Greater trochanteric pain syndrome: predicting who will respond to a local glucocorticoid injection.

Objectives: This study aimed to explore whether certain clinical tests or a rapid improvement in lateral hip pain following periarticular injection are predictive of subsequent efficacy of local glucocorticoid (GC) injection in greater trochanteric pain syndrome (GTPS).Method: This secondary analysis of a randomized controlled trial of an injection of GC and local anaesthetic (LA) versus placebo included 44 patients with GTPS. Two subgroups of patients were defined: (i) 30 min responders, reporting a decrease of ≥ 50% of the initial pain at 30 min post-injection; and (ii) positive triple test, presenting a combination of three positive clinical tests (30-second single-leg stance, FABER, and Lequesne). Median level of numeric rating scale for pain at 1 month was the primary outcome. Interaction analysis of treatment effect in the subgroups was performed using a linear regression adjusting for pain at baseline.Results: Sixteen patients (36%) were 30 min responders. In this group, GC treatment was associated with a significant improvement in pain at 1 month compared to non-responders (p = 0.03). The 30 min response was not associated with the use of LA. Positive triple test (22% of patients) was associated with higher pain scores at baseline (p = 0.03). In this group, patients who received placebo had significantly more pain at 1 month than those with the cortisone injection (p = 0.04).Conclusion: Patients with GTPS who present a rapid decrease in pain after periarticular injection, and those who display a combination of three specific clinical tests, are more likely to benefit from an injection with GC and anaesthetic.