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Jill Cook - One of the best experts on this subject based on the ideXlab platform.
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pathological Tendons maintain sufficient aligned fibrillar structure on ultrasound tissue characterization utc
Scandinavian Journal of Medicine & Science in Sports, 2016Co-Authors: Sea Docking, Jill CookAbstract:Structural disorganization in the tendon is associated with tendinopathy, with little research investigating whether disorganization overwhelms the overall structural integrity of the tendon. This study investigated the mean cross-sectional area (CSA) of aligned fibrillar structure as detected by ultrasound tissue characterization (UTC) in the pathological and normal Achilles and patellar Tendons. Ninety-one participants had their Achilles and/or patellar Tendons scanned using UTC to capture a three-dimensional image of the tendon and allow a semi-quantification of the echopattern. The mean CSA of aligned fibrillar structure (echo type I + II) and disorganized structure (echo type III + IV) was calculated based on UTC algorithms. Each tendon was classified as either pathological or normal based solely on gray-scale ultrasound. The mean CSA of aligned fibrillar structure was significantly greater (P ≤ 0.001) in the pathological tendon compared with the normal tendon, despite the pathological tendon containing greater amounts of disorganized structure (P ≤ 0.001). A significant relationship was observed between the mean CSA of disorganized structure and anteroposterior diameter of the Achilles (R(2) = 0.587) and patellar (R(2) = 0.559) Tendons. This study is the first to show that pathological Tendons have sufficient levels of aligned fibrillar structure. Pathological Tendons may compensate for areas of disorganization by increasing in tendon thickness.
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foot posture is associated with morphometry of the peroneus longus muscle tibialis anterior tendon and achilles tendon
Scandinavian Journal of Medicine & Science in Sports, 2014Co-Authors: George S Murley, R M Edwards, J De Luca, Shannon E Munteanu, Jill CookAbstract:: The aim of this study was to investigate the association between foot type and the morphometry of selected muscles and Tendons of the lower limb. Sixty-one healthy participants (31 male, 30 female; aged 27.1 ± 8.8 years) underwent gray-scale musculoskeletal ultrasound examination to determine the anterior-posterior (AP) thickness of tibialis anterior, tibialis posterior, and peroneus longus muscles and Tendons as well as the Achilles tendon. Foot type was classified based on arch height and footprint measurements. Potentially confounding variables (height, weight, hip and waist circumference, rearfoot and ankle joint range of motion, and levels of physical activity) were also measured. Multiple linear regression models were used to determine the association between foot type with muscle and tendon morphometry accounting for potentially confounding variables. Foot type was significantly and independently associated with AP thickness of the tibialis anterior tendon, peroneus longus muscle, and Achilles tendon, accounting for approximately 7% to 16% of the variation. Flat-arched feet were associated with a thicker tibialis anterior tendon, a thicker peroneus longus muscle, and a thinner Achilles tendon. Foot type is associated with morphometry of Tendons that control sagittal plane motion of the rearfoot; and the peroneus longus muscle that controls frontal plane motion of the rearfoot. These findings may be related to differences in tendon loading during gait.
