|Year : 2015 | Volume
| Issue : 2 | Page : 200-205
Continuous femoral nerve against psoas compartment block for analgesia in total knee arthroplasty
Amr M.A. Sayed MD , Kareem Yousef
Department of Anesthesiology, Intensive Care, and Pain Management, Faculty of Medicine, Ain-Shams University, Cairo, Egypt
|Date of Submission||03-Sep-2013|
|Date of Acceptance||11-Oct-2013|
|Date of Web Publication||8-May-2015|
Amr M.A. Sayed
Department of anesthesiology, Intensive Care, and Pain Management, Faculty of Medicine, Ain-Shams University, 11371 Cairo
Source of Support: None, Conflict of Interest: None
Total knee arthroplasty (TKA) is a surgical procedure that often demands potent analgesia. Anesthetists commonly rely on continuous epidural analgesia or psoas compartment block. After the American Society of Regional Anesthesia (ASRA) recent recommendation against the implication of deep regional blocks in the setting of perioperative anticoagulation, femoral nerve block might be a suitable alternative technique. Its effectiveness in TKA is a questionable issue. Our study is hypothesizing that continuous femoral block could provide an analgesic profile similar to continuous psoas compartment block.
Patients and method
Sixty patients undergoing TKA were randomly assigned into two groups to receive continuous femoral block or continuous psoas compartment block using ultrasound and nerve stimulation guidance. A bolus of 20 ml 0.25% levobupivacaine was injected through a perineural catheter in each group before surgery followed by a 5 ml bolus of 0.125%, and then 5 ml/h infusion at completion of surgery. A bolus of 5 ml 0.125% levobupivacaine was injected when numerical rating scale (NRS) was at least 5. In the first 24 h postoperatively, the median value and the interquartile range of the NRS at 1, 6, 12, and 24 h and after the first physiotherapy session were recorded as the primary end point. The total levobupivacaine and morphine consumption during the same 24-h period were the secondary end points, apart from patient's satisfaction with analgesia during hospitalization.
The median and interquartile range of the NRS were 4.00 and 2.00 in the first hour, 4.00 and 1.5 in the sixth hour, 4.00 and 1.5 in the 12 th hour, 4.00 and 2.00 in the 24 th hour, and 4.00 and 2.00 after the first physiotherapy session, respectively, in the Fm group, and 3.00 and 3.00 in the first hour, 4.00 and 2.00 in the sixth hour, 4.00 and 1.5 in the 12 th hour, 3.00 and 2.5 in the 24 th hour, and 3.00 and 2.00 after the first physiotherapy session, respectively, in the Ps group. The total mean levobupivacaine and morphine consumption in the Fm and the Ps groups were 218. ± 7.89 vs. 216.6 ± 8.42 and 15.5 ± 4.01 vs. 13.50 ± 4.38, respectively, with no statistically significant difference between both the groups. The catheter insertion time was significantly shorter in the Fm group (8.53 ± 3.1 min) compared with (10.5 ± 3.2 min) the Ps group (P = 0.021).
Continuous femoral nerve block provides a suitable alternative analgesic technique in patients undergoing TKA when psoas compartment block is unwarranted in the setting of perioperative anticoagulation as recommended by ASRA.
