Properties Of Achilles Tendon Research Articles

Determinants of Achilles tendon thickness and their influence on knee function and foot alignment in knee osteoarthritis

Knee osteoarthritis (OA) significantly impacts the quality of life of individuals globally. However, the interconnections between Achilles tendon thickness, knee symptoms/functions, and foot alignment remain understudied in knee OA patients. This study determines the relationships between Achilles tendon thickness (ATT), knee symptoms/functions, and foot alignment in knee OA patients, considering their interconnected biomechanical nature. In a cross-sectional analysis involving 122 knee OA patients, Knee injury and Osteoarthritis Outcome Score (KOOS) assessed knee function and symptoms. Forefoot, midfoot, and rearfoot alignment were measured using hallux valgus angle, navicular/foot ratio, and rearfoot angle. The navicular/foot ratio represented the ratio of navicular height to total foot length. ATT was measured using a digital calliper. Pearson correlations and stepwise multiple linear regression models were employed to explore relationships and determinants. Out of 122 participants, 88 (72.1%) were females. ATT correlated significantly with ankle range of motion, forefoot alignment, and midfoot alignment. In stepwise multivariable regression, ankle range of motion, navicular/foot ratio, and age were significantly associated with ATT (adjusted R2 = 0.44). Similarly, KOOS-Symptoms scores were linked to the OA severity, navicular/foot ratio, ankle range of motion, gastrocnemius strength, and age (adjusted R2 = 0.22). KOOS-Function scores were significantly associated with knee OA severity, gastrocnemius strength, ankle range of motion, and age (adjusted R2 = 0.19). Midfoot alignment was significantly associated with ATT and knee symptoms in patients with Knee OA. This suggests potential benefits of interventions targeting both Achilles tendon properties and foot alignment for improved knee OA outcomes.

The Effect of Biomechanical and Viscoelastic Properties of Gastrocnemius (Lateral-Medial) Muscle and Achilles Tendon on Jumping Performance in Professional Soccer Players

The Effect of Biomechanical and Viscoelastic Properties of Gastrocnemius (Lateral-Medial) Muscle and Achilles Tendon on Jumping Performance in Professional Soccer Players

Probing nanoscale structural response of collagen fibril in human Achilles tendon during loading using in situ SAXS

The specific viscoelastic mechanical properties of the human Achilles tendon are strongly dependent on the structural characteristics of collagen. Although research on the deformation mechanisms of the Achilles tendon in various animals is extensive, understanding of these mechanisms in the human Achilles tendon remains largely empirical and macroscopic. In this work, the evolution of D-space, orientation, and average length of voids between fibers are investigated during the stretching using SAXS techniques. Initially, the void length increases marginally, while the misorientation breadth decreased rapidly as the D-space steadily increased. In the second region, D-space and the void length increase sharply under rising stress, even though misorientation width decreased. During the third region, the increases in void length and D-space decelerate, but the misorientation width widens, suggesting the onset of irreversible microscopic fibril failure in the Achilles tendon. In the final region, the fibers undergo macroscopic failure, with D-space and void length returning to their initial states. The macroscopic alterations are elucidated by the nanoscale structural responses, providing a fundamental understanding of the mechanisms driving the complex biomechanics, tissue structural organization, and Achilles tendon regeneration.

Gastrocnemius medialis and Achilles tendon properties do not differ between children with unilateral or bilateral spastic cerebral palsy

Spastic cerebral palsy (SCP) is a common neurodevelopmental disorder in children, which can be categorized into unilateral and bilateral subtypes. Most studies examining the muscle-tendon properties of the lower extremities in individuals with SCP do not distinguish between subtypes. However, spastic muscle morphology is an important determinant for its function. Therefore, differences in muscle-tendon pathology might lead to different treatment strategies. The aim of this retrospective study was to investigate the muscle–tendon properties between children with unilateral SCP and those with bilateral SCP.Overall, 33 ambulatory children (15 with unilateral SCP and 18 with bilateral SCP, Gross Motor Function Classification System Level I–III) were included. Ankle joint range of motion, isometric muscle strength, and muscle–tendon properties of the gastrocnemius medialis (GM) muscle–tendon unit (MTU) (e.g., muscle volume, tissue lengthening behavior) were assessed with isokinetic dynamometry, 3D motion capture, and ultrasound, respectively. Independent t-tests or Mann-Whitney tests were used to test for group differences (α = 0.05). Effect sizes (Cohen’s d) were also calculated.No significant differences in any assessed parameter were found between children with unilateral SCP and children with bilateral SCP (p > 0.05, d < 0.57).Our findings suggest that the functional and morphological properties of the GM MTU are similarly developed in children with unilateral SCP and children with bilateral SCP. We assume that activity levels might be the decisive factor. Nonetheless, our investigations need be extended by including gait parameters and associated tissue dynamics.

