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.

Genom att generera mer information om hälsenan i form av dess elasticitet kan förhoppningsvis fler slutsater nås gällande diagnostik och behandling. Elastografi med hjälp av ultraljud skulle kunna vara en metod för att bidra med denna information. För att utföra detta anpassades en mjukvara utifrån ett grundläggande basprogram för elastografimätningar, utvecklat av företaget Verasonics, för att kunna utföra elastografi av hälsenan genom programmering i matlab. Tidigare undersökningsmetoder för elastografi är utvecklade för större organ, varför anpassningen innebar att använda metoder som även ger tillförlitlig information för mindre organ. För att göra detta anpassades först mjukvaran för en mindre fantom med liknande djup som hälsenan. När det konstaterats att skjuvningsvågor genererats på rätt avstånd kunde sedan mätningar göras på hälsenan. Genom att bestämma hastigheten av de genererade skjuvningsvågorna kunde sedan skjuvmodulen, följt av elasticitetsmodulen, beräknas för vävnaden. Denna bestämdes först genom grupphastigheten av skjuvningsvågorna, vilket är den metod som används vid större organ, följt av fashastigheten av skjuvningsvågorna vilket tar hänsyn till vågens dispersion. Detta gav då hälsenans elasticitetsmodul enligt grupphastighet samt fashastighet som sedan kunde jämföras. Slutligen gick det att konstatera att elasticitetsmodulen kommer att variera beroende på vilken typ av hastighet denna härleds från. Detta indikerar då på att sjuvningsvågen interagerar med organets gränsyta vilket orsakar dispersion. / Generating more information about the achilles tendon, such as its elasticity, will hopefully lead to more conclusions and results within both diagnostics as well as treatment. Elastography by ultrasound could be a method to contribute with this information. To do so, a basic software,provided and developed by the company Verasonics for elastography was specialized to fit the achilles tendon by programing in matlab. Earlier methods to perform elastography are developed for larger organs, hence the adjustment will include methods that acquire trustworthy information from smaller organs. To do so the adjustment of the software was first made to work on a smaller phantom with similar symmetry as the achilles tendon. When it was confirmed that shear waves were generated at the correct distance this enabled further measurements on the achilles tendon. By deciding the speed of the generated shear waves the shear modulus, followed by the elastic modulus, could then be estimated for the tissue. This was first decided by the group velocity of the shear waves, as the usual method done on larger organs, followed by the phase velocity that also takes dispersion in mind. The result could then be used to obtain the elastic modulus of the achilles tendon based on group and phase velocity for further comparison.The conclusion was then that the elastic modulus will depend on what kind of velocity it is derived from. This indicates that the shear wave interacts with the organ's boundaries which causes dispersion.

Hälsenan har en viktig roll för motoriken av underbenet samt rörelse vid gång och löpning. I och med detta sker det en stor belastning på hälsenan vid gång och löpning vilket kan leda till bristningar och skador på senan. Dessa bristningar kan ske när hälsenan deformeras i samband med fysisk aktivitet. Deformation av hälsenan är differensen mellan relativ displacement i senan och är ett viktigt koncept inom förståelsen om hälseneskadors etiologi. Syftet med detta examensarbete var att öka kunskapen om displacement i hälsenan och hur det skiljer sig vid habituell löpning med olika löparskor inklusive barfotalöpning. Vidare felsöktes en speckle tracking-algoritm som lägger grund för analysen av displacement i hälsenan. Arbetet är en utökning på ett pågående forskningssamarbete mellan KTH, GIH och KI. Det första steget i arbetet var att MATLAB-programmet för speckle tracking-algoritmen felsöktes och korrigerades. Detta gjordes genom att ändra initiala startvärden i algoritmen såsom centralfrekvensen och värdet för hastigheten av displacement i hälsenan. Efter att hastigheten valts till 2 cm/s fungerade algoritmen felfritt. Nästa steg var att exekvera programmet på den ultraljudsdata för hälsenan som tidigare samlats in från forskningssamarbetet. Algoritmen kördes för tre studiepersoner för habituell löpstil med tre olika löparskor samt barfota. Detta resulterade i att medelvärdeskurvor för ytlig och djup displacement i hälsenan kunde plottas där dess minimum- och maximumvärden kunde jämföras. Efter att differensen för minimum- och maximumvärdet för ytlig och djup displacement hade jämförts mellan samtliga löparskor samt barfota, kunde följande konstateras. Löpning med traditionella skor medförde högst djup displacement följt av skor med kolfibersula, minimalistiska skor och barfotalöpning. Den sko som medförde högst ytlig displacement var skor med kolfibersula följt av traditionella skor, minimalistiska skor samt löpning barfota. Jämförelsen har ej baserats på någon statistisk grund då endast tre studiepersoner analyserades. Detta medför en viss osäkerhet gällande vilken skotyp som medför högst respektive lägst displacement. Bortsätt från denna osäkerhet kan det konstateras att resultat från tidigare studier tyder på liknande insikter. / The Achilles tendon plays a crucial role in the motor function of the lower leg, as well as in the motion involved in walking and running. As a result, the Achilles tendon undergoes significant stress during walking and running, which can lead to tears and injuries to the tendon. These tears can occur when the Achilles tendon is deformed associated with physical activity. The deformation of the Achilles tendon is the difference between the relative displacement in the tendon and is an important concept in understanding the etiology of Achilles tendon injuries. The purpose of this thesis is to increase knowledge about the displacement in the Achilles tendon and how it differs during habitual running with different running shoes, including barefoot running. Furthermore, a speckle tracking algorithm that forms the basis for analyzing the displacement in the Achilles tendon is debugged. The work is an extension of an ongoing research collaboration between KTH, GIH, and KI. The first step in the work was to debug and correct the MATLAB program for the speckle tracking algorithm. This was done by changing initial starting values in the algorithm such as the central frequency and the value for the speed of displacement in the Achilles tendon. After choosing a speed of 2 cm/s, the algorithm worked flawlessly. The next step was to execute the program on the ultrasound data for the Achilles tendon previously collected from the research collaboration. The algorithm was run for test subjects 17, 18, and 21 for habitual running style with three different running shoes and barefoot. This resulted in mean value curves for superficial and deep displacement in the Achilles tendon being plotted, with their minimum and maximum values being compared. After comparing the difference between the minimum and maximum values of superficial and deep displacement across all running shoes as well as barefoot, the following observations were made. Running with traditional shoes caused the highest deep displacement, followed by shoes with carbon fiber soles, minimalist shoes, and barefoot running. The shoe that caused the highest superficial displacement was shoes with carbon fiber soles, followed by traditional shoes, minimalist shoes, and running barefoot. The comparison was not based on any statistical basis since only three test subjects were analyzed. This implies some uncertainty as to which type of shoe causes the highest and lowest displacement. Aside from this uncertainty, it can be noted that the results from previous studies have findings that suggest similar insights.