Patient satisfaction and effectiveness of lumbar plexus and sciatic nerve block for total knee arthroplasty

The Journal of Arthroplasty Vol. 16 No. 1 2001

Patient Satisfaction and Effectiveness of Lumbar Plexus and Sciatic Nerve Block for Total Knee Arthroplasty Martin J. Luber, MD,* Roy Greengrass, MD,† and Thomas Parker Vail, MD*

Abstract: The purpose of this study was to evaluate the efficacy of combined lumbar plexus block techniques for total knee arthroplasty. Long-acting local anesthetics were used to ensure adequate intraoperative and postoperative anesthesia and analgesia. All patients undergoing total knee arthroplasty at our institution were offered lumbar plexus block after obtaining informed consent. Patients for study were a continuous group of 87 patients over a 1-year period. A subset of 40 patients was studied for postoperative analgesia effect. All patients were contacted by phone for a satisfaction survey. There were 87 patients who received initial lumbar plexus and sciatic nerve blocks, 78% (68 of 87) of whom had adequate initial blocks. Sixteen patients (22%) required conversion to general anesthesia intraoperatively because of inadequate anesthesia. A subset of patients studied for postoperative analgesia revealed an average time of 13 hours before the first request for supplemental narcotics. There were no complications related to the lumbar plexus block in our study group of patients. There was a 92% overall satisfaction rate with the anesthesia provided by the lumbar plexus block. Lumbar plexus block can be used successfully for total knee arthroplasty. Lumbar plexus block appears to have advantages for early postoperative analgesia, leading to increased patient comfort and satisfaction. Key words: total knee arthroplasty, peripheral nerve block, anesthesia.

For patients undergoing elective total knee arthroplasty (TKA), postoperative anesthesia–related pulmonary complications and confusion can interfere with recovery, timely discharge, and participation in early physical therapy. For these reasons, the use of regional anesthesia, including spinal, epidural, and peripheral blocks, has increased. Although general anesthesia has long been used with success for these elective operations, the complications attrib-

utable to general anesthesia range from relatively minor to potentially life threatening [1]. Epidural anesthesia is effective in providing intraoperative and postoperative anesthesia and analgesia. Several investigators found that epidural anesthesia decreased the incidence of deep venous thrombosis and pulmonary embolism [1,2]. The benefits of epidural anesthesia must be weighed against the potential for profound hypotension, the need for urinary catheterization, and the risk of epidural hematoma associated with the use of low-molecular-weight heparin [3]. The reported complication rate for epidural anesthesia is approximately 9%, with the following complications: severe hypotension, 1.8%; dural puncture, 2.5%; transient paralysis, 0.1%; and permanent paralysis, 0.02% to 0.002% [4]. Peripheral nerve block is perhaps the most spe-

From the *Division of Orthopaedic Surgery and †Department of Anesthesia, Duke University Medical Center, Durham, North Carolina. Submitted May 19, 1999; accepted June 13, 2000. No benefits or funds were received in support of this study. Reprint requests: Martin J. Luber, MD, Division of Orthopaedic Surgery, Box 3000, Trent Drive, Durham, NC 27705. Copyright © 2001 by Churchill Livingstone威 0883-5403/01/1601-0004$10.00/0 doi:10.1054/arth.2001.16488

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18 The Journal of Arthroplasty Vol. 16 No. 1 January 2001 cific anesthetic technique with the least interference to other organ systems. Peripheral nerve block is an alternative to epidural anesthesia, but these techniques have been used infrequently in lower extremity surgery. Winnie et al [5] described the technique for lumbar plexus block for lower extremity surgery in 1974. Although the techniques were available, regional anesthesia remained a tool of limited use. Because of the above-mentioned complications of general anesthesia and epidural anesthesia, there has been increased interest in regional anesthetic techniques at our institution. To our knowledge, there are no large series in the literature looking at the efficacy of and satisfaction with regional anesthetic techniques for TKA. The purpose of this study was to determine the success rate for lumbar plexus blocks in providing adequate anesthesia for TKA.

