The Journal of Arthroplasty Vol. 25 No. 8 2010
Femoral Nerve Block vs Fascia Iliaca Block for Total Knee Arthroplasty Postoperative Pain Control A Prospective, Randomized Controlled Trial Brisbane Orthopaedic & Sports Medicine Centre Writing Committee*
Abstract: Femoral nerve block (FNB) is an accepted mode of analgesia for lower limb procedures but has a documented complication rate. This study compared femoral nerve and fascia iliaca regional anesthesia for total knee arthroplasty (TKA), using fentanyl consumption as the primary outcome measure. Ninety-eight primary unilateral TKA patients were blinded and randomized into fascia iliaca block (FIB) (n = 51) or FNB (n = 47) groups. No significant differences were found in analgesia use (fentanyl and tramadol) at 12 and 36 hours in pain, nausea and range of motion between the groups. There was one case of paresthesia in the femoral nerve in the FNB group. Fascia iliaca block is as effective as FNB as part of a multimodal anesthetic regimen for TKA. Keywords: TKA, anesthesia, fascia iliaca nerve, femoral nerve, nerve block. © 2010 Elsevier Inc. All rights reserved.
Postoperative pain control is critical to patient care after total knee arthroplasty (TKA) because it accelerates functional recovery . Multimodal analgesia featuring regional techniques are now the gold standard in perioperative analgesia for TKA . Recently, regional nerve blocks have gained popularity for TKA with the advantage of being able to anesthetize a large area while being remote from the operative field and spinal cord . Direct femoral nerve blocks (FNBs) have a recognized incidence of femoral nerve injury and a potential for injury to the femoral vessels [4,5]. It has been proposed that the fascia iliaca block (FIB) avoids these complications by anesthetizing the femoral nerve remotely from important neurovascular structures while still providing adequate analgesia . The purpose of this study was to compare the analgesic efficacy of FNB to FIB in patients undergoing primary unilateral TKA.
*Timothy J. McMeniman, MBBS, Peter J. McMeniman, MBBS, Peter T. Myers, MBBS, David A. Hayes, MBBS, Alex Cavdarski, MBBS, Man-Shun Wong, MBBS, Adrian J. Wilson, MBBS, Mark A. Jones, PhD, and Mark C. Watts, MPhil. Submitted January 28, 2009; accepted November 22, 2009. No benefits or funds were received in support of the study. Reprint requests: Mark C. Watts, MPhil, Brisbane Orthopedic and Sports Medicine Center, Level 5 Specialist Center, Brisbane Private Hospital, 259 Wickham Tce, Brisbane QLD 4000, Australia. © 2010 Elsevier Inc. All rights reserved. 0883-5403/09/2508-0012$36.00/0 doi:10.1016/j.arth.2009.11.018
Methods Approval of the research protocol was obtained through the institutional ethics committee. One hundred four consecutive primary TKA patients with primary diagnosis of osteoarthritis were recruited into the study. Patients were excluded if they had a stated allergy to local anesthetic or medications used in the protocol or had undergone previous surgery in the region of the block. Informed consent was obtained, and the patients were blinded and allocated by block randomization using sealed envelopes to the FNB (n = 52) or FIB (n = 52) groups. The 104 sample size was estimated using a 35% difference in cumulative fentanyl use (primary outcome measure) between the 2 groups, 80% power, and .05 α . The 35% difference in the primary outcome measure was chosen based on the standard administering protocol and the properties of fentanyl; low bolus dose with a short lockout period, very short half-life, and that the amount that can be accumulated over 48 hours can produce very large variances. Six patients received incorrect drugs and were excluded for not following the study protocol. This left 47 patients in the FNB and 51 in the FIB groups. The demographics of the 2 groups were not significantly different (Table 1). The anesthetist performed all blocks using a standard technique after induction of general anesthesia. The femoral nerve block was performed with an 18 gauge needle (Contiplex, B Braun, Melsungen, Germany) with
