presents an iterative estimation and compensation method for unknown payloads based on the steady-state position error and the nominal stiffness coefficient. Owing to the nonlinearity of the actual rubber strings, the position error remains after a single operation of the gravity compensation. However, experiments indicate that the error reduces by a simple iteration of the same compensation operation. Considering the nonlinearity in rubber strings, the mechanism of the error reduction is analyzed theoretically. Although the iterative process is time consuming, the method requires less prior information. In addition, it is cost effective because a sophisticated force sensor is not required. As the mechanism of error reduction applies to typical rubber string materials, it is useful for significant cost-reduction and reconfigurable robotics.

Effect of Physical Training Towards Body Balance in Overweight Condition

An overweight individual has morphological changes in the muscle resulting functional impairment and can cause reduction in body balance system. Balance is an ability to maintain both static and dynamic equilibrium on various positions. An overweight person will experience a decrease in abdominal muscle strength and center of gravity shift. Physical training has positive effects to increase body balance. Stretching exercise maintains and increases the elasticity of muscle, tendon, fascia, ligament and joint motion and improve balance. Resistance exercise increases muscle performance which has benefit effect on balance system dynamically. The proprioceptive, an important part of balance maintenance to feel joint position or body when moving, can be improved by training that performed using balance board. Mechanoreceptor that is stimulated and the adaptation of the body's balance control that is influenced by balance board training results a good proprioceptive.

The Impact of Post Activation Potentiation on Achilles Tendon Stiffness, Elasticity and Thickness among Basketball Players.

The purpose of this study is to examine and further understand the effects of post activation potentiation on Achilles tendon (AT) thickness, elasticity and stiffness among basketball players. Basketball is one of the world’s most popular and widely viewed sports. One of the main factors which athletes depend on during their performance is elastic energy coming straight from the AT. Contractile activity increases the muscular force and is known in science as post activation potentiation (PAP). Twelve basketball players (aged 21.3 ± 2.1 years) from the first Polish league took part in this study. The PAP session consisted of single repetitions of the squat with loads corresponding to 60%, 70%, 80%, 90% and 100% of 1 repetition maximum (RM). The measurement method for AT thickness was ultrasonography and for the elasticity and stiffness was myotonometry. The measurements were taken before and immediately after PAP training session. Obtained results: AT stiffness increased significantly from the baseline post exercise, while AT thickness and elasticity decreased after the physical effort. The exercise in PAP caused significant changes in stiffness, elasticity and thickness of the AT.

Real-time ultrasound elastography evaluation of achilles tendon properties in patients with mild hemiplegic stroke after rehabilitation training.

This study aims to evaluate the Achilles tendon's properties after rehabilitation training in patients with stroke using real-time ultrasound elastography. A total of 24 patients with mild hemiplegic stroke in the past 6 to 12 months and unilateral lower limb movement disorder were prospectively enrolled. All patients accepted 9-week rehabilitation training with the same schema. The 2-dimensional elastography and real-time elastography findings in the impaired and contralateral normal Achilles tendon were measured at pretraining and at 3, 6, and 9 weeks after training, which included tendon length, thickness, elasticity score (grade 1-3), and strain ratio of fat to tendon. The functional properties, which include the 10-meter walk test and timed up-and-go scores, were evaluated before and after the 9-week training. The impaired Achilles tendon had a longer length (P = .002), lower frequency of grade 1 (P = .012), and lower strain ratio (P = .009) than the contralateral tendon before training. The impaired tendons at the third, sixth, and ninth weeks after training were compared to ones before training, respectively, which revealed shorter length, increased frequency of grade 1, and increased strain ratio. The first statistically significant changes in the length were observed at the sixth week, while such changes in elasticity score and strain ratio were observed at the ninth week. Two-dimensional elastography and real-time elastography can provide valuable imaging markers for quantitatively evaluating the Achilles tendon's properties after rehabilitation training in patients with stroke.

Effect of High-Induction Magnetic Stimulation on Elasticity of the Patellar Tendon

Nowadays, a high-induction magnetic stimulation is starting to be increasingly applied as a biophysical stimulation in the conservative treatment of the degenerative locomotor system diseases. These are mainly in correlation with the changes in soft tissue elasticity, which should be positively influenced by the flow-induced electrical currents of high current density during high-induction magnetic stimulation. This assumption was verified within the interventional and prospective study using the ultrasound elastography. The group consisted of 6 volunteers, whose elasticity of the patellar tendons was measured using the 2D shear-wave ultrasound elastography. The volunteers were then exposed to a 20-minute high-induction magnetic stimulation session with a frequency of 20 Hz, in 2 s package intervals, with a 5 s pause, and a induced electric current density of 100 Am−2 in the tendons area. A tendon tension was measured five times for all volunteers, where mean tension at the marked area of the tendon, as well as the highest point tension indicated by the Q-Box, was monitored. The measurement results show that high-induction magnetic stimulation has an influence on the patellar tendon tension change, which occurred in the case of all involved volunteers when the patellar tension was decreased.

