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Comparing the Effects of Single Shot Sciatic Nerve Block Versus Posterior Capsule Local Anesthetic Infiltration on Analgesia and Functional Outcome After Total Knee Arthroplasty
The Journal of Arthroplasty 29 (2014) 1149–1153
Contents lists available at ScienceDirect
The Journal of Arthroplasty journal homepage: www.arthroplastyjournal.org
Comparing the Effects of Single Shot Sciatic Nerve Block Versus Posterior Capsule Local Anesthetic Infiltration on Analgesia and Functional Outcome After Total Knee Arthroplasty A Prospective, Randomized, Double-Blinded, Controlled Trial Ben Safa, MSc, MD, FRCPC a, Jeffrey Gollish, MD. FRCSC b, Lynn Haslam, RN(EC) a, Colin J.L. McCartney, MBChB, FRCA, FFARCSI, FRCPC a a b
Department of Anesthesia, Sunnybrook Health Sciences Center, Toronto, Ontario, Canada Department of Orthopedics, Holland Orthopedic and Arthritic Institute, Toronto, ON, Canada
a r t i c l e
i n f o
Article history: Received 27 September 2013 Accepted 26 November 2013 Keywords: total knee arthroplasty (TKA) peripheral nerve block sciatic nerve block posterior capsule local anesthetic infiltration analgesia
a b s t r a c t Peripheral nerve blocks appear to provide effective analgesia for patients undergoing total knee arthroplasty. Although the literature supports the use of femoral nerve block, addition of sciatic nerve block is controversial. In this study we investigated the value of sciatic nerve block and an alternative technique of posterior capsule local anesthetic infiltration analgesia. 100 patients were prospectively randomized into three groups. Group 1: sciatic nerve block; Group 2: posterior local anesthetic infiltration; Group 3: control. All patients received a femoral nerve block and spinal anesthesia. There were no differences in pain scores between groups. Sciatic nerve block provided a brief clinically insignificant opioid sparing effect. We conclude that sciatic nerve block and posterior local anesthetic infiltration do not provide significant analgesic benefits. © 2014 Elsevier Inc. All rights reserved.
Total knee arthroplasty (TKA) is a common surgical procedure and is associated with severe pain in 60% and moderate pain in 30% of patients [1] and effective analgesia is paramount. Optimal perioperative analgesia will enhance functional recovery, including timely recovery of knee mobility, and reduce postoperative morbidity. Inadequate analgesia can produce unnecessary distress, suboptimal knee mobilization and medical complications. These factors may delay rehabilitation and discharge from hospital. There are several methods available for providing postoperative analgesia, including systemic or epidural opioids and epidural local anesthetics as well as peripheral nerve blocks. Parenteral opioids are associated with excessive adverse effects, such as nausea, pruritus, and respiratory depression and provide inadequate pain relief [2]. Epidural analgesia can provide good pain control, however it is commonly associated with adverse effects such as bilateral motor blockade, shivering, and hypotension [3]. Peripheral neural blockade, specifically femoral nerve blockade, has been shown to provide effective analgesia following TKA, with potentially fewer adverse effects than epidural technique and systemic opioids [3–5].
Funding: Funding for this study was provided by Physician Services Incorporated Foundation (PSIF). The Conflict of Interest statement associated with this article can be found at http://dx.doi.org/10.1016/j.arth.2013.11.020. Reprint requests: Ben Safa, MD, Department of Anesthesia, Sunnybrook Health Sciences Center, 2075 Bayview Avenue, M2, Suite 300, Toronto, Ontario, M4N 3M5. http://dx.doi.org/10.1016/j.arth.2013.11.020 0883-5403/© 2014 Elsevier Inc. All rights reserved.
The knee joint is innervated primarily by the femoral nerve but also receives branches of the obturator and sciatic nerves. The addition of sciatic nerve block (SNB) has become a growing practice to provide improved analgesia to the posterior aspect of the knee following TKA. Indeed, SNB has been the standard practice for postoperative analgesia following TKA in many centers, however the true benefit of adding SNB to a femoral nerve block (FNB) postoperative analgesia after TKA is controversial and remains uncertain, particularly when combined with a multimodal analgesic regimen. Some clinical trials suggest that SNB when added to FNB in patients undergoing TKA could improve postoperative analgesia [6–9]. Nevertheless, two published meta-analyses [10,11] and one systematic review [12] failed to demonstrate a clear advantage in terms of pain relief when either single-injection or continuous SNB is added to continuous femoral nerve block, however, these conclusions were heavily influenced by one small-randomized trial [13]. A more recent systematic review concluded that there is insufficient evidence at this time to qualitatively define the effect of adding SNB to FNB for analgesia following TKA [14]. In recent years Local Anesthetic Infiltration Analgesia (LIA) at the surgical site has gained popularity for hip and knee surgical procedures. LIA can produce effective analgesia and has the advantage of relative simplicity compared with other regional anesthesia techniques [15,16]. A similar technique whereby the terminal fibers of the sciatic nerve can be blocked by intraoperative deposition of local anesthetic in the posterior capsule (P-LIA) has also been described. The utility of this technique was demonstrated in a small group of patients
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B. Safa et al. / The Journal of Arthroplasty 29 (2014) 1149–1153
following TKA by lowering pain scores, earlier ambulation and reduced hospital stay [17]. The goal of our study was to evaluate the effect of adding SNB to FNB for postoperative analgesia as well as functional outcomes following TKA. In addition we evaluated the technique of local anesthetic infiltration of the posterior capsule as a possible alternative to SNB for analgesia to the posterior aspect of the knee.
hydromorphone pump for 48 h. Controlled release oxycodone 10 mg every eight hours was started at 0600 the morning after surgery. To facilitate the weaning of the PCA pumps at 48 h, oxycodone 5 mg, every hour as needed (prn) was made available to patients when the PCA unit was discontinued.
