Regional anesthesia for knee surgery

Regional Anesthesia for Knee Surgery Peter G. Atanassoff,

MD, and Maximilian

WB Hartmannsgruber,

Knee surgery may be performed under general anesthesia, preferably, however, under regional anesthesia because of the profound preemptive analgesic effect that is provided by regional anesthetic techniques. Both centroneuraxis (spinal, epidural) as well as peripheral nerve blocks may be used for knee surgery. Although the former may be used less frequently in the near future in knee surgery because of increasing administration of low molecular heparins with resultant epidural hematoma formation, the latter enjoy more and more popularity. Peripheral nerve blocks used mostly for knee surgery include femoral/sciatic nerve blocks and intra-articular injection of local anesthetics and/or opioids into the knee joint. They are devoid of extensive sympathectomy and provide sufficient surgical analgesia and motor block. Copyright 9 1999 by W.B. Saunders Company

uccessful anesthesia for orthopedic procedures on the knee can be achieved by a variety of regional techniques. These not only offer an alternative or supplement to general anesthesia (GA), they add the following distinct advantages:

S

1. Preemptive analgesic effects, ie, reduction of pain beyond the pharmacologic action of the local anesthetic agent, 1-3 reduction of the stress response. 4 2. Catheters inserted during these blocks can be used for postoperative pain relief. 3. Allowance of earlier mobilization, 5 reduction of deep venous thrombus formation, and pulmonary embolism. 6 4. Reduced PACU time and cost. 7 The three most common interventions on the knee are arthroscopy, arthroplasty, and repair of the anterior cruciate ligament (ACL). In general, surgical time for these procedures only rarely exceeds the pharmacologic duration of longer lasting local anesthetic agents. However, open knee procedures are extremely painful; therefore, continuous catheters for continuous analgesia are frequently inserted. These catheters enable patients to tolerate mobilization immediately after surgery. This provides faster, less painful rehabilitation as well as superior functional resuhs. 5 This report describes our rationale for selecting one regional anesthetic technique over the other and what we believe are key points in order to achieve successful regional anesthesia for surgical procedures on the knee.

From the Department of Anesthesiology Yale University School of Medicine New Haven, CT. Address reprint requests to Peter G. Atanassoff, MD, Department of Anesthesiology, Yale University School of Medicine, 333 Cedar Street, PO Box 208051, New Haven, CT 06520-8051. Copyright 9 1999 by W.B. Saunders Company 1084-208X/99/0302/0006510.00/0

MD

Spinal Anesthesia Spinal anesthesia provides a temporary interruption of nerve transmission achieved by the injection of a relatively small amount of a local anesthetic solution into the subarachnoid space. This space is separated from the epidural space by the dura and contains cerebrospinal fluid and nerve fibers. In most adults, the spinal cord ends at L1-L2, therefore spinal anesthesia can be safely administered between L2 and L5. Generally, spinal anesthesia is achieved via single injection of a local anesthetic agent. Continuous spinal anesthesia can be achieved with the use of extremely thin intrathecal catheters (28 and 32 gauge [G]) that were briefly commercially available in the United States. This technique has been widely abandoned in the United States because of fear of cauda equina syndrome (paresthesia, motor weakness, and paralysis of the lower extremities, bladder and bowel dysfunction) that were associated with the microcatheter technique. 8 However, large cumulative doses of local anesthetic agents, not the microcatheter technique, may have been responsible for the development of neurotoxicity.9 Microcatheters continue to be used in Europe with great success. The most common agent used is 0.5% bupivacaine administered in doses of 5 to 7.5 mg.10 Continuous spinal anesthesia is still performed here with macrocatheters (18 to 20 G) placed through an epidural needle. This technique is particularly attractive if an epidural needle is inserted accidentally into the subarachnoid space. Rather than remove the needle and reinserte it at a different interspace, the authors recommend intrathecal injection of the local anesthetic through the epidural needle and/or insertion of an intrathecal catheter. Surgical anesthesia may then be managed with repeat injections of 0.5% bupivacaine in 0.5 mL increments. Spinal anesthesia compared with epidural anesthesia offers the advantage of a dense sensory and motor block with a short onset time. Administration of a hypobaric local anesthetic such as plain bupivacaine 0.5% enables the patient to perceive a temperature increase in the lower extremities about 30 to 60 seconds after injection, hinting towards correct subarachnoid needle placement. If a unilateral block is preferred, a hyperbaric local anesthetic solution should be used. Complex procedures on the knee frequently require the use of an upper thigh tourniquet. Tourniquet pain develops despite adequate sensory or motor block at various times, depending on the local anesthetic used. Concepcion reported a statistically significant difference in the incidence of tourniquet pain when bupivacaine (15 mg) was compared to tetracaine (15 mg) in patients undergoing lower extremity procedures using thigh tourniquets. ~ Patients given bupivacaine reported tourniquet pain 25% of the time compared to 60% for patients given tetracaine despite longer tourniquet times in the bupivacaine group. An explanation for the prolonged tourniquet

