EUROANESTHESIA 2008 Copenhagen, Denmark, 31 May - 3 June RC2

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1 PERIPHERAL NERVE BLOCKS FOR LOWER LIMB SURGERY: PRACTICAL GUIDELINES EUROANESTHESIA 2008 Copenhagen, Denmark, 31 May - 3 June RC2 XAVIER CAPDEVILA, MATTHIEU PONROUCH Lapeyronie University Hospital Montpellier, France Saturday, May 31, :00-14:45 Room C1-M1 In this lecture we shall review the anatomy of the lower extremity including the lumbar and sacral plexus relevant for nerve blocks using computer simulation, anatomic models and live models (see Figure 1); describe the approaches for peripheral nerve blocks in the lower extremity including single injection and catheter techniques where indicated; and describe the indications and contra-indications for these blocks for surgery and postoperative pain management. For lower limb orthopaedic surgery, the use of peripheral nerve blocks (PNB) with or without a catheter is recommended and this procedure is constantly progressing [1, 2,]. Femoral or lumbar plexus block (in association with sciatic block when indicated ) provide excellent anaesthesia and optimal postoperative pain relief allowing active physiotherapy [1, 2] and facilitating timely discharge. FIGURE 1. LUMBAR PLEXUS AND SACRAL PLEXUS IN HUMAN

2 BLOCKS OF THE LUMBAR PLEXUS LUMBAR PLEXUS BLOCK Lumbar plexus block (LPB) is a technique of anesthetising the lumbar plexus through a single injection of local anaesthetic. Recent studies have been focused on the advantages of this block in the peri-operative period. A posterior approach (psoas compartment block, PCB) is performed using a modified Winnie s technique [3]. The patient is placed in the lateral position, hips flexed, with the side to be blocked uppermost. Three lines are drawn: one joining the spinous process of L3, L4, and L5; another joining the iliac crests (which indicates the L4-L5 level); and one parallel to the first and passing through the posterior superior iliac crest. The site of puncture is located at the junction of the lateral one-third and the medial two-thirds of the distance between the first and third lines at the L4 level. The spinous process of L4 is estimated to be approximately 1 cm cephalad to the upper edge of the iliac crests. A 10 cm needle connected to a peripheral nerve stimulator (PNS) is inserted perpendicular to the skin and advanced until it encounters the L 4 transverse process. The depth of transverse process is noted. Upon contacting the transverse process, the needle is walked off the process to elicit twitches of the quadriceps femoris muscle. Once the quadriceps twitches are obtained at ~ 0.5 ma and no more than 2 cm beyond the transverse process, ml of local anaesthetic are injected with intermittent aspiration to prevent inadvertent intravascular injection. A recent study examined the exact relationship between the needle and the plexus using an ultrasonographic method. There is a slight increase of the skin-lumbar plexus distance from L3 to L5 ( 5.5 ± 1.4 cm to 5.8 ± 1.3 cm) with differences between normal weight ( 5.2 ± 0.6 cm), overweight ( 7.3 ± 0.6 cm ) and obese ( 8.8±0.9 cm) patients at the L4 level. There is a strong correlation between plexus depth and BMI but the distance between the transverse process and the lumbar plexus is constant despite changes in BMI [3, 4]. These landmarks and guidelines are important despite the fact that ultrasound can be used to define the area of the lumbar plexus close to the transverse process. The psoas muscle and, in some children, the roots of the lumbar plexus themselves can be seen. The literature reports that the obtained blocks are much more complete than those commonly reported with the anterior approach [5, 6].The difficulty in obtaining a lumbar plexus block using the perivascular three-in-one approach is due to failure to block the obturator nerve [6-9]. Lumbar plexus block results in layering of local anaesthetic within the sheath of the psoas muscle and blockade of the entire lumbar plexus. Within the psoas muscle, the branches of the lumbar plexus are close to each other. The resulting block confers anaesthesia to the hip, antero-lateral and medial thigh and medial skin bellow the knee. When combined with sciatic block through the posterior approach, a LPB confers anaesthesia to the entire lower extremity. The introduction of newer equipment, specifically peripheral nerve stimulators, insulated needles and needles for continuous peripheral nerve blocks, have resulted in a renewed interest in this technique. In patients undergoing total knee arthroplasty under lumbar plexus and sciatic nerve blocks with 0.5% ropivacaine