Acoustic Radiation Force Impulse Elastography and Ultrasonographic Findings of Achilles Tendon in Patients with and without diabetic peripheral neuropathy: a cross-sectional study

Aims We aimed to evaluate the elastographic features of Achilles tendon with Acoustic Radiation Force Impulse in patients with and without diabetic neuropathy. Methods According to the presence of peripheral neuropathy, 45 patients with type 2 diabetes were divided into 2 subgroups. Those with peripheral neuropathy were defined as group I (22 patients) and those without peripheral neuropathy were defined as group II (23 patients). A total of thirty age-, gender-, and body mass index-matched healthy individuals were selected as controls. All participants underwent both ultrasonographic and Acoustic Radiation Force Impulse elastographic examination in order to evaluate Achilles Tendon thickness and stiffness. Results Achilles tendon thicknesses were similar between groups (p=0.991). Achilles tendon thicknesses of both patient groups were significantly higher than the control group (group I vs control p=0.01; group II vs control p=0.006). Stiffness values of Achilles tendons were similar between the control group and group II (p=0.993). Shear Wave Velocity was significantly lower in group I than group IIand control group (p Conclusion Diabetic patients with neuropathy have thicker and softer Achilles tendon while the elasticity of Achilles tendon in diabetic patients without neuropathy is similar to the healthy controls. Softening of the Achilles tendon may be an early sign of diabetic foot and reveal the patients with a risk of diabetic foot.

Three-Dimensional Shear Wave Elastography of Skeletal Muscle: Preliminary Study.

Two-dimensional (2D) shear wave elastography (SWE) can measure the elasticity of skeletal muscle, tendons, and ligaments. Three-dimensional (3D) SWE has been used to detect breast cancer but has not been applied to the musculoskeletal system. This study aimed to investigate whether 3D SWE could be used in skeletal muscles in vivo. The study enrolled 20 healthy volunteers at Beijing Chaoyang Hospital from August to October 2016. Two-dimensional and 3D SWE scans were used to measure the Young modulus of the flexor carpi radialis in the relaxed state. Longitudinal and transverse scanning was performed. Data were analyzed by a 1-way analysis of variance/least significant difference post hoc test, a paired t test, and Bland-Altman plots. The participants included 10 male and 10 female volunteers with a mean age ± SD of 25 ± 5 years. The Young modulus did not differ between 3D and 2D SWE for the sagittal plane (longitudinal scanning, 34.9 ± 5.7 versus 32.7 ± 5.2 kPa; P = .096) or transverse plane (transverse scanning, 9.1 ± 2.1 versus 9.2 ± 1.6 kPa; P = .877). The Young modulus did not differ between sagittal, transverse, and coronal planes for 3D SWE longitudinal scanning (34.9 ± 5.7, 34.3 ± 5.8, and 34.8 ± 5.9 kPa, respectively; P = .936) or 3D SWE transverse scanning (9.1 ± 2.0, 9.1 ± 2.1, and 8.8 ± 2.1 kPa; P = .838). However, the Young modulus for each individual plane (sagittal, transverse, or coronal) differed significantly between longitudinal and transverse scanning (P < .001). Both 2D SWE and 3D SWE are suitable techniques for clinical use, depending on the examiner's experience/preference. However, 3D SWE provides a multiplanar/multislice view that better illustrates the spatial characteristics of muscle tissue. Three-dimensional SWE may be a new method for fully visualizing the musculoskeletal system.

Sensor-Motor Maps for Describing Linear Reflex Composition in Hopping.

