Localization of hyaluronan in pseudocapsule from total hip arthroplasty.

Hyaluronan is a large glycosaminoglycan present in normal synovial fluid imparting 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. Prosthetic joint fluid contains large amounts of hyaluronan, the source of which has not been determined. Pseudocapsules from patients who had total hip arthroplasty and were having revision surgery for nonloosened and nonseptic conditions were fixed in 10% acid formalin with 70% alcohol and stained for hyaluronic 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 the pseudocapsule of total hip arthroplasty may be responsible for the persistent production of hyaluronan in prosthetic joint fluid.