Techniques in RegionalAnesthesia and Pain Management, Vol 3, No 2 (April), 1999: pp 107-112

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tolerance with bupivacaine is that tetracaine offers less prolonged blockade of C fibers. 12 Other maneuvers shown to improve tourniquet tolerance time are the addition of an opioid, the addition of epinephrine, larger volumes of local anesthetic, and avoidance of glucose in the local anesthetic solution. 13 When glucose was added to bupivacaine, the incidence of tourniquet pain at similar sensory levels was 37% versus 13% when the same volume of plain isobaric bupivacaine was used. The addition of an intrathecal opioid extends and outlasts the effect .of even long-acting local anesthetics. The addition of morphine 0.25 to 0.3 mg to the local anesthetic extends the duration of the anesthesia and analgesia in a dose dependent fashion. 14

Epidural Anesthesia Epidural anesthesia provides both surgical anesthesia and effective postoperative pare relief and is the most extensively used regional anesthesia technique for procedures on the lower extremities. When employed for k n e e replacements, this technique has been shown to reduce perioperative mortality due to pulmonary embolism. 6 This reduction in postoperative mortality from pulmonary embolism is consistent with reports of decreased incidence of deep venous thrombosis in patients receiving epidural anesthesia. Sonographically detected lower extremity deep venous thrombosis (DVT) is more frequent in patients who had received general rather than epidural anesthesia. 15 Both spinal and epidural techniques improve blood flow to the lower limbs by inducing arterial and venodilation. Venous stasis is thereby reduced. 16 Epidural anesthesia may have the added benefit of generating high local anesthetic plasma concentrations which have been shown to decrease platelet aggregation. 17 Earlier ambulation and discharge times may also play an important role in preventing deep venous thrombosis formation. Effective continuous epidural analgesia with local anesthetics with or without opioids allows early postoperative ambulation, use of continuous passive motion (CPM) machines, and active physical rehabilitation immediately following surgery. In contrast, even high dose epidural fentanyl (5 pg/kg) was unable to sufficiently relieve pain for passive mobilization following knee surgery. 18 Of note is that effective epidural analgesia with low concentrated local anesthetic solutions such as lidocaine 0.25% does not interfere with normal muscle function; muscle strength improved most likely due to the reduction in pain, and thereby prevented some of the postoperative muscle atrophy. 19 To access the epidural space the patient is positioned in the sitting or lateral decubitus position. Although the effect of gravity is controversial, reliability of blockade of S1, which is necessary for knee procedures, is probably increased with the patient in the sitting position. Alternatively, patients who have a history of fainting or who are heavily premedicated should have their catheter inserted while in the lateral position. To increase involvement of the S1 segment, patients should then be placed in a modified reverse Trendelenburg position (Hammock position) prior to injection of the local anesthetic. When patients were randomly allocated to one of two groups with supine horizontal position versus supine 30 ~ trunk elevation with 30 ~ leg elevation (hammock position), the latter position markedly improved the percentage of patients (60% v 13%) having adequate anesthesia for knee surgery. 2~ 1 08