Hyperlipidemia Induced Pathological Changes with no Effect in Biomechanical Properties in the Achilles Tendon of Young Swine.

Hyperlipidemia is linked to atherosclerosis and various diseases. Its strong association with Achilles tendinopathies and xanthomas affects tendon properties through lipid deposition in tendon tissue. We examined the impact of hyperlipidemia on the biomechanical properties of the swine Achilles tendons. Swines were fed a high-cholesterol-high-fat diet to induce hyperlipidemia, and their Achilles tendons were collected and examined for biomechanical properties. The ultimate tensile strength, modulus of elasticity and viscoelastic properties did not exhibit significant differences between hyperlipidemic and control swines. H&E and pentachrome staining revealed extracellular matrix (ECM) disorganization and cellular infiltration in the hyperlipidemic swines, highlighting a marked difference between the control and hyperlipidemic groups. These results suggest hyperlipidemia in young swines alters the tendon composition and may contribute to weak biomechanical properties with time.

Achilles tendon and triceps surae muscle properties in athletes

PurposeThe aim of this study was to investigate internal Achilles tendon (AT) displacement, AT shear wave velocity (SWV), and triceps surae (TS) muscle shear modulus in athletes.MethodsInternal AT displacement was assessed using ultrasound during isometric contraction. Shear wave elastography was used to assess AT SWV (m × s–1) at rest and TS muscle shear modulus (kPa) during passive ankle dorsiflexion.ResultsA total of 131 athletes participated in this study. Athletes who had not exercised within two days had greater AT non-uniformity and mean anterior tendon displacement, and lower SWV at the proximal AT measurement site (mean difference [95% CI]: 1.8 mm [0.6–2.9], p = 0.003; 1.6 mm [0.2–2.9], p = 0.021; – 0.9 m × s–1 [– 1.6 to – 0.2], p = 0.014, respectively). Male basketball players had a lower mean AT displacement compared to gymnasts (– 3.7 mm [– 6.9 to – 0.5], p = 0.042), with the difference localised in the anterior half of the tendon (– 5.1 mm [– 9.0 to – 1.1], p = 0.022). Male gymnasts had a smaller absolute difference in medial gastrocnemius-minus-soleus shear modulus than basketball players (59.6 kPa [29.0–90.2], p < 0.001) and track and field athletes (52.7 kPa [19.2–86.3], p = 0.004). Intraclass correlation coefficients of measurements ranged from 0.720 to 0.937 for internal AT displacement, from 0.696 to 0.936 for AT SWE, and from 0.570 to 0.890 for TS muscles.ConclusionThis study provides a reliability assessment of muscle and tendon SWV. The relative differences in passive TS muscle shear modulus suggest sport-specific adaptation. Importantly, in healthy individuals, lower AT displacement after exercise may reflect the time required for tendon recovery.

Effects of Collagen and Exercise on Tendon Properties and Pain: A Critically Appraised Topic.

Achilles tendon ruptures are prevalent and devastating injuries that require the need for extensive rehabilitation. The methods for preventing these injuries vary between different exercise methods and nutritional supplementation. Although proven effective for decreasing pain and increasing tendon properties, the influence of these 2 methods in combination has not yet been evaluated. Does exercise combined with collagen supplementation improve Achilles tendon structural and mechanical properties and diminish subsequent patient-reported pain compared with exercise alone in adults? Exercise training, including eccentric training protocols and concentric resistance training protocols, combined with collagen supplementation influence Achilles tendon properties and subsequent patient-reported pain compared with exercise alone. Evidence supports that collagen along with exercise training has a significant influence on pain mitigation, augmented cross-sectional area, and tendon thickness, but may have little to no influence on tendon stiffness and microvascularity compared with exercise alone. Further research is needed to determine the effects of combined methods on various populations. Collectively, the body of evidence included to answer the clinical question aligns with the strength of recommendation of A.