Methods
Pain Scores and Side Effects The numerical pain rating scale is a one-dimensional tool to obtain a pain score. Patients were asked to rate their pain, on a scale of 0–10, where “0” represents no pain, and “10” represents the worst possible pain. For construct validity, the NRS was shown to be highly correlated to the verbal analog scale (VAS) [18]. Additionally, the NRS and the VAS have been shown to give almost identical values in the same patient at various times after surgery [18]. Pain scores at rest and movement were obtained at the time of starting PCA in the postanesthesia care unit (hour “0”) and every 4 h thereafter; scores were collected for the following 48 h. The PCA pump was set to deliver a 0.2 mg bolus of hydromorphone per demand with a 5 min lockout and no background infusion. All patients were instructed to maintain their pain score at less than 4 out of 10. If the pain score was 5 or greater at rest, the dose of intravenous PCA hydromorphone was increased to 0.3 mg per demand. If the pain score remained 5 or greater on two consecutive occasions, the standing controlled release oxycodone dose was increased from 10 mg to 15 mg every eight hours. In addition, at each 4-h time point, the incidence and severity of sedation, nausea, vomiting and pruritus were assessed.
Sample After informed consent and with institutional research ethics board approval, 100, ASA I–III patients between the ages of 18 and 75 years scheduled for elective unilateral primary TKA were included in this randomized double-blind controlled trial. Patients were excluded if they met any of the following criteria: preexisting medical conditions contraindicated for spinal anesthesia or peripheral nerve blocks, allergy to any of the medications being used, history of drug or alcohol abuse, chronic pain on slow-release preparations of opioid in excess of 30 mg of morphine equivalents per day, inability to comprehend pain scales or unable to use a Patient Controlled Analgesia (PCA) device, diabetes with impaired renal function and obesity with BMI N45. Patients were recruited at their preoperative assessment visit approximately one to two weeks in advance of their surgery. All subjects were screened, after which the study protocol, as well as the use of the PCA pump and numerical rating scale (NRS) for pain measurement, was explained. Blinded study drug kits were prepared according to a computergenerated randomization schedule in blocks of six, by the hospital investigational pharmacy, which was otherwise not involved in the clinical care of the patients or in the conduct of the trial. On the day of surgery, patients were sequentially assigned a drug kit and hence randomized to one of three treatment arms: Group 1: received a single-shot SNB and sham P-LIA, Group 2: received a P-LIA and a sham SNB, Group 3: received a sham SNB and sham P-LIA. Anesthetic Protocol All patients were prepared for surgery in a specialized block area and received the following oral premedications 1 h prior to surgery: acetaminophen 1 g, celecoxib 400 mg, gabapentin 400 mg. Intravenous midazolam 1 mg to 3 mg was administered at the discretion of the anesthesiologist to achieve appropriate sedation. Femoral and sciatic nerve blocks were performed as previously described [16,17] using a nerve stimulator (with or without ultrasound guidance) to localize the nerves at less than 0.5 mA, followed by 20 cc of Ropivacaine 0.5% deposited adjacent to the femoral nerve; likewise, 20 cc of Ropivacaine 0.5% or normal saline was deposited adjacent to the sciatic nerve. Spinal anesthesia was performed in the lateral decubitus or sitting position. After subcutaneous infiltration with lidocaine 1%, and using a midline approach, a 25 gauge Whitacre needle was inserted at the L3– 4, L4–5, or L5–S1 interspace, when free flow of CSF was obtained, 10 mg of 0.5% hypobaric bupivacaine with 12.5 μg of fentanyl was injected. The patient was then placed in the lateral decubitus position with the side of surgery uppermost and later transferred to the operating room. Intraoperative sedation was provided by an intravenous propofol infusion (25–100 μg/kg/min) until the end of surgery. At the end of the surgical procedure, 50 ml of 0.2% Ropivacaine or normal saline was injected into the posterior capsule under direct visualization by the surgical team. All patients, regardless of treatment group, received a standard postoperative regimen of celecoxib 200 mg every 12 h for three days, gabapentin 200 mg every eight hours for three days, acetaminophen 1 g every six hours for five days as well as an intravenous PCA
Outcome Measures
Functional Outcome Measures Postoperatively, all patients followed a primary knee arthroplasty care pathway, accompanied by a standardized rehabilitation treatment protocol. All patients began a full weight-bearing regimen, and participated in a progressive rehabilitation program for range of motion, strengthening, balance and ambulation beginning the first day after surgery. Examination of knee range of motion in patients with knee OA has been shown to have adequate reliability [19]. Knee flexion and extension range of motion was recorded preoperatively, on postoperative days 2 and 3 as well as follow-up visits at 6 weeks and 3 months. The timed up and go test (TUG), a less physically challenging measure, suited for the early postoperative period, has been used in a number of studies with arthroplasty patients [20–22]. This measure has demonstrated the ability to detect the deterioration and improvement that occur in the early postoperative period [23]. The test measures the time to rise from an arm chair (seat height, 46 cm), walk 3 m, turn, and return to sitting in the same chair, without physical assistance.TUG was assessed preoperatively, on postoperative day 3 and as well as follow-up visits at 6 weeks and 3 months. Simple functional outcomes such as ability to sit at the edge of the bed, to stand with support and ambulate with support were assessed on postoperative day 1 and 2. Analysis Sample size was based on the power analysis from a similar study [6]. A clinically meaningful, 30% reduction in pain represents an approximate difference of 1.5 in the NRS pain score. To detect this effect at 80% power and alpha of 0.05, an analysis of variance (ANOVA) would require a total of 96 patients for this three arm (two-treatment, one control) parallel-design study, 32 patients per arm. Sample size was inflated to 104 to account for possible dropouts. Descriptive statistics were calculated for all variables of interest. Continuous measures such as age were summarized using means and standard deviations whereas categorical measures were summarized using counts and percentages.
B. Safa et al. / The Journal of Arthroplasty 29 (2014) 1149–1153
3
Table 1 Patient Characteristics in the Three Groups.
Gender (M:F) Age Height (m) Weight (kg) BMI ROM (°) Pain (R) Pain (M) TUG (s) OPIOID
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Control (n = 35)
Sciatic (n = 33)
P-LIA (n = 32)
P
22:13 61.3 1.70 94.68 32.8 106 0.81 2.81 11.93 3/35
15:18 61.2 1.68 87.80 30.7 113 0.79 3.28 11.95 4/33
17:15 60.7 1.73 93.55 31.0 111 1.0 3.12 11.75 5/32
0.35 0.95 0.11 0.29 0.23 0.18 0.86 0.68 0.98 0.67
2.5 2 1.5 1
*§
0.5
*
0
4 Hr
Continuous measures such as opioid consumption were compared between groups over time using repeated measures analysis of variance models followed by post hoc pair wise group comparisons. Categorical measures such as use of antiemetic drugs, were compared between groups using chi-square analyses. All analyses were performed on an intention-to-treat basis and were carried out using SAS Version 9.2 (SAS Institute, Cary, NC, USA).