Keywords: femoral nerve block, levobupivacaine, psoas compartment block, total knee arthroplasty, ultrasound-guided block
|How to cite this article:|
Sayed AM, Yousef K. Continuous femoral nerve against psoas compartment block for analgesia in total knee arthroplasty. Ain-Shams J Anaesthesiol 2015;8:200-5
|How to cite this URL:|
Sayed AM, Yousef K. Continuous femoral nerve against psoas compartment block for analgesia in total knee arthroplasty. Ain-Shams J Anaesthesiol [serial online] 2015 [cited 2021 Oct 22];8:200-5. Available from: http://www.asja.eg.net/text.asp?2015/8/2/200/156684
| Introduction|| |
Total knee arthroplasty (TKA) is a highly effective treatment for end-stage knee osteoarthritis; the surgical procedure carries a remarkable postoperative persistent pain  . Several studies have suggested that implementing adequate postoperative regional analgesic techniques for 48-72 h would result in improved physical therapy and rehabilitation, providing a proper joint range of motion and early hospital dismissal  . Recently, psoas compartment block gained popularity as a postoperative analgesic technique for lower-limb orthopedic procedures, especially hip arthroplasty  ; it is also suitable for TKA  . The newly released guideline of the American Society of Regional Anesthesia (ASRA) recommended applying the same protocols of central neuraxial blocks on deep peripheral nerve catheters in anticoagulated patients or patients requiring postoperative anticoagulation. The ASRA recommendation permits the insertion of superficial perineural catheters when perioperative anticoagulation is warranted and limits the use of continuous epidural and deep compartment block for postoperative analgesia in these patients  . The use of continuous femoral nerve block could be an alternative analgesic technique after TKA  . This study aimed to test the efficacy of providing analgesia through continuous femoral nerve block against continuous psoas compartment block in TKA surgery; the goal was to detect the difference in pain scores between the two techniques during the first 24 h, including the first physical therapy session.
| Patients and methods|| |
After the approval of the hospital ethical committee for the study, patients were provided a written informed consent explaining the procedure and the analgesic option that would be offered to them and advantages and risks of the technique. Sixty adult patients ASA I, II, and III scheduled for elective TKA in the orthopedics department of Ain-Shams University hospitals were enrolled in the study. Exclusion criteria were evident peripheral neuropathy, infection at the site of catheter insertion, BMI more than 50, and known allergy to the studied drugs. Patients were randomized into two groups using a computer-generated randomization program: the Fm group received continuous femoral block, whereas the Ps group received continuous psoas compartment block; the blocking catheters were inserted before surgery in both groups. All patients received intravenous 3 mg midazolam plus 50-75 μg fentanyl during perineural catheter insertion.
Catheters were inserted using peripheral nerve stimulation (EZSTIMTM II Dual-Purpose Peripheral Nerve Stimulator) and an ultrasound machine (SonoScape-A5; SonoScape Co. Ltd, Shenzhen, China); in both groups, a layer of sterile coupling gel was applied to the ultrasound probe surface, and then covered by 3M, Tegaderm Transparent Film Dressings (3M, St. Paul, MN, USA) in a sterile manner. In the Fm group, a linear-array 10L1 (6-12 MHz) was used; the patient was placed in the supine position; after skin disinfection, the probe was placed along the inguinal crease, scanning for the femoral nerve as a hyperechoic flattened oval structure lateral to the femoral artery beneath the fascia iliaca. In the Ps group, a convex C543 (2-5 MHz) probe was used, and the patient was placed in the lateral decubitus - blocked-side up - position. The probe was placed on the patient's back in the paramedian longitudinal position, and then smoothly moved laterally identifying the trident sign formed by the bone shadow of lumber transverse processes and the psoas muscle lying in between; in this study, the L3-L4 interspace was used to perform the block. The 'Contiplex Stim Set (B. Braun Medical Inc. Melsungen, Germany), 18 Ga × 2" insulated Tuohy Needle and Stimulating Catheter (SCNB2) was used in the femoral group and the Contiplex Stim Set, 18 Ga × 4" insulated Tuohy Needle and Stimulating Catheter (SCNB4) was used in the psoas compartment group. The stimulating catheter was connected to the nerve stimulator and threaded inside the insulated needle, where its tip is protected inside the introducer needle from being damaged by tissues. The out-of-plane technique was used in both groups: a quadriceps contraction at a current of 0.3-0.5 mA was the desired motor response in all patients. In the femoral group, the stimulating catheter was threaded 3-5 cm beyond the needle tip, and in the psoas compartment block, the catheter was threaded 1-2 cm past the needle tip with preserved quadriceps motor response. Both catheters were tunneled subcutaneously, secured by 3M Tegaderm Transparent Film Dressings after applying (fucidin) antibiotic cream at the catheter's exit site.
