Changes In Tendon Research Articles

Obesity/Type II Diabetes Promotes Function-limiting Changes in Murine Tendons that are not reversed by Restoring Normal Metabolic Function

Type II Diabetes (T2DM) negatively alters baseline tendon function, including decreased range of motion and mechanical properties; however, the biological mechanisms that promote diabetic tendinopathy are unknown. To facilitate identification of therapeutic targets we developed a novel murine model of diabetic tendinopathy. Mice fed a High Fat Diet (HFD) developed diet induced obesity and T2DM and demonstrated progressive impairments in tendon gliding function and mechanical properties, relative to mice fed a Low Fat Diet (LFD). We then determined if restoration of normal metabolic function, by switching mice from HFD to LFD, was sufficient to halt the pathological changes in tendon due to obesity/T2DM. However, switching from a HFD to LFD resulted in greater impairments in tendon gliding function than mice maintained on a HFD. Mechanistically, IRβ signaling is decreased in obese/T2DM murine tendons, suggesting altered IRβ signaling as a driver of diabetic tendinopathy. However, knock-down of IRβ expression in S100a4-lineage cells (IRcKOS100a4) was not sufficient to induce diabetic tendinopathy as no impairments in tendon gliding function or mechanical properties were observed in IRcKOS100a4, relative to WT. Collectively, these data define a murine model of diabetic tendinopathy, and demonstrate that restoring normal metabolism does not slow the progression of diabetic tendinopathy.

Validation of Sonography findings of synovitis and tenosynovitis of hands and wrists in patients with systemic sclerosis.

Validating musculoskeletal ultrasound features of the joints and tendons of the hands in a large scleroderma cohort. A total of 81 scleroderma patients participated in this prospective, cross-sectional study. Grayscale and power Doppler musculoskeletal ultrasound images of 13 joints and 5 tendons of the wrist and hand were obtained. Clinical assessment included modified Rodnan skin thickness score, joint count, and Scleroderma Health Assessment Questionnaire. Face validity, content validity, construct validity, and feasibility were assessed. Mean age was 53.8 years (range 22-80), 76.5% were females, and disease duration ranged from 0.25 to 29 years. Mean length of the examination was 36 min. Scleroderma Health Assessment Questionnaire-Disability Index correlated with musculoskeletal ultrasound erosions (r = 0.5, p = 0.0003). Skin score correlated with tendinitis grayscale (r = 0.26, p = 0.02). Intra-reader correlation coefficient for musculoskeletal ultrasound was 0.96 for the joints and could not be calculated for tendons because there were too few positive findings. When tendon changes existed, percent of agreement was 77.7%-83.3%. Musculoskeletal ultrasound of 13 joints and 5 tendons of the hands and wrist has face and content validity. Construct validity was shown for the tendons and erosion scores. Feasibility and reliability were partially validated.

Evaluating the role of subacromial impingement in rotator cuff tendinopathy: Development and analysis of a novel murine model.

Subacromial impingement of the rotator cuff is understood as a contributing factor in the development of rotator cuff tendinopathy. However, changes that occur in the impinged tendon are poorly understood and warrant further study. To enable further study of rotator cuff tendinopathy, we performed a controlled laboratory study to determine feasibility and baseline characteristics of a new murine model for subacromial impingement. This model involves surgically inserting a microvascular clip into the subacromial space in adult C57Bl/6 mice. Along with a sham surgery arm, 90 study animals were distributed among time point groups for sacrifice up to 6 weeks. All animals underwent bilateral surgery (total N = 180). Biomechanical, histologic, and molecular analyses were performed to identify and quantify the progression of changes in the supraspinatus tendon. Decreases in failure force and stiffness were found in impinged tendon specimens compared to sham and no-surgery controls at all study time points. Semi-quantitative scoring of histologic specimens demonstrated significant, persistent tendinopathic changes over 6 weeks. Quantitative real-time polymerase chain reaction analysis of impinged tendon specimens demonstrated persistently increased expression of genes related to matrix remodeling, inflammation, and tendon development. Overall, this novel murine subacromial impingement model creates changes consistent with acute tendonitis, which may mimic the early stages of rotator cuff tendinopathy. A robust, simple, and reproducible animal model of rotator cuff tendinopathy is a valuable research tool to allow further studies of cellular and molecular mechanisms and evaluation of therapeutic interventions in rotator cuff tendinopathy. © 2018 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:2780-2788, 2018.

