DISTRIBUTION OF COLLAGENS AND GLYCOSAMINOGLYCANS IN THE JOINT CAPSULEOF THE PROXIMAL INTERPHALANGEAL JOINT OF THE HUMAN FINGER

Background: The capsule of the proximal interphalangeal joint consists of the central slip of the extensor tendon dorsally, the collateral l igaments at the sides and the palmar ligament ventrally, Fibrocartilag inous menisci have been reported extending into the joint cavity and t he central slip has a sesamoid fibrocartilage articulating with the pr oximal phalanx, This study relates ECM composition in the joint capsul e to function, Methods: Each part of the capsule from 24 fingers amput ated because of trauma, carcinoma, isthaemia, fixed-flexion deformitie s or Dupuytren's contracture, was dissected out, Sections were prepare d for routine histology or immunolabelled with a panel of monoclonal a nd polyclonal antibodies against collagens and glycosaminoglycans usin g the avidin/biotin/peroxidase procedure. Results: All parts of the ca psule consistently labelled for types I, III and VI collagens and for dermatan and keratan sulphate, though labelling was more pericellular in fibrocartilaginous regions, In contrast, only certain regions of th e capsule in some fingers labelled for type II collagen, chondroitin 4 or 6 sulphate, The sesamoid fibrocartilage in the central slip showed the greatest degree of fibrocartilage differentiation, especially in fixed-flexion deformity fingers, and the palmar ligament the least, Co nclusions: The immunolabelling patterns suggest that there is an order ed sequence of matrix changes accompanying fibrocartilage differentiat ion, Chondroitin sulphate-containing proteoglycans accumulate first, a nd type II collagen appears later, The presence or absence of type II collagen probably relates to different levels of compressive loading, No fibrocartilaginous menisci were found in normal joints and those de scribed previously are regarded as synovial folds. (C) 1998 Wiley-Liss , Inc.