The catheter insertion time (CIT) was calculated from the time the insulted needle punctured the patient's skin till the catheter settled in the proper place. In both groups, 20 ml of 0.25% levobupivacaine was injected through the perineural catheter; decreased pain sensation after 20 min on the anterior aspect of the knee using a noncrushing forceps plus weak knee extension on the ipsilateral compared with the contralateral knee indicated successful catheter placement. Patients who had unsuccessful catheter placement were removed from the study. All patients had general anesthesia for the knee arthroplasty using propofol, O 2 /air 70/30 mixture, isoflurane, fentanyl, endotracheal intubation. No muscle relaxant was used during the surgical procedure. At the conclusion of the surgery, 5 ml bolus of 0.125% levobupivacaine was injected through the perineural catheter followed by a basal continuous infusion at a rate of 5 ml/h same late concentration. Postoperatively, pain measurements were evaluated using the 10-point numerical rating scale (NRS)  (wherein 0 = no pain and 10 = worst imaginable pain). Patients in both groups received 1 g intravenous paracetamol eight hourly, and for any breakthrough pain with NRS at least 5, a 5 ml bolus of the same local anesthetic was infused through the perineural catheter; after 10 min, if there was further uncontrolled pain, 5 mg intravenous morphine was given to the patient. The pain score in the first 24-h postoperative period was recorded at 1, 6, 12, and 24 h starting from full recovery after general anesthesia, and also after the first postoperative physiotherapy session. Patients underwent physiotherapy as planned by the physical medicine department on the first postoperative day; any quadriceps femoris weakness limiting proper ambulation during the physical session was documented. The total levobupivacaine and morphine consumed in milligrams through the first 24 h in both groups were recorded. Seven days after surgery, patients were contacted by phone and asked about their satisfaction with the postoperative analgesia before hospital discharge (0-10; 0 = very unsatisfied and 10 = very satisfied).
We used the method of Armitage et al.  for equivalency trials, whereby we concluded equivalence if the 95% confidence interval for the difference was within a tolerated interval. A difference of 1.6 on the NRS (1 SD) was considered to be of clinical relevance. If the confidence interval was between−1.6 and 1.6, then it was concluded that the effect of the two treatments was equivalent. To calculate power, we simulated 10 000 trials with a total enrolled sample size of 60, assuming an SD in each group of 1.6 and 10% dropout. This sample size yielded 82% power to conclude the equivalence correctly, and the probability of falsely concluding equivalence in the presence of a simulated group difference of 1.6 was 2.5% (α). Statistical presentation and analysis of the present study were conducted using the mean, SE, the unpaired Student t-test, and the χ2 -test using SPSS V17 (IBM software, NY, USA). The unpaired Student t-test was used to compare two groups of quantitative data. The χ2 -test indicates that the row and column variables are independent, without indicating the strength or the direction of the relationship.