Materials and Methods After informed consent was obtained, 87 consecutive patients undergoing elective TKA agreed to undergo a combination lumbar plexus and sciatic nerve block. A dedicated team of regional anesthesiologists performed the blocks. The blocks were performed in the preoperative holding area with the use of standard monitors and intravenous sedation. The average time for placement of the blocks was 18 minutes. The average time for complete anesthesia varied but averaged approximately 40 minutes to skin incision, at which point the efficacy of the blocks was documented. A combination of midazolam and fentanyl was used for pain relief, anxiolytic, and amnesic effects. The lumbar plexus block was performed using the psoas compartment technique described by Winnie et al [5], and the sciatic block was performed using the modified Labatt approach [6], with the use of nerve stimulators and the B. Braun stimplex needle. The reported complication rates with the techniques used are less than 4% [4,7]. The blocks were performed using either 0.5% bupivacaine or 0.5% ropivacaine with epinephrine (Figs. 1 and 2). The patients were checked to determine adequacy of anesthesia before the beginning of surgery. The patients were monitored intraoperatively for the continued effectiveness of the anesthesia. Intravenous sedation was used as needed based on individual patient anxiety and preference. Postoperatively, 40 patients were tracked to determine the time to first request for supplemental narcotic analgesia. Patient records were used to determine the number of patients requiring urinary

catheter insertion. A telephone survey was performed on all 87 patients in an effort to determine patient satisfaction with the anesthetic and analgesic properties of the block.

Results Patient demographics are summarized in Table 1. A total of 87 patients were enrolled in the study. Five attending surgeons at our institution who perform TKA routinely performed the surgeries. The average age of the patients was 60.7 years. There were 65% female and 34% male study participants. There were 82% white and 18% African-American patients. The American Society of Anesthesiologists scores were all ⬎2. The average weight was ⬎84 kg. No patients were excluded for obesity; and the heaviest patient enrolled weighed 142 kg. A total of 87 patients received primary lumbar plexus and sciatic nerve blocks. Six patients required repeat block before skin incision because of inadequate anesthesia. Of these 6 initial failures, 3 of the repeat blocks were successful in providing adequate anesthesia. Of 87 patients, 16 (18%) required conversion to general anesthesia because of inadequate anesthesia for the operative procedure. For the patients who required conversion to general anesthesia, the average time was 44 minutes after the skin incision. Peripheral block alone was successful in 78% (68 of 87) of patients. The patients who underwent successful TKA with regional block received varying amounts of intravenous sedation, which depended on their desired level of awareness

Fig. 1. Patient position and landmarks for lumbar plexus and sciatic blocks.

Nerve Block for TKA • Luber et al.

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Fig. 3. Study questionnaire.

Fig. 2. Needle location for the lumbar plexus block.

during the procedure. The duration of pain relief from the block alone averaged 13.2 hours (range, 4.25–⬎22 hours). Ten patients (9%) required urinary catheter insertion during the immediate postoperative period. Of 87 patients, 86 (99%) participated in the patient satisfaction survey. Fig. 3 is the questionnaire that was developed for this study; these questions have not appeared in the literature previously. Of this group, 74% (64 of 87) had had previous surgery, 38% (33 of 87) of whom had a prior TKA. Of patients with previous surgical experience, 85% had a prior general anesthetic. Most patients (92% [59 of 64]) with prior general anesthesia thought that the lumbar plexus and sciatic block was easier to recover from. The 33 patients who had had a previous TKA, regardless of their previous anesthetic, all responded that the lumbar plexus block was superior. Most patients (97%) did not remember the events surrounding the block and did not describe it as unpleasant or painful. The patients

with successful blocks reported no or minimal discomfort intraoperatively and excellent pain relief postoperatively. The overall satisfaction rate was 92%, and 95% of patients agreed to consider lumbar plexus block at the time of any future lower extremity surgery. The failure rate of adequate anesthesia for the surgical procedure was 22%. This failure of adequate anesthesia did not relate to inadequate analgesia in the same patients in the postoperative period. It was postulated that the inadequate anesthetic effect might have been related to increased time needed for the block to reach full effectiveness in some patients. No other complications were associated with the use of lumbar plexus blocks in this study population. There were no infections related to the catheter insertion, and there were no hematomas at the injection site. No patients in the study complained of postoperative paresthesias, which our anesthesiologists believe is related to the use of a nerve stimulator for accurate placement of the block.

Discussion Demands are ever increasing to decrease hospital stay and increase patient satisfaction. Early ambu-

Table 1. Patient Demographics

Age (y) Sex Race Height (cm) Weight (kg)

Bupivacaine 0.5%

Ropivacaine 0.5%

68 ⫾ 8 75% female, 25% male 75% white, 25% African-American 163 ⫾ 10 80 ⫾ 20

68 ⫾ 8* 56% female, 43% male 88% white, 12% African-American 166 ⫾ 11* 88 ⫾ 15*

NOTE. Values are mean ⫾ SD. P ⬍ .05. *Not significant.

