To assess symptomatic change after intra-articular corticosteroid (IAST) injection at 2 doses in hip osteoarthritis (OA), and to examine dose response and predictors of response.
Patients with hip OA (90 women and 30 men and median age 64 yrs) referred for IAST fluoroscopic injection were included in this longitudinal, clinical trial. WOMAC scores, body mass index (BMI), conventional radiographic grade (Kellgren and Lawrence scoring) and ultrasound measures (including capsular thickness and osteophyte assessments) were recorded at baseline. In the first phase of the study, 75 patients were injected with 40 mg methylprednisolone; another 45 patients were injected with 80 mg in the second phase. Change in WOMAC scores from baseline to weeks 6 and 12 were calculated for each dose and then dose comparisons were made. Clinical responders (>15% reduction in baseline pain score) were identified in order to establish predictors of response.
For the 40 mg dose, there was a statistically significant improvement in pain (P < 0.001) and stiffness (P < 0.001) but not disability at week 6, and only the improvement in stiffness at week 12 was maintained (P = 0.041). For the 80 mg dose, there was significant improvement in pain (P < 0.001), stiffness (P < 0.001) and disability (P < 0.001) at week 6, which was maintained for all domains at week 12 (P = 0.002; P = 0.001; P < 0.001). When the doses were compared, the 80 mg dose demonstrated a significant improvement compared with the 40 mg group for stiffness at week 12 (P = 0.026) and disability at both weeks 6 and 12 (P = 0.026; P = 0.004). Imaging findings did not relate to severity of symptoms or response to IAST.
In these two hip OA cohorts, both the 40 mg and 80 mg IAST doses had a beneficial effect at week 6, while the 80 mg dose maintained this improvement at week 12. Comparison of the two dose groups provided some evidence of a dose response. Randomized controlled trials of IAST for hip OA are now required.