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Femoral and lateral femoral cutaneous nerve block
Femoral and Lateral Femoral Cutaneous Nerve Block Richard
W. R o s e n q u i s t ,
MD, and
George
Lederhaas,
Blockade of the lateral femoral cutaneous and femoral nerves is most commonly performed to provide postoperative analgesia for procedures on the knee. It can also provide the sole anesthetic for quadriceps muscle biopsy in the patient at risk for malignant hyperthermia. Recent advancements in understanding pelvic and femoral anatomy have provided additional techniques to improve the clinical success rate of femoral and lateral femoral cutaneous nerve blocks. The relationship of the fascia lata and fascia iliaca to these nerves plays a key role in appropriate needle placement and spread of the local anesthetic injectate. Peripheral nerve stimulation has facilitated the teaching of these techniques and performance of femoral nerve blocks in children under general anesthesia. Continuous femoral catheter infusions have been performed successfully in both children and adults. With understanding of the relevant anatomy and appropriate patient selection, blocks of these nerves have been remarkably safe and effective. Copyright 9 1999 by W.B. Saunders Company
nerve blocks of the lower extremity are used p eripheral increasingly in light of recent concerns over low molecular weight heparins and central neuraxial blocks. Blockade of the femoral and lateral femoral cutaneous nerves can be performed with a number of different techniques. This article highlights the pertinent anatomy, surgical and medical indications, techniques used, adult and pediatric applications, and available clinical outcome studies. Complications related to these blocks and the etiology of peripheral nerve injury are reviewed.
A n a t o m i c Considerations The lumbar plexus is formed from the vertical rami of the first through the fourth lumbar nerve roots. Together, with a contribution from T12, they give rise to the iliohypogastric, ilioinguinal, genitofemoral, lateral femoral cutaneous, femoral, and obturator nerves. Two of these nerves, the lateral femoral cutaneous and the femoral, are commonly blocked for lower extremity anesthesia and analgesia and are reviewed in greater detail. The lateral femoral cutaneous nerve is derived from the second and third lumbar nerve roots. It is a direct branch of the lumbar plexus and is a pure sensory nerve. After coursing laterally over the iliacus muscle, where it is covered by the fascia iliaca, it passes under the lateral end of the ilioinguinal ligament and is covered by the fascia lata. From there, it pierces the fascia lata within 5 cm of the anterior superior iliac spine. It subsequently divides into anterior and posterior branches. The From The University of Iowa Hospitals and Clinics, Iowa City, IA. Address reprint requests to Richard W. Rosenquist, MD, The University of Iowa Hospitals and Clinics, Department of Anesthesia, 200 Hawkins Drive 6 JCP, Iowa City, IA 52242-1079. Copyright 9 1999 by W.B. Saunders Company 1084-208X/99/0301-0006510.00/0
MD
anterior branch provides sensation to the lateral aspect of the thigh as far as the knee, with variable input to the patellar plexus. The posterior branch supplies the skin over the lateral part of the buttock distal to the greater trochanter and the proximal portion of the lateral thigh.1 The femoral nerve is composed of branches of the second, third, and fourth lumbar nerve roots. It has both motor and sensory fibers. It emerges from the body of the iliopsoas to course in the groove between the iliacus and iliopsoas. The nerve is covered by the fascia iliaca as it descends to the femoral triangle. This fascial sheath is not continuous with the lumbar plexus. 2,3 At the level of the inguinal ligament and lateral to the femoral artery, it separates into anterior and posterior divisions. These divisions are deep to the fascia lata and the fascia iliaca. The anterior bundle provides sensory innervation to the anterior thigh and a motor branch to the sartorius muscle. The posterior bundle provides sensory fibers to the knee and hip joints, periosteum of the femur, and terminates as the saphenous nerve on exiting the adductor canal. The posterior bundle also provides motor innervation to the quadriceps group.L
Femoral and Lateral Femoral C u t a n e o u s Nerve Block Indications Blockade of the femoral and lateral femoral cutaneous nerves can provide anesthesia for procedures involving the anterolateral thigh (skin grafting, quadriceps muscle biopsy). This can be used to avoid volatile anesthetics for individuals at risk for malignant hyperthermia. 4,5 More commonly, it is used to provide anesthesia or postoperative analgesia for procedures on the knee (knee arthroscopy, total knee arthroplasty, patellar reconstruction). 6-1~ For procedures below the knee or involving the tibial plateau, a sciatic nerve block must also be performed and is the most common situation in clinical practice. Femoral nerve block (single shot or continuous) is capable of providing analgesia for the setting or providing traction of femoral shaft and neck fractures. 12-14The painful entrapment neuropathy of the lateral femoral cutaneous nerve (meralgia paresthetica) can be treated diagnostically and therapeutically with local anesthetic/corticosteroid injections. 15 Recent literature reports the efficacy of femoral nerve blocks combined with genitofemoral nerve supplementation to provide complete anesthesia for saphenous vein stripping. 16 In pediatric cases, femoral and lateral femoral cutaneous nerve blocks have been performed to provide postoperative analgesia following varus derotation osteotomies and percutaneous pinning of slipped femoral capital epiphyses. Dalens et al. 17 reported the largest pediatric series of fascia iliaca and 3-in-1 blocks to date. For further discussion of their technique see Fascia Iliaca Approach.
Techniques in Regional Anesthesia and Pain Management, Vol 3, No 1 (January), 1999: pp 33-38
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Lateral Femoral Cutaneous Approaches The lateral femoral cutaneous nerve is most commonly anesthetized using a large volume (10 to 15 mE) with a "field" block technique. A 22-G short bevel needle is introduced and advanced perpendicular 2 cm medial and 2 cm inferior to the anterior superior iliac spine. A distinct loss of resistance or "pop" should be appreciated as the needle pierces the fascia lata. A total of 5 m k of local anesthetic should be placed while withdrawing the needle tip into the subcutaneous tissue. This should be repeated in the medial and lateral directions to achieve adequate distribution of solution both deep and superficial to the fascia lata is (Fig 1). To avoid systemic local anesthetic toxicity when this block is combined with femoral and sciatic blocks, Brown 19 recommends using a lesser concentration of local anesthetic (eg, bupivacaine 0.25%, lidocaine 0.75%) and maintaining a large volume. A technique based on the use of a nerve stimulator has been advocated by Shannon and colleagues, z~ A hand-held transdermal nerve stimulator (settings: 20 mA, 2 Hz) is placed medial to the anterior superior iliac spine and just beneath the ilioinguinal ligament to elicit a paresthesia referred to the lateral thigh. At the area of the most intense paresthesia, a 26-G uninsulated needle attached to a nerve stimulator is advanced. Nerve localization is considered successful at a stimulator setting of 0.6 mA at 1 Hz with paresthesia along the lateral aspect of the knee. Using a volume of 6 m k (lidocaine 2% with epinephrine 1:200,000), they reported a success rate of 85% to 100%. When using a fanning technique, as described previously, but using only 6 mL of local anesthetic, the success rate was less than 40%. The authors noted that when attempting to use a 22-G insulated needle, there was excessive patient discomfort. Although this approach required approximately 5 more minutes to perform than a "field" block, they considered its success rate and fast speed of onset well worth the initial time investment. Of further significance, this approach localized the nerve to within 1 cm of the anterior superior iliac spine. Thus, the traditional approach may be better served by having the initial needle entry site 1 cm from the anterior superior iliac spine and just below the ilioinguinal ligament.