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abnormal tenocyte morphology is more prevalent than collagen disruption in asymptomatic athletes patellar Tendons
Journal of Orthopaedic Research, 2004Co-Authors: Jill Cook, Julia A Felle, S F Ona, Karim M KhaAbstract:This study investigated the prevalence of each of the four features of patellar tendinosis in asymptomatic athletic subjects undergoing patellar tendon anterior cruciate ligament (ACL) reconstruction. Fifty subjects (39 males and 11 females) undergoing ACL reconstruction using a patellar tendon graft were screened for previous tendon symptoms, training and playing history and had their patellar Tendons examined with ultrasound prior to surgery. During surgery, a small piece of proximal posterocentral tendon was harvested, fixed and examined under light microscopy. Histopathological changes were graded for severity. Results demonstrate that 18 Tendons were abnormal on light microscopy and 32 were normal. There were no differences between subjects with and without pathology in respect of training, recovery after surgery and basic anthropometric measures. Three Tendons were abnormal on ultrasound but only one had proximal and central changes. Tendons showed a consistent series of changes. Tenocyte changes were found in all but one of the abnormal Tendons. In all but one of the Tendons with increased ground substance there were tenocyte changes, and collagen separation was always associated with both tenocyte changes and increased ground substance. No Tendons demonstrated neovascularization. It appears that cellular changes must be present if there is an increase in ground substance, or collagen and vascular changes. Further research is required to confirm these findings. © 2003 Orthopaedic Research Society. Published by Elsevier Ltd. All rights reserved
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patellar tendon ultrasonography in asymptomatic active athletes reveals hypoechoic regions a study of 320 Tendons
Institute of Health and Biomedical Innovation, 1998Co-Authors: Jill Cook, Karim M Kha, P R Harcou, Z S Kiss, M W Fehrma, Ly R Griffiths, Joh D WarkAbstract:OBJECTIVE: To compare patellar tendon sonographic findings in active, currently asymptomatic, elite athletes with those in nonathletic controls. DESIGN: Cross-sectional cohort study with convenience control sample. SETTING: The Victorian Institute of Sport Tendon Study Group, an institutional elite athlete study group in Australia. PATIENTS AND PARTICIPANTS: Two hundred elite male and female athletes from the sports of basketball, cricket, netball, and Australian rules football. Forty athletes who had current symptoms of jumper's knee were excluded from analysis, leaving 320 subject Tendons in athletes who were currently asymptomatic. Twenty-seven nonathletic individuals served as controls. MAIN OUTCOME MEASURE: Sonographic patellar tendon appearance. We measured the dimensions of subject Tendons and noted the presence or absence of hypoechoic regions and tendon calcification. Dimensions of hypoechoic regions were measured, and approximate cross-sectional areas were calculated. Chi-squared analysis was used to test the prevalence of hypoechoic regions in subjects and controls and men and women. RESULTS: In currently asymptomatic subjects, hypoechoic regions were more prevalent in athlete Tendons (22%) than in controls (4%), in male subject Tendons (30%) than in female subjects (14%), and in basketball players (32%) than in other athletes (9%) (all p < 0.01). Bilateral tendon abnormalities were equally prevalent in men and women but more prevalent in basketball players (15%) than in other athletes (3%) (p < 0.05). Sonographic hypoechoic regions were present in 35 of 250 (14%) patellar Tendons in athletes who had never had anterior knee pain. CONCLUSIONS: Patellar tendon sonographic hypoechoic areas were present in asymptomatic patellar Tendons of a proportion of elite athletes but rarely present in controls. This has implications for clinicians managing athletes with anterior knee pain.
Hakan Alfredson - One of the best experts on this subject based on the ideXlab platform.
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neovascularisation and pain in jumper s knee a prospective clinical and sonographic study in elite junior volleyball players
British Journal of Sports Medicine, 2005Co-Authors: Karl Gisslen, Hakan AlfredsonAbstract:Background: The nature of tendon neovascularisation associated with pain over time has not been studied. Objective: To prospectively study the patellar Tendons in elite junior volleyball players. Methods: The patellar Tendons in all students at the Swedish National Centre for high school volleyball were evaluated clinically and by ultrasonography (US) and Power Doppler (PD) sonography. Results: Altogether 120 patellar Tendons were followed for 7 months. At inclusion, jumper's knee was diagnosed clinically in 17 patellar Tendons. There were structural changes on US in 14 Tendons, in 13 of which PD sonography showed neovascularisation. There were 70 clinically normal Tendons with normal US and PD sonography, 24 clinically normal Tendons with abnormal US but normal PD sonography, and nine clinically normal Tendons with abnormal US and neovascularisation on PD sonography. At 7 month follow up, jumper's knee was diagnosed clinically and by US in 19 patellar Tendons, in 17 of which there was neovascularisation. Three of nine clinically normal Tendons with structural changes and neovascularisation at inclusion developed jumper's knee. Two of 24 Tendons clinically normal at inclusion, with abnormal US but normal PD sonography, developed jumper's knee with abnormal US and neovascularisation on PD sonography. A total of 20 clinically normal Tendons with normal US and PD sonography at inclusion developed structural tendon changes and 12 of these also developed neovascularisation. Conclusions: The clinical diagnosis of jumper's knee is most often associated with neovascularisation in the area with structural tendon changes. The finding of neovessels might indicate a deterioration of the condition.