In human and animal motor control several sensory organs contribute to a network of sensory pathways modulating the motion depending on the task and the phase of execution to generate daily motor tasks such as locomotion. To better understand the individual and joint contribution of reflex pathways in locomotor tasks, we developed a neuromuscular model that describes hopping movements. In this model, we consider the influence of proprioceptive length (LFB), velocity (VFB) and force feedback (FFB) pathways of a leg extensor muscle on hopping stability, performance and efficiency (metabolic effort). Therefore, we explore the space describing the blending of the monosynaptic reflex pathway gains. We call this reflex parameter space a sensor-motor map. The sensor-motor maps are used to visualize the functional contribution of sensory pathways in multisensory integration. We further evaluate the robustness of these sensor-motor maps to changes in tendon elasticity, body mass, segment length and ground compliance. The model predicted that different reflex pathway compositions selectively optimize specific hopping characteristics (e.g., performance and efficiency). Both FFB and LFB were pathways that enable hopping. FFB resulted in the largest hopping heights, LFB enhanced hopping efficiency and VFB had the ability to disable hopping. For the tested case, the topology of the sensor-motor maps as well as the location of functionally optimal compositions were invariant to changes in system designs (tendon elasticity, body mass, segment length) or environmental parameters (ground compliance). Our results indicate that different feedback pathway compositions may serve different functional roles. The topology of the sensor-motor map was predicted to be robust against changes in the mechanical system design indicating that the reflex system can use different morphological designs, which does not apply for most robotic systems (for which the control often follows a specific design). Consequently, variations in body mechanics are permitted with consistent compositions of sensory feedback pathways. Given the variability in human body morphology, such variations are highly relevant for human motor control.

Real-time ultrasound elastography of the Achilles tendon in patients with cerebral palsy: is there a correlation between strain ratio and biomechanical indicators?

Our aim was to comparatively investigate the strain ratio and thickness of the Achilles tendon in children with cerebral palsy (CP), and to elucidate whether there is a correlation between biomechanical features of the Achilles tendon and strain ratio. A total of 155 participants (72 CP patients and 83 healthy controls) who underwent real-time elastography of both Achilles tendons were studied. A linear transducer (4.8-11.0MHz) was used to obtain the images. Correlation analysis between age, length, and thickness of the Achilles tendon, and strain ratio (SR) was performed by means of Pearson correlation and Spearman's rho tests. Comparison of results obtained from CP patients and controls showed that the length of the Achilles tendon was shorter (p<0.001) and SR was higher (p<0.001) in CP patients. In CP patients, there was a positive correlation between SR and age and between SR and the thickness and length of the Achilles tendon (p<0.001 for all). Furthermore, the length of the tendon and age were positively associated (p<0.001). ROC analysis revealed that the cut-off value for SR was 1.89. The results of the present study demonstrated that real-time elastography can constitute a simple, practical, and noninvasive method for evaluation of the elasticity of the Achilles tendon in children with CP.

Neuromorphic meets neuromechanics, part I: the methodology and implementation

Objective: One goal of neuromorphic engineering is to create ‘realistic’ robotic systems that interact with the physical world by adopting neuromechanical principles from biology. Critical to this is the methodology to implement the spinal circuitry responsible for the behavior of afferented muscles. At its core, muscle afferentation is the closed-loop behavior arising from the interactions among populations of muscle spindle afferents, alpha and gamma motoneurons, and muscle fibers to enable useful behaviors. Approach. We used programmable very- large-scale-circuit (VLSI) hardware to implement simple models of spiking neurons, skeletal muscles, muscle spindle proprioceptors, alpha-motoneuron recruitment, gamma motoneuron control of spindle sensitivity, and the monosynaptic circuitry connecting them. This multi-scale system of populations of spiking neurons emulated the physiological properties of a pair of antagonistic afferented mammalian muscles (each simulated by 1024 alpha- and gamma-motoneurones) acting on a joint via long tendons. Main results. This integrated system was able to maintain a joint angle, and reproduced stretch reflex responses even when driving the nonlinear biomechanics of an actual cadaveric finger. Moreover, this system allowed us to explore numerous values and combinations of gamma-static and gamma-dynamic gains when driving a robotic finger, some of which replicated some human pathological conditions. Lastly, we explored the behavioral consequences of adopting three alternative models of isometric muscle force production. We found that the dynamic responses to rate-coded spike trains produce force ramps that can be very sensitive to tendon elasticity, especially at high force output. Significance. Our methodology produced, to our knowledge, the first example of an autonomous, multi-scale, neuromorphic, neuromechanical system capable of creating realistic reflex behavior in cadaveric fingers. This research platform allows us to explore the mechanisms behind healthy and pathological sensorimotor function in the physical world by building them from first principles, and it is a precursor to neuromorphic robotic systems.