Psoriasis and the risk of foot and ankle tendinopathy or enthesopathy in the absence of psoriatic arthritis: a population-based study

ObjectivesImaging studies in patients with cutaneous psoriasis have demonstrated asymptomatic bone and tendon changes, commonly of the foot and ankle. We sought to determine if patients with cutaneous psoriasis have...

Towards Wearable A-Mode Ultrasound Sensing for Real-Time Finger Motion Recognition.

It is evident that surface electromyography (sEMG) based human-machine interfaces (HMI) have inherent difficulty in predicting dexterous musculoskeletal movements such as finger motions. This paper is an attempt to investigate a plausible alternative to sEMG, ultrasound-driven HMI, for dexterous motion recognition due to its characteristic of detecting morphological changes of deep muscles and tendons. A multi-channel A-mode ultrasound lightweight device is adopted to evaluate the performance of finger motion recognition; an experiment is designed for both widely acceptable offline and online algorithms with eight able-bodied subjects employed. The experiment result presents that the offline recognition accuracy is up to 98.83% ± 0.79%. The real-time motion completion rate is 95.4% ± 8.7% and online motion selection time is 0.243 ± 0.127 s. The outcomes confirm the feasibility of A-mode ultrasound based wearable HMI and its prosperous applications in prosthetic devices, virtual reality, and remote manipulation.

Time dependent variation of carrying capacity of prestressed precast beam

The article deals with the evaluation of the precast concrete element time dependent carrying capacity. The variation of the resistance is inherited property of laboratory as well as in-situ members. Thus the specification of highest, yet possible, laboratory sample resistance is important with respect to evaluation of laboratory experiments based on the test machine loading capabilities. The ultimate capacity is evaluated through the bending moment resistance of a simply supported prestressed concrete beam. The probabilistic assessment is applied. Scatter of random variables of compressive strength of concrete and effective height of the cross section is considered. Monte Carlo simulation technique is used to investigate the performance of the cross section of the beam with changes of tendons’ positions and compressive strength of concrete.

Radiologic and Histologic Evaluation of Proximal Bicep Pathology in Patients With Chronic Biceps Tendinopathy Undergoing Open Subpectoral Biceps Tenodesis

To correlate preoperative magnetic resonance imaging (MRI) and intraoperative anatomic findings within the proximal long head biceps tendon to histologic evaluation of 3 separate zones of the tendon in patients with chronic biceps tendinopathy. Sixteen patients with chronic biceps tendinopathy were treated with open subpectoral biceps tenodesis. Preoperative MRI tendon grading was as follows: normal tendon, increased signal, tendon splitting, incomplete/complete tear. The removed portion of the biceps tendon was split into 3 segments: zone 1, 0-3.5cm from the labral insertion; zone 2, 3.5-6.5cm; and zone 3, 6.5-9cm, and was histologically evaluated using the Bonar score. Tenosynovium adjacent to the tendon was assessed histologically using the Osteoarthritis Research Society International score. CD31, CD3, and CD79a immunohistochemistries were conducted to determine vascularization, T-cell infiltrates, and B-cell infiltrates, respectively. Analysis of variance and Pearson correlations were performed for statistical analysis. Preoperative MRI showed no significant differences in tendon appearance between zones 1-3. Intraoperative findings included nonspecific degenerative SLAP tears or mild/moderate biceps tenosynovitis in all cases. Significantly (P< .001) higher Bonar scores were noted for tendon in zones 1 (7.9 ± 1.8) and 2 (7.3 ± 1.5) compared with zone 3(5.0± 1.1). Cell morphology scores in zone 1 (1.9 ± 0.4) and zone 2 (1.5 ± 0.6) were significantly higher than that in zone 3(0.8 ± 0.3) (P < .05). Inflammatory tenosynovium showed weak correlation with tendon changes in zone 1(r=0.08), zone 2 (r= 0.03), or zone 3 (r= 0.1). In patients with chronic long head biceps tendinopathy who underwent open subpectoral tenodesis, MRI and intraoperative assessment did not show significant structural abnormalities within the tendon despite significant histopathologic changes. Severity of tendon histopathology was more pronounced in the proximal and mid-portions of the tendon. Proximal versus distal biceps tenodesis is a subject of frequent debate. This study contributes to the ongoing evaluation of the characteristics of the proximal biceps in this type of pathologic condition.

