FOOT & ANKLE INTERNATIONAL Copyright  2009 by the American Orthopaedic Foot & Ankle Society DOI: 10.3113/FAI.2009.1196

Sciatic Nerve Blockade: A Survey of Orthopaedic Foot and Ankle Specialists in North America and the United Kingdom Paul D. Hamilton, FRCS(Tr&Orth)1 ; Christopher J. Pearce, FRCS(Tr&Orth), MFSEM(UK)1 ; Stephen J. Pinney, MD2 ; James DF Calder, MD, FRCS(Tr&Orth)1,3 Basingstoke, UK

ABSTRACT

it is clear that the standard of care does not mandate either of these. The differences between US and UK practice are probably cultural and do not appear to affect the number of complications encountered.

Background: Sciatic nerve blocks are used to reduce postoperative pain and allow early discharge for patients undergoing foot and ankle surgery. This study aimed to identify the utilization of this procedure in the US and UK and to establish the standard of care with respect to the level of anesthesia that the patient is under and use of ultrasound localization when performing sciatic nerve blocks. Materials and Methods: A survey of current committee members of AOFAS and members of BOFAS. Results: Two hundred sixty-three surgeons were contacted with a response rate of 44%. Eighty-two percent commonly used a sciatic nerve blockade. Sixty-nine percent never or only sometimes used ultrasonography and variable levels of nerve stimulation were used. Forty-two percent where happy to have the block performed under full anesthesia. There were significant differences between British and American practices regarding the level of nerve stimulation and the level of anesthesia used. The most common complication cited was prolonged anesthesia of which the vast majority spontaneously resolved. Performing blocks awake or sedated did not seem to alter number of complications seen. Conclusion: This study represents a current practice review of sciatic nerve blocks performed amongst senior foot and ankle surgeons. Although no absolute consensus has been reached as to the use of ultrasound or whether the patient needs to be awake for the procedure,

Key Words: Sciatic Nerve Blockage; Survey; Practice Pattern INTRODUCTION

Regional anesthesia especially peripheral nerve blockade is becoming increasingly popular.8 The concept is to provide safe and effective analgesia in the perioperative period. This may reduce the need for general anesthesia and lessen the patient’s postoperative analgesic requirements, specifically as an opioid sparing strategy. Resistance to the use of peripheral nerve block among surgeons may come from the increased anesthetic time incurred, the perceived potential complications and a lack of experience and expertise among both surgeons and their anesthesiology colleagues. There may also be concerns about the medicolegal implications of such interventions. The aim of this study was to identify current practice among senior orthopedic foot and ankle specialists from North America and the United Kingdom in the use of sciatic nerve blockade and highlight any differences between the two. In particular, the study sought to establish an intercontinental standard with respect to the level of anesthesia that the patient receives and use of ultrasound localization when performing sciatic nerve blocks for foot and ankle surgery.

1

Department of Trauma and Orthopedic Surgery, Basingstoke and North Hampshire Hospitals NHS Foundation Trust, Basingstoke, UK 2 Department of Orthopaedic Surgery, University of California – San Francisco, San Francisco, CA 3 Imperial College School of Medicine Science and Technology, London, UK No benefits in any form have been received or will be received from a commercial party related directly or indirectly to the subject of this article.

MATERIALS AND METHODS

Corresponding Author: Christopher J. Pearce, FRCS(Tr&Orth) Basingstoke & North Hampshire Hospitals NHS Foundation Trust Orthopaedics Aldermaston Road Basingstoke, Hampshire RG24 9NA United Kingdom E-mail: [email protected] For information on pricings and availability of reprints, call 410-494-4994, x232.

