Immunohistochemical localization of collagen VI in arthrofibrosis

Arthrofibrosis is a disabling complication after knee trauma and surgery. C linically, it is characterized by pain and joint stiffness due to massive c onnective tissue proliferation. In similar pathological conditions with fib rotic transformation such as lung fibrosis or superficial fibromatoses, an increased expression of collagen type VI has been reported. Collagen VI, wh ich forms a filamentous network, is thought to serve as an anchoring elemen t between collagen I/III fibrils and basement membranes and as a cell bindi ng structure. Collagen VI may also play a contributing role in the pathogen esis of arthrofibrosis. The aim of the present study was therefore to demon strate the localization and distribution of type VI collagen in arthrofibro tic tissue. Tissue samples from the infrapatellar fat pad and intercondylar synovia of 13 patients suffering from arthrofibrosis were taken at surgery . The expression of type VI collagen was studied immunohistochemically usin g an immunoperoxidase method for light microscopic visualization. Histologi c analysis showed a synovial hyperplasia with inflammatory cell infiltratio n and vascular proliferation. Compared with normal synovial tissue, type VI collagen was widely distributed as a network subsynovially and around the capillary walls. The results of the present study suggest that dysregulatio n of collagen VI synthesis could be an important contributing factor in the complex mechanisms of disordered matrix protein deposition leading to arth rofibrosis.