Substrate fiber alignment mediates tendon cell response to inflammatory signaling

Healthy tendon tissue features a highly aligned extracellular matrix that becomes disorganized with disease. Recent evidence suggests that inflammation coexists with early degenerative changes in tendon, and that crosstalk between immune-cells and tendon fibroblasts (TFs) can contribute to poor tissue healing. We hypothesized that a disorganized tissue architecture may predispose tendon cells to degenerative extracellular matrix remodeling pathways, particularly within a pro-inflammatory niche. This hypothesis was tested by analyzing human TFs cultured on electrospun polycaprolactone (PCL) mats with either highly aligned or randomly oriented fiber structures. We confirmed that fibroblast morphology, phenotype, and markers of matrix turnover could be significantly affected by matrix topography. More strikingly, the TF response to paracrine signals from polarized macrophages or by stimulation with pro-inflammatory cytokines featured significant downregulation of signaling related to extracellular synthesis, with significant concomitant upregulation of gene and protein expression of matrix degrading enzymes. Critically, this tendency towards degenerative re-regulation was exacerbated on randomly oriented PCL substrates. These novel findings indicate that highly aligned tendon cell scaffolds not only promote tendon matrix synthesis, but also play a previously unappreciated role in mitigating adverse resident fibroblast response within an inflammatory milieu. Statement of SignificanceUse of biomaterial scaffolds for tendon repair often results in tissue formation characteristic of scar tissue, rather than the highly aligned type-1 collagen matrix of healthy tendons. We hypothesized that non-optimal biomaterial surfaces may play a role in these outcomes, specifically randomly oriented biomaterial surfaces that unintentionally mimic structure of pathological tendon. We observed that disorganized scaffold surfaces do adversely affect early cell attachment and gene expression. We further identified that disorganized fiber surfaces can prime tendon cells toward pro-inflammatory signaling. These findings represent provocative evidence unstructured fiber surfaces may underlie inflammatory responses that drive aberrant collagen matrix turnover. This work could be highly relevant for the design of cell instructive biomaterial therapies that yield positive clinical outcomes.

Does elasticity of Achilles tendon change after suture applications? Evaluation of repair area by acoustic radiation force impulse elastography

BackgroundAchilles tendon injuries are one of the most common tendon injuries. Surgical treatment is preferred in young and active patients. Although there are studies which evaluate the repair area with magnetic resonance imaging and ultrasonography after surgical treatment, there are very few studies which analyzes the elasticity of the tendon by quantitative methods. ARFI (acoustic radiation force impulse) elastography is a simple and non-invasive method that can quantitatively measure the elasticity of the soft tissues. Our study aims to evaluate the elasticity in the repair area of the surgically treated Achilles tendons, compare them to the non-injured side, and evaluate the effect of the suture method to the elasticity of the repaired tendons by using ARFI elastography.MethodsIn our retrospectively designed study, 19 patients who underwent surgical treatment with Krackow and modified Kessler suture methods after the Achilles tendon rupture between 2006 and 2014 were included. Shear wave velocity (SWV) of the repaired and non-injured Achilles tendons were measured by ARFI elastography in four different positions of the ankle.ResultsIt was determined that SWV in the surgically repaired tendons were significantly higher in each four different position of the ankle, compared to the non-injured side (p < 0.01), indicating less elasticity in the repaired tendons. There was no statistically significant difference between the SWV of Krackow and modified Kessler suture method groups at four different positions of the ankle (p > 0.05). AOFAS Ankle-Hindfoot, VISA-A, VAS, and FAOS scores were not also statistically different between these two suture methods (p > 0.05).ConclusionsIn the repaired Achilles tendon, there is a decrease in the elasticity compared to the non-injured side. The functional and elastographic results of Krackow and modified Kessler suture methods are similar in long-term follow-ups of the patients.