Correlations between elastic modulus and ultrashort echo time (UTE) adiabatic T1ρ relaxation time (UTE-Adiab-T1ρ) in Achilles tendons and entheses

Patients with psoriatic arthritis commonly have abnormalities of their entheses, which are the connections between tendons and bone. There are shortcomings with the use of conventional magnetic resonance imaging (MRI) sequences for the evaluation of entheses and tendons, whereas ultrashort echo time (UTE) sequences are superior for the detection of high signals, and can also be used for non-invasive quantitative assessments of these structures. The combination of UTE-MRI with an adiabatic-T1ρ preparation (UTE-Adiab-T1ρ) allows for reliable assessment of entheses and tendons with decreased susceptibility to detrimental magic angle effects. This study aimed to investigate the relationship between quantitative UTE-MRI measures and the biomechanical properties of Achilles tendons and entheses. In total, 28 tendon-enthesis sections were harvested from 11 fresh-frozen human cadaveric foot–ankle specimens (52 ± years old). Tendon-enthesis sections were scanned using the UTE-Adiab-T1ρ and UTE-T1 sequences on a clinical 3 T scanner. MRI-based measures and indentation tests were performed on the enthesis, transitional, and tensile tendon zones of the specimens. Hayes’ elastic modulus showed significant inverse correlations (Spearman’s) with UTE-Adiab-T1ρ in all zones (R= − 0.46, − 0.54, and − 0.61 in enthesis, transition, and tensile tendon zones, respectively). Oliver-Pharr’s elastic modulus showed significant inverse correlations with UTE-Adiab-T1ρ in transition (R= − 0.52) and tensile tendon zone (R=- 0.60). UTE-T1 did not show significant correlations with the elastic modulus. UTE-MRI and elastic modulus were significantly lower in the tensile tendon compared with the enthesis regions This study highlights the potential of the UTE-Adiab-T1ρ technique for the non-invasive evaluation of tendons and enthuses.

Effects of passive static stretching on the Achilles tendon properties of adults: a randomized controlled trial

Effects of passive static stretching on the Achilles tendon properties of adults: a randomized controlled trial

Multimodal and multiscale characterization reveals how tendon structure and mechanical response are altered by reduced loading.

Tendons are collagen-based connective tissues where the composition, structure and mechanics respond and adapt to the local mechanical environment. Adaptation to prolonged inactivity can result in stiffer tendons that are more prone to injury. However, the complex relation between reduced loading, structure, and mechanical performance is still not fully understood. This study combines mechanical testing with high-resolution synchrotron X-ray imaging, scattering techniques and histology to elucidate how reduced loading affects the structural properties and mechanical response of rat Achilles tendons on multiple length scales. The results show that reduced in vivo loading leads to more crimped and less organized fibers and this structural inhomogeneity could be the reason for the altered mechanical response. Unloading also seems to change the fibril response, possibly by altering the strain partitioning between hierarchical levels, and to reduce cell density. This study elucidates the relation between in vivo loading, the Achilles tendon nano-, meso‑structure and mechanical response. The results provide fundamental insights into the mechanoregulatory mechanisms guiding the intricate biomechanics, tissue structural organization, and performance of complex collagen-based tissues. STATEMENT OF SIGNIFICANCE: Achilles tendon properties allow a dynamic interaction between muscles and tendon and influence force transmission during locomotion. Lack of physiological loading can have dramatic effects on tendon structure and mechanical properties. We have combined the use of cutting-edge high-resolution synchrotron techniques with mechanical testing to show how reduced loading affects the tendon on multiple hierarchical levels (from nanoscale up to whole organ) clarifying the relation between structural changes and mechanical performance. Our findings set the first step to address a significant healthcare challenge, such as the design of tailored rehabilitations that take into consideration structural changes after tendon immobilization.

How do Achilles tendon properties correlate with gait performance in cerebral palsy?

How do Achilles tendon properties correlate with gait performance in cerebral palsy?

