Continuous Block of the Articular Branches of the Femoral Nerve as a Novel Technique for Pain Control after Hip Arthroplasty

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1 IJUTPC Continuous Block of the Articular Branches of the Femoral Nerve as a Novel Technique for Pain Control after Hip Arthroplasty ORIGINAL ARTICLE Continuous Block of the Articular Branches of the Femoral Nerve as a Novel Technique for Pain Control after Hip Arthroplasty 1 Thomas M Hemmerling, 2 Carmelo Minardi, 3 Luca Bevilacqua, 3 Cedrick Zaouter 1 Avinash Sinha, 4 Michael Tanzer 1 Department of Anaesthesiology, MUHC, McGill University, Montreal, Canada 2 Department of Anaesthesiology, Policlinico University Hospital, Catania, Italy 3 Department of Anaesthesiology, University Pisa, Italy 4 Depatment of Surgery, MUHC, McGill University, Montreal, Canada Correspondence: Thomas M Hemmerling, Professor, Department of Anaesthesiology (McGill University), Institute de Genie Biomedical (Université de Montréal), Director, NRG (Neuromuscular Research Group), ITAG (Intelligent Technologies in Anaesthesia Group), PeriCARG (Perioperative Cardiac Research Group), Montreal General Hospital, 1650 Cedar Avenue Montreal, H3G 1A4, Phone: Ext or 43261, Fax: , Abstract Background: We present a novel continuous block of the articular branches of the femoral nerve (ABFN) for analgesia after hip arthroplasty. Methods: In this prospective audit, twenty-five patients underwent hip arthroplasty performed by the same surgeon (MT) under spinal anaesthesia performed by the same anaesthesiologist (TH) using 10 to 15 mg of Bupivacaine 0.5%. Before February 2008, pain management after hip arthroplasty was provided solely using patient-controlled analgesia (PCA) with morphine (N = 10; PCA-group). After February 2008, block of ABFN with Ropivacaine 2% at 6 to 8 ml/h for 24 hours was additionally performed immediately after surgery (N = 15; PCA + ABFN-group) in the postoperative care unit (PACU). Pain scores were compared using a numeric pain score (NPS) at discharge from the PACU, 24 hours after surgery; total morphine consumption for the first 12 and 24 hours after surgery was compared. Data presented as means ± SD and compared using Mann-Whitney rank sum test or Fisher test. P < 0.05 was considered to show a statistically significant difference. Results: Patients demographic data were not significantly different. Pain scores were significantly lower in the PCA + ABFN-group (1 ± 1.2 vs 3.5 ± 2.9 in the PCA-group) at the time of discharge from the PACU, but did not differ significantly 24 hours after surgery. Morphine consumption both at 12 hours (14.7 ± 7.4 mg vs 36.8 ± 13.3) and 24 hours (25.7 ± 14 mg vs 52.5 ± 26.8) after surgery was significantly lower in the PCA + ABFN-group. Discussion: Blocking the ABFN combined with PCA morphine provides superior analgesia after hip arthroplasty than PCA morphine alone. Keywords: Ultrasound, regional anaesthesia, peripheral nerve block, hip arthroplasty. INTRODUCTION There are an increasing number of elderly patients undergoing hip arthroplasty. Hip arthroplasty causes severe postoperative pain. 1 Whereas intraoperative anaesthesia is mostly provided by spinal anaesthesia, there is controversy about the choice of postoperative analgesia. Present postoperative analgesia is mostly based on opioids or epidural analgesia, both techniques are prone to significant side effects. 2 Patient-controlled analgesia using morphine (PCA morphine) carries the risk of sedation, vomiting, nausea or constipation impairing postoperative recovery and mobilisation. 3 The utilisation of continuous epidural analgesia has been complicated by increasingly aggressive thromboprophylaxis regimens 4 and the urge to start physical rehabilitation as early as possible. 5 Pain from the hip arthroplasty site is transmitted via the articular branches of the femoral nerve (ABFN). Using ultrasound, we evaluated the possibility to identify the nerve branches, insert a catheter and provide additive analgesia to a conventional PCA morphine via a continuous infusion of local anaesthesia. The aim of this prospective audit was to assess whether this novel block of the ABFN would improve pain control after hip arthroplasty and allow a reduction in Morphine consumption in the first 24 hours. METHODS Twenty-five patients were included in this prospective audit after having obtained approval by the institutional review International Journal of Ultrasound and Applied Technologies in Perioperative Care, January-April 2010;1(1):