Lipofibromatous Hamartoma of the Plantar Nerve An Extremely Rare Localization.

Lipofibromatous hamartoma (LFH) is a rare, benign, tumor-like soft-tissue lesion that affects the peripheral nerves and forms a palpable neurogenic mass. Lipofibromatous hamartoma is associated with pain and sensory and/or motor deficits in the area of innervation of the affected nerve. This report describes a rare case of LFH of the plantar nerve. A 48-year-old woman presented to our outpatient orthopedic clinic with pain and a burning sensation on her left foot. The patient had a history of Morton's neuroma and had undergone a tarsal tunnel operation 2 years earlier at another center. None of her symptoms was alleviated by two previous operations. Magnetic resonance imaging with contrast revealed tenosynovitis of the flexor hallucis longus tendon and signal changes at deep tissue planes of the foot at the levels of the second and third toes, on the dorsal site and subcutaneous soft-tissue planes, suggesting edema and Morton's neuroma. The lesion was excised under spinal anesthesia, and histopathologic examination of the specimen revealed a diagnosis of LFH. The patient was discharged without any symptoms and her foot was normal at 8-month outpatient follow-up, with no indications of postoperative complications and/or recurrence.

Altered Achilles tendon function during walking in people with diabetic neuropathy: implications for metabolic energy saving.

The Achilles tendon (AT) has the capacity to store and release elastic energy during walking, contributing to metabolic energy savings. In diabetes patients, it is hypothesized that a stiffer Achilles tendon may reduce the capacity for energy saving through this mechanism, thereby contributing to an increased metabolic cost of walking (CoW). The aim of this study was to investigate the effects of diabetes and diabetic peripheral neuropathy (DPN) on the Achilles tendon and plantarflexor muscle-tendon unit behavior during walking. Twenty-three nondiabetic controls (Ctrl); 20 diabetic patients without peripheral neuropathy (DM), and 13 patients with moderate/severe DPN underwent gait analysis using a motion analysis system, force plates, and ultrasound measurements of the gastrocnemius muscle, using a muscle model to determine Achilles tendon and muscle-tendon length changes. During walking, the DM and particularly the DPN group displayed significantly less Achilles tendon elongation (Ctrl: 1.81; DM: 1.66; and DPN: 1.54 cm), higher tendon stiffness (Ctrl: 210; DM: 231; and DPN: 240 N/mm), and higher tendon hysteresis (Ctrl: 18; DM: 21; and DPN: 24%) compared with controls. The muscle fascicles of the gastrocnemius underwent very small length changes in all groups during walking (~0.43 cm), with the smallest length changes in the DPN group. Achilles tendon forces were significantly lower in the diabetes groups compared with controls (Ctrl: 2666; DM: 2609; and DPN: 2150 N). The results strongly point toward the reduced energy saving capacity of the Achilles tendon during walking in diabetes patients as an important factor contributing to the increased metabolic CoW in these patients. NEW & NOTEWORTHY From measurements taken during walking we observed that the Achilles tendon in people with diabetes and particularly people with diabetic peripheral neuropathy was stiffer, was less elongated, and was subject to lower forces compared with controls without diabetes. These altered properties of the Achilles tendon in people with diabetes reduce the tendon's energy saving capacity and contribute toward the higher metabolic energy cost of walking in these patients.