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high prevalence of jumper s knee and sonographic changes in swedish elite junior volleyball players compared to matched controls
British Journal of Sports Medicine, 2005Co-Authors: Karl Gisslen, C Gyulai, Kerstin Soderman, Hakan AlfredsonAbstract:Background: Jumper's knee is a common and troublesome condition among senior volleyball players, but its prevalence among elite junior players compared to matched non-sports active controls is not known. Objective: To clinically, and by sonography, examine the patellar Tendons in elite junior volleyball players (15–19 years) at the Swedish National Centre for volleyball and in matched controls. Methods: The patellar Tendons in the 57 students at the Swedish National Centre for high school volleyball and in 55 age, height, and weight matched not regularly sports active controls were evaluated clinically and by grey scale ultrasonography (US) and power Doppler (PD) sonography. Results: There were no significant differences in mean age, height, and weight between the volleyball players and the controls. In the volleyball group, jumper's knee was diagnosed clinically and by US in 12 patellar Tendons (10 male and two female). In 12/12 Tendons, PD sonography demonstrated a neovascularisation in the area with structural tendon changes. In another 10 pain free Tendons, there were structural tendon changes and neovessels. In the control group, no individual had a clinical diagnosis of jumper's knee. US demonstrated structural tendon changes in 11 Tendons, but there was no neovascularisation on PD sonography. Conclusions: A clinical diagnosis of jumper's knee, together with structural tendon changes and neovascularisation visualised with sonography, was seen among Swedish elite junior volleyball players but not in matched not regularly sports active controls. Structural tendon change alone was seen in 10% of the control Tendons.
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chronic midportion achilles tendinopathy an update on research and treatment
Clinics in Sports Medicine, 2003Co-Authors: Hakan AlfredsonAbstract:Chronic painful conditions in the midportion of the Achilles tendon, often referred to as Achilles tendinopathy, are relatively common, especially among recreational athletes in the age group between 30 and 60. In the athletic population, the etiology is considered to be associated with overuse of the aged tendon, but scientifically, the etiology and pathogenesis are unknown. In general, Achilles tendinopathy has been considered to include an inflammatory component, and the nomenclature often used (tendinitis, tendonitis) implies inflammatory involvement. Recent research using microdialysis technique and gene technology, however, has clarified that there is no chemical inflammation in chronic midportion Achilles tendinosis (tendinopathy with ultrasonographically verified tendon changes). Interestingly, the neurotransmitter glutamate and its NMDAR1 receptor were found for the first time in human Tendons by using microdialysis and immunohistochemical techniques. The concentrations of glutamate were significantly higher in painful Tendons with tendinosis than in normal, pain-free Tendons. Treatment of Achilles tendinopathy is considered difficult, and in chronic Achilles tendinosis surgery is often needed. Recent research, however, has shown promising clinical results using nonsurgical methods. Painful eccentric calf muscle training as treatment of painful midportion chronic Achilles tendinosis has been demonstrated to give good short-term clinical results. Also, in a very recent pilot study, sclerosing of neovessels in the area with pain and tendon changes showed promising short-term clinical results. The Achilles tendon has a high capacity to withstand tensional forces, and is the strongest tendon in the human body. Chronic painful conditions in the tendon are relatively common, especially among middle-aged recreational athletes [1]. The etiology and pathogenesis are unknown. There is a wide range of suggested etiological factors, but the scientific background to most of these suggestions is
David E Birk - One of the best experts on this subject based on the ideXlab platform.
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structure physiology and biochemistry of collagens
Advances in Experimental Medicine and Biology, 2014Co-Authors: Michael J. Mienaltowski, David E BirkAbstract:Tendons and ligaments are connective tissues that guide motion, share loads, and transmit forces in a manner that is unique to each as well as the anatomical site and biomechanical stresses to which they are subjected. Collagens are the major molecular components of both Tendons and ligaments. The hierarchical structure of tendon and its functional properties are determined by the collagens present, as well as their supramolecular organization. There are 28 different types of collagen that assemble into a variety of supramolecular structures. The assembly of specific supramolecular structures is dependent on the interaction with other matrix molecules as well as the cellular elements. Multiple suprastructural assemblies are integrated to form the functional tendon/ligament. This chapter begins with a discussion of collagen molecules. This is followed by a definition of the supramolecular structures assembled by different collagen types. The general principles involved in the assembly of collagen-containing suprastructures are presented focusing on the regulation of tendon collagen fibrillogenesis. Finally, site-specific differences are discussed. While generalizations can be made, differences exist between different Tendons as well as between Tendons and ligaments. Compositional differences will impact structure that in turn will determine functional differences. Elucidation of the unique physiology and pathophysiology of different Tendons and ligaments will require an appreciation of the role compositional differences have on collagen suprastructural assembly, tissue organization, and function.