or 0.5% bupivacaine (each local anaesthetic contained epinephrine 1:400,000), onset times and success rates were identical. However, the sensory block with bupivacaine was longer (17 ± 3 h) than with ropivacaine (13 ± 2 h). Stevens et al [5] performed a posterior lumbar plexus block with 0.4 ml/kg of 0.5% bupivacaine in 30 patients scheduled for total hip replacement. In comparison with a group of patients without a LPB, they reported better analgesia (VAS pain score in PACU 1.3 ± 2 vs. 5.6 ± 3), a reduction of intra- and postoperative opioid requirements and less blood loss. Furthermore, in patients in whom haemodynamic stability is important, it has been suggested that a combination of lumbar and sacral plexus blocks can be beneficial for hip fractures, as it results in fewer haemodynamic complications than spinal anaesthesia. Analgesia can be extended by inserting a psoas compartment catheter and using a continuous infusion of local anaesthetics [10]. FEMORAL, THREE-IN-ONE AND FASCIA ILIACA COMPARTMENT BLOCKS Classically, femoral nerve block produces anaesthesia in the antero-lateral thigh and the medial skin bellow the knee. With a nerve stimulator, location of the femoral nerve using the relationship of the femoral nerve to the femoral artery at the inguinal crease level was reported to result in a 100% success rate for surgical anaesthesia [11]

3 FIGURE 2. TERRITORIES WITH A SENSORY BLOCK AFTER A PSOAS COMPARTMENT BLOCK (FIG 2A) AND A FEMORAL BLOCK (FIG 2B) Figure 2a Figure 2b In an anatomical model the success rate of femoral nerve block is due to the insertion of the needle at the level of the inguinal crease and immediately adjacent to the lateral border of the femoral artery. At the level of the inguinal ligament, the distance between the two structures varies from 0 to 13 mm. Similar to upper limb neural blocks, some authors have described a multiple stimulation technique to identify two or more distinct branches of the nerve or a plexus to be blocked. Upon obtaining the stimulation of these individual neuronal components (the nerves to vastus medialis, vastus intermedius and vastus lateralis), smaller doses of local anaesthetics are injected to block each individual component. The theoretical advantages of this technique include a reduction in a total dose of local anaesthetic required to successfully block the nerve, a better success rate (> 93%) and a faster onset of blockade [12]. Using 0.5% ropivacaine for a femoral nerve block, the mean (95% CI) volume for blocking the nerve with a multiple injection technique is 14 (12-16) ml compared with 23 (20-26) ml needed with a single injection technique. In other hands the onset of femoral nerve blocks with 0.75% ropivacaine required 10 ± 3.7 min with a multiple stimulation and 30 ± 11 min with a single stimulation technique. With the multiple stimulation technique 14% of patients reported unintentional paraesthesia, 29% poor acceptance of the technique and 28% discomfort during block placement [7]. One concern of this technique is that multiple needle insertions in partially anesthetised tissues may be associated with a higher risk of nerve injury. After injection of an initial dose of local anaesthetic, the localisation of other nerves may be impeded by the resultant nerve blockade. With the multiple injection technique using the minimum local anaesthetic volume of 0.5% ropivacaine or bupivacaine to block the femoral nerve in 50% of patients scheduled for elective knee arthroscopy, the volume of 0.5% ropivacaine (14 ± 2 ml) required to produce effective block (loss of pinprick sensation) was similar to that of 0.5% bupivacaine (15 ± 2 ml). When femoral or three in one block is combined with sciatic block anaesthesia of the entire lower extremity below the level of blockade can normally be achieved. In a multicenter, randomised, blinded study Casati and co-workers [13] compared 225 mg of 0.5%, 0.75% or 1% ropivacaine with 500 mg of 2% mepivacaine. 0.75% ropivacaine seemed the most suitable choice of local anaesthetic providing an onset time similar to mepivacaine (12.5 ± 8 min vs. 12 ± 8 min, respectively) and prolonged postoperative analgesia (14.3 ± 5 h vs. 5.1 ± 2.7 h, respectively). The ability to achieve block of the lumbar plexus through the three-in-one block technique remains a subject of considerable controversy. Capdevila et al [7] compared two single-injection, anterior approach techniques ( three-in-one and fascia iliaca compartment block) in order to simultaneously block the femoral, obturator and lateral femoral cutaneous (LFC) nerves in patients scheduled for lower limb orthopaedic procedures. A lumbar plexus block was obtained in 38% and 34% of the three-in-one and fascia iliaca compartment blocks, respectively. The local anaesthetic solution reached the lumbar plexus in 7 % of patients. Blockade was obtained primarily by the spread of local anaesthetic under the fascia iliaca and only

