Objective: Intra-articular injection is being used widely for both diagnostic and therapeutic purposes in the hip. However, its efficacy is not always predictable in patients with hip osteoarthritis (OA). The purpose of this study was to determine whether the degree of radiographic severity of OA was predictive of the response to intra-articular injection of local anesthetic with corticosteroid and to determine the relationship between immediate pain relief resulting from the anesthetic and delayed pain relief resulting from corticosteroid administration.
Materials and methods: This retrospective study included 217 patients (220 injections) with diagnosis of hip OA who underwent a fluoroscopically guided therapeutic hip injection of local anesthetic and corticosteroid. Hip radiographs were scored using the Kellgren-Lawrence scale. Immediate and delayed pain relief was documented using a visual analog scale. Logistic regression analysis was performed to investigate whether age, gender or radiographic severity of OA were independent predictors of pain relief. Degree of agreement between immediate and delayed response was assessed with the kappa coefficient.
Results: Immediate pain relief was reported in 68.2% of hips and delayed relief in 71.4% of hips. A high level of agreement was observed between immediate and delayed pain relief (kappa = 0.80, p < 0.001). 94% of patients reporting immediate relief also reported relief 2 weeks later. Univariate and multivariate analysis revealed that neither gender nor age was related to immediate or delayed pain relief. Only severity of OA (based on radiographic analysis) was observed to be predictive of pain relief.
Conclusion: Pain relief following intra-articular hip injection correlated with radiographic severity of OA. This intervention may be of therapeutic and prognostic value in patients awaiting hip arthroplasty.