Classic Approach of Labat to the Femoral Nerve The key anatomic landmarks are identifying the ilioinguinal ligament and the femoral arterial pulsation immediately below it. In obese individuals, an assistant may be necessary to retract the overlying abdominal pannus. The needle entry site to be marked is 1 to 2 cm lateral to the arterial pulsation and 1 to 2 cm below the inguinal ligament. Adequate preparation of the skin and sterile technique should be used in all regional techniques. A 5 cm, 22-G needle is advanced perpendicular through the skin until a paresthesia is obtained. With compression of the overlying subcutaneous tissue, this should be obtained at a depth of 3 cm or less. A total of 20 mL of local anesthetic is deposited in incremental doses after slow aspiration to avoid intravascular injection zl (Fig 2). If no paresthesias are elicited with the preceding needle direction, the needle should be directed in medial and lateral directions (fanning) at the same entry site. Next 10 mL of a local anesthetic solution is deposited in each region. This may be considered a "field block. ''22 With a 22-G short bevel needle, a loss of resistance or "pop" may be appreciated when the
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Fig 1. Lateral cutaneous nerve block (see text). The lateral cutaneous nerve of the thigh passes inferiorly on iliacus muscle covered by iliacus fascia, Just medial to the anterior superior iliac spine, it turns anteriorly to pass just below the inguinal ligament and runs deep to the fascia lata until it emerges subcutaneously. The lateral cutaneous nerve can be blocked just medially to the anterior superior iliac spine or 1 to 2 cm below it. (Reprinted with permission from Bridenbaugh?l).
needle passes through fascial layers. It is important to keep in mind that the femoral vessels are covered only by the fascia lata, whereas the femoral nerve is deep to both the fascia lata and fascia iliaca. Thus, two "pops" need to be appreciated to achieve sufficient needle depth. With the advent of insulated needles, nerve stimulation is used increasingly in clinical practice and resident education. A 22-G, 5 cm, short-bevel needle is used. This permits the appreciation of fascial "pops" and muscle contraction. Initial nerve stimulator settings are 1.0 mA at 1 Hz. However, successful needle tip location is considered when muscle contraction is demonstrated at less than 0.5 mA. Quadriceps ROSENQUIST AND LEDERHAAS
'al Nerve
~1Artery ]1 Vein
Js Muscle .~rlying Iliaca
Fig 2. Inguinal structures showing fascial envelope around femoral nerve and relationships for inguinal paravascular femoral nerve block techniques. (Reprinted with permission from Bridenbaugh.21). group activation is ideally sought. However, if only sartorius contraction is evident and the site of needle entry is immediately lateral to the femoral arterial pulsation, this may be considered successful location of the anterior division of the femoral nerve. If surgical anesthesia is to be achieved, 20 mL of mepivacaine 1.5% to 2%, bupivacaine 0.5% to 0.75% with or without epinephrine, or ropivacaine 0.5% to 0.75% is used. For postoperative analgesia, bupivacaine 0.25% to 0.5% with or without epinephrine 1:200,000 is most commonly provided.
3-in-1 Block Winnie and colleagues z3 described an inguinal paravascular approach to block the femoral, lateral femoral cutaneous, and LATERAL FEMORAL CUTANEOUS NERVE BLOCK
obturator nerves with a single injection. Their initial entry site is the classic approach of Labat. However, the needle is directed cephalad at a 45 ~ angle to the skin. Before injection, a paresthesia was elicited in the distribution of the femoral nerve. Distal pressure was maintained during injection. They reported that when at least 20 mL of local anesthetic was administered, blockade of all three nerves was assured. Subsequent investigators have not been able to duplicate these clinical results or provide cadaveric support for a femoral "sheath" continuous with the entire lumbar plexus. In a clinical study involving patients undergoing vastus medialis biopsy. Madej and co-workers 5 used 0.6 mL/kg (maximal volume 40 mL) of either lidocaine 1% with norepinephrine 1:100,000 or bupivacaine 0.25% after eliciting a paresthesia in the distribution of the femoral nerve. They reported an 87.5% and 67.5% success rate in providing complete anesthesia of the femoral and lateral femoral cutaneous nerves, respectively. No clinical evidence of obturator nerve blocks, as assessed by weakness in thigh abduction, was reported. Seeberger and Urwyler 24 compared 20 mL to 40 mL of mepivacaine 1% for 3-in-1 block. A notable difference in their technique was the use of a 22-G insulated needle with stimulation of one of the quadriceps muscles at 0.5 mA or less at a frequency of 1 Hz. Firm pressure was applied distal to the needle as in the Winnie and Madej studies. Complete femoral nerve blockade was achieved in 92% and 93%, respectively, in the 20 mL and 40 mL groups, sensory nerve blockade of the obturator nerve in 62% and 78%, and blockade of the lateral femoral cutaneous nerve in 41% and 44%. Why was there a difference in outcomes? Madej attributed sensory anesthesia of the medial thigh to the medial cutaneous nerve originating from the femoral nerve. After the local anesthetic injection was performed, this was the earliest region to develop anesthesia. Seeberger attributed sensory innervation of the medial thigh to the obturator nerve. No time onset for anesthesia of the medial thigh was provided. Lang and colleagues 25 used the same technique as Winnie et al. 23 and Madej et al. 5 and used 30 mL (either lidocaine 2% with epinephrine 1:200,000 or bupivacaine 0.375% with epinephrine 1:200,000) and could demonstrate obturator motor block in only one of 26 patients. 25 Finally, a cadaveric study by Ritter 3 using 20 mL and 40 mL of methylene blue dye injected into the femoral nerve sheath did not demonstrate spread of the injectate from the femoral nerve to the lumbar plexus or obturator nerve. On dissection of the group with the larger volume of injectate, staining of the lateral femoral cutaneous nerve was noted based on diffusion through the fascia iliaca. Although the 3-in-1 block is attractive on theoretical grounds, anatomic and clinical studies do not support it. It is best considered a 2-in-1 block when larger volumes of local anesthetic are used. When blockade of the lateral femoral cutaneous nerve must be assured, we recommend a separate injection (10 to 15 mL). A smaller volume (20 mL) may then can be given to provide sole anesthesia of the femoral nerve.
Fascia lliaca Approach Anatomic dissections and clinical studies by Dalens and colleagues 17 have demonstrated that large volumes of local anesthetic deposited inferior to the ilioinguinal ligament and beneath the fascia iliaca can spread rostrally. The solution will 35
primarily come in contact with the femoral and lateral femoral cutaneous nerves, but may also bathe the genitofemoral and obturator nerves. The approach for both adults and children is the same. 26 The needle entry site is 1 cm below the point at which the lateral third of the ilioinguinal ligament meets the middle third. This may also be considered the midpoint between the initial entry points for the traditional femoral and lateral femoral cutaneous blocks. A 22-G short bevel needle is directed perpendicular to the skin. After the skin is pierced, two distinct "pops" should be appreciated as the needle passes through the fascia lata and fascia iliaca. The needle will contact femur if advanced too deeply. After careful aspiration and application of manual pressure on the anterior thigh or application of a thigh tourniquet, the anesthetic solution is administered in divided doses. The recommended volume in adults is 30 mL. The following volume recommendations in children are based on a 50:50 mixture of lidocaine 1% and bupivacaine 0.5%, both with epinephrine 1:200,000:0.7 mL/kg for 20 kg or less, 5 mL for 20 to 30 kg, 20 mL for 30 to 40 kg, 25 mL for 40 to 50 kg, and 27.5 mL for those greater than 50 kg. 17 Fig 3 demonstrates spread of contrast with the fascia iliaca and Winnie's 3-in-1 technique.