Higher volumes of local anesthetic solutions compared to spinal anesthesia are necessary to ensure sensory and motor blockade of the knee. A combination of lidocaine 2% with epinephrine (5 lag/mL) and ropivacaine 0.75% or 1%, or lidocaine 2% with epinephrine (5 lag/mL) and bupivacaine 0.5% or 0.75% in a 1:1 ratio provide both rapid onset and long duration of blockade. Postoperative pain following major knee surgery can be effectively managed with patient controlled epidural analgesia (PCEA). The patient receives a basic continuous infusion and may additionally self-administer bolus doses. Dilute Solutions of local anesthetic with the addition of an opioid such as morphine, fentanyl, or hydromorphone have been shown to provide effective pain relief in the absence of motor b!ockade. 21 Very dilute bupivacaine (1/32%) combined with hydromorphone (10 lag/mL) at a rate of 10 to 12 mL/hour is used for pain relief in the authors' institution and enables the patients to undergo early postoperative rehabilitation.

Combined Spinal/Epidnral Anesthesia Combined spinal-epidural anesthesia (CSE) offers distinct advantages for surgery on the knee. First, it provides the rapid onset and reliable sensory and motor blockade of spinal anesthesia. Second, there is the option to improve an inadequate spinal blockade or extend the dermatomal level. Third, it permits repeat injections through an indwelling epidural catheter, and fourth the needle-through-needle technique confirms proper positioning of the Tuohy needle and therefore may improve the rate of successful catheter placement. The technique usually invoices placing an epidural needle into the epidural space first and then advancing a long 27-G spinal needle through the Tuohy needle into the subarachnoid space. Placing the Tuohy needle in the midline rather than paraspinally is preferred by the investigators because it seems TABLE

1. D a t a o n 1 5 C o n s e c u t i v e

Cases

of Epiduroscopy

Migration of Catheter Single Dural Multiple Dural Single Dural Puncture Punctures Puncture With Spinal With Spinal WithTuohy

Case Age No. (yr) Sex Spinal Level Needle 1

81

F

L3-L4 L2-L3

2

79

F

Failure

3 4

87 79

F F

L3-L4 L2-L3 L3-L4 L2-L3 L3-L4 L1-L2 L2-L3 L3-L4 L2-L3 L3-L4 L2-L3 L1-L2 Failure Failure Ls-L4 L2-L3 Failure L3-L4 L1-L2 L3-L4 L2-L3

5

69

F

6

72

M

7 8

96 62

F M

9 10 11 12 13 14

92 70 39 79 68 89

F M F F M F

15

94

F

Needles

Needle

m

m

m

--

+

--

4-

-m

44-

4-

+

n

m

m

m

n

m

m

m

m

m

Reproduced with permission from Holmstrom Bet al.22 ATANASSOFF AND HARTMANNSGRUBER

to lead to a higher success rate of spinal needle placement. Provided the spinal needle is correctly positioned, a local anesthetic with or without the addition of an opioid is injected intrathecally. Following removal of the spinal needle the epidural catheter is inserted. In the investigators' institution. patients frequently receive intrathecal hypobaric bupivacaine 0.5% 1 to 3 mL with epinephrine (5 gg/mL) and epidural hydromorphone 0.5 to 1 mg. This combination provides long lasting intraoperative surgical anesthesia that extends into the postoperative period. Further postoperative pain relief is then achieved by the previously mentioned combination of dilute bupivacaine and hydromorphone. Theoretically, there is the concern of accidental passage of the epidural catheter through the hole o f the dural puncture site. 22 This possibility is very small as demonstrated in cadavers by epiduroscopy where even after multiple dural punctures with 25 to 26 G spinal needles no m~gration of epidural catheters was seen (Table 1).