Structure and collagen crimp patterns of functionally distinct equine tendons, revealed by quantitative polarised light microscopy (qPLM)

Structure-function relationships in tendons are directly influenced by the arrangement of collagen fibres. However, the details of such arrangements in functionally distinct tendons remain obscure. This study demonstrates the use of quantitative polarised light microscopy (qPLM) to identify structural differences in two major tendon compartments at the mesoscale: fascicles and interfascicular matrix (IFM). It contrasts functionally distinct positional and energy storing tendons, and considers changes with age. Of particular note, the technique facilitates the analysis of crimp parameters, in which cutting direction artefact can be accounted for and eliminated, enabling the first detailed analysis of crimp parameters across functionally distinct tendons.IFM shows lower birefringence (0.0013 ± 0.0001 [−]), as compared to fascicles (0.0044 ± 0.0005 [−]), indicating that the volume fraction of fibres must be substantially lower in the IFM. Interestingly, no evidence of distinct fibre directional dispersions between equine energy storing superficial digital flexor tendons (SDFTs) and positional common digital extensor tendons (CDETs) were noted, suggesting either more subtle structural differences between tendon types or changes focused in the non-collagenous components.By contrast, collagen crimp characteristics are strongly tendon type specific, indicating crimp specialisation is crucial in the respective mechanical function. SDFTs showed much finer crimp (21.1 ± 5.5 µm) than positional CDETs (135.4 ± 20.1 µm). Further, tendon crimp was finer in injured tendon, as compared to its healthy equivalents. Crimp angle differed strongly between tendon types as well, with average of 6.5 ± 1.4° in SDFTs and 13.1 ± 2.0° in CDETs, highlighting a substantially tighter crimp in the SDFT, likely contributing to its effective recoil capacity. Statement of SignificanceThis is the first study to quantify birefringence in fascicles and interfascicular matrix of functionally distinct energy storing and positional tendons. It adopts a novel method – quantitative polarised light microscopy (qPLM) to measure collagen crimp angle, avoiding artefacts related to the direction of histological sectioning, and provides the first direct comparison of crimp characteristics of functionally distinct tendons of various ages.A comparison of matched picrosirius red stained and unstained tendons sections identified non-homogenous staining effects, and leads us to recommend that only unstained sections are analysed in the quantitative manner.qPLM is successfully used to assess birefringence in soft tissue sections, offering a promising tool for investigating the structural arrangements of fibres in (soft) tissues and other composite materials.

Effects of replacing soybean meal with chickpea seeds in the diet on mechanical and thermal properties of tendon tissue in broiler chicken

The efficiency of the musculoskeletal system of broiler chickens, in particular during locomotion and in ensuring its supportive function, depends directly on the adequate function and mechanical endurance of soft tissues, including tendons. However, little is known whether the properties of musculoskeletal soft tissues can be influenced by changes of dietary protein. We substituted soybean meal with raw chickpea seeds as the primary protein source in the diet and studied the effects it had on the mechanical and thermal properties of drumstick tendons in broiler Ross 308 chickens. In the experiment, 160 chicks were divided into 2 groups, receiving in their diet either soybean meal (n = 80) or chickpea seeds (n = 80). The experiment lasted 42 days. The physical condition of the drumstick tendons was analyzed on the basis of a tensile test and the results of thermal denaturation as measured by a differential scanning calorimetry. The mechanical evaluation of tendon tensile strength of the broilers fed with chickpea seeds demonstrated an increase in the ultimate strain (for over 22%, P < 0.04) and total energy absorbed by the tendon until rupture (for over 57%, P < 0.05) as when compared to the group fed with soybean meal. Thermal analysis demonstrated alterations in tendon collagen cross-linking as transition onset temperature decreased (from 63.8 to 61.8°C, P < 0.001), whereas the calorimetric enthalpy increased (from 16.2 to 22.1 J⋅g-1, P < 0.05) in the group fed with chickpea seeds. In summary, this study demonstrated that dietary protein source can impact the physical properties of tendons and showed that thermal analysis can be a useful tool for studying the effect of nutrition on the development and structural changes in tendons of broiler chickens.