A NEW METHOD FOR SIGNATURE VERIFICATION BASED ON PHYSIOLOGICAL CHARACTERISTICS OF HAND MUSCLES AND TENDONS

Signature authentication with static and dynamic features of signature has been studied for decades, in this paper a novel and new method based on estimating elasticity and viscoelasticity characteristics of the muscles and tendons of index finger of the right hand was presented and the angles between the finger knuckles were collected by data collection glove and the location of digital pen tip on sensitive pad is stored in computer too. With NMC model and writing required mathematical equations and inverse modeling, physiological characteristics of muscles and tendons of right hand were estimated by LMS criteria. This approach has been applied on 30 right-hand persons that of each individual 5 genuine signature and some ordinary forgers to counterfeit genuine signature only by seeing the shape of original signature. 93.4% forgery signatures could have been recognized from genuine and only 6.6% could not have been detected. For verification, we used 5-fold cross-validation, with mean of EER[Formula: see text] 3.57 and standard deviation of EER[Formula: see text] 0.736. Therefore, we identified the physiological viscoelasticity and elasticity of muscles and tendons of hand as a new biometric.

Quantifying tendon elasticity in healthy and diseased tendon using shearwave elastography: A systematic review

Quantifying tendon elasticity in healthy and diseased tendon using shearwave elastography: A systematic review

Altered patterns of displacement within the Achilles tendon following surgical repair

PurposeUltrasound speckle tracking was used to compare tendon deformation patterns between uninjured and surgically repaired Achilles tendons at 14–27-month follow-up. The hypothesis was that the non-homogenous displacement pattern previously described in uninjured tendons, where displacement within deep layers of the tendons exceeds that of superficial layers, is altered following tendon rupture and subsequent surgical repair.MethodsIn the first part of this study, an in-house-developed block-matching speckle tracking algorithm was evaluated for assessment of displacement on porcine flexor digitorum tendons. Displacement data from speckle tracking were compared to displacement data from manual tracking. In the second part of the study, eleven patients with previous unilateral surgically treated Achilles tendon rupture were investigated using ultrasound speckle tracking. The difference in superficial and deep tendon displacement was assessed. Displacement patterns in the surgically repaired and uninjured tendons were compared during passive motion (Thompson’s squeeze test) and during active ankle dorsiflexion.ResultsThe difference in peak displacement between superficial and deep layers was significantly (p < 0.01) larger in the uninjured tendons as compared to the surgically repaired tendons both during Thompson’s test (−0.7 ± 0.2 mm compared to −0.1 ± 0.1 mm) and active dorsiflexion (3.3 ± 1.1 mm compared to 0.3 ± 0.2 mm). The evaluation of the speckle tracking algorithm showed correlations of r ≥ 0.89 between displacement data acquired from speckle tracking and the reference displacement acquired from manual tracking. Speckle tracking systematically underestimated the magnitude of displacement with coefficients of variation of less than 11.7%.ConclusionsUninjured Achilles tendons display a non-uniform displacement pattern thought to reflect gliding between fascicles. This pattern was altered after a mean duration of 19 ± 4 months following surgical repair of the tendon indicating that fascicle sliding is impaired. This may affect modulation of the action between different components of the triceps surae, which in turn may affect force transmission and tendon elasticity resulting in impaired function and risk of re-rupture.

Real-time sonoelastography of the patellar and quadriceps tendons: pattern description in profesional athletes and healthy volunteers.

The comparison of elastographic features of quadriceps and patellar tendons in a group of professional athletes and healthy volunteers and the description of elasticity characteristics of these tendons. Thirty-nine professional athletes (22 male, 17 female; mean age 18.5 years) and 35 healthy volunteers (21 male, 14 female; mean age 19 years) were included. They were divided into two groups by gender. Quadriceps tendon, patellar side of the patellar tendon, and tibial side of the patellar tendon elasticity patterns and strain ratios were investigated with real-time ultrasound elastography. The elasticity features of the dominant leg and non-dominant leg of athletes and volunteers legs were compared. In addition quadriceps and patellar tendons were compared separately for three distinct tendon locations. There was no difference between the athletes and the healthy volunteers and also between the dominant leg and non-dominant leg of athletes. At tendon comparison, the quadriceps tendon was harder than the patellar tendon at both side and patellar side of patellar tendon was found to be stiffer than the tibial side of patellar tendon. Although biomechanical studies showed that tendon stiffness increased after long exercise, no significant difference was found between athletes' and healthy volunteers' tendon elasticity. These three tendon locations exhibit different elasticity features and the knowledge of the elasticity feature will be useful in assessing tendon pathologies.