Pediatric Applications The fascia iliaca and 3-in-1 blocks have been successfully used in children to provide postoperative analgesia for placement and removal of femoral hardware, percutaneous pinning of slipped capital femoral epiphyses, femoral fracture, anterior procedures of the thigh, and varus derotation osteotomies. 17 Combined femoral and lateral femoral cutaneous blocks have been performed to provide surgical anesthesia for quadriceps muscle biopsy. 4 It should be recognized that this was performed with the patient under conscious/deep sedation. In the Dalens study, fascia iliaca and Winnie's 3-in-1 blocks were compared for procedures above the knee. All blocks were performed while the patients were under general anesthesia. The 3-in-1 block was performed with a 22-G insulated short-bevel needle with settings as previously described. The volume and local anesthetic compositions were as noted in the previous section. Adequate postoperative analgesia was present in more than 90% of the fascia iliaca group and in only 20% of the 3-in-1 group. The average duration of analgesia was 6 hours before supplemental analgesics were required. These results were attributable to sensory anesthesia of the lateral femoral cutaneous, obturator, and genitofemoral nerves in 85% to 95% of the fascia iliaca group. There was a 100% success rate of femoral nerve anesthesia in both groups. For children with mid-shaft fractures of the femur, single femoral nerve injections and continuous infusions have proven efficacious in providing analgesia. Ronchi et aP 2 used a single injection of bupivacaine 0.5% (0.4 mL/kg) that provided at least 3 hours of analgesia. During this time period, radiographic analysis and application of traction and casting were performed in a painless manner. Their approach was one finger breadth lateral to the femoral arterial pulse and directly below the inguinal ligament. Paresthesias were not sought. Rather, loss of resistance ("pops") as the 23-G needle passed through the fascia lata and fascia iliaca was the desired end-point. Placement of femoral sheath catheters has been described by Johnson 13 and Tobias. 14 They elected to provide pain manage-
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Fig. 3. Spread of a solution containing contrast media. (A) 3-in-1 block. Note that the solution does not reach the psoas compartment where the lumbar plexus lies. (B) Fascia iliaca compartment block. Note the spread of the solution along the anterior aspect of the iliacus muscle and the medial increase in opacity, probably due to superimposition resulting from the reflection of the fascia iliaca compartment covering successively (1) the anterior aspect of the iliacus muscle, then (2) the posterior, and (3) the anterior aspect of the psoas muscle.
ROSENQUIST AND LEDERHAAS
ment in this manner because of concerns over administering opioids to trauma patients with closed head injuries. The Tobias approach is as follows: A 3 Fr G, 8-cm single lumen central venous catheter was placed in the femoral sheath via a Seldinger technique. The introducer needle was placed just lateral to the arterial pulse and 2 to 4 cm inferior to the inguinal ligament. After experiencing two "pops," the guidewire was advanced, the needle was removed, and 3 Fr catheter advanced over the guidewire. The initial bolus of local anesthetic was 0.5 mL/kg (maximum 20 mL) of bupivacaine 0.25% with epinephrine 1:200,000. A continuous infusion of bupivacaine 0.2% was provided at 0.15 mL/kg/h (0.3 mg/kg/hr). If additional analgesia was required, a bolus of 0.25 mL/kg of bupivacaine 0.2% was provided and the rate increased to 0.25 mL/kg/hr (0.5 mg/kg/hr). This rate was not exceeded because bupivacaine delivery greater than this would place the child at risk for local anesthetic toxicity.27 Local anesthetic delivery in the Johnson study 13 adhered to the same principles. However, the rate of infusion was 0.3 mL/kg/hr of bupivacaine 0.125%. Back leak was noted at the site of catheter insertion and more frequent episodes of breakthrough pain requiring supplemental opioids were reported than in the Tobias 14 series. In the Johnson series of patients, a 20-G epidural catheter was inserted 5 to 8 cm through an 18-gauge Touhy needle after double loss of resistance. It is our clinical intuition that the differences in analgesic efficacy may have been the result of anesthetic concentration and not technique.
Clinical Outcome Studies The majority of studies documenting improved outcomes after femoral nerve block have been in patients undergoing knee surgery. In adults having anterior cruciate reconstruction, performance of a femoral nerve block with bupivacaine 0.5% (20 mL) before surgical incision reduced intramuscular opioid administration by 80% in the recovery room and 40% in the first 24 postoperative hours. 7 The authors emphasized that it was technically easier to perform the block at the start of surgery than at completion when the hip and knee are relatively immobilized. A similar reduction in opioid use was documented in patients after total knee replacement who had femoral sheath catheters and received intermittent doses of bupivacaine 0.5% (0.3 mL./kg) at 6- to 8-hour intervals. 11 However, the catheter and control groups were provided with patient-controlled analgesia (PCA) devices to deliver intravenous morphine. Overall pain scores and antiemetic requirements were not significantly different. The provision of PCA was a significant advantage to these patients over the previous study. Superior pain relief and decreased opioid requirements have been shown in patients who received a continuous local anesthetic infusion. 9 In this series of patients having total knee arthroplasty, the catheter was initially dosed with bupivacaine 0.5% (0.4 mL/kg) and a continuous infusion of bupivacaine 0.25% maintained at 0.15 mI_/kghr for 16 hours. There was also a trend toward fewer side effects (nausea, vomiting, urinary retention) in the group receiving local anesthetics, but an inadequate number of patients were enrolled in the study to achieve statistical significance. Hirst and colleagues 6 randomized their series of total knee
LATERAL FEMORAL CUTANEOUS NERVE BLOCK
arthroplasties to morphine PCA alone or morphine PCA with single femoral nerve bolus (bupivacaine 0.5% with epinephrine 1:200,000--20 mL) or bolus plus an infusion of bupivacaine 0.125% at < 0.1 mL/kg/hr (6 mL/hr). 6 Both local anesthetic groups had superior analgesia in the recovery room, but there was no difference on the ward. The incidence of nausea, however, was greater in the morphine PCA alone group. The Hirst study delivered less than half the amount of bupivacaine than the Dahl study. From the pediatric and adult literature, it appears that more concentrated local anesthetic solutions are required to obtain the analgesic benefits of continuous peripheral catheter techniques. Continuous femoral nerve blockade is not a complete anesthetic for total knee replacement because the tibia is innervated by sciatic nerve. In comparing regional techniques, femoral nerve block with genitofemoral infiltration for long saphenous vein stripping proved superior to spinal anesthesia. 16 The femoral nerve block was performed with 30 mL of alkalinized chloroprocaine 3% and the spinal anesthetic consisted of 65 mg of 5% hyperbaric lidocaine. Patients who received the peripheral nerve block had less postoperative pain and blockade, greater satisfaction with the technique, and shorter overall hospital stays. For the knee arthroscopy that is converted to an open procedure, continuous femoral nerve block has been compared with continuous lumbar epidural morphine infusion, l~ The femoral infusion was preceded by a bolus of bupivacaine 0.5% (0.4 mL/kg) and the bupivacaine 0.25% at 0.14 mL/kg/hr. The epidural group had a morphine bolus of 4 mg followed by an infusion of 0.33 mg/hr. Both of these regimens were initiated at the completion of surgery. Intramuscular morphine was provided for breakthrough pain. Pain scores and supplemental morphine requirements were equivalent for the first postoperative day. The distinct advantage in the femoral nerve block group was the markedly lower incidence of nausea, vomiting, pruritus, and urinary retention. These last two articles validate extending a practitioner's regional anesthesia practice beyond the central neuraxial techniques. Provision of an adequate concentration and rate of delivery of local anesthetic are crucial to the success of femoral blocks. In addition, the use of this technique should not preclude the concurrent use of morphine PCA devices. Excellent postoperative analgesia can be obtained with a multimodal approach.