4 rarely by contact with the lumbar plexus. The spread of local anaesthetics is, however, unpredictable. The local anaesthetic can travel sufficiently under the fascia iliaca to block the femoral and LFC nerves but it does not always migrate proximally and internally in sufficient quantity to block the obturator nerve. Marhofer et al [8] used magnetic resonance imaging and concluded that there was no consistent cephalad spread of the injectate that could result in three-in-one block. Based on this finding, it appears that the mechanism for the three-inone block, if it exists, is the lateral, medial, and caudal spread of the local anaesthetic. While this may effectively block the femoral and LFC nerves, as well as the distal anterior branch of the obturator nerve in some patients, it is unlikely to yield a consistent success rate in blocking all three branches. It has been recently demonstrated that the use of a combined, separate obturator nerve block is necessary to obtain an optimal anaesthetic block of the thigh and knee and total pain relief. The approach to the two branches of the obturator nerve within the adductor muscles is very easy and rapid using a nerve stimulator or ultrasound machine [14, 15]. The use of a combined sciatic nerve block with continuous femoral blockade has been studied [16]. The use of combined sciatic and femoral nerve blocks with bupivacaine pre-operatively can result in superior analgesia and reduced morphine consumption in the first 24 h after lower extremity surgery. However, studies have found that the addition of a sciatic nerve block to continuous femoral nerve or lumbar plexus blocks does not further improve analgesia after total knee replacement. Clinical experience suggests that patients benefit from the addition of a sciatic block to femoral block, especially if they are to undergo aggressive passive continuous motion device therapy postoperatively and they had a fixed flexion deformity of the knee prior to surgery. In the last five years low current-intensity nerve stimulation (< 0.5 ma) or injection of larger volumes of local anaesthetic have become essential to the reliability of this technique. The use of ultrasound can be recommended in order to see the femoral nerve and the spread of local anaesthetic surrounding it (the doughnut sign ). It is fundamental for a successful block that the spread of local anaesthetic, or the catheter tip, lies in the inferior part of the nerve. There has been recent interest in using ultrasound for more precise placement of the block needle during femoral nerve blockade. Marhofer et al. [17] suggested that ultrasound can reduce the onset time and improve the distribution of the local anaesthetic and the quality of sensory block when performing the three-in-one technique compared with conventional nerve stimulator techniques. Using ultrasound to visualize the femoral nerve and guide the needle placement, the authors achieved a success rate of 95% in obtaining sensory block of the femoral, lateral femoral cutaneous and obturator nerves. Recent reports have shown that there is only a short-term (a few hours) benefit from a single-shot threein-one block. After open knee or hip surgery continuous femoral nerve block is the analgesic technique of choice [4, 5]. During a continuous three-in-one block, the threaded catheter rarely reaches the lumbar plexus. The quality of sensory and motor blockade and initial pain relief depend on the location of the catheter tip under the fascia iliaca [18]. Despite the fact that only 40% of catheters are positioned in an ideal location (that is, the lumbar plexus area), a continuous fascia iliaca block with 0.2% bupivacaine reduced opioid requirements and VAS pain values and improved the range of motion in comparison with a placebo group. In the same way, Syngelin et al [19, 20] demonstrated that after knee or hip surgery, better early postoperative pain relief is obtained with PCA techniques with local anaesthetics than with continuous infusion. The continuous infusion of 0.125% bupivacaine at 0.14 ml/kg/h is considered the gold standard to maintain continuous femoral nerve or fascia iliaca block. However, this technique leads to administration of large volumes of local anaesthetic with the potential for toxicity [19]. PCA techniques are associated with the smallest local anaesthetic