All members of the British Orthopaedic Foot and Ankle Society (BOFAS) and committee members of the American Orthopedic Foot and Ankle Society (AOFAS) were contacted. The contact details for BOFAS members were obtained from the British Orthopedic Association (BOA) 1196

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1. What percentage of your current practice is foot and ankle surgery? (Please circle) Less than 10%, 11-20%, 21-30%, 31-40%, 41-50%, 51-60%, 61-70%, 71-80%, 81-90%, over 90% 2. In your practise do you use the following regional blockades? (Please tick) Sciatic nerve blockade - subgluteal approach Sciatic nerve blockade - popliteal approach Ankle block Other (please specify) 3. Who performs the block if a sciatic nerve block is performed? Operating surgeon Surgical team Anaethetist Other (please specify) 4. In performing the sciatic nerve block do you or your anaesthetic team use ultrasound guidance? Yes Sometimes No 5. If you use the peripheral nerve stimulator, which level stimulation in milliamps do you or your anaesthetic team use prior to injection to ensure correct placement? (Please circle) 1

Other (please specify) 6. In performing a sciatic block, do you or your anaesthetic team leave an infusion catheter in situ for post operative pain management? Yes Sometimes No Other (please specify) 7. Do you send your patients’ home with a catheter in situ? Yes Sometimes No 8. What type of infusion do you use in those patients with a sciatic nerve block? Patient controlled Continuous Other (please specify) 9. When performing a sciatic nerve block is the patient Awake Sedated Under full anaesthesia 10. When performing a sciatic nerve block is the patient Prone Lateral Supine Other (please specify) 11. In your experience how many complications have you had with the use of a sciatic nerve block? Number Please elaborate on your complications

Fig. 1: Questionnaire.

handbook 2008 and the AOFAS committee members from the AOFAS membership roster 2007. A questionnaire was sent out by email and subsequently by mail to the non-responders (Figure 1). Questionnaire responses were reviewed and entered into a computerized database. Statistical analysis was performed using MedCalc for Windows, version 9.6.4 (MedCalc

software, Mariakerke, Belgium).Descriptive statistics were used to summarize the responses to all questions. Differences in group demographic characteristics were tested by the Chi squared test for categorical data. The Mann-Whitney test was used to compare groups of non-parametric data. Statistical significance was accepted if p < 0.05, and a Bonferroni correction was used when appropriate.

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RESULTS

In total, 263 senior orthopedic foot and ankle surgeons were contacted. We received 115 replies in total (44%); 73 out of 176 (41%) from the members of BOFAS and 42 out of 87 (48%) from the committee members of AOFAS. Over half of the surgeons questioned indicated that greater than 90% of their practice was foot and ankle surgery with 87% of respondents performing over 50% foot and ankle surgery. The majority of surgeons used the sciatic nerve block in their practice (82%) either via the popliteal (77%) or subgluteal approach (23%), compared with 90% of surgeons who used ankle blocks for forefoot surgery. The most common patient position was supine with 80% of respondents indicating that this was their usual practice. Most of the blocks were performed by the anesthesiologist (76%). Ten percent of surgeons performed their own sciatic nerve blocks with a further 14% occasionally performing them. Thirty-two percent of sciatic nerve blocks used ultrasound localization as standard practice, 39% never used ultrasound and 29% occasionally used it. There was no difference between American and British practice in this regard (p = 0.25). There was a significant difference in practice between the British and American surgeons with respect to the level of anesthesia that the patient is under when the block is performed (p
0.0001) with the majority of British surgeons opting for general anesthesia and US surgeons preferring that the patient be awake or under sedation (Table 1). The different levels of nerve stimulation used prior to injection after identification of the sciatic nerve are shown in Figure 2. Again there was a significant difference between the American and British surgeons with the British opting for a lower level of nerve stimulation than the Americans (p = 0.001). Twenty-two percent of British surgeons used infusion catheters compared with 54% of American surgeons. Only one British surgeon sent patients home with a catheter in situ compared with 14 (36%) of the American surgeons surveyed. Table 1: Level of Anaesthetic Used When Performing the Sciatic Nerve Block Comparing American and British Surgeons Level of Anaesthesia Awake Under Sedation Under GA

