Tenascin-C levels in pseudosynovial fluid of loose hip prostheses

Objective: Aseptic loosening is one of the most important problems that can occur after total hip arthroplasty (THA). In this study, we analysed levels of large tenascin-C (TN-C) variants and compared them in pseudosynovial fluid from patients with aseptic loosening after THA with those in synovial fluid from patients undergoing primary THA ( control). Methods: Pseudosynovial fluid samples (n=24) were obtained by aspiration at the time of revision THA performed due to aseptic loosening. Synovial fluid samples (n=12) were obtained by aspiration at the time of primary THA. Expression of TN-C splice variants was examined using immunoblotting. TN-C levels were measured using an enzyme-linked immunosorbent assay ( ELISA) system that we developed previously. Results: Western blotting showed the presence of large TN-C variants in pseudosynovial fluid of artificial joints with loosening. TN-C levels were approximately three times higher in pseudosynovial fluid of loose artificial joints (median 151.9 ng/mL) than in synovial fluid controls ( median 50.1 ng/mL) ( p=0.035). Conclusion: Levels of TN-C including large variant subunits are elevated in pseudosynovial fluid of loose artificial joints, indicating that TN-C is a useful novel biochemical marker of loose hip prostheses.