consumption and the greatest patient satisfaction. A reduced background infusion (for example 5 ml/h) of 0.125% bupivacaine and small (for example 2.5 ml/30 min) PCA boluses provided excellent pain relief and a 32% reduction in local anaesthetic consumption [20]. This technique allowed for rapid reinforcement of the block before a physiotherapy session. PCA boluses alone (for example 10 ml/h) achieved comparable results and a greater reduction (58%) in bupivacaine consumption. Comparable results have been recently obtained with ropivacaine. SCIATIC NERVE BLOCKS Sciatic nerve block is a proven technique to provide anaesthesia of the lower extremity. It has been reported that the parasacral approach to sciatic block resulted in a high success rate of anaesthesia of the entire sacral plexus and a motor block of the obturator nerve is also provided. Both the parasacral and posterior approaches to sciatic nerve blocks can be used to reliably provide continuous analgesia by infusion of local anaesthetic after insertion of an indwelling catheter. Using a modified approach for catheter placement a high success rate was reported. A 16G Tuohy type needle was inserted between the greater trochanter and ischial tuberosity and advanced caudally in the predicted course of the sciatic nerve. Similarly, Morris and Lang reported success using an insertion of the block needle 6 cm along the line connecting the posterior superior iliac spine and the ischial tuberosity [21]

5 FIGURE 3. TERRITORIES WITH A SENSORY BLOCK AFTER A PARASACRAL SCIATIC BLOCK (FIG 3A) AND A POSTE- RIOR, ANTERIOR, LATERAL OR SUBGLUTEAL APPROACH (FIG 3B) Figure 3a Figure 3b New landmarks for the anterior approach have been described [22]. Anterior sciatic block can be performed with the patient in the supine position. Chelly et al [22] recently described a modification of Beck s anterior approach using simplified landmarks. The authors emphasised the more practical landmarks which may significantly facilitate nerve localization. The sciatic nerve was identified within 2.5 min, and a complete sensory block of both the common peroneal and tibial nerves territories was obtained within 15 min. In the anterior approach the needle passes just medially to the femur and contacts the sciatic nerve. However, the needle frequently makes contact with the femur before reaching the nerve. Although the classical description of the block suggests that the needle should simply be walked off the bone, this manoeuvre results in displacement of the tip of the needle too medially and away from the nerve. A recent anatomic study showed that internal rotation of the leg at the hip joint may significantly facilitate the needle reaching the sciatic nerve. The use of ultrasound for the proximal approaches to the sciatic nerve is very helpful, particularly for the subgluteal block [23]. Other approaches to the sciatic nerve may be considered [24]. The popliteal block is an excellent anaesthetic for foot and ankle surgery. Anaesthesiologists should know and respect the anatomical relationship of the tibial and common peroneal nerves in the common sciatic nerve sheath. When used as a sole anaesthetic in outpatients, popliteal block provides anaesthesia and postoperative analgesia, allows the use of a calf tourniquet and is devoid of the systemic or local complications seen with general, spinal or epidural anaesthesia. Performed in the supine position, the lateral popliteal approach is an interesting alternative technique, particularly in trauma or obese patients. Hadzic et al [25] compared the posterior to lateral approach with the popliteal block using 40 ml of 1.5% mepivacaine and confirmed the comparable efficacy of both techniques in patients undergoing lower extremity surgery. The lateral approach took longer to accomplish but an advantage of the technique is the more convenient patient positioning and ease of catheter placement. Using the lateral approach some authors have stimulated separately the tibial and peroneal nerves and reported a high success rate. Similarly, studies have reported that a double stimulation technique may result in a better success rate with use of smaller volumes of local anaesthetic (such as 20 ml). The multiple stimulation technique consisted of localising both components of the sciatic nerve (common peroneal and tibial nerves) using a nerve stimulator and injecting 10 ml of local anaesthetic into each. In an attempt to discern which response to nerve stimulation is associated with the highest likelihood of successful block of the entire sciatic nerve in the popliteal fossa, Benzon et al [26] suggested that inversion of the foot may be the best predictor. Alternatively, a single injection of a larger volume of local anaesthetic into the sheath of the sciatic nerve in the popliteal fossa results in a spread of local anaesthetic within the sheath and an excellent success rate