A
8 Hr Control
12 Hr Sciatic
24 Hr
P-LIA
1.6 1.4 1.2 1
Results
0.8
A total of 104 patients were successfully recruited. 4 patients were withdrawn after protocol violation. Thus, 100 patients completed the study—35 patients in the Control Group, 33 patients in Sciatic Group and 32 in P-LIA Group. No significant differences were found between groups for age, weight, preoperative opioid use, preoperative pain scores at rest and with movement, preoperative TUG performance, range of motion or gender distribution (Table 1).
*
0.6 0.4 0.2 0
0-4 Hr
B NRS Pain Score at rest (Mean ± Standard Error) 10 9 8 7 6 5 4 3 2 1 0
4hr
A
8hr 12hr 16hr 20hr 24hr 28hr 32hr 36hr 40hr 44hr 48hr Contol Sciatic P-LIA
4-8 Hr Control
8-12 Hr Sciatic
12-24 Hr
P-LIA
Fig. 2. (A) Cumulative PCA hydromorphone Consumption (mg) Mean ± SD. * Sciatic Group used significantly less opioids than Placebo Group (P = 0.01). § Sciatic Group used significantly less opioids than the P-LIA Group (P b 0.05). (B) Incremental PCA hydromorphone Consumption (mg) Mean ± SD. * Control Group used significantly more opioids in the first 4 h compared to the Sciatic Group (P = 0.01).
There was no statistically significant difference between the three groups with respect to the pain scores at rest or with movement in the first 48 h (Fig. 1). There was significantly less cumulative opioid (PCA) consumption in the Sciatic Group than Control Group at 4 and 8 h (P = 0.01, P = .01). This effect was no longer statistically significant at 12 h (P = .06). On average patients in the sciatic group used 0.29 mg less PCA
NRS Pain Score with movement (Mean ± Standard Error) 10
80
9
70
8 7
60
6
50
5
40
4 3
30
2
20
1 0
B
10 4hr
8hr 12hr 16hr 20hr 24hr 28hr 32hr 36hr 40hr 44hr 48hr Contol Sciatic P-LIA
0 preop
Day3 Control
Fig. 1. NRS Pain Score at rest (Mean ± Standard Error). NRS Pain Score with movement (Mean ± Standard Error).
6week Sciatic
3month
P-LIA
Fig. 3. Timed-UP-and-GO (TUG) TEST (seconds) Mean ± SD.
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160 140 120 100 80 60 40 20 0 ROM0
ROM1
ROM2
Control
ROM3 Sciatic
ROM6WK ROM3M P-LIA
Fig. 4. Range of Motion (degrees) Mean ± SD.
hydromorphone in the first 12 h compared to the Control Group. Patients who received P-LIA had used significantly more patientcontrolled hydromorphone at 8 h than the patients who had received a sciatic nerve block (P b 0.05). At 4 h, patients in the P-LIA group had a trend towards reduced PCA hydromorphone consumption compared to the control group, however this difference did not reach statistical significance (P = .09) (Fig. 2A). Looking at the incremental opioid consumption, the control group used significantly more PCA hydromorphone in the first 4 h (P = .01). There was no significant difference in the opioid consumption between the groups for the time intervals of 4–8 h, 8–12 h and 12–24 h (Fig. 2B). There was no difference between the three groups in opioid related side effects at 12 and 24 h postoperatively. There was no difference between the groups in the TUG assessment on day 3, 6 weeks and 3-month follow-up (Fig. 3). There was no significant difference in the knee flexion and extension range of motion between the three groups on postoperative days 1, 2 and 3 as well as the 6-week and 3-month follow-up (Fig. 4). The pain scores before and after the functional studies were not significantly different between the study groups. There was no difference in ability to sit at the edge of the bed or to stand with support on postoperative days 1 and 2 among the three groups. However, more patients in the Sciatic Group were unable to ambulate with the assistance of a device on postoperative day 1 (P = .02). On postoperative day 2 this effect was no longer observed. The length of stay was not a measured outcome of this study, however all of our TKA patients follow a clinical pathway with standardized discharge criteria. This includes ability to ambulate and negotiate stairs with an assistive device, independent functional transfers and activities of daily living (or a plan in place regarding assistance) as well as knowledge of how to progress and continue an independent exercise program with an established plan for discharge physiotherapy. There was no difference in the mean length of stay for the Control, Sciatic and P-LIA groups, 4.3 ± 0.68, 4.3 ± 0.92 and 4.2 ± 0.99 days respectively.
