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- Arndt, Anton, 1968-, et al.
(author)
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Non-uniform displacement within the Achilles tendon durig passive ankle joint motion.
- 2012
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In: Knee Surgery, Sports Traumatology, Arthroscopy. - : Springer Science and Business Media LLC. - 0942-2056 .- 1433-7347. ; 20:9, s. 1868-74
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Journal article (peer-reviewed)abstract
- PURPOSE:An initial step in the understanding of Achilles tendon dynamics is to investigate the effects of passive motion, thereby minimising muscle activation and reducing internal joint forces. Internal tendon dynamics during passive ankle joint motion have direct implications for clinical rehabilitation protocols after Achilles tendon surgery. The aim of this study was to test the hypothesis that tendon tissue displacement is different in different layers of the Achilles tendon during controlled passive ankle joint movements.METHODS:Ultrasound imaging was conducted on the right Achilles tendon of nine healthy recreationally active males. Standardised isokinetic passive dorsi-plantar-flexion movements were performed with a total range of motion of 35°. The tendon was divided into superficial, central and deep layers in the resulting B-mode ultrasound images viewed in the sagittal plane. A block-matching speckle tracking algorithm was applied post-process, with kernels for the measurement of displacement placed in each of the layers.RESULTS:The mean (SD) displacement of the Achilles tendon during passive dorsiflexion was 8.4 (1.9) mm in the superficial layer, 9.4 (1.9) mm in the central portion and 10.4 (2.1) mm in the deep layer, respectively. In all cases, the movement of the deep layer of the tendon was greater than that of the superficial one (P < 0.01).CONCLUSIONS:These results, achieved in vivo with ultrasonographic speckle tracking, indicated complex dynamic differences in different layers of the Achilles tendon, which could have implications for the understanding of healing processes of tendon pathologies and also of normal tendon function.
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| 2. |
- Bagge, Johan, 1984-
(author)
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TNF-α and neurotrophins in Achilles tendinosis
- 2013
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Doctoral thesis (other academic/artistic)abstract
- Tenocytes are the principal cells of the human Achilles tendon. In tendinosis, changes in the metabolism and morphology of these cells occur. Neurotrophins are growth factors essential for the development of the nervous system. Tumour necrosis factor alpha (TNF-α) has been found to kill sarcomas but has destructive effects in several major diseases. The two systems have interaction effects and are associated with apoptosis, proliferation, and pain signalling in various diseases. Whether these systems are present in the Achilles tendon and in Achilles tendinosis is unknown. The hypothesis is that the tenocytes produce substances belonging to these systems. In Studies I–III, we show that the potent effects of these substances are also likely to occur in the Achilles tendon. We found tenocyte immunoreactions for the neurotrophins brain-derived neurotrophic factor (BDNF), the nerve growth factor (NGF), the neurotrophin receptor p75, and for TNF-α and both of its receptors, TNFR1 and TNFR2. This occurred in both subjects with painful mid-portion Achilles tendinosis, and in controls. Furthermore, we found mRNA expression for BDNF and TNF-α in tenocytes, which proves that these cells produce these substances. TNFR1 mRNA was also detected for the tenocytes, and TNFR1 immunoreactions were upregulated in tendinosis tendons. This might explain why tenocytes in tendinosis undergo apoptosis more often than in normal tendons. Total physical activity (TPA) level and blood concentration of both soluble TNFR1 and BDNF were measured in Study IV. The results showed that the blood concentration of both factors were similar in subjects with tendinosis and in controls. Nevertheless, the TPA level was related to the blood concentration of sTNFR1 in tendinosis, but not in controls. This relationship should be studied further. The findings of this doctoral thesis show that neurotrophin and TNF-α systems are expressed in the Achilles tendon. We believe that the functions include tissue remodelling, proliferation and apoptosis.
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| 3. |
- Bjur, Dennis, 1965-
(author)
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The human Achilles tendon : innervation and intratendinous production of nerve signal substances - of importance in understanding the processes of Achilles tendinosis
- 2010
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Doctoral thesis (other academic/artistic)abstract
- Tendinopathies are painful tendon conditions of presumably multifactorial genesis. In tendinosis, as in Achilles tendinosis, there is apart from pain also morphological changes which are described as degenerative with no signs of inflammation. The exact mechanisms behind these conditions are still, to a large extent, unknown. Pain, being the foremost impairing symptom, leads us to the hypothesis that nerves are deeply involved in the symptoms and processes of Achilles tendinosis. Locally produced nerve signal substances may also be involved in the processes. Knowledge of the innervation patterns within the tendon and knowledge on a possible local nerve signal substance production are therefore of utmost importance. There is a lack of information on these aspects. The specific aims of this thesis were 1) to investigate the innervation patterns regarding general, sensory, cholinergic and sympathetic innervations, and 2) to examine for the possible occurrence of a production of nerve signal substances and a presence of receptors related to these in the tendon cells, the tenocytes. Painfree normal and tendinosis Achilles tendons were examined. Immunohistochemistry, using antibodies against the general nerve marker PGP9.5, the synthesizing enzymes for acetylcholine (choline acetyltransferase; ChAT), and catecholamines (tyrosine hydroxylase; TH), the vesicular acetylcholine transporter (VAChT), neuropeptide Y (NPY), substance P and calcitonin gene-related peptide, was applied. Immunohistochemistry was also used for the delineation of muscarinic (M2R), adrenergic (α1-AR) and NPY-ergic (Y1 and Y2) receptors. To detect mRNA for TH and ChAT, in situ hybridization was used. In normal Achilles tendons, as well as in the tendinosis tendons, there was a very scanty innervation within the tendon tissue proper, the main general, sensory and sympathetic innervations being found in the paratendinous loose connective tissue. Interestingly, the tenocytes showed immunoreactions for ChAT, VAChT, TH, M2R, α1-AR and Y1R. The reactions were clearly more observable in tendons of tendinosis patients than in those of controls. The tenocytes of tendinosis patients also displayed mRNA reactions for ChAT and TH. Nevertheless, all tenocytes in the tendinosis specimens did not show these reactions. Immunoreactions for α1-AR, M2R and Y1R were also seen for blood vessel walls. The present thesis shows that there is a very limited innervation within tendon tissue proper, whilst there is a substantial innervation in the paratendinous loose connective tissue. It also gives evidence for an occurrence of production of catecholamines and acetylcholine in tenocytes, especially for tendinosis tendons. Furthermore, that ACh, catecholamines and NPY can have effects on these, as well as on blood vessels, via the receptors observed. The observations suggest that Achilles tendon tissue, whilst containing a very scarce innervation, exhibits autocrine/paracrine cholinergic/catecholaminergic/NPY-ergic effects that are upregulated in tendinosis. These findings are of great importance as the results of such effects may mimic processes that are known to occur in tendinosis. That includes effects related to proliferation and angiogenesis, and blood vessel and collagen regulating effects. In conclusion, within the Achilles tendon there is a very scarce innervation, whilst there appears to be a marked local production of nerve signal substances in Achilles tendinosis, namely in the tenocytes, the cells also harbouring receptors for these substances. The observations give a new insight into how the tendon tissue of the Achilles tendon is influenced by signal substances and may give options for new treatments of Achilles tendinosis.