Complications Injury to the lateral femoral cutaneous nerve after performance of a block is exceedingly rare. In our review of the literature, we did not discover any reports. Meralgia paresthetica, however, is not uncommon. 28 Obese adults and parturients are most prone to develop this condition. In adolescents, however, thin, muscular individuals who engage in competitive sports are the more likely patients. 15 Local hematoma formation is the most common problem in performing a femoral nerve block. Femoral arterial or venous puncture should be minimized by careful palpation of the arterial pulse and initial needle placement at least 1 cm laterally. If vascular penetration occurs, manual compression to the site should be applied to the site for at least 5 minutes.
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Reassessment of the site should be performed intraoperatively, particularly if a thigh tourniquet is used. Permanent femoral nerve injury is rare with careful technique. There is no data to support a nerve stimulator approach over a paresthesia-based method. In the American Society of Anesthesiologists Closed Claims Study, femoral nerve injuries accounted for only 6 of 227 claims. 29 It was not clarified in the report whether the injury was due to surgical positioning or regional anesthetic technique. In reviewing the neurology literature, the majority of femoral neuropathies are due to extremes in the lithotomy position (angulation of duration) or inappropriate placement of intraabdominal retractors. 3~ Idiopathic neuropathies have also been reported. 31
Summary Overall, regardless of the technique, blockade of the femoral and lateral femoral cutaneous nerves has an enviable safety record. The success of each technique is predicted on its appropriateness for the planned surgery, knowledge of the relevant anatomic landmarks, and a sufficient volume of local anesthetic. As with all regional techniques, appropriate monitoring and adequate patient sedation are essential. The ability to provide improved postoperative analgesia and shortened hospital stay for planned outpatient procedures makes these blocks attractive. Finally, because they are technically the simplest peripheral nerve blocks to learn, they are an excellent starting point for introducing peripheral block techniques into one's practice.
Acknowledgment We wish to thank Teresa Block for her patience and superb secretarial support.
References 1. Woodburne RT: The lower limb, in Woodburne RT (ed): Essentials of Human Anatomy (ed 7). New York, NY, Oxford University Press, 1983, pp 557-571 2. Capdevila X, Biboulet P, Bouregba M: Comparison of the three-in-one and fascia iliaca compartment blocks in adults: Clinical and radiographic analysis. Anesth Analg 69:705-713, 1989 3. Ritter JW: Femoral nerve "sheath" for inguinal paravascular lumbar plexus block is not found in human cadavers. J Clin Anesth 7:470-473, 1995 4. Maccani RM, Wedel DJ, Melton A: Femoral and lateral femoral cutaneous block for muscle biopsies in children. Paediatr Anaesth 5:223-227, 1995 5. Madej TH, Ellis FR, Halsall PJ: Evaluation of "3 in 1" lumbar plexus block in patients having muscle biopsy. Br J Anaesth 62:515-517, 1989 6. Hirst GC, Lang SA, Dust WN: Femoral nerve block single injection versus continuous infusion for total knee arthroplasty. Reg Anesth 21:292-297, 1996 7. Ringrose NH, Cross MJ: Femoral nerve block in knee joint surgery. Am J Sports Med 12:398-401, 1984
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8. Bonicalzi V, Gallino M: Comparison of two regional anesthetic techniques for knee arthroscopy. Arthroscopy 11:207-212, 1995 9. Dahl JB, Christiansen CL, Daugaard JJ: Continuous blockade of the lumbar plexus after knee jury: Postoperative analgesia and bupivacaine plasma concentrations. A controlled clinical trial. Anaesthesia 43:1015-1018, 1988 10. Schultz P, Christensen EF, Anker-Moller E: Postoperative pain treatment after open knee surgery: Continuous lumbar plexus block with bupivacaine versus epidural morphine. Reg Anesth 16:34-37, 1991 11. Serpell MG, Millar FA, Thomson MF: Comparison of lumbar plexus block versus conventional opioid analgesia after total knee replacement. Anaesthesia 46:275-277, 1991 12. Ronchi L, Rosenbaum D, Athouel A: Femoral nerve blockade in children using bupivacaine. Anesthesiology 70:622-624, 1989 13. Johnson CM: Continuous femoral nerve blockade for analgesia in children with femoral fractures. Anaesth Intensive Care 22:281-283, 1994 14. Tobias JD: Continuous femoral nerve block to provide analgesia following femur fracture in a paediatric ICU population. Anaesth Intensive Care 22:616-618, 1994 15. Edelson R, Stevens P: Meralgia paresthetica in children. J Bone Joint Surg 76A:993-999, 1994 16. Vloka JD, Hadzic A, Mulcare R: Femoral and genitofemoral nerve blocks versus spinal anesthesia for outpatients undergoing long saphenous vein stripping. Anesth Analg 84:749-752, 1997 17. Dalens B, Vanneuville G, Tanguy A: Comparison of the fascia iliaca block with the 3-in-1 block in children. Anesth Analg 69:705-713, 1989 18. McQuillan PM: Lateral femoral cutaneous nerve, in Hahn MB, McQuillan PM, Sheplock GJ (eds): RegionalAnesthesia: An Atlas of Anatomy and Techniques (ed 1). St. Louis, MO, Mosby, 1996, pp 143-145 19. Brown DL: Lateral femoral cutaneous block, in Brown DL (ed): Atlas of Regional Anesthesia (ed 1). Philadelphia, PA, W.B. Saunders Company, 1992, pp 99-101 20. Shannon J, Lang SA, Yip RW: Lateral femoral cutaneous nerve block revisited: A nerve stimulator technique. Reg Anesth 20:100-104, 1995 21. Bridenbaugh PO: The lower extremity: Somatic blockade, in Cousins M, Bridenbaugh PO (eds): Neural Blockade (ed 2). Philadelphia, PA, J.B. Lippincott, 1988, pp 417-441 22. Brown DL: Femoral nerve, in Brown DL (ed): Atlas of Regional Anesthesia (ed 1). Philadelphia, PA, W.B. Saunders Company, 1992, pp 91-95 23. Winnie AP, Ramamurthy S, Durrani Z: The inguinal paravascular technique of lumbar plexus anesthesia: The "3-in-1 block." Anesth Analg 52:989-996, 1973 24. Seeberger MD, Urwyler A: Paravascular lumbar plexus block: Block extension after femoral nerve stimulation and injection of 20 vs. 40 ml mepivacaine 10 mg/ml. Acta Anaesthesiol Scand 39:769-773, 1995 25. Lang SA, Yip RW, Chang PC: The femoral 3-in-1 block revisted. J Clin Anesth 5:292-296, 1993 26. Capdevila X, Biboulet P, Bouregba M: Comparison of the three-in-one and fascia iliaca compartment blocks in adults: Clinical and radiographic analysis. Anesth Analg 86:1039-1044, 1998 27. Berde CB: Convulsions associated with pediatric regional anesthesia. Anesth Analg 75:164-166, 1992 28. Kitchen C, Simpson J: Meralgia paresthetica: A review of 67 patients. Acta Neurol Sand 48:547-555, 1972 29. Krall DA, Caplan RA, Posner K: Nerve injury associated with anesthesia. Anesthesiology 73:202-207, 1990 30. AI Hakim M, Katirji B: Femoral mononeuropathy induced by the lithotomy position: A report of 5 cases with a review of the literature. Muscle Nerve 16:891-895, 1993 81. Carter GT, McDonald CM: Isolated femoral mononeuropathy to the vastus lateralis: EMG and MRI findings. Muscle Nerve 18:341-344, 1995
ROSENQUIST AND LEDERHAAS
W. R o s e n q u i s t ,
MD, and
George
Lederhaas,
Blockade of the lateral femoral cutaneous and femoral nerves is most commonly performed to provide postoperative analgesia for procedures on the knee. It can also provide the sole anesthetic for quadriceps muscle biopsy in the patient at risk for malignant hyperthermia. Recent advancements in understanding pelvic and femoral anatomy have provided additional techniques to improve the clinical success rate of femoral and lateral femoral cutaneous nerve blocks. The relationship of the fascia lata and fascia iliaca to these nerves plays a key role in appropriate needle placement and spread of the local anesthetic injectate. Peripheral nerve stimulation has facilitated the teaching of these techniques and performance of femoral nerve blocks in children under general anesthesia. Continuous femoral catheter infusions have been performed successfully in both children and adults. With understanding of the relevant anatomy and appropriate patient selection, blocks of these nerves have been remarkably safe and effective. Copyright 9 1999 by W.B. Saunders Company
nerve blocks of the lower extremity are used p eripheral increasingly in light of recent concerns over low molecular weight heparins and central neuraxial blocks. Blockade of the femoral and lateral femoral cutaneous nerves can be performed with a number of different techniques. This article highlights the pertinent anatomy, surgical and medical indications, techniques used, adult and pediatric applications, and available clinical outcome studies. Complications related to these blocks and the etiology of peripheral nerve injury are reviewed.