518-P: Prior to Development of Neuropathy, People with Diabetes Have Altered Morphological and Mechanical Properties of the Ankle Joint, Tendons, and Muscles

Diabetes-related anatomical changes to the foot that foment ulcer formation are attributed to diabetic neuropathy. We hypothesized that prior to development of neuropathy, diabetes is associated with biomechanical changes in the ankle joint. To test this hypothesis, morphological properties of Achilles tendon, soleus, medial and lateral gastrocnemius muscles were evaluated by a LOGIQ ultrasound device at preset ankle (−30, −15,0,10) and knee (90,180) positions in both subjects with diabetes without neuropathy (DM; n=11, age 53±11, 3M, 8F, 87±16 kg, HbA1c 7.37±1.80, disease duration 75±79 months) and nondiabetic controls (CON; n=12, age 45±17, 5M, 7F, 75±14 kg). Monofilament (5.07/10 g) testing confirmed absence of neuropathy. As compared to CON, DM demonstrated significantly shorter Achilles length (p=0.002), smaller cross section area (p=0.018), higher Achilles stiffness (p=0.006), shorter muscle fascicles across the soleus muscle (p=0.03), higher stiffness in the soleus (p=0.001) and lateral gastrocnemius (p=0.002), and higher pennation angles for all three muscles (p&amp;lt;0.05). The current study demonstrates altered muscle-tendon unit mechanical properties in subjects with diabetes without neuropathy. These changes indicate a pathological process that may contribute to plantar ulcer formation even in absence of diabetic neuropathy. Disclosure R. Hoveizavi: None. F. Gao: None. S. Fisher: None.

Pro-inflammatory activity of long noncoding RNA FOXD2-AS1 in Achilles tendinopathy

Achilles tendinopathy is a prevalent clinical problem that plagues athletes and general populations. Achilles tendon healing is a complex process, and so far, there is no successful long-term solution to Achilles tendinopathy in the field of microsurgery due to its poor natural regeneration ability. Limitations in understanding the pathogenesis of Achilles tendon development and Achilles tendon injury hinder clinical treatment developments. There is an increasing demand for innovative conservative treatments that can improve Achilles tendon injury. In this study, a Sprague–Dawley rat model of Achilles tendinopathy was established. Lentiviral vectors that interfere with the expression of FOXD2-AS1, miR-21-3p, or PTEN were injected every 3 days. Rats were euthanized after 3 weeks, and the effect of FOXD2-AS1, miR-21-3p, or PTEN on Achilles tendon healing was analyzed by histological observation, biomechanical test, and examinations of inflammatory factors and tendon markers. As measured, downregulating FOXD2-AS1 or upregulating miR-21-3p improved histological structure, suppressed inflammation, promoted the expression of tendon markers, and optimized the biomechanical properties of Achilles tendon. Upregulating PTEN was capable of reversing the promoting effect of inhibition of FOXD2-AS1 on Achilles tendon healing. As concluded, deficiency of FOXD2-AS1 accelerates the healing of Achilles tendon injury and improves tendon degeneration by regulating the miR-21-3p/PTEN axis and promoting the activation of the PI3K/AKT signaling pathway.

Adolescent boys who participate in sports exhibit similar ramp torque control with young men despite differences in strength and tendon characteristics.

The goal of this paper was to determine if sports participation influences torque control differently for adolescent boys and young men during a slow ramp task. Twenty-one adolescent boys (11 athletes) and 31 young men (16 athletes) performed a slow ramp increase in plantar flexion torque from 0 to maximum. We quantified torque control as the coefficient of variation (CV) of torque during the ramp and quantified the Achilles tendon mechanical properties using ultrasonography. Relative to adolescent boys, young men were taller, heavier, stronger, and had a longer and stiffer Achilles tendon. However, these characteristics were not different between athletes and non-athletes in adolescent boys. For the CV of torque, there was a significant interaction with sports participation, indicating that only adolescent boys who were non-athletes had greater variability than young men. The CV of torque of all participants was predicted from the maximum torque and torque oscillations from 1 to 2Hz, whereas the CV of torque for adolescent boys was predicted only from torque oscillations from 1 to 2Hz. These findings suggested that adolescent boys who participate in sports exhibited lower torque variability during a slow ramp task, which was not explained by differences in Achilles tendon properties or strength.

