Patients with knee osteoarthritis (OA) often suffer pain that is not fully controlled by analgesics and often require intra-articular therapies. The aim of this study was to compare the benefits of intra-articular corticosteroid injections (CSIs) and tidal irrigation (TI) in patients with OA of the knee.
We performed a dual-centre, single blind, randomised, parallel group trial comparing TI and CSI. Patients with knee OA were randomised to either irrigation using a 3.2mm arthroscope under local anaesthesia or an intra-articular injection of 40 mg triamcinolone acetonide and 1% lidocaine. Patients were followed for 6 months. The primary outcome measure was the Western Ontario and McMaster Universities OA Index total pain score (visual analogue scale, VAS).
One hundred and fifty patients were recruited of whom 71 received TI and 79 CSI. In both treatment groups, over 80% of patients reported improvement at 2 and 4 weeks. After this time, the benefit of CSI decreased whereas that of TI was maintained: at 26 weeks the pain relief afforded by TI was significantly greater than that of CSI. At 26 weeks 29% of the CSI group reported improvement vs 64% of the TI group (P<0.001). Patients with a knee effusion responded better to both treatments, however, this was most apparent for CSI. Patients with less severe radiographic OA also obtained the greatest improvement from both treatments.
Both procedures lead to significant short-term pain relief of at least 4 weeks, however, TI displayed a significantly greater duration of benefit. Patients with effusions and milder radiographic change obtained the best response to treatment.