Volume of a wash and the other conditions for maximum therapeutic effect of arthroscopic lavage in rheumatoid knees.

The objective of this study was to determine the appropriate volume of saline to obtain a beneficial effect of arthroscopic lavage and the prognostic factors related to the clinical effect in a refractory rheumatoid knee. Arthroscopic lavage or arthrocentesis was performed in a random manner in 142 patients with relapsing rheumatoid arthritis. All patients were followed up for 24 months. Intra-articular lavage with 5 l (p < 0.01) or 3 l (p < 0.05) of saline gave better clinical results than did arthrocentesis. There was no significant difference between the cumulative incidence of recurrence of knee synovitis in patients who underwent arthrocentesis and that in patients who underwent lavage with 1 l of saline. Cox regression analysis showed that patients with knee arthritis of more than 6 months in duration and with Larsen grade II or less were more responsive to lavage with 5 or 3 l of saline. The duration of the effect of lavage with 3 l of saline was increased 2.9-fold (p = 0.04) by injection of both steroids and high molecular weight hyaluronan. No bleeding or infectious complications occurred after those procedures. Arthroscopic lavage with 5 l of saline is safe and has good therapeutic effects for rheumatoid knees with mild destruction in which arthritis has persisted for more than 6 months. Lavage with 3 l of saline is recommended when intra-articular injection of corticosteroid and high molecular weight hyaluronan is performed after lavage.