WITHDRAWN: Aging upregulates CCN-1 expression leading to cell senescence and tissue degenerative changes in tendons

// Qibin Song 1 , Zhe Wang 2 , Yuling Wang 1 and Abdul Razaq 3 1 Department of Plastic Surgery, Shengjing Hospital of China Medical University, Shenyang 110004, P.R. China 2 Department of Pathology, Shengjing Hospital of China Medical University, Shenyang 110004, P.R. China 3 Department of Dermatology, Shengjing Hospital of China Medical University, Shenyang 110004, P.R. China Correspondence to: Qibin Song, email: sqb_cmu1@163.com Keywords: CCN-1; aging; tendon stem cell; senescence; differentiation Received: September 06, 2017 Accepted: December 22, 2017 Published: January 02, 2018 ABSTRACT Aging leads to degenerative changes in tissues and organs. Tendinopathy is a kind of tendon degenerative diseases found commonly in aging populations. A matricellular protein, CCN family member-1 (CCN-1) plays an important role in cell proliferation and differentiation. However, the precise cellular mechanisms responsible for the effects of CCN-1 on tendons, especially aging tendons are largely unknown. In this study we investigated the effects of aging and CCN-1 on tendon stem/progenitor cells (TSCs) of young (3 and 6 months old) and aging (12 and 18 months old) rats. We found CCN-1 expression markedly enhanced in rat tendons in an age-dependent manner. The CCN-1 mRNA was 5 times higher in 18 months old tendons than that of 3 months old tendons. Aging also increased cell senescence, decreased proliferation and “stemness” of the TSCs. Furthermore, CCN-1 treatment of young TSCs exhibited similar results found in aging TSCs. The expression of SA-β-Gal on young TSCs treated with CCN-1 significantly increased in a CCN-1 concentration-dependent manner. Moreover, some senescence-related genes, such as IL-1α, IL-1β, IL-6, TNF-α, IP-10, MMP-13, and GRO-1, were also increased in CCN-1 treated young TSCs in a CCN-1 concentration-dependent manner. These results were further verified with western blot. On the other hand, tenocyte-related genes including collagen type I and tenomodulin were decreased in young TSCs treated with CCN-1. Our findings indicate that CCN-1 plays an important role in degenerative tendon diseases. The inhibition of CCN-1 may slow down aging tendon degenerations and provide a new approach for treatment of tendon diseases.

Oral Ibuprofen Interferes with Cellular Healing Responses in a Murine Model of Achilles Tendinopathy.

Background:The attempted healing of tendon after acute injury (overloading, partial tear or complete rupture) proceeds via the normal wound healing cascade involving hemostasis, inflammation, matrix synthesis and matrix remodeling. Depending on the degree of trauma and the nature of the post-injury milieu, a variable degree of healing and recovery of function occurs. Post-injury analgesia is often achieved with NSAIDs such as Ibuprofen, however there is increasing evidence that NSAID usage may interfere with the healing process. This study aimed to investigate the cellular mechanism by which IBU therapy might lead to a worsening of tendon pathology.Methods:We have examined the effect of oral Ibuprofen, on Achilles tendon healing in a TGFb1-induced murine tendinopathy model. Dosing was started 3 days after initial injury (acute cellular response phase) and continued for 22 days or started at 9 days after injury (transition to matrix regeneration phase) and given for 16 days. Cellular changes in tendon and surrounding peritenon were assessed using Hematoxylin/Eosin, chondroid accumulation with Safranin O and anti-aggrecan immunohistochemistry, and neo-vessel formation with GSI Lectin histochemistry. Markers of inflammation included histochemical localization of hyaluronan, immunohistochemistry of heavy chain 1 and TNFα-stimulated glycoprotein-6 (TSG6). Cell responses were further examined by RT-qPCR of 84 NFκB target genes and 84 wound healing genes. Biomechanical properties of tendons were evaluated by tensile testing.Results:At a clinically-relevant dosage, Ibuprofen prevented the process of remodeling/removal of the inflammatory matrix components, hyaluronan, HC1 and TSG6. Furthermore, the aberrant matrix remodeling was accompanied by activation at day 28 of genes (Col1a2, Col5a3, Plat, Ccl12, Itga4, Stat3, Vegfa, Mif, Col4a1, Rhoa, Relb, F8, Cxcl9, Lta, Ltb, Ccl12, Cdkn1a, Ccl22, Sele, Cd80), which were not activated at any time without the drug, and so appear most likely to be involved in the pathology. Of these, Vegfa, Col4a1, F8, Cxcl9 and Sele, have been shown to play a role in vascular remodeling, consistent with the appearance at 25 days of vasculogenic cell groups in the peritenon and fat pad stroma surrounding the Achilles of the drug-dosed mice. Tensile stiffness (p = 0.004) and elastic modulus (p = 0.012) were both decreased (relative to age-matched uninjured and non-dosed mice) in mice dosed with Ibuprofen from day 3 to day 25, whether injured or not.Conclusion:We conclude that the use of Ibuprofen for pain relief during inflammatory phases of tendinopathy, might interfere with the normal processes of extracellular matrix remodeling and cellular control of expression of inflammatory and wound healing genes. It is proposed that the known COX2-mediated anti-inflammatory effect of ibuprofen has detrimental effects on the turnover of a pro-inflammatory HA matrix produced in response to soft-tissue injury, thus preventing the switch to cellular responses associated with functional matrix remodeling and eventual healing.