Femoral/Sciatic Nerve Block Many anesthesiologists prefer spinal and/or epidural techniques over peripheral nerve blocks for lower extremity surgery. 23 Because of the risk of permanent neurologic damage from epiduraI hematoma formation, neuraxiaI techniques are contraindicated in anticoagutated patients. Low molecular weight heparin, in particular, has elicited discussions on safety of centroneuraxis blockade following publication of a series of

neuraxial hematomas, which resulted in long-term or permanent paralysis. Several incidences occurred when the first dose of low molecular weight heparin was administered within 12 hours after surgery. Epidural hematomas were also described following epidural catheter removal within 10 to 12 hours after dosing low molecular weight heparin, or when subsequent dosing was not delayed at least 2 hours after epidural catheter removal (See Horlocker, "Regional Anesthesia and Analgesia in the Orthopedic Patient Receiving Thromboprophylaxis"). 24 Because of these concerns anesthesiologists may shift away from neuraxial towards peripheral nerve blocks. Further advantages of peripheral nerve blocks are that hemodynamic changes as seen with spinal and epidural anesthesia are less likely to occur, and normal bladder and bowel function are preserved. A theoretical disadvantage of lower extremity peripheral nerve blockade is larger volumes of local anesthetic that are required. However. the risk of systemic toxicity is not proportionately increased because of the decreased uptake of local anesthetics from peripheral sites. 25 Four nerves innervate the knee, ie, the femoral, the lateral femoral cutaneous, the obturator, and the sciatic nerves. The first three arise from L1-L4, the sciatic nerve originates from L5-$2. The femoral nerve is blocked inferior to the inguinal ligament and immediately lateral to the femoral artery. The lateral femoral cutaneous nerve is anesthetized as it emerges from the fascia lata inferomedial to the anterior superior iliac spine. The obturator nerve is blocked as it emerges from the obturator canal (Fig 1). An alternative to these individual

Fig 1. Obturator nerve block technique. Reprinted with permission from Brown: Atlas of Regional Anesthesia, PhiladeEphia, PA, Saunders, 1992.

REGIONAL ANESTHESIA FOR KNEE SURGERY

109

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Fig 2. Laying across the forceps, the femoral (middle) and lateral femoral cutaneous (right) nerves are dyed blue following femoral intraneural injection of 40 mL of methylene blue dye. The obturator nerve (left) is not dyed. Reprinted from J Clin Anesth, 7, Ritter JW, Femoral nerve "sheath" for inguinal paravascular lumbar plexus block is not found in human cadavers, 470-473, 1995, with permission of Elsevier Science.

Greater trochanter

Piriformi,,

Posterior superior:; iliac spine;: f: ,r

Sciatic n.

Ischial tuberosil :Y : :

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Fig 3. Sciatic nerve block: classic technique and positioning. Reprinted with permission from Brown: Atlas of Regional Anesthesia, Philadelphia, PA, Saunders, 1992.

110

ATANASSOFF AND HARTMANNSGRUBER

3-in-1 blocks added to a general anesthetic compared to those who received general anesthesia only. 31,32

Intrarticular Anesthesia

Fig 4. Sciatic nerve block: anterior technique. Reprinted with permission from Brown: Atlas of Regional Anesthesia, Philadelphia, PA, Saunders, 1992. blocks is the 3-in-1 block which theoretically blocks the three nerves by a single injection, provided sufficient volume of local anesthetic is injected. 26 For knee arthroscopy the 3-in-1 block provides a greater degree of muscle relaxation and a longer postoperative analgesia than the femoral nerve block alone. 2r Electromyographic and anatomical studies, however, have shown that the obturator nerve may not be blocked even when using up to 50 mL of local anesthetic solution 28,29 (Fig 2). This may not be an important factor in ACL repair or knee arthroscopy, but as the obturator nerve provides sensory innervation to the medial aspect of the thigh and knee, separate blockade of this nerve may be warranted for knee arthroplasty. To provide complete anesthesia for the knee, a sciatic nerve block must accompany the 3-in-1 block. The sciatic nerve can be located by a variety of approaches. The classic posterior approach described by Labat (Fig 3), the anterior approach (Fig 4), or the lithotomy approach. Combined 3-in-l/sciatic nerve blocks for knee arthroscopy provides excellent intraoperative and postoperative analgesia and reduces postoperative complication rates. 25,3~ For postoperative pain management following open-knee procedures, the 3-in-1 block is an excellent adjunct to general anesthesia. Two studies have documented lower pain scores with less narcotic usage in patients who received continuous

