Does response to preoperative intra-articular anesthetic injections predict outcomes of femoroacetabular impingement syndrome?

Abstract

Introduction: Some patients with femoroacetabular impingement syndrome (FAIS) who undergo surgery do not show satisfactory outcomes. Reliable tests that can inform prognosis of FAIS surgery are needed for optimized indications and contraindications to surgery. We aimed to review and critically appraise available literature on the capability of patient response to preoperative intra-articular anesthetic injections (PIAI) to predict post-surgical outcomes in patients with FAIS.

Materials and methods: This study was conducted in accordance with the PRISMA statement. Studies that assessed the patient pain response to PIAI and post-surgical outcomes in patients with FAIS were considered eligible. Study selection and data collection were performed by three independent reviewers. Main outcomes evaluated were those measured by hip outcome scales often used in assessing postoperative pain and functional recovery, such as the modified Harris Hip Score (mHHS) and international Hip Outcome Tool (iHOT). The likelihood ratio of achieving satisfactory postoperative outcomes at the mHHS (LHR) was extracted or calculated-for patients with significant response to PIAI and for those without a significant response to PIAI. The risk of bias was assessed using the Quality In Prognosis Studies (QUIPS) tool.

Results: Six studies were considered eligible for analysis. Five studies indicated that patient response to PIAI are associated to surgical outcomes for patients with FAIS, with a greater reduction in pain typically indicating a better surgical outcome. Additionally, the LHR ranged from 1.15 to 1.92 for patients with significant response to PIAI (I² = 90.6%). For patients without a significant response, the LHR ranged from 0.18 to 0.65 (I² = 87.5). An overall high risk of bias was observed for all studies included in the analysis. Study attrition, the prognostic factor measurement and the presence of confounding factors were the main sources of bias.

Conclusions: Greater reductions in pain with preoperative intra-articular anesthetic injections were found to be associated to better outcomes after FAIS surgery, but all available studies contain a high risk of bias.

Keywords: Hip; Lidocaine; Pain; Patient-reported outcome measures.