Automatic Myotendinous Junction Tracking in Ultrasound Images with Phase-Based Segmentation.

Displacement of the myotendinous junction (MTJ) obtained by ultrasound imaging is crucial to quantify the interactive length changes of muscles and tendons for understanding the mechanics and pathological conditions of the muscle-tendon unit during motion. However, the lack of a reliable automatic measurement method restricts its application in human motion analysis. This paper presents an automated measurement of MTJ displacement using prior knowledge on tendinous tissues and MTJ, precluding the influence of nontendinous components on the estimation of MTJ displacement. It is based on the perception of tendinous features from musculoskeletal ultrasound images using Radon transform and thresholding methods, with information about the symmetric measures obtained from phase congruency. The displacement of MTJ is achieved by tracking manually marked points on tendinous tissues with the Lucas-Kanade optical flow algorithm applied over the segmented MTJ region. The performance of this method was evaluated on ultrasound images of the gastrocnemius obtained from 10 healthy subjects (26.0 ± 2.9 years of age). Waveform similarity between the manual and automatic measurements was assessed by calculating the overall similarity with the coefficient of multiple correlation (CMC). In vivo experiments demonstrated that MTJ tracking with the proposed method (CMC = 0.97 ± 0.02) was more consistent with the manual measurements than existing optical flow tracking methods (CMC = 0.79 ± 0.11). This study demonstrated that the proposed method was robust to the interference of nontendinous components, resulting in a more reliable measurement of MTJ displacement, which may facilitate further research and applications related to the architectural change of muscles and tendons.

Comparison of Photobiomodulation and Anti-Inflammatory Drugs on Tissue Repair on Collagenase-Induced Achilles Tendon Inflammation in Rats

Tendinopathy is characterized by pain, edema, and structural changes in tendon tissue. In this animal study we decided to compare the short- and medium-term effects of low-level laser therapy (LLLT), dexamethasone, and diclofenac on inflammation and tendon tissue repair in collagenase-induced tendinitis. Two hundred five female Wistar rats were randomly divided into five groups. Animals in the control group were given a saline injection and the experimental groups received a collagenase injection (100 μg/tendon) in the peritendinous Achilles and received no treatment, LLLT (3 J, 810 nm, 100 mW), diclofenac (1.1 mg/kg), or dexamethasone (0.02 mg/kg). Histological analyses were performed at 10 time points up to 60 days (n = 5/group each time point), and included an assessment of the severity of inflammation, collagen fiber content, and organization. Collagenase injection induced a severe inflammatory reaction with significant reduction in collagen content for 48 h, and disorientation of collagen fibers lasting between 14 and 21 days. Diclofenac and dexamethasone reduced inflammatory signs during the first 2 days, although there was prolongation of the inflammatory phase and slower normalization of tendon quality, particularly in the dexamethasone group. LLLT prevented hemorrhage, reduced inflammation severity, and preserved tendon morphology compared with the other groups. LLLT showed a significant superiority over commonly used anti-inflammatory pharmaceutical agents in acute collagenase-induced tendinitis.

