Hyaluronate in total hip replacement.

We studied the composition of the fluid in joint cavity of the hip joint in primary osteoarthritis (OA) from samples obtained at primary total hip replacement (THR) operations (N = 21) and in the THR pseudojoint, where the samples were obtained in revision operations for the common type of prosthesis loosening (N = 17). Protein concentrations differed little in both groups (31.8 +/- 1.9 mg/ml vs 34.4 +/- 1.9 mg/ml, p < 0.01), which suggests similar transcapillary flow in the degenerative hip joint and THR pseudojoint. Hyaluronate was found in OA joint fluid and in the fluid from the THR pseudojoint (2.21 +/- 0.23 mg/ml vs 0.43 +/- 0.04 mg/ml, p < 0.005) and high performance liquid chromatography (HPLC) analysis, calibrated using laser light scatter analyzed molecular weight standards, disclosed the low molecular weight nature of the OA synovial fluid compared to the THR pseudojoint fluid (1.12 +/- 0.84 x 10(6) vs 2.63 +/- 1.13 x 10(6) Da, NS). This suggests that THR arthroplasties cause an adaptive tissue response and formation of fibroblast-like B type lining cells able to synthesize and secrete hyaluronate.