Discussion In this study we were unable to demonstrate reduced pain scores in patients having a primary TKA who had a single shot sciatic nerve block in addition to a single shot femoral nerve block. Our patients had a robust multimodal analgesia regimen and access to patient controlled analgesia for 48 h postoperatively and were instructed on the use of PCA and to maintain their pain score between 2 and 4. There was a small but statistically significant reduction in cumulative
opioid consumption in patients who had a sciatic block in the early (first 12 h) postoperative period. Reducing opioid consumption should have benefits in terms of reducing opioid-related side effects before it can be considered clinically significant. The small opioid sparing effect of the sciatic nerve block did not lead to a reduction in opioid related side effects in this group, hence could not be considered clinically significant. One possible explanation for this observation is the multimodal analgesic regimen applied to the patients may have further minimized the relative contribution of sciatic innervation to postoperative pain management. Patients in the sciatic group were less likely to be able to ambulate with assistance on postoperative day 1; an effect attributed to possible residual muscular weakness from the two peripheral nerve blocks. However, there were no falls or long-term sequelae in terms functional recovery and length of stay in hospital. Local anesthetic infiltration of the posterior capsule did not prove to be an effective analgesic technique. A short-lived statistically insignificant trend towards reduced opioid consumption was observed in the first 4 h in keeping with the expected duration of action of any infiltration technique. Due to the blinded design of our study, the nerve blocks were not tested and an “intention to treat approach” was utilized. This could potentially be viewed as a possible limitation of this study. As with every medical procedure there is an inherent risk associated with performing a sciatic nerve block, therefore its application should only be considered when the potential benefits outweigh the potential risks. Sciatic block adds to the production pressure in terms of additional time, cost and skills required by the operators. Single-injection sciatic nerve block has similar complication rates as with any other nerve blocks, with permanent injury being exceptionally rare. However, knee surgery, even in the absence of a sciatic nerve block, can place significant stress on the sciatic nerve. Some risk factors, such as valgus deformity ≥10°, total tourniquet time ≥ 120 min, preexisting neuropathy and postoperative bleeding have been described [24]. The overall incidence of TKA-related incidence of sciatic nerve palsy is estimated to be 0.2% to 2.4% [24]. Performing a sciatic nerve block could theoretically increase the risk of nerve injury and more importantly, it could cloud the diagnosis and delay treatment. Furthermore a well-recognized side effect of peripheral nerve block is muscular weakness. The combination of femoral and sciatic nerve blocks could result in intense motor effects which may render patients unable to actively participate in early aggressive rehabilitation maneuvers, hence, raising concerns regarding post-TKA physical therapy expectations. On the other hand poorly managed pain may also inhibit the early intense rehabilitation. This in turn may result in impaired functional outcome. Peripheral nerve blocks have the potential to provide superior analgesia with fewer side effects allowing for accelerated functional recuperation, and the addition of a sciatic nerve block to a FNB should theoretically provide additional pain reduction following TKA. Currently there is insufficient evidence in the literature to qualitatively define the effect of adding single shot SNB to FNB for analgesia following TKA [9,11,13]. Two observational studies lend support to reduced opioid consumption and improved analgesia [6,7]. Hunt et al in a randomized study where patients in the sciatic group were not a part of the randomized arm, reported benefits of adding sciatic nerve block to FNB after TKA in terms of reduced early opioid consumption and analgesia [9]. Conversely, Allen et al in a small randomized, blinded study found no analgesic difference after FNB versus FNB and single shot sciatic nerve block [13]. In conclusion our results indicate that the addition of a single shot sciatic nerve block only transiently reduced opioid consumption without influencing the incidence of opioid-related side effects. This opioid sparing effect comes at the expense of reduced ability to ambulate with assistance on the first postoperative day. Based on the
B. Safa et al. / The Journal of Arthroplasty 29 (2014) 1149–1153
results of this study, in patients undergoing a primary TKA the routine addition of a single shot sciatic nerve block to femoral nerve block and a multimodal analgesic regimen may need to be reconsidered. Clinicians should consider the risk-to-benefit ratio for each case individually. Furthermore we do not recommend the P-LIA technique in addition to the multi-modal approach or a substitution for sciatic nerve block. The sciatic block may be beneficial in patients with preoperative chronic pain or opioid tolerance and in an as-yet to be defined population of patients who experience greater posterior knee pain at the completion of a TKA. Further research should identify patients who are more likely to suffer increased pain after TKA and may warrant a more intensive regional anesthesia approach including single injection or continuous sciatic nerve block. Acknowledgments The authors thank the research assistants and study coordinators, Beth Goudie RN and Ashley Pope, as well as the Holland Orthopedic and Arthritic Centre's nursing staff and the pharmacy and physiotherapy departments for their support. References 1. Postoperative pain. In: Bonica J, editor. The management of pain. 2nd ed. Philadelphia, PA: Lea & Febiger; 1990. p. 461. 2. Rowlingson A, McGready J, Cohen S, et al. Does continuous peripheral nerve block provide Superior Pain control to opioids? A meta-analysis. Anesth Analg 2006;102:248. 3. Singelyn F, Deyaert M, Joris D, et al. Effects of IV PCA with morphine, continuous epidural analgesia, and continuous 3 in 1 block on postoperative pain and knee rehabilitation after unilateral total knee arthroplasty. Anesth Analg 1998;87:88. 4. Capdevila X, Barthalet Y, Biboulet P, et al. Effects of perioperative anesthesia technique on surgical outcome and duration of rehabilitation after major knee surgery. Anesthesiology 1999;91:8. 5. Vloka JD, Hadzic A, Drobnik L, et al. Anatomical landmarks for femoral nerve block: a comparison of four needle insertion sites. Anesth Analg 1999;89(6):1467. 6. Cook P, Stevens J, Gaudron C. Comparing the effects of femoral nerve block versus femoral and sciatic nerve block on pain and opiate consumption after total knee arthroplasty. J Arthroplasty 2003;18:583.