All Surgeons

British Surgeons

American Surgeons

23% 35% 43%

16% 15% 69%

28% 65% 7%

Half of all respondents, in their experience, had had no complications, at all from the use of a sciatic nerve blockade with 80% having had two or fewer complications ever. When questioned further about these, the vast majority had resolved spontaneously with only two surgeons reporting a permanent injury. Table 2 shows a list of the common and serious complications described. There was no difference in the number of complications encountered between those who always perform the block with the patient awake versus those who perform it under GA (p = 0.186) or between those who always versus never use ultrasound guidance (p = 0.554). DISCUSSION

In foot and ankle surgery peripheral nerve blockade can be used on its own or in combination with general or regional anesthesia. Its increasing popularity can be attributed to increased patient satisfaction, reduced post operative analgesia requirements and increased recovery rate.15,16,25 There is debate about the use of ultrasound,1,4,22 the level of anesthesia when performing the blockade6,7,9,13 and level of nerve stimulation used prior to injection of the anesthetic in sciatic nerve blocks.24 We have surveyed a proportion of senior surgeons who perform mainly foot and ankle surgery in their practice. This has given us a guide to the current practice of surgeons in the UK and North America. Although use of neuro-stimulation alone has been shown to be safe and effective, 20 the use of ultrasound can increase success rates of sciatic nerve blockade when used with nerve stimulation. It has not, however, been shown to decrease the complication rate or decrease the time taken to perform a block.4,19 Currently the use of ultrasound is variable among foot and ankle surgeons and their anesthesiologists. A significant proportion of surgeons and their anesthesiologists do not use ultrasound routinely on either side of the Atlantic. The potential advantage of performing the block awake is that sudden pain on injection is a potential sign of intraneural injection which has potentially serious risks of nerve damage.5 However, the potential disadvantages include increased patient discomfort and the concern that a sudden uncontrolled movement by the patient during injection could increase the chance of a neural injury. The majority of British surgeons surveyed performed the blockade under general anesthesia although the American surgeons preferred to perform the block either awake or under sedation. Seven percent of the Americans surveyed routinely performed the block under GA. Herr et al. reviewed the literature to assess complication rates comparing blocks performed with the patients awake versus under anesthesia. In a review of five studies representing over 19,000 consecutive patients they found no reported permanent neurological injuries in patients who had a block performed under anesthesia.10 It

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Fig. 2: Level of neurostimulation prior to injection of the anaesthetic.

Table 2: Number of Complications Ever Seen by the Respondents

Total Less than 7 days 7 days to 2 months 2 months to 1 year More than 1 year Permanent

Paresthesia

Neuralgia (persistent pain)

Motor deficit (foot drop)

Complete palsy

36 3 4 4 1 1

22

6

7

10 2 2

3 1

3 2 1 1

may be that the higher proportion of blocks being performed under sedation by American surgeons is attributable to medico-legal concerns, rather than a reflection of the medical literature. There was no difference in the reported complications from surgeons who routinely perform the blockade awake versus those who perform it under GA. A recent survey of anesthesiologists in Oxford, UK, found that only 16% of respondents thought that sciatic blocks should be performed prior to anesthetic induction and only 12% actually did this in their practice.6 They reported a change away from performing regional anesthetic blocks with the patients awake when comparing the results of their 2008 survey with a similar survey they undertook in 2001.6,13 We found that most surgeons used a level of nerve stimulation prior to injection to be around the acceptable level of 0.5 mA.24 Those that used lower levels (less than 0.3 mA) may be at a higher risk of nerve complications but this could not be correlated in this study. Additionally, those using higher levels (greater than 0.5 mA) may have greater failure rates. Again the difference between the American and British practice may be cultural in that the Americans use higher levels of nerve stimulation, presumably to ensure that they are less likely to inadvertently perform an intra-neural injection. Again, in this survey, there