2 Thomas M Hemmerling et al board for chart review. Patients were scheduled for total hip arthroplasty from 15 January 2007 to 15 October 2009 (N = 25). The same surgical team performed all operations. There were no changes in surgical technique or protocols for hip arthroplasty (MT) during the study period. The same anaesthesiologist (TH), with extensive experience in peripheral nerve block techniques using ultrasound guidance, performed all postoperative blocks. Routine anaesthetic monitoring was conducted in the operating room using noninvasive blood pressure, peripheral oxygen saturation, and continuous 5-lead electrocardiography. Patients received spinal anaesthesia performed in standard fashion (L2-L3) using 10 to 15 mg of isobaric bupivacaine 0.5%. In the postanaesthesia care unit (PACU) before February 2008, postoperative pain management was provided solely using PCA morphine (bolus: 1 mg; lockout: 7 minutes) (PCAgroup). After February 2008, a continuous block of the ABFN was additionally performed immediately after surgery (PCA + ABFN-group). Imaging of the inguinal region was performed in each subject by using a linear 10 to 5 MHz ultrasound probe (Sonosite Inc, Seattle, USA). First, the femoral artery is visualised in short axis, the probe is then moved laterally for 3 to 4 cm along the sartorius muscle, 3 to 4 cm inferior to the inguinal ligament. The ABFN is then recognised as a white triangular to oval shaped area, usually an area of 0.5 to 1 cm between the sartorius muscle and the rectus femoris muscle (Figs 1A to C). After sterile preparation, a 4 cm long 18 Gauge Tuohy needle was placed under ultrasound guidance (out-of-plane technique) targeting the nerve and 10 ml of lidocaine 2% injected through the needle visualising the ABFN surrounded by the local anaesthetic and literally lifting the sartorius muscle. A 20 G catheter was placed, inserting 2 to 3 cm within the nerve sheath, tunneled and secured via transparent adhesive tape. Ropivacaine 2% was continuously administered at 6 to 8 ml/h for 24 hours. After the placement of the catheter, the patients were monitored in the PACU until complete return of motor and sensory function in the upper thigh. Pain scores were assessed using a numeric pain score (NPS) (0 to 10, with 0 being no pain at all and 10 being the worst imaginable pain) and recorded at the time of discharge from the PACU, and at 24 hours after surgery; Morphine consumption was recorded at 2- hour intervals until 24 hours after surgery. Discharge criteria from the PACU were a return of normal motor and sensory function and NPS < 4. The following distances between anatomical landmarks and the centre of puncture site of the articular branches of 14 Fig. 1A: Ultrasound image of the articular branches of the femoral nerve underneath the sartorius muscle, medial to the rectus femoris muscle. The articular branches of the femoral nerve (ABFN) appeared as a hyperechoic triangular or oval-shaped structure Fig. 1B: This figure shows a schematic representation of the anatomy relevant to the ABFN block. ABFN, articular branch of the femoral nerve; FN, femoral nerve; L, lateral; M, medial Fig. 1C: Anatomical representation of the site of the needle puncture to block the articular branches of the femoral nerve (ABFN) JAYPEE

3 Continuous Block of the Articular Branches of the Femoral Nerve as a Novel Technique for Pain Control after Hip Arthroplasty the femoral nerve were measured: distance to the lower border of the inguinal ligament, distance to the lateral border of the femoral artery and distance to the skin surface. Patient data were compared using Mann-Whitney rank sum test for continuous and Fisher test for categorical data. Pain assessment using NPS was evaluated at rest at the time of discharge from the PACU and 24 hours after surgery and compared via Mann-Whitney rank sum test. The total morphine consumption within 12 and 24 hours were compared using Mann-Whitney rank sum test. P < 0.05 was considered as showing a statistically significant difference between the two groups. RESULTS In the PCA + ABFN-group, the distance between the lateral border of the femoral artery and the ABFN was 3.3 ± 0.7 cm, the distance between the skin surface and the ABFN was 3.1 ± 0.8 cm, and the distance between the lower border of the inguinal ligament and the ABFN was 3.2 ± 0.9 cm. Patient characteristics (sex, age, weight, ASA classification, the side of the surgery and the duration of PACU stay) were not different between the two groups (Table 1). At the time of discharge from PACU, motor and sensory functions were completely restored in all patients. Patients were discharged at 3.5 ± 0.6 hour from the PACU in the PCA + ABFN-group vs 3.7 ± 0.5 hour in the PCA-morphine group, without being statistically different. Pain scores at rest at discharge from the PACU were significantly lower in the PCA + ABFN-group at 1 ± 1.2 vs 3.5 ± 2.9, respectively (P < 0.05), whereas, pain scores 24 hours after surgery were not different between the two groups. Morphine consumption within 12 and 24 hours after the surgery was significantly lower (P < 0.001, and P < 0.05) in the PCA + ABFN-group (Fig. 2). Table 1: Patient and surgery data PCA + ABFN PCA P Age (years) 63 ± ± 15 NS Sex (F/M) 7/8 5/5 NS Weight (kg) 87 ± ± 13 NS ASA (I,II,III) 7, 7, 1 5, 4, 1 NS Side of the surgery (R/L) 7/8 7/3 NS Time in PACU (minutes) 201 ± ± 79 NS Pain score at discharge from 1 ± ± 2.9 < 0.05 PACU Data presented as mean ± SD. P < 0.05 was considered statistically significant. Mann-Whitney demonstrates a significant group difference in pain assessment at the exit from the recovery room 3 hours after the surgery (P < 0.05). PACU, postoperative anaesthesia care unit; R, right; L, left Fig. 2: Postoperative consumption of morphine within 12 and 24 hours after the surgery in mg, data presented as mean ± SD. Study group PCA + ABFNB, control group PCA only. ABFNB, articular branch of the femoral nerve block; PCA, patient-controlled analgesia using morphine; *p < 0.001; # p < 0.05 When tested 24 hours after surgery, all patients could mobilize the leg of the surgical site, no impairment in form of paraesthesia due to the ABFN block was noted. The force created by spontaneous leg movement was similar in both groups. DISCUSSION We present a novel method of pain treatment after hip arthroplasty via continuous block of the ABFN. The combination of standard PCA morphine and ABFN block decreased the patients pain, leaving the PACU by 75% and the morphine consumption within 24 hours after surgery by 50%. Patients undergoing hip arthroplasty are predominantly elderly patients 1 and postoperative analgesia is based on intravenous opioids or epidural analgesia. Although patient controlled administration of opioids produces better pain relief than conventional intramuscular opioid therapy, 6,7 it is less efficient for pain due to movement and ineffective in preventing reflex spasms of the quadriceps muscle, which are frequent after hip arthroplasty. 8 Epidural analgesia is frequently administered to provide analgesia after hip arthroplasty. Choi and colleagues 2 conducted a Cochrane review comparing epidural analgesia with parenteral opioid-based analgesia following lower limb arthroplasty. They observed that epidural analgesia was associated with lower visual analog pain score in the early postoperative period and a decreased incidence of sedation. Epidural analgesia, however, was associated with a greater incidence of urinary retention, pruritus, and hypotension. International Journal of Ultrasound and Applied Technologies in Perioperative Care, January-April 2010;1(1):

4 Thomas M Hemmerling et al Although not addressed in this meta-analysis, excessive motor block limiting postoperative mobilisation presents a potential limitation to the wider application of this technique for patients undergoing hip arthroplasty. Furthermore, epidural haematoma, which is a rare but potentially disastrous complication of epidural analgesia, remains a concern among patients having hip arthroplasty who receive postoperative thromboprophylaxis. If due to aggressive thromboprophylaxis regimens the epidural catheter is removed early after surgery before initiation of physical therapy, the patient is deprived of an optimal postoperative pain control at the time when pain control is much needed. 9 Several authors have advocated the use of lumbar plexus block with or without sciatic nerve block, 10,11 femoral lateral nerve block 12 and fascia iliaca block 13 following hip arthroplasty. Peripheral nerve blocks provide analgesia similar to epidural catheters and are superior to systemic opioids for pain relief. 