Are the mechanical properties of Achilles tendon Altered in CrossFit athletes? Reliability and accuracy of myotonometry

Purpose Tendons adapt to loads affecting them, by changing tendons’ mechanical and morphological properties. The aim of the study has been to investigate the influence of involvement in sport activities in the form of CrossFit training by individuals of different age upon the mechanical properties of Achilles tendon. Methods 231 persons participated in the study. One group consisted of subjects who train CrossFit as amateurs, the other group comprised subjects who were not physically active. Achilles tendon was studied for various positions of the ankle joint: 0° DF/PF, 10° DF, 20° DF, 20° PF and 40° PF. The following mechanical and viscoelastic tendon properties were measured using MyotonPRO: frequency [Hz], stiffness [N/m], decrement [log], relaxation time [ms] and creep [De]. The results have been compared in reference to physical activity, BMI, age, and length of training history. Results Both the tension and stiffness increased with degree of Achilles tendon stretching and decreased as it contracted. Higher values have been noted in the group of people in training and with higher BMI values. The elasticity of Achilles tendon decreased with plantar flexion increase. Lower elasticity has been recorded in the group in training and with higher BMI. No significant influence of age and length of training history upon the parameters achieved has been noted. Conclusions The specificity of Crossfit training and accompanying mechanical load result in development of adaptation changes in Achilles tendon, in the form of its higher tone/tension and stiffness, as well as lower elasticity.

Nanoscale characterization of collagen structural responses to in situ loading in rat Achilles tendons

The specific viscoelastic mechanical properties of Achilles tendons are highly dependent on the structural characteristics of collagen at and between all hierarchical levels. Research has been conducted on the deformation mechanisms of positional tendons and single fibrils, but knowledge about the coupling between the whole tendon and nanoscale deformation mechanisms of more commonly injured energy-storing tendons, such as Achilles tendons, remains sparse. By exploiting the highly periodic arrangement of tendons at the nanoscale, in situ loading of rat Achilles tendons during small-angle X-ray scattering acquisition was used to investigate the collagen structural response during load to rupture, cyclic loading and stress relaxation. The fibril strain was substantially lower than the applied tissue strain. The fibrils strained linearly in the elastic region of the tissue, but also exhibited viscoelastic properties, such as an increased stretchability and recovery during cyclic loading and fibril strain relaxation during tissue stress relaxation. We demonstrate that the changes in the width of the collagen reflections could be attributed to strain heterogeneity and not changes in size of the coherently diffracting domains. Fibril strain heterogeneity increased with applied loads and after the toe region, fibrils also became increasingly disordered. Additionally, a thorough evaluation of radiation damage was performed. In conclusion, this study clearly displays the simultaneous structural response and adaption of the collagen fibrils to the applied tissue loads and provide novel information about the transition of loads between length scales in the Achilles tendon.

Achilles Tendons Display Region-Specific Transcriptomic Signatures Associated With Distinct Mechanical Properties

Background: Previous studies have examined the transcriptomes and mechanical properties of whole tendons in different regions of the body. However, less is known about these characteristics within a single tendon. Purpose: To develop a regional transcriptomic atlas and evaluate the region-specific mechanical properties of Achilles tendons. Study Design: Descriptive laboratory study. Methods: Achilles tendons from 2-month-old male Sprague Dawley rats were used. Tendons were isolated and divided into proximal, middle, and distal thirds for RNA sequencing (n = 5). For mechanical testing, the Achilles muscle-tendon-calcaneus unit was mounted in a custom-designed materials testing system with the unit clamped over the musculotendinous junction (MTJ) and the calcaneus secured at 90° of dorsiflexion (n = 9). Tendons were stretched to 20 N at a constant speed of 0.0167 mm/s. Cross-sectional area, strain, stress, and Young modulus were determined in each tendon region. Results: An open-access, interactive transcriptional atlas was generated that revealed distinct gene expression signatures in each tendon region. The proximal and distal regions had the largest differences in gene expression, with 2596 genes significantly differentially regulated at least 1.5-fold (q < .01). The proximal tendon displayed increased expression of genes resembling a tendon phenotype and increased expression of nerve cell markers. The distal region displayed increases in genes involved in extracellular matrix synthesis and remodeling, immune cell regulation, and a phenotype similar to cartilage and bone. There was a 3.72-fold increase in Young modulus from the proximal to middle region (P < .01) and an additional 1.34-fold increase from the middle to distal region (P = .027). Conclusion: Within a single tendon, there are region-specific transcriptomic signatures and mechanical properties, and there is likely a gradient in the biological and functional phenotype from the proximal origin at the MTJ to the distal insertion at the enthesis. Clinical Relevance: These findings improve our understanding of the underlying biological heterogeneity of tendon tissue and will help inform the future targeted use of regenerative medicine and tissue engineering strategies for patients with tendon disorders.

