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Effect of Adductor Canal Block on Acute Perioperative Pain and Function in Total Knee Arthroplasty
The Journal of Arthroplasty 34 (2019) S164eS167
Contents lists available at ScienceDirect
The Journal of Arthroplasty journal homepage: www.arthroplastyjournal.org
Primary Arthroplasty
Effect of Adductor Canal Block on Acute Perioperative Pain and Function in Total Knee Arthroplasty Richard D. Rames, MD *, Toby N. Barrack, Robert L. Barrack, MD, Ryan M. Nunley, MD Department of Orthopaedic Surgery, Washington University in St. Louis, Barnes-Jewish Hospital, St. Louis, MO
a r t i c l e i n f o
a b s t r a c t
Article history: Received 7 December 2018 Received in revised form 14 February 2019 Accepted 21 February 2019 Available online 25 February 2019
Background: Multimodal pain management strategies are commonplace in perioperative management of total knee arthroplasty (TKA), although controversy remains regarding the role of adductor canal blocks (ACB) in this algorithm. The purpose of this study is to independently evaluate the effect of ACB on shortterm postoperative outcomes including (1) length of stay (LOS), (2) postoperative narcotic utilization, and (3) function with physical therapy in the era of modern TKA. Methods: We retrospectively identified a cohort of consecutive patients from January 2014 to January 2018 who had undergone unilateral primary TKA using a single-shot ACB in addition to a standardized multimodal pain regimen vs those who only received a multimodal pain regimen. These 2 groups were compared using independent sample t-tests with primary end points of interest being LOS, distance ambulated with therapy, and inpatient narcotic use. Results: There were 624 patients in the ACB group, with a mean age of 64.5 years. The group without ACB consisted of 69 patients, with a mean age of 67.2 years. We observed no significant difference in narcotic utilization postoperatively (2.361 vs 2.097, P ¼ .088). The ACB group ambulated significantly further with therapy (75.8 vs 59.9 ft, P ¼ .008) and had a shorter LOS in both total hours and percentage of postoperative day 1 (%POD1) discharges (34.8 vs 40.6 hours, P ¼ .01, 83% vs 66.6%, P ¼ .01). Conclusion: ACB did not decrease postoperative pain medication utilization. The modest improvement in distance ambulated with therapy on POD1 (16 ft) and LOS (16% greater POD1 discharges) may not support the cost-effectiveness of this intervention. Level of Evidence: III, Retrospective Cohort. © 2019 Elsevier Inc. All rights reserved.
Keywords: primary TKA adductor canal block periarticular injection opiates multimodal pain regimen
Over 600,000 total knee arthroplasties (TKAs) are performed each year in the United States, and it is projected that the demand for TKA is anticipated to increase by greater than 600% by the year 2030 [1,2]. Despite the increasing number of procedures performed, studies suggest that a significant amount of these patients experience moderate to severe pain in the immediate postoperative period [3]. Poorly controlled pain can result in poor function with physical therapy, prolonged hospitalization, and
One or more of the authors of this paper have disclosed potential or pertinent conflicts of interest, which may include receipt of payment, either direct or indirect, institutional support, or association with an entity in the biomedical field which may be perceived to have potential conflict of interest with this work. For full disclosure statements refer to https://doi.org/10.1016/j.arth.2019.02.049. Source of funding: No outside sources of funding were used for this study. * Reprint requests: Richard D. Rames, MD, Department of Orthopaedic Surgery, Washington University in St. Louis, Barnes-Jewish Hospital, 660 S. Euclid Avenue, Campus Box 8233, St. Louis, MO 63110. https://doi.org/10.1016/j.arth.2019.02.049 0883-5403/© 2019 Elsevier Inc. All rights reserved.
