Pre-operative Lumbar Plexus Block Provides Superior Post-operative Analgesia when Compared with Fascia Iliaca Block or General Anesthesia Alone in Hip Arthroscopy

OBJECTIVES: Nerve block administration in concert with general anesthesia can help manage post-operative pain and provide favorable muscle relaxation of the operative leg in hip surgery. However, the optimal nerve blockade_if any_for arthroscopic surgery of the hip remains undefined. Considerations specific to hip arthroscopy include control of intra-operative pain, adequate muscle relaxation to allow for distraction for work in the central compartment, and post-operative pain control. Dold et al. recently reported in AJSM that a pre-operative femoral nerve block administered in concert with general anesthesia led to decreased patient-reported pain scores at the 60 minute mark post-operatively. Given this demonstrated benefit of the pre-operative femoral nerve block, we hypothesized that a regional block that anesthetized the femoral nerve and the lateral femoral cutaneous nerve (as the fascia iliaca block does), or one that anesthetized the obturator nerve in addition to the femoral and lateral femoral cutaneous nerves (i.e. the lumbar plexus block), would provide additional benefit. The purpose of this study is to examine the effects of pre-operative fascia iliaca and lumbar plexus nerve blocks on post-operative pain and secondary post-operative variables following arthroscopic surgery of the hip. METHODS: A retrospective chart analysis was conducted on 145 patients undergoing arthroscopic surgery of the hip in 3 groups. Group 1 (n=55) received general anesthesia only, Group 2 (n=30) received general anesthesia and a fascia iliaca nerve block, and Group 3 (n=60) received general anesthesia and a lumbar plexus nerve block. Post-operative measures were recorded, examined and compared. The primary outcome measure was patient reported pain scores (0-10) at 0, 30, 60, 90 and 120 minutes in the post-anesthesia care unit (PACU). Secondary variables examined included time spent in the PACU, morphine equivalent administered, and presence of nausea requiring anti-emetic medication. RESULTS: Mid-term analysis revealed no benefit to the fascia iliaca block; this regional anesthesia technique showed no significant effect on any of the measured post-operative variables when compared to general anesthesia alone. We therefore abandoned this block in favor of the lumbar plexus block. Patients receiving a lumbar plexus block exhibited significantly decreased pain at each time point when compared to the fascia iliaca group, and at all but one time point when compared to the general anesthesia group (P<0.05). There was no difference in the time spent in the PACU, nor in morphine equivalent administered between any of the groups. CONCLUSION: The results of the current study indicate that for arthroscopic surgery of the hip, a pre-operative lumbar plexus regional block performed in conjunction with general anesthesia provides significant and clinically meaningful decreases in post-operative pain reported in the PACU when compared with general anesthesia alone or general anesthesia with fascia iliaca block. This relative benefit we found in our lumbar plexus block patients is likely attributable to the more complete and proximal nervous blockade afforded by the lumbar plexus block. Pre-operative fascia iliaca block provides no benefit compared with general anesthesia alone. Consideration should be given to abandoning fascia iliaca regional nerve block for anesthesia for hip arthroscopy.