The Achilles Tendon in Healthy Subjects: An Anthropometric and Ultrasound Mapping Study

Ultrasonography is an inexpensive, fast, and reliable imaging technique widely used to assess the Achilles tendon. Although significant data exists regarding pathologic tendon changes, ultrasound data from healthy individuals are more limited. We aimed to better characterize ultrasound Achilles tendon measurements in healthy individuals and identify important correlating factors. The information collected included patient demographics, body habitus, activity level, foot dominance, and resting ankle angle. Ultrasound analysis was performed bilaterally on the Achilles tendons of 50 subjects using a high-frequency transducer to measure tendon width, thickness, cross-sectional area, and length. Males had a significantly larger mean tendon length, width, thickness, and cross-sectional area. No statistically significant difference was found in any tendon dimension between the white and black participants. Similarly, no difference was found in any tendon parameter when comparing right versus left leg dominance. Healthy subjects had a mean ankle resting angle of 45.1° ± 24° with no statistically significant difference between right and left ankles. Considering all individuals, each tendon parameter (tendon length, width, thickness, and cross-sectional area) correlated positively with subject height, weight, tibia length, and foot size. Only the Achilles cross-sectional area correlated significantly with the activity level. The resting angle of the ankle correlated positively with both tendon length and thickness. In conclusion, we found significant variations in Achilles tendon anatomy in the healthy adult population. We have thoroughly characterized significant correlations between healthy tendon dimensions and various body habitus, activity levels, and ankle parameters. Greater knowledge of the normal Achilles tendon anatomy and characterization of its variations in the healthy population will potentially allow for better pathologic diagnosis and surgical repair.

A cross-sectional study on the mechanical properties of the Achilles tendon with growth.

This study aimed to elucidate growth pattern of mechanical properties of the Achilles tendon and to examine if imbalance between growth of bone and muscle-tendon unit occurs during adolescence. Fourteen elementary school boys, 30 junior high school boys, 20 high school boys and 15 male adults participated in this study. Based on estimated age at peak height velocity (PHV), junior high school boys were separated into two groups (before or after PHV). An ultrasonography technique was used to determine the length, cross-sectional area, stiffness and Young's modulus of Achilles tendon. In addition, the maximum strain in "toe region" (strainTP) was determined to describe the balance between growth of bone and muscle-tendon unit. No group difference was observed in length, cross-sectional area and strainTP among the groups. However, stiffness and Young's modulus in after PHV groups were significantly higher than those of elementary school boys and before PHV groups(p ≤ 0.05). These results indicate that mechanical properties of Achilles tendon change dramatically at and/or around PHV to increased stiffness. The widely believed assumption that muscle-tendon unit is passively stretched due to rapid bone growth in adolescence is not supported.

Applying physical science principles to mid-substance Achilles tendinopathy and the relationship to eccentric lengthening exercises.

Mid-substance Achilles tendinopathy is common in the active population. Eccentric (lengthening) exercises are known to be effective in alleviating the clinical condition. To better understand mid-substance Achilles tendinopathy and the response to lengthening exercises physical science principles of elasticity are applied. We apply elastic motion laws to the spring-like tendon as well as the normal and pathological adaptation seen with this common injury. We will validate important assumptions of the spring-like behavior of the tendon and then apply these findings to the injured and rehabilitating states. Our analysis considers that the tendon can be viewed as being spring-like with elasticity principles being applicable and the force exerted on the tendon during lengthening is primarily in a uniaxial direction. This applied lengthening force results in tendon mechanical and structural adaptation. Injury, and ultimately the clinical condition, occurs when the applied force exceeds the ability of the tendon to normally adapt. Morphological changes of the injured tendon are an attempt by the body to make the tendon more compliant. Lengthening exercises can be assessed as achieving this task with an improvement of tendon compliance. Physical science analysis proposes that the preferred rehabilitation tendon pathway is to try and decrease tendon stiffness to allow for more tendon lengthening. The body's morphological alterations of the pathological tendon are also consistent with this approach. For mid-substance Achilles tendinopathy, this adaptation of decreased stiffness ultimately increases the tendons ability to withstand applied force during lengthening.