A n a t o m i c Considerations The lumbar plexus is formed from the vertical rami of the first through the fourth lumbar nerve roots. Together, with a contribution from T12, they give rise to the iliohypogastric, ilioinguinal, genitofemoral, lateral femoral cutaneous, femoral, and obturator nerves. Two of these nerves, the lateral femoral cutaneous and the femoral, are commonly blocked for lower extremity anesthesia and analgesia and are reviewed in greater detail. The lateral femoral cutaneous nerve is derived from the second and third lumbar nerve roots. It is a direct branch of the lumbar plexus and is a pure sensory nerve. After coursing laterally over the iliacus muscle, where it is covered by the fascia iliaca, it passes under the lateral end of the ilioinguinal ligament and is covered by the fascia lata. From there, it pierces the fascia lata within 5 cm of the anterior superior iliac spine. It subsequently divides into anterior and posterior branches. The From The University of Iowa Hospitals and Clinics, Iowa City, IA. Address reprint requests to Richard W. Rosenquist, MD, The University of Iowa Hospitals and Clinics, Department of Anesthesia, 200 Hawkins Drive 6 JCP, Iowa City, IA 52242-1079. Copyright 9 1999 by W.B. Saunders Company 1084-208X/99/0301-0006510.00/0
MD
anterior branch provides sensation to the lateral aspect of the thigh as far as the knee, with variable input to the patellar plexus. The posterior branch supplies the skin over the lateral part of the buttock distal to the greater trochanter and the proximal portion of the lateral thigh.1 The femoral nerve is composed of branches of the second, third, and fourth lumbar nerve roots. It has both motor and sensory fibers. It emerges from the body of the iliopsoas to course in the groove between the iliacus and iliopsoas. The nerve is covered by the fascia iliaca as it descends to the femoral triangle. This fascial sheath is not continuous with the lumbar plexus. 2,3 At the level of the inguinal ligament and lateral to the femoral artery, it separates into anterior and posterior divisions. These divisions are deep to the fascia lata and the fascia iliaca. The anterior bundle provides sensory innervation to the anterior thigh and a motor branch to the sartorius muscle. The posterior bundle provides sensory fibers to the knee and hip joints, periosteum of the femur, and terminates as the saphenous nerve on exiting the adductor canal. The posterior bundle also provides motor innervation to the quadriceps group.L
Femoral and Lateral Femoral C u t a n e o u s Nerve Block Indications Blockade of the femoral and lateral femoral cutaneous nerves can provide anesthesia for procedures involving the anterolateral thigh (skin grafting, quadriceps muscle biopsy). This can be used to avoid volatile anesthetics for individuals at risk for malignant hyperthermia. 4,5 More commonly, it is used to provide anesthesia or postoperative analgesia for procedures on the knee (knee arthroscopy, total knee arthroplasty, patellar reconstruction). 6-1~ For procedures below the knee or involving the tibial plateau, a sciatic nerve block must also be performed and is the most common situation in clinical practice. Femoral nerve block (single shot or continuous) is capable of providing analgesia for the setting or providing traction of femoral shaft and neck fractures. 12-14The painful entrapment neuropathy of the lateral femoral cutaneous nerve (meralgia paresthetica) can be treated diagnostically and therapeutically with local anesthetic/corticosteroid injections. 15 Recent literature reports the efficacy of femoral nerve blocks combined with genitofemoral nerve supplementation to provide complete anesthesia for saphenous vein stripping. 16 In pediatric cases, femoral and lateral femoral cutaneous nerve blocks have been performed to provide postoperative analgesia following varus derotation osteotomies and percutaneous pinning of slipped femoral capital epiphyses. Dalens et al. 17 reported the largest pediatric series of fascia iliaca and 3-in-1 blocks to date. For further discussion of their technique see Fascia Iliaca Approach.
Techniques in Regional Anesthesia and Pain Management, Vol 3, No 1 (January), 1999: pp 33-38
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Lateral Femoral Cutaneous Approaches The lateral femoral cutaneous nerve is most commonly anesthetized using a large volume (10 to 15 mE) with a "field" block technique. A 22-G short bevel needle is introduced and advanced perpendicular 2 cm medial and 2 cm inferior to the anterior superior iliac spine. A distinct loss of resistance or "pop" should be appreciated as the needle pierces the fascia lata. A total of 5 m k of local anesthetic should be placed while withdrawing the needle tip into the subcutaneous tissue. This should be repeated in the medial and lateral directions to achieve adequate distribution of solution both deep and superficial to the fascia lata is (Fig 1). To avoid systemic local anesthetic toxicity when this block is combined with femoral and sciatic blocks, Brown 19 recommends using a lesser concentration of local anesthetic (eg, bupivacaine 0.25%, lidocaine 0.75%) and maintaining a large volume. A technique based on the use of a nerve stimulator has been advocated by Shannon and colleagues, z~ A hand-held transdermal nerve stimulator (settings: 20 mA, 2 Hz) is placed medial to the anterior superior iliac spine and just beneath the ilioinguinal ligament to elicit a paresthesia referred to the lateral thigh. At the area of the most intense paresthesia, a 26-G uninsulated needle attached to a nerve stimulator is advanced. Nerve localization is considered successful at a stimulator setting of 0.6 mA at 1 Hz with paresthesia along the lateral aspect of the knee. Using a volume of 6 m k (lidocaine 2% with epinephrine 1:200,000), they reported a success rate of 85% to 100%. When using a fanning technique, as described previously, but using only 6 mL of local anesthetic, the success rate was less than 40%. The authors noted that when attempting to use a 22-G insulated needle, there was excessive patient discomfort. Although this approach required approximately 5 more minutes to perform than a "field" block, they considered its success rate and fast speed of onset well worth the initial time investment. Of further significance, this approach localized the nerve to within 1 cm of the anterior superior iliac spine. Thus, the traditional approach may be better served by having the initial needle entry site 1 cm from the anterior superior iliac spine and just below the ilioinguinal ligament.
