title: Arguments for an increasing differentiation towards fibrocartilaginous components in midportion Achilles tendinopathy.
abstract: OBJECTIVE
  The objective of this study was to investigate the fibrocartilaginous differentiation occurring in midportion Achilles tendinopathy.
  
  
  METHODS
  Tendon samples were retrospectively collected from 23 patients, who had undergone surgery for midportion Achilles tendinopathy resistant to conservative treatment. Based on histological scores, the biopts were subdivided into three categories: a light, moderate and severe histopathological stage. Throughout these stages, immunohistochemical staining was performed against biglycan, aggrecan and collagen type II, components characteristic for fibrocartilage. Staining of these components was evaluated using a semi-quantitative scoring method.
  
  
  RESULTS
  The immunohistochemical scores of biglycan and aggrecan were statistically significant between the histopathological stages (P < 0.001). The immunohistochemical scores were positively correlated with the increasing histopathological stages [Spearman's correlation coefficient = 0.93 for biglycan and 0.78 for aggrecan (P < 0.001)]. Staining for collagen type II remained negative throughout these stages.
  
  
  CONCLUSIONS
  Immunohistochemical staining of the fibrocartilaginous components biglycan and aggrecan showed a progressive increase, correlated with a further evolved histopathological stage. This observation gave arguments for an increased differentiation towards fibrocartilaginous components at protein level in midportion Achilles tendinopathy.
authors.affiliation: Faculty of Medicine and Health Sciences, Ghent University Hospital, Ghent University, De Pintelaan 185, 9000, Ghent, Belgium. arne.burssens@ugent.be
authors.forename: A
authors.initials: A
authors.lastname: Burssens
authors.forename: R
authors.initials: R
authors.lastname: Forsyth
authors.forename: W
authors.initials: W
authors.lastname: Bongaerts
authors.forename: M
authors.initials: M
authors.lastname: Jagodzinski
authors.forename: N
authors.initials: N
authors.lastname: Mahieu
authors.forename: M
authors.initials: M
authors.lastname: Praet
authors.forename: J
authors.initials: J
authors.lastname: Victor
mesh_terms: D000125:Achilles Tendon / Q000737:chemistry / Q000378:metabolism / Q000473:pathology*; D000328:Adult; D000368:Aged; D053674:Aggrecans / Q000032:analysis / Q000378:metabolism; D058578:Biglycan / Q000032:analysis / Q000378:metabolism; D002454:Cell Differentiation; D024043:Collagen Type II / Q000032:analysis / Q000378:metabolism; D051445:Fibrocartilage / Q000378:metabolism / Q000473:pathology*; D006801:Humans; D007150:Immunohistochemistry; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies; D052256:Tendinopathy / Q000378:metabolism / Q000473:pathology* / Q000601:surgery
chemical_list: D053674:Aggrecans; D058578:Biglycan; D024043:Collagen Type II