REGIONAL ANESTHESIA FOR KNEE SURGERY

Knee arthroscopy and ACL repair are frequently performed on an outpatient basis. Knee arthroscopy is performed in many centers using intraarticular local anesthetics with monitored anesthesia care. Volumes of 50 to 60 mL of a local anesthetic solution (ie, bupivacaine 0.25%) are required to ensure sufficient surgical anesthesia. Even with those high volumes, plasma levels remain 10 to 15 times below a nontoxic plasma level. This is presumably due to slow absorption through the synovia and considerable washout of the local anesthetic after the arthroscopy. 33 Furthermore, peak serum bupivacaine concentrations can be reduced by adding epinephrine and injecting the local anesthetic solution after tourniquet inflation. 34 A questionnaire sent to patients who had undergone arthroscopy as an outpatient procedure showed that the degree of satisfaction after local or spinal anesthesia was the same. 33A retrospective review examined a series of knee arthroscopic procedures that were completed using local, general, or regional anesthesia to evaluate the efficacy of these anesthetic techniques. Surgical time, complications or failures, procedures successfully performed, recovery room time, postoperative stay, and patient satisfaction were recorded. Local anesthesia with intravenous sedation compared favorably with the other techniques: surgical time was not increased, a large variety of operative procedures were successfully completed, recovery time was significantly shortened, and patient satisfaction remained high. It was concluded that this technique may offer several advantages over other types of anesthesia for knee arthroscopy, including improved cost effectiveness.35 In the presence of inflammation, peripheral opioid receptors may become accessible. Systemically ineffective doses administered into the knee joint after surgery have been shown to elicit potent and long lasting postoperative analgesiaY The low lipid solubility of morphine and therefore its slow uptake into the circulation were postulated to account for the high degree of analgesia. In contrast, two other studies could not confirm the existence of peripheral opioid receptors in the knee joint after arthroscopy, described, however, the analgesic advantages of intraarticular local anesthetics. 3r tn conclusion there are several viable options of regional anesthetic techniques for knee surgery. They all have in common substantial preemptive analgesic effects and may contribute to an overall reduction of patient morbidity.

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5. Ecker ML, Lotke PA: Postoperative care of the total knee patient. Ortho Clin North America 20:55-62, 1989 6. Sharrock NE, Cazan MG, Hargett MJL, et al: Changes in mortality after total hip and knee arthroplasty over a ten-year period. Anesth Analg 80:242-248, 1995 7. Lintner S, Shawen S, Lohnes J, et al: Local anesthesia in outpatient knee arthroscopy: a comparison of efficacy and cost. Arthroscopy 12:482-488, 1996 8. Pitk~.enen M: Continuous spinal anaesthesia. Curr Opin Anaesthesiol 5:676-680, 1992 g. Rigter ML, Drasner K, Krejcie TC, et al: Cauda equina syndrome after continuous spinal anesthesia. Anesth Analg 72:275-281. 1991 10. Lambert LA, Lamber DH, Strichartz GR: Irreversible conduction block in isolated nerve by high concentrations of local anesthetics. Anesthesiology 80:1082-1093, 1994 11. Concepion MA, Lambert DH, Welch KA, et al: Tourniquet pain during spinal anesthesia: A comparison of plain solutions of tetracaine and bupivacaine. Anesth Analg 67:828-832, 1988 12. StewartA, Lambert DH, Concepion MA, et al: Decreased incidence of tourniquet pain during spinal anesthesia with bupivacaine: a possible explanation.Anesth Analg 67:833-837, 1988 13. Haiaszynski TM, Hartmannsgruber MWB: Anatomy and physiology of a spinal and epidural anesthesia. Sem Anesth Periop Med 17:24-37, 1998 14. Bailey PL, Rhondean S, Schafer PG, et al: Dose-respense pharmacology of intrathecal morphine in human volunteers. Anesthesiology 79:49-59, 1993 15. Davidson HC, Mazzu D, Gage BF,.et al: Screening for deep venous thrombosis in asymptomatic postoperative orthopedic patients using color Doppler sonography: analysis of prevalence and risk factors. Am J Roentgen 166:659-662, 1996 16. Modig J, Borg T, Karlstr6m G, et al: Thromboembolism after total hip replacement: Role of epidural and general anesthesia. Anesth Analg 62:174-180, 1983 17. Borg T, Modig J: Potential anti-thrombotic effects of local anesthetics due to their inhibition of platelet aggregation. ActaAnaesthesiol Scand 29:739-742, 1985 18. Pierrot M, Blaise M, Dupuy A, et al: Peddural analgesia with high doses of fentanyl: Failure of the method for early postoperative kinesitherapy in knee surgery. Can Anaesth Soc J 29:587-592, 1982 19. Arvidsson I, Eriksson E, Knutsson E, et al: Reduction of pain inhibition on voluntary muscle activation by epidural analgesia. Orthopedics 9:1415-1419, 1986 20. Ponhold H, Kulier AH, Rehak PH: 30 degree trunk elevation of the patient and quality of lumbar epidural anesthesia. Effects of elevation in operations on the lower extremities. Anaesthesist 42:788-792, 1993 21. Sinatra RS: Acute pain management and acute pain services, in Cousins MJ, Bridenbaugh PO (eds): Neural Blockade. Philadelphia, PA, Lippincott-Raven, 1998, pp 793-835