Classic Approach of Labat to the Femoral Nerve The key anatomic landmarks are identifying the ilioinguinal ligament and the femoral arterial pulsation immediately below it. In obese individuals, an assistant may be necessary to retract the overlying abdominal pannus. The needle entry site to be marked is 1 to 2 cm lateral to the arterial pulsation and 1 to 2 cm below the inguinal ligament. Adequate preparation of the skin and sterile technique should be used in all regional techniques. A 5 cm, 22-G needle is advanced perpendicular through the skin until a paresthesia is obtained. With compression of the overlying subcutaneous tissue, this should be obtained at a depth of 3 cm or less. A total of 20 mL of local anesthetic is deposited in incremental doses after slow aspiration to avoid intravascular injection zl (Fig 2). If no paresthesias are elicited with the preceding needle direction, the needle should be directed in medial and lateral directions (fanning) at the same entry site. Next 10 mL of a local anesthetic solution is deposited in each region. This may be considered a "field block. ''22 With a 22-G short bevel needle, a loss of resistance or "pop" may be appreciated when the
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Fig 1. Lateral cutaneous nerve block (see text). The lateral cutaneous nerve of the thigh passes inferiorly on iliacus muscle covered by iliacus fascia, Just medial to the anterior superior iliac spine, it turns anteriorly to pass just below the inguinal ligament and runs deep to the fascia lata until it emerges subcutaneously. The lateral cutaneous nerve can be blocked just medially to the anterior superior iliac spine or 1 to 2 cm below it. (Reprinted with permission from Bridenbaugh?l).
needle passes through fascial layers. It is important to keep in mind that the femoral vessels are covered only by the fascia lata, whereas the femoral nerve is deep to both the fascia lata and fascia iliaca. Thus, two "pops" need to be appreciated to achieve sufficient needle depth. With the advent of insulated needles, nerve stimulation is used increasingly in clinical practice and resident education. A 22-G, 5 cm, short-bevel needle is used. This permits the appreciation of fascial "pops" and muscle contraction. Initial nerve stimulator settings are 1.0 mA at 1 Hz. However, successful needle tip location is considered when muscle contraction is demonstrated at less than 0.5 mA. Quadriceps ROSENQUIST AND LEDERHAAS
'al Nerve
~1Artery ]1 Vein
Js Muscle .~rlying Iliaca
Fig 2. Inguinal structures showing fascial envelope around femoral nerve and relationships for inguinal paravascular femoral nerve block techniques. (Reprinted with permission from Bridenbaugh.21). group activation is ideally sought. However, if only sartorius contraction is evident and the site of needle entry is immediately lateral to the femoral arterial pulsation, this may be considered successful location of the anterior division of the femoral nerve. If surgical anesthesia is to be achieved, 20 mL of mepivacaine 1.5% to 2%, bupivacaine 0.5% to 0.75% with or without epinephrine, or ropivacaine 0.5% to 0.75% is used. For postoperative analgesia, bupivacaine 0.25% to 0.5% with or without epinephrine 1:200,000 is most commonly provided.
3-in-1 Block Winnie and colleagues z3 described an inguinal paravascular approach to block the femoral, lateral femoral cutaneous, and LATERAL FEMORAL CUTANEOUS NERVE BLOCK
obturator nerves with a single injection. Their initial entry site is the classic approach of Labat. However, the needle is directed cephalad at a 45 ~ angle to the skin. Before injection, a paresthesia was elicited in the distribution of the femoral nerve. Distal pressure was maintained during injection. They reported that when at least 20 mL of local anesthetic was administered, blockade of all three nerves was assured. Subsequent investigators have not been able to duplicate these clinical results or provide cadaveric support for a femoral "sheath" continuous with the entire lumbar plexus. In a clinical study involving patients undergoing vastus medialis biopsy. Madej and co-workers 5 used 0.6 mL/kg (maximal volume 40 mL) of either lidocaine 1% with norepinephrine 1:100,000 or bupivacaine 0.25% after eliciting a paresthesia in the distribution of the femoral nerve. They reported an 87.5% and 67.5% success rate in providing complete anesthesia of the femoral and lateral femoral cutaneous nerves, respectively. No clinical evidence of obturator nerve blocks, as assessed by weakness in thigh abduction, was reported. Seeberger and Urwyler 24 compared 20 mL to 40 mL of mepivacaine 1% for 3-in-1 block. A notable difference in their technique was the use of a 22-G insulated needle with stimulation of one of the quadriceps muscles at 0.5 mA or less at a frequency of 1 Hz. Firm pressure was applied distal to the needle as in the Winnie and Madej studies. Complete femoral nerve blockade was achieved in 92% and 93%, respectively, in the 20 mL and 40 mL groups, sensory nerve blockade of the obturator nerve in 62% and 78%, and blockade of the lateral femoral cutaneous nerve in 41% and 44%. Why was there a difference in outcomes? Madej attributed sensory anesthesia of the medial thigh to the medial cutaneous nerve originating from the femoral nerve. After the local anesthetic injection was performed, this was the earliest region to develop anesthesia. Seeberger attributed sensory innervation of the medial thigh to the obturator nerve. No time onset for anesthesia of the medial thigh was provided. Lang and colleagues 25 used the same technique as Winnie et al. 23 and Madej et al. 5 and used 30 mL (either lidocaine 2% with epinephrine 1:200,000 or bupivacaine 0.375% with epinephrine 1:200,000) and could demonstrate obturator motor block in only one of 26 patients. 25 Finally, a cadaveric study by Ritter 3 using 20 mL and 40 mL of methylene blue dye injected into the femoral nerve sheath did not demonstrate spread of the injectate from the femoral nerve to the lumbar plexus or obturator nerve. On dissection of the group with the larger volume of injectate, staining of the lateral femoral cutaneous nerve was noted based on diffusion through the fascia iliaca. Although the 3-in-1 block is attractive on theoretical grounds, anatomic and clinical studies do not support it. It is best considered a 2-in-1 block when larger volumes of local anesthetic are used. When blockade of the lateral femoral cutaneous nerve must be assured, we recommend a separate injection (10 to 15 mL). A smaller volume (20 mL) may then can be given to provide sole anesthesia of the femoral nerve.
Fascia lliaca Approach Anatomic dissections and clinical studies by Dalens and colleagues 17 have demonstrated that large volumes of local anesthetic deposited inferior to the ilioinguinal ligament and beneath the fascia iliaca can spread rostrally. The solution will 35
primarily come in contact with the femoral and lateral femoral cutaneous nerves, but may also bathe the genitofemoral and obturator nerves. The approach for both adults and children is the same. 26 The needle entry site is 1 cm below the point at which the lateral third of the ilioinguinal ligament meets the middle third. This may also be considered the midpoint between the initial entry points for the traditional femoral and lateral femoral cutaneous blocks. A 22-G short bevel needle is directed perpendicular to the skin. After the skin is pierced, two distinct "pops" should be appreciated as the needle passes through the fascia lata and fascia iliaca. The needle will contact femur if advanced too deeply. After careful aspiration and application of manual pressure on the anterior thigh or application of a thigh tourniquet, the anesthetic solution is administered in divided doses. The recommended volume in adults is 30 mL. The following volume recommendations in children are based on a 50:50 mixture of lidocaine 1% and bupivacaine 0.5%, both with epinephrine 1:200,000:0.7 mL/kg for 20 kg or less, 5 mL for 20 to 30 kg, 20 mL for 30 to 40 kg, 25 mL for 40 to 50 kg, and 27.5 mL for those greater than 50 kg. 17 Fig 3 demonstrates spread of contrast with the fascia iliaca and Winnie's 3-in-1 technique.
