Objectif. Etudier l'association entre la degenerescence du tendon et les modifications de la composition de la matrice de collagene dans les tendinopathies du jambier posterieur. Methodes. Des echantillons issus de regions anormales de tendons de neuf patients atteints de tendinopathies du jambier posterieur etaient prepares pour analyses histologiques. Les collagenes de type<space>I, III et V etaient analyses par empreinte immunologique et une quantification etait realisee en densitometrie apres SDS-PAGE. Les residus proline et hydroxyproline etaient mis en evidence par chromatographie en milieu liquide. Les temoins etaient constitues de quatre echantillons homologues de regions normales de tendons et d'un echantillon de tendon provenant d'un patient ayant une arthrodese de cheville apres un accident. Resultats. Dans les tendons tibiaux posterieurs anormaux, trois types d'images histopathologiques de degre variables etaient observes<space>: augmentation de la teneur en mucine, hypercellularite fibroblastique et neovascularisation. De plus, des hausses de 79,3 et 32,4<space>% du contenu en proline et en hydroxyproline etaient respectivement mises en evidence dans ces tendons. Enfin, les tissus degeneres contenaient une proportion plus importante de collagene de type<space>III et de collagene de type<space>V (augmentation moyenne de 53,6 et 26,4<space>%, respectivement), associe a une reduction du collagene de type<space>I (baisse moyenne de 41,4<space>%). Conclusion. Dans les tendinopathies du jambier posterieur, la degenerescence tissulaire resulte de modifications profondes de la structure et de la composition moleculaire de la matrice de collagene. Les proportions importantes de collagenes de type<space>V et III dans les tendons leses semblent etre en partie a l'origine d'une baisse de resistance mecanique des tissus.
Objective. To investigate whether tendon degeneration in posterior tibial tendon dysfunction syndrome is associated with changes in extracellular matrix collagen composition. Methods. Specimens from grossly abnormal tendon regions from 9 patients with posterior tibial tendon dysfunction syndrome were prepared for routine histology. Collagens<space>I, III and V were typed by immunoblotting and quantified by densitometry after SDS-PAGE. Proline and hydroxyproline residues were determined by liquid chromatography. Four other samples from grossly normal homologous tendon regions and one surgical specimen from a healthy patient undergoing arthrodesis of the ankle after an accident were included as control. Results. In the grossly abnormal surgical posterior tibial tendon specimens we observed three types of histopathologic conditions present to varying degrees: increased mucin content, fibroblast hypercellularity and neovascularization. Analysis of degenerate tendons demonstrated a 79.3% increase in total proline and a 32.4% increase in 4-hydroxyproline. In addition, damaged tissue contained a higher proportion of collagen type III (mean increase: 53.6%) associated with a concomitant increase in type V collagen (mean increase: 26.4%). These alterations were accompanied by a reduction in type I collagen (mean decrease: 41.4%). Conclusion. In posterior tibial tendon dysfunction syndrome, the degenerative process results from marked changes in both structural organization and molecular composition of matrix collagens. The higher proportion of type V and type III collagens in degenerated tendons is likely to contribute to a decrease in the mechanical resistance of the tissue.