Localization of hyaluronan in pseudocapsule from total hip arthroplasty

Hyaluronan is a large glycosaminoglycan present in normal synovial fluid im parting important viscoelastic properties for joint lubrication. In normal and noninflammatory conditions, hyaluronan has been localized to the lining layer of the synovial membrane, specifically synovial fibroblasts. Prosthe tic joint fluid contains large amounts of hyaluronan, the source of which h as not been determined, Pseudocapsules from patients who had total hip arth roplasty and were having revision surgery for nonloosened and nonseptic con ditions were fixed in 10% acid formalin with 70% alcohol and stained for hy aluronic acid with biotinylated hyaluronic acid binding protein as a probe. Hyaluronan was localized strongly to the lining layer of the pseudocapsule , as in normal and osteoarthritic synovial membranes. The fibroblasts in th e pseudocapsule of total hip arthroplasty may be responsible for the persis tent production of hyaluronan in prosthetic joint fluid.