Pediatric Applications The fascia iliaca and 3-in-1 blocks have been successfully used in children to provide postoperative analgesia for placement and removal of femoral hardware, percutaneous pinning of slipped capital femoral epiphyses, femoral fracture, anterior procedures of the thigh, and varus derotation osteotomies. 17 Combined femoral and lateral femoral cutaneous blocks have been performed to provide surgical anesthesia for quadriceps muscle biopsy. 4 It should be recognized that this was performed with the patient under conscious/deep sedation. In the Dalens study, fascia iliaca and Winnie's 3-in-1 blocks were compared for procedures above the knee. All blocks were performed while the patients were under general anesthesia. The 3-in-1 block was performed with a 22-G insulated short-bevel needle with settings as previously described. The volume and local anesthetic compositions were as noted in the previous section. Adequate postoperative analgesia was present in more than 90% of the fascia iliaca group and in only 20% of the 3-in-1 group. The average duration of analgesia was 6 hours before supplemental analgesics were required. These results were attributable to sensory anesthesia of the lateral femoral cutaneous, obturator, and genitofemoral nerves in 85% to 95% of the fascia iliaca group. There was a 100% success rate of femoral nerve anesthesia in both groups. For children with mid-shaft fractures of the femur, single femoral nerve injections and continuous infusions have proven efficacious in providing analgesia. Ronchi et aP 2 used a single injection of bupivacaine 0.5% (0.4 mL/kg) that provided at least 3 hours of analgesia. During this time period, radiographic analysis and application of traction and casting were performed in a painless manner. Their approach was one finger breadth lateral to the femoral arterial pulse and directly below the inguinal ligament. Paresthesias were not sought. Rather, loss of resistance ("pops") as the 23-G needle passed through the fascia lata and fascia iliaca was the desired end-point. Placement of femoral sheath catheters has been described by Johnson 13 and Tobias. 14 They elected to provide pain manage-
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Fig. 3. Spread of a solution containing contrast media. (A) 3-in-1 block. Note that the solution does not reach the psoas compartment where the lumbar plexus lies. (B) Fascia iliaca compartment block. Note the spread of the solution along the anterior aspect of the iliacus muscle and the medial increase in opacity, probably due to superimposition resulting from the reflection of the fascia iliaca compartment covering successively (1) the anterior aspect of the iliacus muscle, then (2) the posterior, and (3) the anterior aspect of the psoas muscle.
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ment in this manner because of concerns over administering opioids to trauma patients with closed head injuries. The Tobias approach is as follows: A 3 Fr G, 8-cm single lumen central venous catheter was placed in the femoral sheath via a Seldinger technique. The introducer needle was placed just lateral to the arterial pulse and 2 to 4 cm inferior to the inguinal ligament. After experiencing two "pops," the guidewire was advanced, the needle was removed, and 3 Fr catheter advanced over the guidewire. The initial bolus of local anesthetic was 0.5 mL/kg (maximum 20 mL) of bupivacaine 0.25% with epinephrine 1:200,000. A continuous infusion of bupivacaine 0.2% was provided at 0.15 mL/kg/h (0.3 mg/kg/hr). If additional analgesia was required, a bolus of 0.25 mL/kg of bupivacaine 0.2% was provided and the rate increased to 0.25 mL/kg/hr (0.5 mg/kg/hr). This rate was not exceeded because bupivacaine delivery greater than this would place the child at risk for local anesthetic toxicity.27 Local anesthetic delivery in the Johnson study 13 adhered to the same principles. However, the rate of infusion was 0.3 mL/kg/hr of bupivacaine 0.125%. Back leak was noted at the site of catheter insertion and more frequent episodes of breakthrough pain requiring supplemental opioids were reported than in the Tobias 14 series. In the Johnson series of patients, a 20-G epidural catheter was inserted 5 to 8 cm through an 18-gauge Touhy needle after double loss of resistance. It is our clinical intuition that the differences in analgesic efficacy may have been the result of anesthetic concentration and not technique.
Clinical Outcome Studies The majority of studies documenting improved outcomes after femoral nerve block have been in patients undergoing knee surgery. In adults having anterior cruciate reconstruction, performance of a femoral nerve block with bupivacaine 0.5% (20 mL) before surgical incision reduced intramuscular opioid administration by 80% in the recovery room and 40% in the first 24 postoperative hours. 7 The authors emphasized that it was technically easier to perform the block at the start of surgery than at completion when the hip and knee are relatively immobilized. A similar reduction in opioid use was documented in patients after total knee replacement who had femoral sheath catheters and received intermittent doses of bupivacaine 0.5% (0.3 mL./kg) at 6- to 8-hour intervals. 11 However, the catheter and control groups were provided with patient-controlled analgesia (PCA) devices to deliver intravenous morphine. Overall pain scores and antiemetic requirements were not significantly different. The provision of PCA was a significant advantage to these patients over the previous study. Superior pain relief and decreased opioid requirements have been shown in patients who received a continuous local anesthetic infusion. 9 In this series of patients having total knee arthroplasty, the catheter was initially dosed with bupivacaine 0.5% (0.4 mL/kg) and a continuous infusion of bupivacaine 0.25% maintained at 0.15 mI_/kghr for 16 hours. There was also a trend toward fewer side effects (nausea, vomiting, urinary retention) in the group receiving local anesthetics, but an inadequate number of patients were enrolled in the study to achieve statistical significance. Hirst and colleagues 6 randomized their series of total knee
LATERAL FEMORAL CUTANEOUS NERVE BLOCK
arthroplasties to morphine PCA alone or morphine PCA with single femoral nerve bolus (bupivacaine 0.5% with epinephrine 1:200,000--20 mL) or bolus plus an infusion of bupivacaine 0.125% at < 0.1 mL/kg/hr (6 mL/hr). 6 Both local anesthetic groups had superior analgesia in the recovery room, but there was no difference on the ward. The incidence of nausea, however, was greater in the morphine PCA alone group. The Hirst study delivered less than half the amount of bupivacaine than the Dahl study. From the pediatric and adult literature, it appears that more concentrated local anesthetic solutions are required to obtain the analgesic benefits of continuous peripheral catheter techniques. Continuous femoral nerve blockade is not a complete anesthetic for total knee replacement because the tibia is innervated by sciatic nerve. In comparing regional techniques, femoral nerve block with genitofemoral infiltration for long saphenous vein stripping proved superior to spinal anesthesia. 16 The femoral nerve block was performed with 30 mL of alkalinized chloroprocaine 3% and the spinal anesthetic consisted of 65 mg of 5% hyperbaric lidocaine. Patients who received the peripheral nerve block had less postoperative pain and blockade, greater satisfaction with the technique, and shorter overall hospital stays. For the knee arthroscopy that is converted to an open procedure, continuous femoral nerve block has been compared with continuous lumbar epidural morphine infusion, l~ The femoral infusion was preceded by a bolus of bupivacaine 0.5% (0.4 mL/kg) and the bupivacaine 0.25% at 0.14 mL/kg/hr. The epidural group had a morphine bolus of 4 mg followed by an infusion of 0.33 mg/hr. Both of these regimens were initiated at the completion of surgery. Intramuscular morphine was provided for breakthrough pain. Pain scores and supplemental morphine requirements were equivalent for the first postoperative day. The distinct advantage in the femoral nerve block group was the markedly lower incidence of nausea, vomiting, pruritus, and urinary retention. These last two articles validate extending a practitioner's regional anesthesia practice beyond the central neuraxial techniques. Provision of an adequate concentration and rate of delivery of local anesthetic are crucial to the success of femoral blocks. In addition, the use of this technique should not preclude the concurrent use of morphine PCA devices. Excellent postoperative analgesia can be obtained with a multimodal approach.
