Therapeutic hip injections: is the injection volume important?

AIM

To assess whether an increased volume of local anaesthetic injection given with intra-articular steroids improves symptom relief in osteoarthritis of the hip.

MATERIALS AND METHODS

One hundred and ten patients with hip osteoarthritis were randomized into two groups (A and B). All patients were given 40 mg triamcinolone and 2 ml bupivicaine, and patients from group B were also given 6 ml of sterile water for injection. Change in WOMAC (Western Ontario and McMaster University Osteoarthritis Index Version 3.1) scores from baseline to 3 months were calculated and assessed for clinical and statistical significance. The patients were assessed for pain at 2 weekly intervals using the Oxford pain chart.

RESULTS

Patients from group B showed some reduction in stiffness (7%) and improved function (3%) compared with group A, and there were more clinical responders in these two categories. However, there was no significant statistical or clinical difference in WOMAC scores between the two groups at 3 months. There was also no statistical difference in pain symptoms between the two groups during the study period, measured at 2 weekly intervals. One hundred and two patients reached the study endpoint; eight patients who had bilateral hip injections were subsequently included in the analysis, and these patients did not alter the findings significantly.

CONCLUSIONS

Published total injection volumes used for treating osteoarthritis of the hip with intra-articular steroids vary from 3 to 12 ml. The present study has shown that there is no detriment to using a larger volume of injectate, and recommends that practitioners use total volumes between 3 and 9 ml.