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7. Weber A, Fournier R, Van Gessel E, et al. Sciatic nerve block and the improvement of femoral nerve block analgesia after total knee replacement. Eur J Anaesthesiol 2002;19:834. 8. Ben-David B, Schmalenberger K, Chelly JE. Analgesia after total knee arthroplasty: is continuous sciatic blockade needed in addition to continuous femoral blockade? Anesth Analg 2004;98:747. 9. Hunt K, Bourne M, Mariani E. Single-injection femoral and sciatic nerve blocks for pain control after total knee arthroplasty. J Arthroplasty 2009;24:533. 10. Paul J, Arya A, Hurlburt L, et al. Femoral nerve block improves analgesia outcomes after total knee arthroplasty: a meta-analysis of randomized controlled trials. Anesthesiology 2010;113:1144. 11. Fowler SJ, Symons J, Sabato S, et al. Epidural analgesia compared with peripheral nerve blockade after major knee surgery: a systematic review and meta-analysis of randomized trials. Br J Anaesth 2008;100:154. 12. Fischer HBJ, Simanski CJP, Sharp C, et al. A procedure-specific systematic review and consensus recommendations for postoperative analgesia following total knee arthroplasty. Anesthesia 2008;63:1105. 13. Allen HW, Liu SS, Ware PD, et al. Peripheral nerve blocks improve analgesia after total knee replacement surgery. Anesth Analg 1998;87:93. 14. Faraj W, Abdallah, Brull R. Is sciatic nerve block advantageous when combined with femoral nerve block for postoperative analgesia following total knee arthroplasty? A systematic review. Regional Anesthesia Pain Med 2011;36:493. 15. Kerr DR, Kohan L. Local infiltration analgesia: a technique for the control of acute postoperative pain following knee and hip surgery: a case study of 325 patients. Acta Orthop Belg 2008;79:174. 16. Affas F, Nygårds E, Stiller C, et al. Pain control after total knee arthroplasty: a randomized trial comparing local infiltration anesthesia and continuous femoral block. Acta Orthop Belg 2011;82(3):441. 17. Rooney ME, Lang SA, Klassen L. Intraoperative transcruciate injection: a new approach to postoperative analgesia following total knee arthroplasty. Techn Reg Anesth Pain Manag 1999;3:13. 18. Breivik EK, Bjo¨rnsson GA, Skovlund E. A comparison of pain rating scales by sampling from clinical trial data. Clin J Pain 2000;16:22. 19. Cibere J, Bellamy N, Thorne A, et al. Reliability of the knee examination in osteoarthritis: effect of standardization. Arthritis Rheumatol 2004;50(2):458. 20. Freter SH, Fruchter N. Relationship between timed ‘up and go’ and gait time in an elderly orthopaedic rehabilitation population. Clin Rehabil 2000;14(1):96. 21. Ouellet D, Moffet H. Locomotor deficits before and two months after knee arthroplasty. Arthritis Rheumatol 2002;47(5):484. 22. Walsh M, Kennedy D, Stratford PW, et al. Perioperative functional performance of women and men following total knee arthroplasty. Physiother Can 2001;53:92. 23. Kennedy D, Stratford P, Wessel J, et al. Assessing stability and change of four performance measures: a longitudinal study evaluating outcome following total hip and knee arthroplasty. Musculoskelet Disord 2005;6:3. 24. Horlocker T, Cabanela ME, Wedel DJ. Does postoperative epidural analgesia increase the risk of peroneal nerve palsy after total knee arthroplasty? Anesth Analg 1994;79:495.
Contents lists available at ScienceDirect
The Journal of Arthroplasty journal homepage: www.arthroplastyjournal.org
Comparing the Effects of Single Shot Sciatic Nerve Block Versus Posterior Capsule Local Anesthetic Infiltration on Analgesia and Functional Outcome After Total Knee Arthroplasty A Prospective, Randomized, Double-Blinded, Controlled Trial Ben Safa, MSc, MD, FRCPC a, Jeffrey Gollish, MD. FRCSC b, Lynn Haslam, RN(EC) a, Colin J.L. McCartney, MBChB, FRCA, FFARCSI, FRCPC a a b
Department of Anesthesia, Sunnybrook Health Sciences Center, Toronto, Ontario, Canada Department of Orthopedics, Holland Orthopedic and Arthritic Institute, Toronto, ON, Canada
a r t i c l e
i n f o
Article history: Received 27 September 2013 Accepted 26 November 2013 Keywords: total knee arthroplasty (TKA) peripheral nerve block sciatic nerve block posterior capsule local anesthetic infiltration analgesia
a b s t r a c t Peripheral nerve blocks appear to provide effective analgesia for patients undergoing total knee arthroplasty. Although the literature supports the use of femoral nerve block, addition of sciatic nerve block is controversial. In this study we investigated the value of sciatic nerve block and an alternative technique of posterior capsule local anesthetic infiltration analgesia. 100 patients were prospectively randomized into three groups. Group 1: sciatic nerve block; Group 2: posterior local anesthetic infiltration; Group 3: control. All patients received a femoral nerve block and spinal anesthesia. There were no differences in pain scores between groups. Sciatic nerve block provided a brief clinically insignificant opioid sparing effect. We conclude that sciatic nerve block and posterior local anesthetic infiltration do not provide significant analgesic benefits. © 2014 Elsevier Inc. All rights reserved.
Total knee arthroplasty (TKA) is a common surgical procedure and is associated with severe pain in 60% and moderate pain in 30% of patients [1] and effective analgesia is paramount. Optimal perioperative analgesia will enhance functional recovery, including timely recovery of knee mobility, and reduce postoperative morbidity. Inadequate analgesia can produce unnecessary distress, suboptimal knee mobilization and medical complications. These factors may delay rehabilitation and discharge from hospital. There are several methods available for providing postoperative analgesia, including systemic or epidural opioids and epidural local anesthetics as well as peripheral nerve blocks. Parenteral opioids are associated with excessive adverse effects, such as nausea, pruritus, and respiratory depression and provide inadequate pain relief [2]. Epidural analgesia can provide good pain control, however it is commonly associated with adverse effects such as bilateral motor blockade, shivering, and hypotension [3]. Peripheral neural blockade, specifically femoral nerve blockade, has been shown to provide effective analgesia following TKA, with potentially fewer adverse effects than epidural technique and systemic opioids [3–5].
Funding: Funding for this study was provided by Physician Services Incorporated Foundation (PSIF). The Conflict of Interest statement associated with this article can be found at http://dx.doi.org/10.1016/j.arth.2013.11.020. Reprint requests: Ben Safa, MD, Department of Anesthesia, Sunnybrook Health Sciences Center, 2075 Bayview Avenue, M2, Suite 300, Toronto, Ontario, M4N 3M5. http://dx.doi.org/10.1016/j.arth.2013.11.020 0883-5403/© 2014 Elsevier Inc. All rights reserved.
The knee joint is innervated primarily by the femoral nerve but also receives branches of the obturator and sciatic nerves. The addition of sciatic nerve block (SNB) has become a growing practice to provide improved analgesia to the posterior aspect of the knee following TKA. Indeed, SNB has been the standard practice for postoperative analgesia following TKA in many centers, however the true benefit of adding SNB to a femoral nerve block (FNB) postoperative analgesia after TKA is controversial and remains uncertain, particularly when combined with a multimodal analgesic regimen. Some clinical trials suggest that SNB when added to FNB in patients undergoing TKA could improve postoperative analgesia [6–9]. Nevertheless, two published meta-analyses [10,11] and one systematic review [12] failed to demonstrate a clear advantage in terms of pain relief when either single-injection or continuous SNB is added to continuous femoral nerve block, however, these conclusions were heavily influenced by one small-randomized trial [13]. A more recent systematic review concluded that there is insufficient evidence at this time to qualitatively define the effect of adding SNB to FNB for analgesia following TKA [14]. In recent years Local Anesthetic Infiltration Analgesia (LIA) at the surgical site has gained popularity for hip and knee surgical procedures. LIA can produce effective analgesia and has the advantage of relative simplicity compared with other regional anesthesia techniques [15,16]. A similar technique whereby the terminal fibers of the sciatic nerve can be blocked by intraoperative deposition of local anesthetic in the posterior capsule (P-LIA) has also been described. The utility of this technique was demonstrated in a small group of patients
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B. Safa et al. / The Journal of Arthroplasty 29 (2014) 1149–1153
following TKA by lowering pain scores, earlier ambulation and reduced hospital stay [17]. The goal of our study was to evaluate the effect of adding SNB to FNB for postoperative analgesia as well as functional outcomes following TKA. In addition we evaluated the technique of local anesthetic infiltration of the posterior capsule as a possible alternative to SNB for analgesia to the posterior aspect of the knee.
