Chronic achilles paratenonitis. An immunohistologic study of fibronectin and fibrinogen.

Pathological alterations in chronic Achilles paratenonitis were studied histologically and using immunofluorescence techniques for fibronectin and fibrinogen in tissue samples obtained operatively from 11 athletes with this complaint and from 4 male cadavers serving as controls. The average duration of the paratenonitis was 20.4 months. The paratendineal fatty areolar tissue was clearly thickened and edematous, showing widespread fat necrosis and considerable connective tissue proliferation. The blood vessels were often obliterated and degenerated. Fibronectin and fibrinogen were commonly found in the proliferating connective tissue areas and in the vascular walls. Exudates rich in fibrinogen and fibronectin were seen in the inflamed paratendineal tissues, but not in the controls. The results indicate that increased vascular permeability and fibrin formation still persist in chronic Achilles paratenonitis and that marked obliterative and degenerative alterations of the blood vessels are frequent. The presence of fibronectin and fibrinogen points to an immature nature of scar tissue in chronic paratenonitis.