6 FIGURE 4. TERRITORIES WITH A SENSORY BLOCK AFTER A POPLITEAL SCIATIC NERVE BLOCK To prolong postoperative analgesia the use of long-lasting local anaesthetics is recommended. A 20 ml injection of either 0.75 % ropivacaine or 0.5% bupivacaine has been compared. The median times to onset of complete anaesthesia were 27.5 min and 25 min, respectively, and the duration of analgesia 13.4 h and 15.8 h. Adding 1 µg/kg clonidine to 0.75% ropivacine lengthened postoperative analgesia by 3 h (to 16.8 h) after hallux valgus repair, with no clinically relevant side-effects. Popliteal block is suitable for placement of a catheter and continuous infusion of local anaesthetics [27]. When compared with a classical continuous infusion (for example 0.1 ml/kg/h 0.2% ropivacaine), PCA boluses alone (0.1 ml/kg of 0.2% ropivacaine) or combined with a low basal infusion rate (5 ml/h 0.2% ropivacaine) provided comparable pain relief but significantly reduced local anaesthetic consumption. It has become the standard technique for postoperative analgesia after foot surgery in many centres [28]. This technique is especially useful in patients undergoing extensive foot surgery and recent studies report experience with the use of elastomeric pumps after foot surgery in day case patients receiving patient controlled analgesia or continuous infusion of local anaesthetics [29]. Once again, the use of ultrasound is probably one of the most important technological advances in popliteal nerve block. The use of stimulating catheters is should also be considered for popliteal nerve block. CONCLUSIONS Pain is a major concern during and after lower limb orthopaedic surgery. It not only causes patient discomfort but also compromises early physiotherapy. Peripheral nerve blocks provide better analgesia than IV PCA morphine. As efficient as epidural analgesia, they are associated with much less side-effects and technical problems. Femoral nerve or fascia iliaca block is the most appropriate technique after major hip, femoral shaft, or knee surgery. Sciatic nerve block is the technique of choice after major foot or ankle surgery. The Mayo Clinic group have emphasised the use of a continuous peripheral nerve block programme in hip and knee surgery in order to optimise the surgical result and decrease the hospital stay. Such techniques should have a place in the armamentarium of each anaesthesiologist involved in the treatment of lower limb surgery. The choice of different pereiphreal nerve block techniques in our institution are summarized in Tables 1 and

7 KEY LEARNING POINTS Pain is a major concern during and after lower limb orthopaedic surgery. Lower limb peripheral nerve blocks provide always better analgesia than IV PCA morphine and are associated with less side-effects and technical problems than epidural analgesia Femoral nerve or fascia iliaca block is the most appropriate technique after major hip, femoral shaft, or knee surgery Sciatic nerve block (popliteal or subgluteal aproach) is the technique of choice after major foot or ankle surgery The use of ultrasound is probably one of the most important technological advances for distal lower limb peripheral nerve blocks. Stimulating catheters may be useful REFERENCES 1. Capdevila X, Barthelet Y, Biboulet Ph, Rubenovitch J, d Athis F. Effects of perioperative analgesic technique on the surgical outcome and duration of rehabilitation after major knee surgery. Anesthesiology 1999; 91: Singelyn FJ, Deyaert M, Joris D, Pendeville E, Gouverneur JM. Effects of intravenous patient-controlled analgesia with morphine, continuous epidural analgesia, and continuous three-in-one block on postoperative pain and knee rehabilitation after unilateral total knee arthroplasty. Anesth Analg 1998; 87; Capdevila X, Macaire Ph, Dadure Ch, Choquet O, Biboulet Ph, Ryckwaert Y, et al. Continuous psoas compartment block for postoperative analgesia after total hip arthroplasty: new landmarks, technical guidelines, and clinical evaluation Anesth Analg 2002; 94: Kirchmair L, Entner T, Wissel J, Morigel G, Kapral S, Mitterschiffthaler G. A study of paravertebral anatomy for ultrasound-guided posterior lumbar plexus block. Anesth Analg 2001; 93: Stevens RD, Van Gressel E, Flory N, Fournier R, Gamulin Z. Lumbar plexus block reduces pain and blood loss associated with total hip arthroplasty. Anesthesiology 2000; 93: Parkinson SK, Mueller JB, Little