hydromorphone pump for 48 h. Controlled release oxycodone 10 mg every eight hours was started at 0600 the morning after surgery. To facilitate the weaning of the PCA pumps at 48 h, oxycodone 5 mg, every hour as needed (prn) was made available to patients when the PCA unit was discontinued.
Methods
Pain Scores and Side Effects The numerical pain rating scale is a one-dimensional tool to obtain a pain score. Patients were asked to rate their pain, on a scale of 0–10, where “0” represents no pain, and “10” represents the worst possible pain. For construct validity, the NRS was shown to be highly correlated to the verbal analog scale (VAS) [18]. Additionally, the NRS and the VAS have been shown to give almost identical values in the same patient at various times after surgery [18]. Pain scores at rest and movement were obtained at the time of starting PCA in the postanesthesia care unit (hour “0”) and every 4 h thereafter; scores were collected for the following 48 h. The PCA pump was set to deliver a 0.2 mg bolus of hydromorphone per demand with a 5 min lockout and no background infusion. All patients were instructed to maintain their pain score at less than 4 out of 10. If the pain score was 5 or greater at rest, the dose of intravenous PCA hydromorphone was increased to 0.3 mg per demand. If the pain score remained 5 or greater on two consecutive occasions, the standing controlled release oxycodone dose was increased from 10 mg to 15 mg every eight hours. In addition, at each 4-h time point, the incidence and severity of sedation, nausea, vomiting and pruritus were assessed.
Sample After informed consent and with institutional research ethics board approval, 100, ASA I–III patients between the ages of 18 and 75 years scheduled for elective unilateral primary TKA were included in this randomized double-blind controlled trial. Patients were excluded if they met any of the following criteria: preexisting medical conditions contraindicated for spinal anesthesia or peripheral nerve blocks, allergy to any of the medications being used, history of drug or alcohol abuse, chronic pain on slow-release preparations of opioid in excess of 30 mg of morphine equivalents per day, inability to comprehend pain scales or unable to use a Patient Controlled Analgesia (PCA) device, diabetes with impaired renal function and obesity with BMI N45. Patients were recruited at their preoperative assessment visit approximately one to two weeks in advance of their surgery. All subjects were screened, after which the study protocol, as well as the use of the PCA pump and numerical rating scale (NRS) for pain measurement, was explained. Blinded study drug kits were prepared according to a computergenerated randomization schedule in blocks of six, by the hospital investigational pharmacy, which was otherwise not involved in the clinical care of the patients or in the conduct of the trial. On the day of surgery, patients were sequentially assigned a drug kit and hence randomized to one of three treatment arms: Group 1: received a single-shot SNB and sham P-LIA, Group 2: received a P-LIA and a sham SNB, Group 3: received a sham SNB and sham P-LIA. Anesthetic Protocol All patients were prepared for surgery in a specialized block area and received the following oral premedications 1 h prior to surgery: acetaminophen 1 g, celecoxib 400 mg, gabapentin 400 mg. Intravenous midazolam 1 mg to 3 mg was administered at the discretion of the anesthesiologist to achieve appropriate sedation. Femoral and sciatic nerve blocks were performed as previously described [16,17] using a nerve stimulator (with or without ultrasound guidance) to localize the nerves at less than 0.5 mA, followed by 20 cc of Ropivacaine 0.5% deposited adjacent to the femoral nerve; likewise, 20 cc of Ropivacaine 0.5% or normal saline was deposited adjacent to the sciatic nerve. Spinal anesthesia was performed in the lateral decubitus or sitting position. After subcutaneous infiltration with lidocaine 1%, and using a midline approach, a 25 gauge Whitacre needle was inserted at the L3– 4, L4–5, or L5–S1 interspace, when free flow of CSF was obtained, 10 mg of 0.5% hypobaric bupivacaine with 12.5 μg of fentanyl was injected. The patient was then placed in the lateral decubitus position with the side of surgery uppermost and later transferred to the operating room. Intraoperative sedation was provided by an intravenous propofol infusion (25–100 μg/kg/min) until the end of surgery. At the end of the surgical procedure, 50 ml of 0.2% Ropivacaine or normal saline was injected into the posterior capsule under direct visualization by the surgical team. All patients, regardless of treatment group, received a standard postoperative regimen of celecoxib 200 mg every 12 h for three days, gabapentin 200 mg every eight hours for three days, acetaminophen 1 g every six hours for five days as well as an intravenous PCA
Outcome Measures
Functional Outcome Measures Postoperatively, all patients followed a primary knee arthroplasty care pathway, accompanied by a standardized rehabilitation treatment protocol. All patients began a full weight-bearing regimen, and participated in a progressive rehabilitation program for range of motion, strengthening, balance and ambulation beginning the first day after surgery. Examination of knee range of motion in patients with knee OA has been shown to have adequate reliability [19]. Knee flexion and extension range of motion was recorded preoperatively, on postoperative days 2 and 3 as well as follow-up visits at 6 weeks and 3 months. The timed up and go test (TUG), a less physically challenging measure, suited for the early postoperative period, has been used in a number of studies with arthroplasty patients [20–22]. This measure has demonstrated the ability to detect the deterioration and improvement that occur in the early postoperative period [23]. The test measures the time to rise from an arm chair (seat height, 46 cm), walk 3 m, turn, and return to sitting in the same chair, without physical assistance.TUG was assessed preoperatively, on postoperative day 3 and as well as follow-up visits at 6 weeks and 3 months. Simple functional outcomes such as ability to sit at the edge of the bed, to stand with support and ambulate with support were assessed on postoperative day 1 and 2. Analysis Sample size was based on the power analysis from a similar study [6]. A clinically meaningful, 30% reduction in pain represents an approximate difference of 1.5 in the NRS pain score. To detect this effect at 80% power and alpha of 0.05, an analysis of variance (ANOVA) would require a total of 96 patients for this three arm (two-treatment, one control) parallel-design study, 32 patients per arm. Sample size was inflated to 104 to account for possible dropouts. Descriptive statistics were calculated for all variables of interest. Continuous measures such as age were summarized using means and standard deviations whereas categorical measures were summarized using counts and percentages.
