Diagnostic injections are predictive of similar improvements following total hip arthroplasty in patients with radiologically mild osteoarthritis.

Abstract

Aims: Intra-articular (IA) injections are a useful diagnostic tool in patients presenting with debilitating hip pain but radiologically mild osteoarthritis (OA). We aim to explore the clinical and patient-reported outcomes (PROs) associated with patients who have radiologically mild OA and undergo total hip arthroplasty (THA) after an IA injection.

Methods: Patients undergoing primary, elective THA at a single centre between January 2017 and December 2023 were identified. Only those patients who underwent an IA injection into the operative hip within one year of surgery were included. Patients were divided into two cohorts based on the severity of their OA: those with Kellgren-Lawrence (KL) grade I to II arthritis were classified as 'mild', whereas those with KL grade III to IV arthritis were classified as 'severe'. Clinical outcomes and PROs, including the Hip disability and Osteoarthritis Outcome score for Joint Replacement, the Harris Hip Score, Single Assessment Numeric Evaluation, and Veterans Rand 12-Item Health Survey Mental and Physical subscales were compared between cohorts.

Results: The final cohorts included 25 and 225 patients with radiologically mild and severe OA, respectively. There were no baseline differences in age, sex, or time between IA injection and THA between cohorts. There were no significant differences in the preoperative or postoperative PRO values between patients with mild or severe arthritis (all p > 0.05). There were no significant differences in the change in PRO scores from the preoperative to final follow-up, or the percentage of patients who achieved the minimal clinically important difference on any of the PROs between cohorts. There were also no significant differences in the studied complications between groups.

Conclusion: Patients with radiologically mild OA who feel relief of their hip pain following an IA injection report similar preoperative debility and postoperative improvements in PROs following THA compared with patients with radiologically severe OA.