| Results|| |
In our study, we enrolled randomly 60 patients who underwent TKA: 30 in each group, over a period of 6 months starting from February 2013. Patients in the Fm group received continuous femoral block, whereas those in the Ps group received continuous psoas compartment block. Both groups showed comparable demographic data ([Table 1]). All patients in the studied groups had successful catheter insertion evident by loss of pain on the surgical site 20 min after bolus injection of the local anesthetic. In our study, the CIT was shorter in the Fm group (8.5 ± 3.1 min) compared with the Ps group (10.5 ± 3.2 min), with a P-value less than 0.05 ([Table 2] and [Figure 1]). The total levobupivacaine were 218. ± 7.89 mg in the Fm group and 216.6 ± 8.42 mg in the Ps group, which was of no statistically significant difference (P = 0.51; [Table 2]). The total levobupivacaine included the starting bolus dose, continuous infusion, and also breakthrough top ups. The total milligrams of morphine that were consumed in case of breakthrough pain when NRS was at least 5 in the first 24-h postoperative period were 15.5 ± 4.01 in the Fm group and 13.5 ± 4.38 in the Ps group, with no significant difference between the groups (P = 0.07; [Table 2]). As for the median and the interquartile range of the NRS, in the Fm group, it was 4.00 and 2.00 in the first hour, 4.00 and 1.5 in the sixth hour, 4.00 and 1.5 in the 12th hour, and 4.00 and 2.00 in the 24 th hour, respectively, whereas in the Ps group, it was 3.00 and 3.00 in the first hour, 4.00 and 2.00 in the sixth hour, 4.00 and 1.5 in the 12th hour, and 3.00 and 2.5 in the 24 th hour, 3.00 and 2.00 after the first physiotherapy session, respectively ([Table 3] and [Figure 2]). After the first physiotherapy session, the NRS was 4.00 and 2.00 in the Fm group and 3.00 and 2.00 in the Ps group ([Table 3] and [Figure 3]). Both groups showed no statistically significant differences at each of the designated time intervals.
|Figure 1: The catheter insertion time in the two studied groups, which was shorter in the Fm group than in the Ps group (P < 0.05).|
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|Figure 2: The median value of the numerical rating scale (NRS) in the 1, 6, 12, and 24 h postoperative period showing no significant difference among both groups.|
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|Figure 3: The median value of the numerical rating scale (NRS) after the first postoperative physiotherapy session (NRS) and patient satisfaction showing no significant difference among both groups.|
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|Table 2 The total levobupivacaine and morphine consumed throughout the study|
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|Table 3 The numerical rating scale at the designated time interval and after the completion of the first postoperative physiotherapy session and patients' satisfaction|
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Satisfactions among patients regarding the effectiveness of postoperative analgesia was reviewed through telephone conversation after 1 week, rating (0-10) wherein 0 = very unsatisfied and 10 = very satisfied; the median and interquartile range was 8.00 and 1.00 in the Fm group compared with 8.00 and 1.5 in the Ps group, with no difference in the satisfaction rating between both groups (P = 0.135) ([Table 3] and [Figure 3]). We did not encounter neurological adverse events (parathesia, hyperthesia, motor deficits) throughout the study.
| Discussion|| |
Our study showed an equivalent degree of analgesia when using continuous femoral nerve block compared with continuous psoas compartment block in patients undergoing TKA, which is demonstrated as a nonsignificant difference in the total milligrams of levobupivacaine and morphine consumed in both groups. The delivery of systemic opioids results in acceptable analgesia and patient satisfaction; it is a popular postoperative analgesic regimen for TKA as they are relatively simple to administer  . Nevertheless, postoperative pain after TKA remains severe in many instances and the side effects of excessive use of systemic opioids such as sedation, nausea, and pruritus are not uncommon  . Peripheral nerve blocks provide an effective technique in pain control after lower-limb and knee joint surgery, which would reduce opioid consumption, thus preventing their added adverse effects. In a study by Kaloul et al.  , they concluded that continuous psoas block and continuous three-in-one femoral block provided better pain control than patient-controlled intravenous analgesia with a significant reduction in morphine consumption after TKA. In our study, we had a successful block in all patients with no failure episode based on the sensory and motor assessment for the operative side by noncrushing forceps and weak knee extension, respectively. Experienced anesthetists trained for ultrasound-guided blocks performed the study. In the study, the femoral CIT was significantly shorter compared with the psoas compartment catheter. This is attributed to the complexity of localizing and visualizing the deep psoas compartment, in comparison with the easy detection of the superficial femoral nerve and its proximity to a pulsating femoral artery. Catheter tunneling prevented its dislodgment from insertion sites throughout the study, especially during the physiotherapy session. The NRS was similar in both groups during the study intervals and after the first physiotherapy session ([Figure 2]); values were within the range reported by Singelyn et al.  using a continuous FEM block after TKA. In a study performed by McNamee et al.  , they demonstrated that the obturator nerve block played an important role in analgesia after TKA: the posterior obturator nerve gives off an articular branch that supplies the posterior aspect of the knee, and this nerve may be responsible for the part of the pain experienced in the posterior aspect of the knee after knee surgery; however, despite the consistent blockade of the obturator nerve with psoas compartment block, but not in the femoral nerve blockade, our study did not demonstrate a significant difference between both blocks in terms of the 24-h morphine consumption and NRS scores, which suggests that the obturator nerve does not make a solid contribution to the TKA postoperative pain. In the study of McNamee et al., there was an additional sciatic nerve block, which provided another dermatomal block, and they used a single-injection protocol unlike our case, in which the continuous infusion policy was used. Capdevila et al.  documented that pain experienced in the posterior aspect of the knee is often short-lived and is effectively controlled with 'single-shot' blocks. Continuous femoral nerve block has been demonstrated to improve the outcome of TKA  . Morphine utilization in both groups was indicative for a dermatomal sparing on surgical sites innervated by the sacral plexus. Some investigators mentioned that femoral and psoas block cannot be used as a single analgesic procedure for TKA. The addition of single or continuous sciatic nerve block is advocated in conjunction with femoral and psoas block ,,, . Data from a randomized trial comparing the continuous femoral and psoas compartment techniques failed to find a superior one in pain control after TKA  . Quadriceps femoris weakness is a possible disadvantage associated with lower-limb regional blocks with added functional disability  and raises the risk of falls, especially in elderly patients, which is avoidable by minimizing the local anesthetic dose in perineural infusion  . Both continuous femoral and posterior lumbar plexus blocks are associated with an increased risk of falling after knee and hip arthroplasty, respectively  . In the current study, no noticeable significant degree of weakness was found during ambulation in the physiotherapy session according to the attending physiotherapist; the concentration of 0.125% levobupivacaine at a rate of 5 ml/h produced sensory rather than motor block effectively. None of our patients had falling episodes during their motions, and all patients followed the physical therapy department protocol in first ambulation by using a nonwheeled walker in the presence of a physiotherapist.
Perineural catheter insertion under ultrasound guidance requires specialized training and expensive equipments unlike the single-shot procedure. A perineural catheter maintained for a duration of over 48 h could raise the hazard of infection, and the concentration and the rate of the local anesthetic used may also result in local anesthetic toxicity. From the literature available to date, the maintenance of a catheter for longer than 36 h probably increases the risks for the patient without any clearly demonstrable benefit over patient-controlled intravenous analgesia , . In our study, the perineural catheter was removed within 48 h after controlling the pain of the first physiotherapy session. None of our patients had documented catheter-site infection. Continuous psoas compartment block is considered as an effective method for controlling TKA pain. Potential complications noted with psoas block are epidural extension, total spinal block, renal injury, and retroperitoneal hematoma. The use of an ultrasound-guided approach helps in the reduction of such complications and improves its safety profile  . Patients suffering cardiac disorders on anti-coagulant medications could have a hazard of such retroperitoneal hematoma when medications are utilized in the perioperative period; this hazard could be eliminated by shifting patients to continuous femoral block, which was shown to be an analgesic modality comparable and equipotent to psoas compartment block in this study, making it an alternative approach for pain control after TKA. Further studies on different local anesthetic concentrations, bolus volumes, and rates of infusion are warranted.
| Conclusion|| |
Continuous femoral nerve block is as effective as continuous psoas compartment block for TKA pain. Owing to the recommendation of the ASRA and pain management concerning deep blocks in anticoagulated patients, femoral block is a substitute for hazardous deep psoas compartment block in such situations.
| Acknowledgements|| |
Conflicts of interest
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[Figure 1], [Figure 2], [Figure 3]
[Table 1], [Table 2], [Table 3]