B. Safa et al. / The Journal of Arthroplasty 29 (2014) 1149–1153
3
Table 1 Patient Characteristics in the Three Groups.
Gender (M:F) Age Height (m) Weight (kg) BMI ROM (°) Pain (R) Pain (M) TUG (s) OPIOID
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Control (n = 35)
Sciatic (n = 33)
P-LIA (n = 32)
P
22:13 61.3 1.70 94.68 32.8 106 0.81 2.81 11.93 3/35
15:18 61.2 1.68 87.80 30.7 113 0.79 3.28 11.95 4/33
17:15 60.7 1.73 93.55 31.0 111 1.0 3.12 11.75 5/32
0.35 0.95 0.11 0.29 0.23 0.18 0.86 0.68 0.98 0.67
2.5 2 1.5 1
*§
0.5
*
0
4 Hr
Continuous measures such as opioid consumption were compared between groups over time using repeated measures analysis of variance models followed by post hoc pair wise group comparisons. Categorical measures such as use of antiemetic drugs, were compared between groups using chi-square analyses. All analyses were performed on an intention-to-treat basis and were carried out using SAS Version 9.2 (SAS Institute, Cary, NC, USA).
A
8 Hr Control
12 Hr Sciatic
24 Hr
P-LIA
1.6 1.4 1.2 1
Results
0.8
A total of 104 patients were successfully recruited. 4 patients were withdrawn after protocol violation. Thus, 100 patients completed the study—35 patients in the Control Group, 33 patients in Sciatic Group and 32 in P-LIA Group. No significant differences were found between groups for age, weight, preoperative opioid use, preoperative pain scores at rest and with movement, preoperative TUG performance, range of motion or gender distribution (Table 1).
*
0.6 0.4 0.2 0
0-4 Hr
B NRS Pain Score at rest (Mean ± Standard Error) 10 9 8 7 6 5 4 3 2 1 0
4hr
A
8hr 12hr 16hr 20hr 24hr 28hr 32hr 36hr 40hr 44hr 48hr Contol Sciatic P-LIA
4-8 Hr Control
8-12 Hr Sciatic
12-24 Hr
P-LIA
Fig. 2. (A) Cumulative PCA hydromorphone Consumption (mg) Mean ± SD. * Sciatic Group used significantly less opioids than Placebo Group (P = 0.01). § Sciatic Group used significantly less opioids than the P-LIA Group (P b 0.05). (B) Incremental PCA hydromorphone Consumption (mg) Mean ± SD. * Control Group used significantly more opioids in the first 4 h compared to the Sciatic Group (P = 0.01).
There was no statistically significant difference between the three groups with respect to the pain scores at rest or with movement in the first 48 h (Fig. 1). There was significantly less cumulative opioid (PCA) consumption in the Sciatic Group than Control Group at 4 and 8 h (P = 0.01, P = .01). This effect was no longer statistically significant at 12 h (P = .06). On average patients in the sciatic group used 0.29 mg less PCA
NRS Pain Score with movement (Mean ± Standard Error) 10
80
9
70
8 7
60
6
50
5
40
4 3
30
2
20
1 0
B
10 4hr
8hr 12hr 16hr 20hr 24hr 28hr 32hr 36hr 40hr 44hr 48hr Contol Sciatic P-LIA
0 preop
Day3 Control
Fig. 1. NRS Pain Score at rest (Mean ± Standard Error). NRS Pain Score with movement (Mean ± Standard Error).
6week Sciatic
3month
P-LIA
Fig. 3. Timed-UP-and-GO (TUG) TEST (seconds) Mean ± SD.
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B. Safa et al. / The Journal of Arthroplasty 29 (2014) 1149–1153
160 140 120 100 80 60 40 20 0 ROM0
ROM1
ROM2
Control
ROM3 Sciatic
ROM6WK ROM3M P-LIA
Fig. 4. Range of Motion (degrees) Mean ± SD.
hydromorphone in the first 12 h compared to the Control Group. Patients who received P-LIA had used significantly more patientcontrolled hydromorphone at 8 h than the patients who had received a sciatic nerve block (P b 0.05). At 4 h, patients in the P-LIA group had a trend towards reduced PCA hydromorphone consumption compared to the control group, however this difference did not reach statistical significance (P = .09) (Fig. 2A). Looking at the incremental opioid consumption, the control group used significantly more PCA hydromorphone in the first 4 h (P = .01). There was no significant difference in the opioid consumption between the groups for the time intervals of 4–8 h, 8–12 h and 12–24 h (Fig. 2B). There was no difference between the three groups in opioid related side effects at 12 and 24 h postoperatively. There was no difference between the groups in the TUG assessment on day 3, 6 weeks and 3-month follow-up (Fig. 3). There was no significant difference in the knee flexion and extension range of motion between the three groups on postoperative days 1, 2 and 3 as well as the 6-week and 3-month follow-up (Fig. 4). The pain scores before and after the functional studies were not significantly different between the study groups. There was no difference in ability to sit at the edge of the bed or to stand with support on postoperative days 1 and 2 among the three groups. However, more patients in the Sciatic Group were unable to ambulate with the assistance of a device on postoperative day 1 (P = .02). On postoperative day 2 this effect was no longer observed. The length of stay was not a measured outcome of this study, however all of our TKA patients follow a clinical pathway with standardized discharge criteria. This includes ability to ambulate and negotiate stairs with an assistive device, independent functional transfers and activities of daily living (or a plan in place regarding assistance) as well as knowledge of how to progress and continue an independent exercise program with an established plan for discharge physiotherapy. There was no difference in the mean length of stay for the Control, Sciatic and P-LIA groups, 4.3 ± 0.68, 4.3 ± 0.92 and 4.2 ± 0.99 days respectively.