FNB vs FIB After TKA: A Prospective, Randomized Controlled Trial
nerve stimulator (Multistim Vario, Pajunk, Geisingen, Germany) introduced to the region of the femoral nerve. The nerve stimulator was used to ensure that the needle was adjacent to, but not within, the femoral nerve. A loading dose of 60 mL of 0.2% ropivacaine was given, followed by an infusion via catheter of 8 mL/h. The FIB group had the same 18 gauge needle with stimulator introduced 0.5 to 1 cm below the junction of the lateral 1/3 and medial 2/3 of the inguinal ligament, usually 2 finger breadths lateral to the artery. After placement of the needle, the nerve stimulator was then applied to check the proximity to the femoral nerve by the presence or absence of quadriceps activation. Absence of femoral nerve stimulation indicated that the needle and infusion catheter were away from the nerve. The protocol was then the same as that for FNB with a loading dose and ongoing catheter infusion. All patients underwent general anesthesia using propofol for induction; maintenance was then achieved with a mixture of air/oxygen and sevoflurane. Cisatracurium was used if indicated. All cases were performed through an anterior incision and medial parapatellar approach. All patients enrolled in the study were prescribed regular oral paracetamol (1 g 6 hourly) and celecoxib (200 mg 12 hourly). Patients were also provided with a patient controlled analgesia (PCA) pump for breakthrough pain containing fentanyl 10 μg/mL, with a 10 μg bolus and a 5-minute lockout period with no background. Oral tramadol and subcutaneous morphine were prescribed on an “as-required” basis. The nerve block catheters were removed at approximately 48 hours postoperatively and all patients underwent the same standard postoperative mobilization and rehabilitation regimen. Postoperative analgesia use, visual analog pain scales (VAS), and postoperative nausea and vomiting scores were recorded by the patient at 12, 36, and 60 hours postsurgery. Maximum knee flexion and extension were recorded by an independent observer at 5 days, 6 weeks, and 3 months postsurgery. All complications were recorded. The data were entered into a database, and statistical analysis was performed using SPSS 13.0 software (SPSS Inc, Chicago, Ill) and Stata version for Windows 9.2 Table 1. Patient Demographics for the FIB and FNB Groups Treatment Age at surgery (y),x ± 95% confidence interval Male-female ratio (%) Right-left knee ratio (%) Preoperative pain, VAS x ± 95% confidence interval Weight (kg), x ± 95% confidence interval
68.2 ± 2.7
67.7 ± 2.5
39.2:60.8 62.7:37.3 3.0 ± 0.4
40.4:59.6 59.6:40.4 3.1 ± 0.4
.86 .62 .74
85.3 ± 4.9
84.9 ± 4.0
Fig. 1. Cumulative fentanyl use.
(StatCorp LP, College Station, Tex). Student t tests, Pearsons χ2, and Poisson regression analysis were used to assess differences between groups. Robust standard errors were assumed to take account of overdispersion. Differences were reported as incidence-rate ratios with 95% confidence intervals. Statistical significance was assumed if P was less than .05.
Results The quantities of fentanyl administered via the PCA at 12 and 36 hours and tramadol use at 12 and 36 hours were not significantly different between the FNB and FIB groups (Figs. 1, 2; Table 2). The VAS pain, postoperative nausea and vomiting, and range of motion (flexion and extension) data showed no statistical difference between the groups (Table 3). Subcutaneous morphine was used in 10 patients (4 in FIB, 6 in FNB) with a mean total dosage of 32.8 mg ± 4.2 mg for FIB and 32.4 mg ± 7.1 mg for FNB. There were no major complications of joint stiffness requiring manipulation, infection, or ongoing pain in either group. One patient in the FNB group did complain of persistent paresthesia in the distribution of the femoral nerve at the 6-week review. This is suggestive of femoral nerve injury, but the injury had resolved by the 3-month follow-up appointment.