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dysfunctional tendon collagen fibrillogenesis in collagen vi null mice
Matrix Biology, 2011Co-Authors: Heather L Ansorge, Louis J Soslowsky, Guiyun Zhang, Paolo Bonaldo, David E BirkAbstract:Abstract Tendons are composed of fibroblasts and collagen fibrils. The fibrils are organized uniaxially and grouped together into fibers. Collagen VI is a non-fibrillar collagen expressed in developing and adult Tendons. Human collagen VI mutations result in muscular dystrophy, joint hyperlaxity and contractures. The purpose of this study is to determine the functional roles of collagen VI in tendon matrix assembly. During tendon development, collagen VI was expressed throughout the extracellular matrix, but enriched around fibroblasts and their processes. To analyze the functional roles of collagen VI a mouse model with a targeted inactivation of Col6a1 gene was utilized. Ultrastructural analysis of C ol6a1−/− versus wild type Tendons demonstrated disorganized extracellular micro-domains and associated collagen fibers in the C ol6a1−/− tendon. In C ol6a1−/− Tendons, fibril structure and diameter distribution were abnormal compared to wild type controls. The diameter distributions were shifted significantly toward the smaller diameters in Col6a1−/− Tendons compared to controls. An analysis of fibril density (number/μm 2 ) demonstrated a ~ 2.5 fold increase in the Col6a1−/− versus wild type Tendons. In addition, the fibril arrangement and structure were aberrant in the peri-cellular regions of Col6a1−/− Tendons with frequent very large fibrils and twisted fibrils observed restricted to this region. The biomechanical properties were analyzed in mature Tendons. A significant decrease in cross-sectional area was observed. The percent relaxation, maximum load, maximum stress, stiffness and modulus were analyzed and Col6a1−/− Tendons demonstrated a significant reduction in maximum load and stiffness compared to wild type Tendons. An increase in matrix metalloproteinase activity was suggested in the absence of collagen VI. This suggests alterations in tenocyte expression due to disruption of cell–matrix interactions. The changes in expression may result in alterations in the peri-cellular environment. In addition, the absence of collagen VI may alter the sequestering of regulatory molecules such as leucine rich proteoglycans. These changes would result in dysfunctional regulation of tendon fibrillogenesis indirectly mediated by collagen VI.
Denitsa Docheva - One of the best experts on this subject based on the ideXlab platform.
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achilles tendon elastic properties remain decreased in long term after rupture
Knee Surgery Sports Traumatology Arthroscopy, 2018Co-Authors: B Frankewycz, A Penz, Johannes Weber, N P Da Silva, F Freimoser, R Bell, Michael Nerlich, E M Jung, Denitsa DochevaAbstract:Rupture of the Achilles tendon results in inferior scar tissue formation. Elastography allows a feasible in vivo investigation of biomechanical properties of the Achilles tendon. The purpose of this study is to investigate the biomechanical properties of healed Achilles Tendons in the long term. Patients who suffered from Achilles tendon rupture were recruited for an elastographic evaluation. Unilateral Achilles tendon ruptures were included and scanned in the mid-substance and calcaneal insertion at least 2 years after rupture using shear wave elastography. Results were compared to patients’ contralateral non-injured Achilles Tendons and additionally to a healthy population. Descriptive statistics, reliability analysis, and correlation analysis with clinical scores were performed. Forty-one patients were included in the study with a mean follow-up-time of 74 ± 30; [26–138] months after rupture. Significant differences were identified in shear wave elastography in the mid-substance of healed Tendons (shear wave velocity 1.2 ±1.5 m/s) compared to both control groups [2.5 ±1.5 m/s (p < 0.01) and 2.8 ±1.6 m/s (p < 0.0001) contralateral and healthy population, respectively]. There was no correlation between the measurements and the clinical outcome. This study shows that the healed Achilles tendon after rupture has inferior elastic properties even after a long-term healing phase. Differences in elastic properties after rupture mainly originate from the mid-substance of the Achilles tendon, in which most of the ruptures occur. Elastographic results do not correspond with subjective perception. Clinically, sonoelastographical measurements of biomechanical properties can be useful to provide objective insights in tendon recovery.