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| 4. |
- Gardin, Anna, et al.
(author)
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Dynamic contrast enhanced magnetic resonance imaging in chronic Achilles tendinosis
- 2013
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In: BMC Medical Imaging. - : Springer Science and Business Media LLC. - 1471-2342. ; 13, s. 39-
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Journal article (peer-reviewed)abstract
- Background: Chronic Achilles tendinosis is a common problem. When evaluating and comparing different therapies there is a need for reliable imaging methods. Our aim was to evaluate if chronic Achilles tendinosis affects the dynamic contrast-enhancement in the tendon and its surroundings and if short-term eccentric calf-muscle training normalizes the dynamic contrast-enhancement. Methods: 20 patients with chronic Achilles tendinopathy were included. Median duration of symptoms was 31 months (range 6 to 120 months). Both Achilles tendons were examined with dynamic contrast enhanced MRI before and after a 12-week exercise programme of eccentric calf-muscle training. The dynamic MRI was evaluated in tendon, vessel and in fat ventrally of tendon. Area under the curve (AUC), time to peak of signal, signal increase per second (SI/s) and increase in signal between start and peak as a percentage (SI%) was calculated. Pain and performance were evaluated using a questionnaire. Results: In the fat ventrally of the tendon, dynamic contrast enhancement was significantly higher in the symptomatic leg compared to the contralateral non-symptomatic leg before but not after treatment. Despite decreased pain and improved performance there was no significant change of dynamic contrast enhancement in symptomatic tendons after treatment. Conclusion: In Achilles tendinosis there is an increased contrast enhancement in the fat ventrally of the tendon. The lack of correlation with symptoms and the lack of significant changes in tendon contrast enhancement parameters do however indicate that dynamic enhanced MRI is currently not a useful method to evaluate chronic Achilles tendinosis.
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| 5. |
- Gärdin, Anna, et al.
(author)
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The long-term clinical and MRI results following eccentric calf muscle training in chronic Achilles tendinosis
- 2010
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In: Skeletal Radiology. - : Springer Science and Business Media LLC. - 0364-2348 .- 1432-2161. ; 39:5, s. 435-442
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Journal article (peer-reviewed)abstract
- PURPOSE: To evaluate the long-term results following eccentric calf-muscle training in patients with chronic Achilles tendinopathy.MATERIALS AND METHODS: A total of 24 patients with chronic Achilles tendinopathy were included in a study evaluating MRI findings and clinical symptoms before and after 3 months of daily eccentric calf-muscle strength training. Median duration of symptoms was 18 months (range 6-120). Four of the patients did not perform the prescribed treatment for different reasons and were followed for 14 months. The resulting 20 treated patients completed 4.2-year (range 29-58 months) follow up. Tendon volume was evaluated by using 3D seed growing technique and signal abnormalities were visually semi-quantitatively graded. Level of pain and performance was categorized using a questionnaire completed by the patient.RESULTS: In the symptomatic treated patients, median intensity level of pain decreased from moderate/severe at time of inclusion to mild at follow up (p < 0.05). Median level of performance increased from severe impairment at time of inclusion to normal at follow up (p < 0.05). 12 out of 20 patients had raised intratendinous signal at time of inclusion compared to 2 out of 20 patients at follow up (p < 0.001). Mean tendon-volume measured 6.7 cm(3) (SD 2.0) at time of inclusion and 6.4 cm(3) (SD 2.0) at follow up (p = 0.18). The four symptomatic non-treated tendons did not improve regarding pain, performance, intratendinous signal or tendon volume.CONCLUSION: We found decreased pain, improved performance and decreased intratendinous signal both compared to index examination and immediately after the 3 months training regimen in a 4.2-year clinical and MRI follow up, in a group of patients treated with heavy loaded eccentric calf-muscle training for chronic Achilles tendinopathy. The improvements were greater at 4.2-year follow up, despite no further active treatment, than immediately after the treatment. This may indicate a good long-term prognosis for Achilles tendinosis patients.
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