Complications Injury to the lateral femoral cutaneous nerve after performance of a block is exceedingly rare. In our review of the literature, we did not discover any reports. Meralgia paresthetica, however, is not uncommon. 28 Obese adults and parturients are most prone to develop this condition. In adolescents, however, thin, muscular individuals who engage in competitive sports are the more likely patients. 15 Local hematoma formation is the most common problem in performing a femoral nerve block. Femoral arterial or venous puncture should be minimized by careful palpation of the arterial pulse and initial needle placement at least 1 cm laterally. If vascular penetration occurs, manual compression to the site should be applied to the site for at least 5 minutes.
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Reassessment of the site should be performed intraoperatively, particularly if a thigh tourniquet is used. Permanent femoral nerve injury is rare with careful technique. There is no data to support a nerve stimulator approach over a paresthesia-based method. In the American Society of Anesthesiologists Closed Claims Study, femoral nerve injuries accounted for only 6 of 227 claims. 29 It was not clarified in the report whether the injury was due to surgical positioning or regional anesthetic technique. In reviewing the neurology literature, the majority of femoral neuropathies are due to extremes in the lithotomy position (angulation of duration) or inappropriate placement of intraabdominal retractors. 3~ Idiopathic neuropathies have also been reported. 31
Summary Overall, regardless of the technique, blockade of the femoral and lateral femoral cutaneous nerves has an enviable safety record. The success of each technique is predicted on its appropriateness for the planned surgery, knowledge of the relevant anatomic landmarks, and a sufficient volume of local anesthetic. As with all regional techniques, appropriate monitoring and adequate patient sedation are essential. The ability to provide improved postoperative analgesia and shortened hospital stay for planned outpatient procedures makes these blocks attractive. Finally, because they are technically the simplest peripheral nerve blocks to learn, they are an excellent starting point for introducing peripheral block techniques into one's practice.
Acknowledgment We wish to thank Teresa Block for her patience and superb secretarial support.
References 1. Woodburne RT: The lower limb, in Woodburne RT (ed): Essentials of Human Anatomy (ed 7). New York, NY, Oxford University Press, 1983, pp 557-571 2. Capdevila X, Biboulet P, Bouregba M: Comparison of the three-in-one and fascia iliaca compartment blocks in adults: Clinical and radiographic analysis. Anesth Analg 69:705-713, 1989 3. Ritter JW: Femoral nerve "sheath" for inguinal paravascular lumbar plexus block is not found in human cadavers. J Clin Anesth 7:470-473, 1995 4. Maccani RM, Wedel DJ, Melton A: Femoral and lateral femoral cutaneous block for muscle biopsies in children. Paediatr Anaesth 5:223-227, 1995 5. Madej TH, Ellis FR, Halsall PJ: Evaluation of "3 in 1" lumbar plexus block in patients having muscle biopsy. Br J Anaesth 62:515-517, 1989 6. Hirst GC, Lang SA, Dust WN: Femoral nerve block single injection versus continuous infusion for total knee arthroplasty. Reg Anesth 21:292-297, 1996 7. Ringrose NH, Cross MJ: Femoral nerve block in knee joint surgery. Am J Sports Med 12:398-401, 1984
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8. Bonicalzi V, Gallino M: Comparison of two regional anesthetic techniques for knee arthroscopy. Arthroscopy 11:207-212, 1995 9. Dahl JB, Christiansen CL, Daugaard JJ: Continuous blockade of the lumbar plexus after knee jury: Postoperative analgesia and bupivacaine plasma concentrations. A controlled clinical trial. Anaesthesia 43:1015-1018, 1988 10. Schultz P, Christensen EF, Anker-Moller E: Postoperative pain treatment after open knee surgery: Continuous lumbar plexus block with bupivacaine versus epidural morphine. Reg Anesth 16:34-37, 1991 11. Serpell MG, Millar FA, Thomson MF: Comparison of lumbar plexus block versus conventional opioid analgesia after total knee replacement. Anaesthesia 46:275-277, 1991 12. Ronchi L, Rosenbaum D, Athouel A: Femoral nerve blockade in children using bupivacaine. Anesthesiology 70:622-624, 1989 13. Johnson CM: Continuous femoral nerve blockade for analgesia in children with femoral fractures. Anaesth Intensive Care 22:281-283, 1994 14. Tobias JD: Continuous femoral nerve block to provide analgesia following femur fracture in a paediatric ICU population. Anaesth Intensive Care 22:616-618, 1994 15. Edelson R, Stevens P: Meralgia paresthetica in children. J Bone Joint Surg 76A:993-999, 1994 16. Vloka JD, Hadzic A, Mulcare R: Femoral and genitofemoral nerve blocks versus spinal anesthesia for outpatients undergoing long saphenous vein stripping. Anesth Analg 84:749-752, 1997 17. Dalens B, Vanneuville G, Tanguy A: Comparison of the fascia iliaca block with the 3-in-1 block in children. Anesth Analg 69:705-713, 1989 18. McQuillan PM: Lateral femoral cutaneous nerve, in Hahn MB, McQuillan PM, Sheplock GJ (eds): RegionalAnesthesia: An Atlas of Anatomy and Techniques (ed 1). St. Louis, MO, Mosby, 1996, pp 143-145 19. Brown DL: Lateral femoral cutaneous block, in Brown DL (ed): Atlas of Regional Anesthesia (ed 1). Philadelphia, PA, W.B. Saunders Company, 1992, pp 99-101 20. Shannon J, Lang SA, Yip RW: Lateral femoral cutaneous nerve block revisited: A nerve stimulator technique. Reg Anesth 20:100-104, 1995 21. Bridenbaugh PO: The lower extremity: Somatic blockade, in Cousins M, Bridenbaugh PO (eds): Neural Blockade (ed 2). Philadelphia, PA, J.B. Lippincott, 1988, pp 417-441 22. Brown DL: Femoral nerve, in Brown DL (ed): Atlas of Regional Anesthesia (ed 1). Philadelphia, PA, W.B. Saunders Company, 1992, pp 91-95 23. Winnie AP, Ramamurthy S, Durrani Z: The inguinal paravascular technique of lumbar plexus anesthesia: The "3-in-1 block." Anesth Analg 52:989-996, 1973 24. Seeberger MD, Urwyler A: Paravascular lumbar plexus block: Block extension after femoral nerve stimulation and injection of 20 vs. 40 ml mepivacaine 10 mg/ml. Acta Anaesthesiol Scand 39:769-773, 1995 25. Lang SA, Yip RW, Chang PC: The femoral 3-in-1 block revisted. J Clin Anesth 5:292-296, 1993 26. Capdevila X, Biboulet P, Bouregba M: Comparison of the three-in-one and fascia iliaca compartment blocks in adults: Clinical and radiographic analysis. Anesth Analg 86:1039-1044, 1998 27. Berde CB: Convulsions associated with pediatric regional anesthesia. Anesth Analg 75:164-166, 1992 28. Kitchen C, Simpson J: Meralgia paresthetica: A review of 67 patients. Acta Neurol Sand 48:547-555, 1972 29. Krall DA, Caplan RA, Posner K: Nerve injury associated with anesthesia. Anesthesiology 73:202-207, 1990 30. AI Hakim M, Katirji B: Femoral mononeuropathy induced by the lithotomy position: A report of 5 cases with a review of the literature. Muscle Nerve 16:891-895, 1993 81. Carter GT, McDonald CM: Isolated femoral mononeuropathy to the vastus lateralis: EMG and MRI findings. Muscle Nerve 18:341-344, 1995
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