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biologics for tendon repair
Advanced Drug Delivery Reviews, 2015Co-Authors: Denitsa Docheva, Sebastian Muller, Martin Majewski, Christopher H EvansAbstract:Tendon injuries are common and present a clinical challenge to orthopedic surgery mainly because these injuries often respond poorly to treatment and require prolonged rehabilitation. Therapeutic options used to repair ruptured Tendons have consisted of suture, autografts, allografts, and synthetic prostheses. To date, none of these alternatives has provided a successful long-term solution, and often the restored Tendons do not recover their complete strength and functionality. Unfortunately, our understanding of tendon biology lags far behind that of other musculoskeletal tissues, thus impeding the development of new treatment options for tendon conditions. Hence, in this review, after introducing the clinical significance of tendon diseases and the present understanding of tendon biology, we describe and critically assess the current strategies for enhancing tendon repair by biological means. These consist mainly of applying growth factors, stem cells, natural biomaterials and genes, alone or in combination, to the site of tendon damage. A deeper understanding of how tendon tissue and cells operate, combined with practical applications of modern molecular and cellular tools could provide the long awaited breakthrough in designing effective tendon-specific therapeutics and overall improvement of tendon disease management.
Rone Schweitze - One of the best experts on this subject based on the ideXlab platform.
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regulation of tendon differentiation by scleraxis distinguishes force transmitting Tendons from muscle anchoring Tendons
Development, 2007Co-Authors: Nicholas D Murchiso, Ia A Price, David A Conne, Douglas R Keene, Eric N Olso, Clifford J Tabi, Rone SchweitzeAbstract:The scleraxis (Scx) gene, encoding a bHLH transcription factor, is expressed in the progenitors and cells of all tendon tissues. To determine Scx function, we produced a mutant null allele. Scx-/- mice were viable, but showed severe tendon defects, which manifested in a drastically limited use of all paws and back muscles and a complete inability to move the tail. Interestingly, although the differentiation of all force-transmitting and intermuscular Tendons was disrupted, other categories of Tendons, the function of which is mainly to anchor muscles to the skeleton, were less affected and remained functional, enabling the viability of Scx-/- mutants. The force-transmitting Tendons of the limbs and tail varied in the severity to which they were affected, ranging from dramatic failure of progenitor differentiation resulting in the loss of segments or complete Tendons, to the formation of small and poorly organized Tendons. Tendon progenitors appeared normal in Scx-/- embryos and a phenotype resulting from a failure in the condensation of tendon progenitors to give rise to distinct Tendons was first detected at embryonic day (E)13.5. In the Tendons that persisted in Scx-/- mutants, we found a reduced and less organized tendon matrix and disorganization at the cellular level that led to intermixing of tenocytes and endotenon cells. The phenotype of Scx-/- mutants emphasizes the diversity of tendon tissues and represents the first molecular insight into the important process of tendon differentiation.
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analysis of the tendon cell fate using scleraxis a specific marker for Tendons and ligaments
Development, 2001Co-Authors: Rone Schweitze, Eric N Olso, Jay H Chyung, Lewis C Murtaugh, Ava E E, Vicki Rose, Andrew Lassa, Clifford J TabiAbstract:Little is known about the genesis and patterning of Tendons and other connective tissues, mostly owing to the absence of early markers. We have found that Scleraxis, a bHLH transcription factor, is a highly specific marker for all the connective tissues that mediate attachment of muscle to bone in chick and mouse, including the limb Tendons, and show that early scleraxis expression marks the progenitor cell populations for these tissues. In the early limb bud, the tendon progenitor population is found in the superficial proximomedial mesenchyme. Using the scleraxis gene as a marker we show that these progenitors are induced by ectodermal signals and restricted by bone morphogenetic protein (BMP) signaling within the mesenchyme. Application of Noggin protein antagonizes this endogenous BMP activity and induces ectopic scleraxis expression. However, the presence of excess tendon progenitors does not lead to the production of additional or longer Tendons, indicating that additional signals are required for the final formation of a tendon. Finally, we show that the endogenous expression of noggin within the condensing digit cartilage contributes to the induction of distal Tendons.
