Arguments for an increasing differentiation towards fibrocartilaginous components in midportion Achilles tendinopathy

• Published in: Knee surgery, sports traumatology, arthroscopy : official journal of the ESSKA Vol. 21; no. 6; pp. 1459 - 1467
• Main Authors: Burssens, A., Forsyth, R., Bongaerts, W., Jagodzinski, M., Mahieu, N., Praet, M., Victor, J.
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer-Verlag 01.06.2013; Springer Nature B.V
• Subjects: Achilles Tendon - chemistry; Achilles Tendon - metabolism; Achilles Tendon - pathology; Adult; Aged; Aggrecans - analysis; Aggrecans - metabolism; Biglycan - analysis; Biglycan - metabolism; Cell Differentiation; Collagen; Collagen Type II - analysis; Collagen Type II - metabolism; Experimental Study; Fibrocartilage - metabolism; Fibrocartilage - pathology; Histopathology; Hospitals; Humans; Immunohistochemistry; Male; Medicine; Medicine & Public Health; Middle Aged; Orthopedics; Pathology; Pathophysiology; Retrospective Studies; Surgery; Tendinopathy - metabolism; Tendinopathy - pathology; Tendinopathy - surgery; Tendons; Belgium; Achilles tendon tendinosis; Fibrocartilaginous differentiation; Achilles tendon histopathology; Achilles midportion tendinopathy
• ISSN: 0942-2056; 1433-7347
• DOI: 10.1007/s00167-012-2203-3

Purpose 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. Conclusion 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. Level of evidence III.