Discussion In this study we were unable to demonstrate reduced pain scores in patients having a primary TKA who had a single shot sciatic nerve block in addition to a single shot femoral nerve block. Our patients had a robust multimodal analgesia regimen and access to patient controlled analgesia for 48 h postoperatively and were instructed on the use of PCA and to maintain their pain score between 2 and 4. There was a small but statistically significant reduction in cumulative
opioid consumption in patients who had a sciatic block in the early (first 12 h) postoperative period. Reducing opioid consumption should have benefits in terms of reducing opioid-related side effects before it can be considered clinically significant. The small opioid sparing effect of the sciatic nerve block did not lead to a reduction in opioid related side effects in this group, hence could not be considered clinically significant. One possible explanation for this observation is the multimodal analgesic regimen applied to the patients may have further minimized the relative contribution of sciatic innervation to postoperative pain management. Patients in the sciatic group were less likely to be able to ambulate with assistance on postoperative day 1; an effect attributed to possible residual muscular weakness from the two peripheral nerve blocks. However, there were no falls or long-term sequelae in terms functional recovery and length of stay in hospital. Local anesthetic infiltration of the posterior capsule did not prove to be an effective analgesic technique. A short-lived statistically insignificant trend towards reduced opioid consumption was observed in the first 4 h in keeping with the expected duration of action of any infiltration technique. Due to the blinded design of our study, the nerve blocks were not tested and an “intention to treat approach” was utilized. This could potentially be viewed as a possible limitation of this study. As with every medical procedure there is an inherent risk associated with performing a sciatic nerve block, therefore its application should only be considered when the potential benefits outweigh the potential risks. Sciatic block adds to the production pressure in terms of additional time, cost and skills required by the operators. Single-injection sciatic nerve block has similar complication rates as with any other nerve blocks, with permanent injury being exceptionally rare. However, knee surgery, even in the absence of a sciatic nerve block, can place significant stress on the sciatic nerve. Some risk factors, such as valgus deformity ≥10°, total tourniquet time ≥ 120 min, preexisting neuropathy and postoperative bleeding have been described [24]. The overall incidence of TKA-related incidence of sciatic nerve palsy is estimated to be 0.2% to 2.4% [24]. Performing a sciatic nerve block could theoretically increase the risk of nerve injury and more importantly, it could cloud the diagnosis and delay treatment. Furthermore a well-recognized side effect of peripheral nerve block is muscular weakness. The combination of femoral and sciatic nerve blocks could result in intense motor effects which may render patients unable to actively participate in early aggressive rehabilitation maneuvers, hence, raising concerns regarding post-TKA physical therapy expectations. On the other hand poorly managed pain may also inhibit the early intense rehabilitation. This in turn may result in impaired functional outcome. Peripheral nerve blocks have the potential to provide superior analgesia with fewer side effects allowing for accelerated functional recuperation, and the addition of a sciatic nerve block to a FNB should theoretically provide additional pain reduction following TKA. Currently there is insufficient evidence in the literature to qualitatively define the effect of adding single shot SNB to FNB for analgesia following TKA [9,11,13]. Two observational studies lend support to reduced opioid consumption and improved analgesia [6,7]. Hunt et al in a randomized study where patients in the sciatic group were not a part of the randomized arm, reported benefits of adding sciatic nerve block to FNB after TKA in terms of reduced early opioid consumption and analgesia [9]. Conversely, Allen et al in a small randomized, blinded study found no analgesic difference after FNB versus FNB and single shot sciatic nerve block [13]. In conclusion our results indicate that the addition of a single shot sciatic nerve block only transiently reduced opioid consumption without influencing the incidence of opioid-related side effects. This opioid sparing effect comes at the expense of reduced ability to ambulate with assistance on the first postoperative day. Based on the
B. Safa et al. / The Journal of Arthroplasty 29 (2014) 1149–1153
results of this study, in patients undergoing a primary TKA the routine addition of a single shot sciatic nerve block to femoral nerve block and a multimodal analgesic regimen may need to be reconsidered. Clinicians should consider the risk-to-benefit ratio for each case individually. Furthermore we do not recommend the P-LIA technique in addition to the multi-modal approach or a substitution for sciatic nerve block. The sciatic block may be beneficial in patients with preoperative chronic pain or opioid tolerance and in an as-yet to be defined population of patients who experience greater posterior knee pain at the completion of a TKA. Further research should identify patients who are more likely to suffer increased pain after TKA and may warrant a more intensive regional anesthesia approach including single injection or continuous sciatic nerve block. Acknowledgments The authors thank the research assistants and study coordinators, Beth Goudie RN and Ashley Pope, as well as the Holland Orthopedic and Arthritic Centre's nursing staff and the pharmacy and physiotherapy departments for their support. References 1. Postoperative pain. In: Bonica J, editor. The management of pain. 2nd ed. Philadelphia, PA: Lea & Febiger; 1990. p. 461. 2. Rowlingson A, McGready J, Cohen S, et al. Does continuous peripheral nerve block provide Superior Pain control to opioids? A meta-analysis. Anesth Analg 2006;102:248. 3. Singelyn F, Deyaert M, Joris D, et al. Effects of IV PCA with morphine, continuous epidural analgesia, and continuous 3 in 1 block on postoperative pain and knee rehabilitation after unilateral total knee arthroplasty. Anesth Analg 1998;87:88. 4. Capdevila X, Barthalet Y, Biboulet P, et al. Effects of perioperative anesthesia technique on surgical outcome and duration of rehabilitation after major knee surgery. Anesthesiology 1999;91:8. 5. Vloka JD, Hadzic A, Drobnik L, et al. Anatomical landmarks for femoral nerve block: a comparison of four needle insertion sites. Anesth Analg 1999;89(6):1467. 6. Cook P, Stevens J, Gaudron C. Comparing the effects of femoral nerve block versus femoral and sciatic nerve block on pain and opiate consumption after total knee arthroplasty. J Arthroplasty 2003;18:583.
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