Preoperative Femoral Nerve Block for Hip Arthroscopy: A Randomized, Triple-Masked Controlled Trial

Arthroscopy has become a standard method of treatment for a variety of intra-articular hip disorders. While most arthroscopic hip procedures are performed as outpatient surgeries, patients can still experience significant postoperative pain and opioid-associated side effects.

The potential benefits of a preoperative femoral nerve block (FNB) in hip arthroscopy were explored in a previous retrospective review. The study objective was to confirm these findings in a prospective randomized study.

Randomized controlled trial; Level of evidence, 1.

Fifty patients undergoing hip arthroscopy were included in this prospective, single-center, randomized controlled trial that was patient-, operator-, and assessor-blinded. Patients received either a preoperative ultrasound-guided FNB with 20 mL of 0.5% bupivacaine (FNB group) or normal saline (control group). Nerve blockade was confirmed via standardized sensory testing before the induction of general anesthesia. The primary endpoint was cumulative consumption of oral morphine equivalent at 24 hours after discharge. Secondary endpoints included opioid use at various time points, pain scores, Quality of Recovery (QoR-27) score, incidence of nausea and vomiting, time to discharge, block-related complications, falls at 24 hours, and patient satisfaction.

Fifty patients completed the study, including 27 in the FNB group and 23 in the control group. Most patient characteristics were statistically similar between groups except for operative time, which was longer in the control group. Cumulative oral morphine consumption was lower in the FNB group at 48 hours; there was no difference at 24 hours or 7 days postoperatively. Pain scores were significantly lower up to 6 hours postoperatively in the FNB group compared with control; however, rebound pain was observed at 24 hours after discharge in patients who received FNB. There was no difference in most secondary outcomes. Importantly, a total of 6 patients in the FNB group reported falls (without injury) within the first 24 hours postoperatively compared with none in the control group. Patient satisfaction with pain control was high in both groups at all time points.

Preoperative FNB may improve early pain control after hip arthroscopy. However, given the observed risk of falls, the routine use of FNB for outpatient hip arthroscopy cannot be recommended.