The aim of this study was to investigate the effect of intra-articular sodium hyaluronate (SH) injections on the main components of plasminogen activator (PA) system in the synovial fluid of temporomandibular joint (TMJ) osteoarthritis (OA).
Forty patients diagnosed with TMJ OA and 20 healthy control subjects were included in this study. Synovial fluid was collected in the OA group and the healthy group at baseline. The OA patients were randomly divided into 2 groups (20 patients for each group): One group received 5 injections of SH, and the other received 5 injections of physiologic saline solution in the upper joint space at weekly intervals. Synovial fluid was collected before and after treatment. Urokinase-type PA (uPA), soluble uPA receptor (suPAR) and PA inhibitor 1 (PAI-1) levels in synovial fluid were quantified by enzyme-linked immunosorbent assay.
The OA patients had significantly higher uPA activity and levels of uPA (median 80.01 ng/L), suPAR (median 7.54 ng/L), and PAI-1 (median 54.9 ng/mL) than the healthy control subjects (median 20.47 ng/L uPA, 2.34 ng/L suPAR, and 19.9 ng/mL PAI-1; (P < .05). The uPA activity and levels of uPA, suPAR, and PAI-1 were significantly decreased after SH injections in TMJs of OA patients (P < .05), and there was no difference after saline injection. Visual analog pain score reduction correlated with changes in uPA and uPAR levels as well as uPA activity.
The effects of SH on PA system provide new insight into a possible underlying mechanism by which SH alleviates pain of patients with TMJ OA.