20 The Journal of Arthroplasty Vol. 16 No. 1 January 2001 lation, effective physical therapy, and early discharge can meet these goals. This study shows that patient satisfaction also can be enhanced by the use of regional anesthesia. The combination of lumbar plexus and sciatic nerve block is a successful anesthetic modality in 78% of our patients during surgery and provided an average of 13 hours of postoperative pain relief in 40 patients studied in the hospital after surgery. Other studies have shown that regional anesthesia results in decreased complications and increased patient satisfaction [8]. Although not analyzed specifically in this study, lumbar plexus blocks have been shown to reduce greatly the incidence of postoperative nausea, while providing pain relief comparable to narcotic analgesics [9]. Epidural anesthesia has been shown to reduce the severity of postoperative pain [8], but epidural anesthesia has no benefits over general anesthesia in terms of postoperative nausea [8]. The high level of patient satisfaction (92%) may be related to the fact that postoperative pain relief lasted ⬎13 hours on average. Reducing postoperative pain can lead to greater patient satisfaction and the ability to participate in physical therapy earlier. Another benefit of the peripheral nerve block was a reduction in the need for urinary catheter insertion. Although urinary catheterization can be avoided in short-acting spinal blocks, it is performed routinely with epidural blocks. The decreased use of urinary catheters could lead to a small diminution in the risk of urinary sepsis associated with urinary tract manipulation [10]. Issues of cost and patient satisfaction make it desirable to reduce the need for catheterization. The reduction of urinary tract manipulation by 90% is an important finding that may favor regional anesthetic techniques over epidural anesthesia. The other important consideration in favor of increased use of lumbar plexus and sciatic nerve blocks for TKA is the risk of developing epidural hematoma with indwelling spinal epidural catheters and concomitant postoperative anticoagulation. Epidural anesthesia may be contraindicated if the orthopaedist plans to use low-molecular-weight heparin for deep venous thrombosis prophylaxis early in the postoperative period. The use of lumbar plexus and sciatic nerve blocks eliminates the possibility of epidural hematoma, while maintaining continuous postoperative block, yet still allows for the early institution of anticoagulation. The possibility for the development of hematoma at the regional block site exists, but at this times the risk has not led to a delay in instituting low-molecularweight heparin in these patients. There were no hematomas in our study group, and to date, we

have not seen this complication, although we are vigilant for it. Patient satisfaction with this technique was high in our study population. Not only were patients able to avoid the potentially life-threatening complications of general anesthesia, but also they tolerated the early postoperative period better because of excellent pain relief and rare postoperative nausea. The technique of lumbar plexus and sciatic nerve block was taught relatively easily at our institution and could be available more widely with some education of anesthesia staff.

Conclusion The results of this study confirm that combination lumbar plexus and sciatic nerve regional anesthesia is safe and effective. The technique provides reliable and long-acting anesthesia and analgesia. It allows for increased patient comfort during the early postoperative period, and as such, it should allow for earlier and more comfortable mobilization. Regional anesthesia is preferable in patients with elevated American Society of Anesthesiologists scores. Because of high patient satisfaction as well as the specificity and success of peripheral nerve blocks, lumbar plexus and sciatic nerve blocks are used commonly at our institution for TKA and other lower extremity surgery. Further studies will include improving the reliability of lumbar catheter techniques as well as perfecting delivery systems for the local anesthetic. One goal is to increase the duration of the analgesic properties of these peripheral blocks to rival that of indwelling epidural catheters with lower risk profile. These changes raise the possibility of early pain-free physical therapy for several days that may lead to reduced hospital stays, increased patient satisfaction, and significant cost reduction in TKA.

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Nerve Block for TKA • Luber et al. blocks for lower extremity surgery. Anesth Rev 1:11, 1974 6. Raj PP: Clinical practice of regional anesthesia. Churchill Livingstone, New York, 1991 7. Sharrock NE, Haas SB, Hagett MJ, et al: Effects of epidural anesthesia on the incidence of deep-vein thrombosis after total knee arthroplasty. J Bone Joint Surg Am 73:502, 1991 8. Sprell MG, Millar FA, Thompson MF: Comparison of

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lumbar plexus block versus conventional opioid analgesia after total knee replacement. Anaesthesia 46: 275, 1991 9. Schultz P, Anker-Moller E, Dahl JB, et al: Postoperative pain treatment after open knee surgery: continuous lumbar plexus block with bupivacaine versus epidural morphine. Reg Anaesth 16:34, 1991 10. Warren JW: Catheter associated urinary tract infections. Infect Dis Clin North Am 11:609, 1997