38 patients were taken from the arthroscopic washout waiting list and randomised after informed consent to receive either a course of sodium hyaluronate injections or an arthroscopic washout. Those patients who had previously had an arthroscopic washout, an intraarticular injection in the last 6 months, mechanical symptoms or hypersensitivity to avian proteins were excluded. The injections were given using an aseptic technique after first aspirating the knee to dryness. An injection was given each week for 5 weeks. The washouts were performed using 0. 9% saline and debridement was undertaken as necessary. The outcome measures used were a visual analogue pain score (VAS), Knee Society function score (FS) and Lequesne index (LI).

19 people were randomised into each group. The groups were similar in terms of age, sex and analgesics used. 2 patients in the arthroscopy group declined arthroscopy after randomisation as their symptoms had improved. There was no significant difference in the pre-intervention VAS or LI. The FS was worse in the arthroscopy group (p< 0. 01). After treatment, 2 patients in each group moved from the area and were lost to follow up.

During the year, 5 patients from the sodium hyaluronate group underwent arthroscopy. 3 patients failed to improve and were listed for total knee replacement. The others had improved at 3 months.

At 1 year, the VAS (NS), FS (p< 0. 02) and LI (p< 0. 04) were all better in the sodium hyaluronate group.

Intra-articular sodium hyaluronate injections should be considered for use in selected patients with knee osteoarthritis without mechanical problems. Further study is required to confirm these findings and improve patient selection.