was no correlation between the level of nerve stimulation routinely used and the number of complications that had been encountered. The use of postoperative continuous nerve blockade has been shown to improve postoperative satisfaction, allow earlier discharge and reduce opioid requirement.3,12,25,26 The use of catheters is higher among North American surgeons than UK surgeons. This is particularly striking when comparing the use at home of in-situ catheters and may relate either to surgical or patient reluctance to be sent home with the catheter, or the availability of discharge care for those patients with the catheters. In a survey of anesthesiologists in 2002,14 there was a reluctance to send patients home with long-acting peripheral nerve blockade of the lower limb but not the upper limb. The foot drop effect of a sciatic nerve blockade does not concern most doctors as the patients will often be immobilized in a splint or cast after hindfoot surgery, however, many of those questioned stated that they were more worried about sending a patient home with an insensate foot than hand. However, many of the patients will be asked not to bear weight on the limb after foot surgery so the fact that the foot is insensate should not matter. Brull et al.2 in a recent review on neurological complications following peripheral nerve blockade found rates of neuropathy following all types of peripheral nerve blockade

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to be less than 3% with only one recorded permanent neurological injury. Studies specifically involving the sciatic nerve are smaller but show complication rates to be very low with no recorded permanent injury.11,12,15−18,20,21 Our findings are in keeping with the literature but we cannot relate this to the number of actual blocks performed. Of note, two permanent nerve injuries were recorded and thus, although rare, do occur. The vast majority of complications encountered by the respondents resolved with varying levels of time. This study has the flaws associated with a questionnaire study with a response rate of 44% but we hope to have surveyed a reasonable proportion of currently practicing, senior foot and ankle surgeons. The finding that a significant proportion of blocks are carried out by the anesthesiologist may also cause inaccuracies in recall in particular the level of nerve stimulation, although one may argue that, since the anesthesiologists very rarely follow patients long-term, it is the surgeon who is better placed to comment on any long term sequelae of the procedure. Complications associated with the block could not be related to the actual number of blocks performed and therefore care must be taken in interpreting them. This study represents a good cross-section of the current practice among foot and ankle surgeons in North America and the UK and their use of sciatic nerve blockade. While no absolute consensus can be reached as to the use of ultrasound or whether the patient needs to be awake for the procedure, it is clear that the standard of care does not mandate either of these. We conclude that, in terms of the standard of care to which a surgeon or anesthesiologist may be held, it is acceptable practice to perform sciatic nerve blocks under general anesthesia or sedation, using a nerve stimulator at differing levels of stimulation, with or without the use of ultrasound guidance. REFERENCES 1. Abrahams, MS; Aziz, MF; Fu, RF; Horn, JL: Ultrasound guidance compared with electrical neurostimulation for peripheral nerve block: a systematic review and meta-analysis of randomized controlled trials. Br J Anaesth. 102 408 – 417,2009. http://dx.doi.org/10.1093/bja/aen384 2. Brull, R; McCartney, CJ; Chan, VW; El-Beheiry, H: Neurological complications after regional anesthesia: contemporary estimates of risk. Anesth Analg. 104 965 – 974,2007. http://dx.doi.org/10.1213/01.ane. 0000258740.17193.ec. 3. di Benedetto, P; Casati, A; Bertini, L: Continuous subgluteus sciatic nerve block after orthopedic foot and ankle surgery: comparison of two infusion techniques. Reg Anesth Pain Med. 27 168 – 172,2002. http://dx.doi.org/10.1097/00115550-200203000-00010 4. Dufour, E; Quennesson, P; Van Robais, AL; et al.: Combined ultrasound and neurostimulation guidance for popliteal sciatic nerve block: a prospective, randomized comparison with neurostimulation alone. Anesth Analg. 106 1553 – 1558, table of contents, 2008. 5. Faccenda, KA; Finucane, BT: Complications of regional anaesthesia Incidence and prevention. Drug Saf. 24 413 – 442,2001. http://dx.doi.org/10.2165/00002018-200124060-00002 6. Feely, NM; Popat, MT; Rutter, SV: Regional anaesthesia for limb surgery: a review of anaesthetists’ beliefs and practice in the Oxford

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