The Efficacy of Fascia Iliaca Blocks After Total Hip Arthroplasty

Introduction: Pain control after THA is an essential component of patient satisfaction. Published studies suggest postoperative fascia iliaca blocks provide additional benefit when used in conjunction with a multi modal pain regimen; however, there have been no studies that describe single shot fascia iliaca blocks after a mini-posterior surgical approach to the hip and their impact on postoperative function and pain. The purpose of this randomized trial was to identify if fascia iliaca blockade, when used in conjunction with a multimodal pain control regimen, reduces postoperative narcotic consumption and improves early functional outcomes in primary THA performed through the mini-posterior approach. Methods: Patients were recruited during pre-operative joints replacement classes from Septmember 2017 to April 2019. Eligible patients had to receive a primary THA with epidural anesthesia. All arthroplasties were performed using a mini-posterior approach to the hip without the use of periarticular injection. In the recovery room, patients were randomized to either receive a fascia iliaca compartment block with 40mL of 0.5% bupivacaine or a placebo block, performed by a regional anesthesiologist. The patients and surgical team were blinded to the procedure. Patients received the same multi-modal pain management and rapid recovery protocols post-operatively. VAS pain scores (0-10) were recorded at 30 minute intervals initially after surgery, then at 4 hour intervals after the first 12 hours. The total narcotic requirement (milliequivalents of morphine) was calculated for each patient. Functional outcomes including distance walked during therapy, timed-up-and-go testing, and quadriceps strength were recorded for each patient. After discharge, the patients completed PROMIS pain and physical function surveys at 4 weeks post-operatively. The primary outcomes in this study were pain scores and narcotic consumption in the first 48 hours postoperatively. Secondary outcomes were distance walked with therapy during the first session, the timed-up-and-go test score on post-operative day 1, incidence of quadriceps weakness, and pain scores at the first post-operative visit. T-tests were used to compare continuous variables between treatment groups, and Chi square tests were used to compare categorical variables between treatment groups (α = 0.05). Results: During study period 110 patients were recruited and included in this analysis. There was no difference in the average pain scores at any time interval between the placebo and block groups during the first 24 hours (p = 0.1-0.83), and there was no difference in pain scores during the week prior to the first post-operative visit (6.88 vs 6.06, p =0.34). There was no difference between the pre-block and post-block pain scores in the block group (4.26 vs. 4.23, p= 0.97). There was no difference in the cumulative morphine equivalents consumed between the placebo and block group during the first 4 hours, 8 hours, 12 hours, 16 hours, 20 hours, or 24 hours postoperatively (p = 0.6 - 0.25). Total morphine equivalents consumed was also the same between the placebo and block groups (86.0 vs. 75.3, p=0.31). Functional testing showed no difference between the two groups in regards to distance walked during the first therapy session (67.1 vs. 68.3 ft, P=0.92) and timed-up-and-go testing (63.7 vs. 66.3 sec, P = 0.86). There was an increased incidence of quadriceps weakness in the block group (0% vs. 22%, p = 0.004). Conclusion: This preliminary analysis shows that the fascia iliaca compartment block does not improve functional performance and does not decrease pain levels or narcotic usage after mini-posterior THA and can increase the risk of quadriceps weakness post-operatively. Based on these results we do not recommend routine fascia iliaca compartment blocks after THA performed with the posterior approach.https://scholarlycommons.henryford.com/merf2019clinres/1046/thumbnail.jp