Preoperative Femoral Nerve Block in Hip Arthroscopic Surgery

Abstract

Background: The utility of a femoral nerve block as an adjunct for pain management has been recognized for various surgical techniques but has yet to be examined in the preoperative setting as an adjunct to general anesthesia for improved postoperative pain control in hip arthroscopic surgery. Purpose: To evaluate the safety and efficacy of a preoperative femoral nerve block for postoperative pain control in patients undergoing hip arthroscopic surgery. Study Design: Cohort study; Level of evidence, 3. Methods: A retrospective chart review of 108 consecutive hip arthroscopic surgery cases (in 103 patients) was carried out. All patients underwent arthroscopic surgery under a general anesthetic with or without a preoperative femoral nerve block. Groups were compared with respect to patient sex, age, and body mass index (BMI); physical status classification according to the American Society of Anesthesiologists (ASA); procedure performed; operative time; total intraoperative morphine-equivalent dose; pain scores (0-10 scale) recorded at 0, 15, 30, 45, and 60 minutes postoperatively in the post-anesthesia care unit (PACU); total morphine-equivalent dose in the PACU; presence of nausea or vomiting in the PACU; time to discharge from the PACU; oxycodone consumption in the surgical day care unit (SDCU); and maximal patient-reported pain score in the SDCU. Results: Twelve cases were excluded from the analysis for a total of 96 cases (in 92 patients). Forty patients had general anesthesia alone (group A), and 56 patients had a preoperative femoral nerve block before the induction of general anesthesia (group B). There was no significant difference between the groups with regard to sex, age, weight, height, BMI, ASA classification, or type of procedure performed. Patients who received a femoral nerve block also received a significantly lower total intraoperative morphine-equivalent dose than did those patients who did not receive a block. Postoperative patient-reported pain scores were lower at all time points for the femoral nerve block group; however, a statistical significance was seen only at the 60-minute postoperative time point. Patients who did not receive a block had significantly higher morphine-equivalent doses in the PACU. There was no difference in the rates of nausea and vomiting and time to discharge from the PACU between the 2 groups. Oxycodone consumption in the SDCU was similar between the groups, but the femoral nerve block group had significantly lower maximal patient-reported pain scores in the SDCU. Two patients in the general anesthesia group were admitted to the hospital postoperatively because of inadequate postoperative pain control. No complications were noted in any patient with regard to the femoral nerve block. Conclusion: A preoperative femoral nerve block is a relatively safe procedure that may decrease the requirement for intraoperative morphine while providing effective postoperative pain control in patients undergoing hip arthroscopic surgery.