Can pre-operative intraarticular injection predict pain relief after total hip arthroplasty?

BackgroundTo study if pain relief after injection and arthroplasty correlate.MethodsA retrospective cohort study included consecutive patients (n = 88; median age 64 (interquartile range (IQR) 22) years, 49 (56%) females) that received fluoroscopic-guided intra-articular hip injection with contrast agent, anaesthetic (diagnostic), and corticosteroid (therapeutic) before implantation of primary total hip arthroplasty. Pain scores were assessed pre-injection, post-injection after 15 min (diagnostic phase) at first clinical follow up (therapeutic phase; median 2 (IQR 2) months), and postoperatively (last follow up (median 15 (IQR 5) months)). Responders had reduction in pain score & GE; 20 (numeric rating scale 0-100) points. The primary outcome was the same (or inverse) response to injection and arthroplasty.ResultsThe median pain scores were higher pre-injection (68 (IQR 30) points) compared to the diagnostic phase (18 (IQR 40) points; p < 0.001), therapeutic phase (50 (IQR 40) points; p < 0.001), and post-operatively (2 (IQR 15) points; p < 0.001). On the one hand, 69 (78%) cases had the same response in the diagnostic phase and post-operatively (rho = 0.58; p < 0.001; sensitivity 83%); on the other hand 32 (36%) cases had the same response in the therapeutic phase and post-operatively (rho = 0.25; p < 0.001; sensitivity 33%). Furthermore, 57% and 91% of patients had an even better response post-operatively than in the diagnostic and therapeutic phases.ConclusionsPre-operative intraarticular injection can predict pain relief after primary total hip arthroplasty. A positive response to hip arthroplasty may be better predicted by the response to local anaesthetic (diagnostic phase) than corticosteroids. Most patients (91%) with osteoarthritis may expect better pain relief after arthroplasty compared to the therapeutic phase after injection.

Automated summary

This retrospective cohort study aimed to investigate the correlation between pain relief after injection and arthroplasty. The study included 88 patients who received intra-articular hip injection before primary total hip arthroplasty. Pain scores were compared at different stages, and it was found that the response to injection could predict pain relief after arthroplasty. The response to local anaesthetic in the diagnostic phase might be a better predictor than corticosteroids. Majority of patients with osteoarthritis can expect better pain relief after arthroplasty compared to the therapeutic phase after injection.