Discussion Multimodal techniques featuring peripheral nerve blocks have demonstrated a significant advantage in perioperative pain relief for TKA patients . The FNB has previously demonstrated adequate perioperative pain relief as well as rapid rehabilitation in the postoperative period [8-12]. In addition, FNB has been found to be superior when compared to PCA administered morphine  and provides equivalent analgesia to epidural anesthesia without the risk of severe neuraxial compression [13,3]. Whereas, the FIB has demonstrated effectiveness in providing analgesia for pediatric femoral fractures , adult hip fractures [15,16], and total hip
1248 The Journal of Arthroplasty Vol. 25 No. 8 December 2010 Table 3. Postoperative Pain VAS, Postoperative Nausea and Vomiting Score, and Knee Range of Motion
Pain VAS Postoperative nausea and vomiting Knee Flexion Extension
Fig. 2. Cumulative tramadol use.
arthroplasty . When compared to a placebo, FIB decreases opioid demand and increases range of motion when used for TKA . When FIB was compared to the 3-in-1 block for anterior cruciate ligament reconstruction, Morau et al  demonstrated no significant difference in postoperative VAS pain scores, opioid consumption, or catheter position. However, this study did show that it took significantly longer to perform the 3-in-1 block (P b .05), and this technique incurred a greater material cost (P b .05) . Although there are some differences in methodology between the article by Morau et al  and the present study, the results are similar. We have shown there to be no significant difference in analgesic efficacy between the FIB and FNB technique in TKA patients. The analgesic use is not the only consideration when comparing FIB and FNB as the complication rate is also important. Femoral nerve block has a recognized incidence of both temporary and permanent femoral nerve injury [4,5,20]. In addition, there is a remote risk of vascular injury or intravascular injection. Whereas with FIB, there are currently few reports of neurologic injuries  and one reported case of pneumoperitoneum . These findings are consistent with our series where we saw one case of temporary femoral nerve injury in the FNB group and no neurovascular injuries in the FIB group. However, this difference in complication rate was not statistically significant between the 2 groups. The major limitation of this study is that it was impossible to use only one anesthetic drug as the
Table 2. Results From Poisson Regression Analysis Comparing the FIB to the FNB
Fentanyl (μg) Tramadol (mg)
Incidence-Rate Ratio (95% Confidence Interval)
12 36 12 36
0.82 (0.58-1.15) 0.82 (0.61-1.10) 1.43 (0.50-4.10) 1.23 (0.70-2.10)
.26 .18 .50 .40
FIB x ± 95% CI
FNB x ± 95% CI
12 h 36 h 12 h 36 h
2.5 ± 0.6 1.8 ± 0.4 0.6 ± 0.4 1.1 ± 0.6
1.7 ± 0.4 2.1 ± 0.3 0.3 ± 0.2 0.7 ± 0.4
.09 .44 .38 .39
6 wk 6 wk
104.2 ± 5.0 3.1 ± 1.2
107.1 ± 3.5 1.7 ± 0.7
outcome measure. The 2 anesthetic drugs (fentanyl and tramadol) have an unknown standard for pain relief, and thus, the volumes of each of the drugs cannot be equated. For safety reasons, PCAs are limited in the volume of narcotic they can deliver at one time; however, the patient's analgesic requirements occasionally exceed this. For ethical and humane reasons, we were required to provide other forms of pain relief to the patients in the event of them requiring more immediate pain relief than the PCA was able to deliver. This, in essence, reduces the purity of the study but is a common problem among anesthetic research. Fentanyl PCA consumption in FIB is not significantly different to FNB. Thus, FIB is as efficacious as FNB in providing postoperative analgesia for TKA patients. When considering the complications of this study, the known incidence of adverse events attributed to FNB and greater distance from neurovascular structures for the FIB technique, we believe that FIB is a safe and effective alternative to FNB. The authors of this article now routinely use the FIB technique as part of a multimodal anesthetic regimen for TKA.
Appendix The writing committee's affiliations are as follows: Brisbane Orthopaedic and Sports Medicine Centre, Brisbane, Queensland, Australia (T.J.M., P.J.M., P.T.M., D.A.H., A.J.W., M.C.W.); Wickham Terrace Anaesthesia, Brisbane, Queensland, Australia (A.C.); Princess Alexandra Hospital, Brisbane, Queensland, Australia (M.W.); School of Population Health, University of Queensland, Brisbane, Queensland (M.A.J.); Institute of Health and Biomedical Innovation, Queensland University of Technology, Brisbane, Queensland, Australia (M.C.W.).
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