10 Peripheral nerve blocks preserve contralateral limb strength that may facilitate postoperative rehabilitation when compared with the bilateral lower extremity motor block often seen with epidural analgesia. Furthermore, hypotension and urinary retention may occur less frequently with peripheral nerve blocks than with epidural analgesia. Despite these advantages, the placement of lumbar plexus and sciatic nerve blocks requires advanced regional anaesthesia skills. They can have serious potential side effects including patients falls and injury, 14 nerve injury, 15 neuraxial block, systemic absorption of local anaesthetic, and retroperitoneal haematoma. 5,16 The differences between the present block of the ABFN and the fascia iliaca block are as follows: The fascia iliaca block first described by Dalens et al, 17 was performed via loss of resistance using anatomical landmarks; using ultrasound, the fascia iliaca, femoral artery, and femoral nerve are identified just inferior to the inguinal ligament. The needle is then inserted into the deep plane towards the fascia iliaca and approximately 1 cm lateral to the femoral nerve. 18 When blocking the ABFN, however, the femoral artery is visualised in short axis, the probe then moved laterally for 3 to 4 cm along the sartorius muscle, 3 to 4 cm inferior to the inguinal ligament. The ABFN can then be recognised as a white triangular to oval-shaped area of usually 0.5 to 1 cm underneath the sartorius muscle and above the rectus femoris muscle. The present study was a prospective audit and not a controlled randomised double-blind study. The main focus was on the technique and consistency of obtaining a visualisation of the ABFN. Future randomised studies are necessary to confirm these preliminary results in a controlled, double-blind fashion. In conclusion, PCA morphine combined with block of the ABFN significantly reduced immediate postoperative pain and morphine consumption within 24 hours after hip arthroplasty in comparison to PCA morphine alone. REFERENCES 1. Singh JA, Lewallen D. Age, gender, obesity, and depression are associated with patient-related pain and function outcome after revision total hip arthroplasty. Clin Rheumatol 2009: Epub ahead of print. 2. Choi PT, Bhandari M, Scott J, Douketis J. Epidural analgesia for pain relief following hip or knee replacement. Cochrane Database Syst Rev 2003:CD Priebe HJ. The aged cardiovascular risk patient. Br J Anaesth 2000;85: Eikelboom JW, Karthikeyan G, Fagel N, Hirsh J. American Association of Orthopaedic Surgeons and American College of Chest Physicians guidelines for venous thromboembolism prevention in hip and knee arthroplasty differ: What are the implications for clinicians and patients? Chest 2009;135: Peters CL, Shirley B, Erickson J. The effect of a new multimodal perioperative anaesthetic regimen on postoperative pain, side effects, rehabilitation, and length of hospital stay after total joint arthroplasty. J Arthroplasty 2006;21: Spetzler B, Anderson L. Patient-controlled analgesia in the total joint arthroplasty patient. Clin Orthop Relat Res 1987; Keita H, Geachan N, Dahmani S, Couderc E, Armand C, Quazza M, Mantz J, Desmonts JM. 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5 Continuous Block of the Articular Branches of the Femoral Nerve as a Novel Technique for Pain Control after Hip Arthroplasty 14. Ilfeld BM, Ball ST, Gearen PF, Le LT, Mariano ER, Vandenborne K, Duncan PW, Sessler DI, Enneking FK, Shuster JJ, Theriaque DW, Meyer RS. Ambulatory continuous posterior lumbar plexus nerve blocks after hip arthroplasty: A dual-centre, randomised, triple-masked, placebo-controlled trial. Anaesthesiology 2008;109: Siddiqui ZI, Cepeda MS, Denman W, Schumann R, Carr DB. Continuous lumbar plexus block provides improved analgesia with fewer side effects compared with systemic opioids after hip arthroplasty: A randomised controlled trial. Reg Anaesth Pain Med 2007;32: Niemi L, Pitkanen M, Tuominen M, Rosenberg PH. Technical problems and side effects associated with continuous intrathecal or epidural postoperative analgesia in patients undergoing hip arthroplasty. Eur J Anaesthesiol 1994;11: Dalens B, Tanguy A, Vanneuville G. Lumbar plexus blocks and lumbar plexus nerve blocks. Anaesth Analg 1989;69: Swenson JD, Bay N, Loose E, Bankhead B, Davis J, Beals TC, Bryan NA, Burks RT, Greis PE. Outpatient management of continuous peripheral nerve catheters placed using ultrasound guidance: An experience in 620 patients. Anaesth Analg 2006;103: International Journal of Ultrasound and Applied Technologies in Perioperative Care, January-April 2010;1(1):