Arthrofibrosis is a disabling complication after knee
trauma and surgery. Clinically, it is characterized by
pain and joint stiffness due to massive connective tissue proliferation. In similar pathological conditions with fibrotic transformation such as lung
fibrosis or superficial
fibromatoses, an increased expression of
collagen type VI has been reported.
Collagen VI, which forms a filamentous network, is thought to serve as an anchoring
element between
collagen I/III fibrils and basement membranes and as a cell binding structure.
Collagen VI may also play a contributing role in the pathogenesis of arthrofibrosis. The aim of the present study was therefore to demonstrate the localization and distribution of
type VI collagen in arthrofibrotic 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 using an immunoperoxidase method for light microscopic visualization. Histologic analysis showed a synovial
hyperplasia with inflammatory cell infiltration 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 dysregulation of
collagen VI synthesis could be an important contributing factor in the complex mechanisms of disordered matrix
protein deposition leading to arthrofibrosis.