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22. Holmstrom B, Rawal N, Axelsson K, et al: Risk of catheter migration during combined spinal epidural block: Percutaneous epiduroscopy study. Anesth Analg 80:747-753, 1995 23. HadzJcA, Vloka JD, Kuroda MM, Koorn R, Birnbach DJ: The practice of peripheral nerve blocks in the United States: a national survey. Reg Anesth Pain Med 23:241-246, 1998 24. Horlocker TT Heit JA: Low molecular weight heparin: biochemistry, pharmacology, perioperative prophylaxis regimens, and guidelines for regional anesthetic management. Anesth Analg 85:874-885, 1997 25. Elmas C, Atanassoff PG: Combined inguinal paravascular (3-ira1) and sciatic nerve blocks for lower limb surgery. Reg Anesth 2:88-92, 1993 26. Winnie AP, Ramamurthy S, Durrani Z: The inguinal paravascular technic of lumbar plexus anesthesia: The "3-in-1 block." Anesth Analg 62:989-996, 1973 27. Bonicalzi V, Gallino M: Comparison of two regional anesthetic techniques for knee arthroscopy. Arthroscopy 11:207-212, 1995 28. Atanassoff PG, Weiss BM, Brull SJ, et al: Electromyographic comparison of obturator nerve block to three-in-one block. Anesth Analg 81:529-53311995 29. FlitterJW: Femoral nerve "sheath" for inguinal paravascular lumbar plexus block is not found in human cadavers. J Clin Anesth 7:470-473, 1995 30. Edwards ND, Wright EM: Continuous low dose 3-in-1 nerve blockade for postoperative pain relief after total knee replacement. Anesth Analg 75:265-267, 1992 31. Serpell MG, Millar FA, Thomson MF: Comparison of lumbar plexus block versus conventional opioid analgesia after total knee replacement. Anaesthesia 46:275-277, 1991 32. Eriksson E, Haggmark T, Saartok T, et al: Knee arthroscopy With local anesthesia in ambulatory patients. Methods, results and patient compliance. Orthopedics 9:186-188, 1986 33. Solanki DR, Enneking FK, Ivey FM, et al: Serum bupivacaine concentrations after intraarticular injection for pain relief after knee arthroscopy. Arthroscopy 8:44-47, 1992 34. Shapiro MS, Safran MR, Crockett H, et al: Local anesthesia for knee arthroscopy. Efficacy and cost benefits. Am J Sports Med 23:50-53, 1995 35. Raja SN, Dickstein RE, Johnson CA: Comparison of postoperative analgesic effects of intraarticular bupivacaine and morphine following arthroscopic knee surgery. Anesthesiology 77:1143-1147, 1992 36. Stein C, ComJsel K, Haimerl E, et al: Analgesic effect of intraarticular morphine after arthroscopic knee surgery. N Engl J Med 325:11231126, 1991 37. Heard SO, Edwards WT, Ferrari D, et al: Analgesic effect of intraarticular bupivacaine or morphine after arthroscopic knee surgery: A randomized, prospective, double-blind study. Anesth Analg 74:822826, 1992

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