Positive Response to Preoperative Intra-articular Anesthetic Injection Suggests Favorable Outcomes After Hip Arthroscopy in Patients With Femoroacetabular Impingement Syndrome: A Systematic Review.
PURPOSE To evaluate the prognostic efficacy of in-office local anesthetic intra-articular injection response in predicting hip arthroscopy outcomes. METHODS This scoping review was conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses for Scoping Reviews using the PubMed, Embase, and Web of Science databases from inception to October 1, 2024. The articles were reviewed, and the risk of bias was assessed. Pertinent data was extracted and analyzed. RESULTS Four studies (n = 368 patients; 48.6% women; mean age 21.6-38.8 years; level of evidence II-IV; mean follow-up 12-24 months) evaluated local anesthetic injections (lidocaine alone or with ropivacaine; 5 to 20 mL) assessed 20 to 30 minutes postinjection for femoroacetabular impingement syndrome. Definitions of positive injection response varied substantially. Three of the 4 studies showed significant associations between positive injection response and superior postoperative outcomes, with positive responders achieving higher Hip Outcome Score Activities of Daily Living, Hip Outcome Score-Sports, Nonarthritic Hip Score, and Patient-Reported Outcome Measure Information System scores (P = .003-0.045) and higher minimum clinically important difference/patient acceptable symptomatic state achievement rates. Change in Visual Analog Scale for Pain predicted substantial clinical benefit (odds ratio 1.2, P < .001), and postinjection International Hip Outcome Tool correlated with 1-year outcomes (r = 0.784, P < .001). Postoperative modified Harris Hip Score ranged from 87.5 to 87.7 in positive responders versus 81.6 to 84 in negative responders. One study found no significant correlation (P = .589), with 49% of patients with poor surgical outcomes showing good injection response. CONCLUSIONS Based on limited available literature, it is suggested that a positive in-office response to intra-articular injection of local anesthetic portends a favorable outcome after hip arthroscopy. A negative response to in-office injection was not suggested to foreshadow a poor surgical outcome and based on the current evidence is inconclusive as a tool by which to help select surgical candidates. LEVEL OF EVIDENCE Level IV, systematic review of Level II to IV studies.