WI, Bailey SI. Extent of blockade with various approaches to the lumbar plexus. Anesth Analg 1989; 68: Capdevila X, Biboulet Ph, Bouregba M, Barthelet Y, Rubenovitch J, d Athis F. Comparison of the three-in-one and fascia iliaca compartment blocks in adults: clinical and radiographic analysis. Anesth Analg 1998; 86: Marhofer P, Nasel C, Sitzwohl C, Kapral S. Magnetic resonance imaging of the distribution of local anaesthetic during the three-in-one block. Anesth Analg 2000; 90: Bouaziz H, Vial F, Jochum D, Macalou D, Heck M, Meuret P, Braun M, Laxenaire MC. An evaluation of the cutaneous distribution after obturator nerve block. Anesth Analg 2002; 94: Chudinov A, Berkenstadt H, Salai M, Cahana A, Perel A. Continuous psoas compartment block for anesthesia and perioperative analgesia in patients with hip fractures. Reg Anesth Pain Med 1999; 24: Vloka D, Hadzic A, Drobnik L, Ernest J, Reiss W, Thys DM. Anatomic landmarks for femoral nerve block: a comparison of four needle insertion sites. Anesth Analg 1999; 89: Fanelli G, Casati A, Garancini P, Torri. Nerve stimulator and multiple injection technique for upper and lower limb blockade: failure rate, patient acceptance and neurologic complications. Anesth Analg 1999; 88: Casati A, Fanelli G, Borghi B, Torri G. Ropivacaine or 2 % mepivacaine for lower limb peripheral nerve blocks. Anesthesiology 1999; 90: Choquet O, Capdevila X, Bennourine K, Feugeas JL, Bringuier-Branchereau S, Manelli JC. A new inguinal approach for the obturator nerve block: anatomical and randomized clinical studies. Anesthesiology 2005; 103: Helayel PE, da Conceição DB, Pavei P, Knaesel JA, de Oliveira Filho GR. Ultrasound-guided obturator nerve block: a preliminary report of a case series. Reg Anesth Pain Med 2007; 32: Pham Dang C, Gautheron E, Guilley J, Fernandez M, Waast D, Volteau C, et al. The value of adding sciatic block to continuous femoral block for analgesia after total knee replacement. Reg Anesth Pain Med 2005; 30: Marhofer P, Schrogendorfer K, Koinig H, Kapral S, Weinstabl C, Mayer N. Ultrasonographic guidance improves sensory block and onset time of three-in-one blocks. Anesth Analg 1997; 85: Capdevila X, Biboulet P, Morau D, Bernard N, Deschodt J, Lopez S, d Athis F. Continuous three-in-one block for postoperative pain after lower limb orthopedic surgery: where do the catheters go? Anesth Analg 2002; 94: , 19. Singelyn FJ, Gouverneur JMA. Extended three-in-one block after total knee arthroplasty: continous versus patientcontrolled techniques. Anesth Analg 2000; 91: Singelyn FJ, Vanderels PE, Gouverneur JMA. Extended femoral nerve sheath block after total hip arthroplasty: continuous versus patient-controlled techniques. Anesth Analg 2001; 92: Morris GF, Lang SA, Dust WN, Van der Wal M. The parasacral sciatic nerve block. Reg Anesth 1997; 22: Chelly JE, Delaunay L. A new anterior approach to the sciatic nerve block. Anesthesiology 1999; 91: Chan VW, Nova H, Abbas S, McCartney CJ, Perlas A, Xu DQ. Ultrasound examination and localization of the sciatic nerve: a volunteer study. Anesthesiology 2006; 104: di Benedetto P, Casati A, Bertini L. Continuous subgluteus sciatic nerve block after orthopedic and ankle surgery: comparison of two infusion techniques. Reg Anesth Pain Med 2002; 27: Hadzic A, Vloka JD. A comparison of the posterior versus lateral approaches to the block of the sciatic nerve in the popliteal fossa. Anesthesiology 1998; 88:

8 26. Benzon HT, Kim C, Benzon HP, Silverstein ME, Jericho B, Prillaman K, Buenaventura R. Correlation between evoked motor response of the sicatic nerve and sensory blockade. Anesthesiology 1997; 87: Syngelin FJ, Aye F, Gouverneur M. Continuous popliteal sciatic nerve block: an original technique to provide postoperative analgesia after foot surgery. Anesth Analg 1997; 84: Ilfeld B, Morey T, Wang R, Enneking FK. Continuous popliteal sciatic nerve block for postoperative pain control at home: a randomized, double-blinded, placebo-controlled study. Anesthesiology 2002; 97: Capdevila X, Dadure C, Bringuier S, Bernard N, Biboulet P, Gaertner E, Macaire P. Effect of patient-controlled perineural analgesia on rehabilitation and pain after ambulatory orthopedic surgery: a multicenter randomized trial. Anesthesiology 2006; 105: TABLE 1. LOWER LIMB BLOCKS FOR DIFFERENT SURGICAL PROCEDURES TABLE 2. ALGORITHM FOR REGIONAL TECHNIQUES FOR LOWER LIMB SURGERY IN OUR INSTITUTION FICB: fascia iliaca compartment block; CPSNB: continuous popliteal sciatic nerve block; CFNB: continuous femoral nerve block; OBT: obturator nerve block ; SNB: sciatic nerve block; CPCB: continuous psoas compartment block ; PTNB: posterior tibial nerve block