The acute effects of higher versus lower load duration and intensity on morphological and mechanical properties of the healthy Achilles tendon: a randomized crossover trial.

ABSTRACTThe Achilles tendon (AT) exhibits volume changes related to fluid flow under acute load which may be linked to changes in stiffness. Fluid flow provides a mechanical signal for cellular activity and may be one mechanism that facilitates tendon adaptation. This study aimed to investigate whether isometric intervention involving a high level of load duration and intensity could maximize the immediate reduction in AT volume and stiffness compared with interventions involving a lower level of load duration and intensity. Sixteen healthy participants (12 males, 4 females; age 24.4±9.4 years, body mass 70.9±16.1 kg, height 1.7±0.1 m) performed three isometric interventions of varying levels of load duration (2 s and 8 s) and intensity (35% and 75% maximal voluntary isometric contraction) over a 3 week period. Freehand 3D ultrasound was used to measure free AT volume (at rest) and length (at 35%, 55% and 75% of maximum plantarflexion force) pre- and post-interventions. The slope of the force–elongation curve over these force levels represented individual stiffness (N mm−1). Large reductions in free AT volume and stiffness resulted in response to long-duration high-intensity loading whilst less reduction was produced with a lower load intensity. In contrast, no change in free AT volume and a small increase in AT stiffness occurred with lower load duration. These findings suggest that the applied load on the AT must be heavy and sustained for a long duration to maximize immediate volume reduction, which might be an acute response that enables optimal long-term tendon adaptation via mechanotransduction pathways.

Effects of specific collagen peptide supplementation combined with resistance training on Achilles tendon properties.

The purpose of this study was to investigate the effect of specific collagen peptides (SCP) combined with resistance training (RT) on changes in tendinous and muscular properties. In a randomized, placebo-controlled study, 40 healthy male volunteers (age: 26.3±4.0years) completed a 14weeks high-load resistance training program. One group received a daily dosage of 5g SCP while the other group received 5g of a placebo (PLA) supplement. Changes in Achilles tendon cross-sectional area (CSA), tendon stiffness, muscular strength, and thickness of the plantar flexors were measured. The SCP supplementation led to a significantly (p=0.002) greater increase in tendon CSA (+11.0%) compared with the PLA group (+4.7%). Moreover, the statistical analysis revealed a significantly (p=0.014) greater increase in muscle thickness in the SCP group (+7.3%) compared with the PLA group (+2.7%). Finally, tendon stiffness and muscle strength increased in both groups, with no statistical difference between the groups. In conclusion, the current study shows that the supplementation of specific collagen peptides combined with RT is associated with a greater hypertrophy in tendinous and muscular structures than RT alone in young physically active men. These effects might play a role in reducing tendon stress (i.e., deposition of collagen in load-bearing structures) during daily activities.

Properties of triceps surae and Achilles tendon in forefoot and non-forefoot strike runners.

The purpose of this study was to compare the properties of the triceps surae and Achilles tendon of forefoot strike runners and non-forefoot strike runners. Fourteen male college forefoot strike runners and 11 non-forefoot strike runners participated in this study. The shear elastic moduli and cross-sectional areas of the medial and lateral gastrocnemius, soleus, and Achilles tendon were measured. Passive ankle joint stiffness, maximum voluntary isometric contraction on plantar flexion and Rebound Jump Index were also measured. Forefoot strike runners had higher shear elastic moduli of the medial and lateral gastrocnemius, higher passive ankle joint stiffness, higher Rebound Jump Index, and greater cross-sectional area of the gastrocnemius and Achilles tendon than non-forefoot strike runners. These findings suggest that forefoot strike runners have different mechanical properties in the gastrocnemius muscles, and different morphological properties in the Achilles tendon and gastrocnemius muscles, compared with non-forefoot strike runners.