reduced patient satisfaction [4e6]. Secondary to concerns associated with side effects and addiction profiles of opioids, a majority of high-volume arthroplasty surgeons have adopted a multimodal pain management strategy [7]. Periarticular injections (PAI) have been described as a component and are commonly used intraoperatively as a combination of local anesthetic with epinephrine and nonsteroidal anti-inflammatory drugs infiltrated locally into exposed tissue [8]. Despite widespread use of multimodal pain strategies, and support from recent Clinical Practice Guidelines published by the AAOS [9], controversy remains regarding the role of peripheral nerve blockade in this algorithm. Femoral nerve blocks (FNB) have been shown to reduce opiate consumption and decrease postoperative pain scores [10,11]. Unfortunately, FNB are associated with motor blockade of the quadriceps muscle which can impair postoperative mobilization and increase risks of early falls [12]. Adductor canal blocks (ACB) provide a more distal nerve blockade, at the mid-thigh, ideally providing sensory blockade in the distribution of the saphenous nerve, posterior branch of the obturator nerve and vastus medialis
R.D. Rames et al. / The Journal of Arthroplasty 34 (2019) S164eS167
nerve while sparing quadriceps function. Literature has supported improved motor function with similar pain control when comparing ACB to FNB [13e16]. Despite the evidence above, concerns exist regarding the widespread adoption of ACB. Those opposed cite the increased cost, the potential for neurovascular injury [17] or inadvertent motor blockade [18], and lack of increased analgesic effect when combined with PAI [19]. The purpose of this study is to independently evaluate the effect of ACB on short-term postoperative outcomes including (1) length of stay (LOS), (2) postoperative narcotic utilization, and (3) function with physical therapy. Methods After institutional review board approval was obtained, our institutional database was used to retrospectively identify 2 cohorts of consecutive patients who had undergone unilateral TKA with a single surgeon. Patients who underwent surgery from January 2014 through January 2018 were included, as this time frame captures patients treated with our current TKA perioperative protocol, including use of tranexamic acid (1 g at incision and 1 g at closure), pericapsular injection (0.5% Marcaine with epinephrine, ketorolac) regional anesthetic, and day of surgery inpatient physical therapy. Patients undergoing single-sided primary TKA were included. Exclusion criteria included simultaneous bilateral TKA, revision surgery, second-stage treatment for infection, or incomplete data recorded postoperatively. All 693 patients in the retrospective study received a standard multimodal pain regimen including 650 mg preoperative oral Tylenol, 100 or 200 mg celecoxib twice daily based on age, 15 or 30 mg intraoperative and postoperative intravenous ketorolac based on age and creatinine clearance, 1-2 tablets of 5/325 mg Percocet titrated to pain, and intravenous Dilaudid for breakthrough. All patients received an intraoperative PAI consisting of 60 cc 0.5% Marcaine with epinephrine and ketorolac injected into the joint capsule, synovium, periosteum, and surrounding soft tissue immediately before implantation of final implants. As a supplement to our standard multimodal pain regimen and PAI mentioned above, one cohort of patients (ACB þ PAI) received a perioperative single-shot ACB consisting of 0.5% bupivacaine with epinephrine performed by our regional anesthetists with an attending anesthesiologist performing or directly overseeing all blocks. Blocks were performed under ultrasound guidance at the midlevel of the medial thigh. Anesthetic doses were based on patient body mass index (BMI) and age. The majority of blocks were performed postoperatively in the post-anesthesia care unit. The patients who did not receive an ACB formed a second cohort of PAI-alone patients. This group did not receive blocks for the following reasons: lack of regional availability, systemic anticoagulation, or patient refusal. These cohorts did not statistically differ in terms of gender, BMI, or percentage requiring preoperative narcotics. To control for time of discharge and hours in the hospital, a subcohort of patients with ACB was then selected based on time of surgery to attempt to isolate the effect of the ACB. During the collection period of this longitudinal study, the surgeon transitioned his practice from all long tourniquet, cemented components to tourniquetless surgery with or without cementation. During the period of study, 42 patients were enrolled in a separate randomized, controlled trial and were excluded from this study. Patients deemed to have inadequate bone stock to support a cementless prosthesis received cement fixation. Retrospective chart review was then conducted to collect perioperative data on each cohort. The data points of interest were LOS
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in both hours and percentage of postoperative day 1 (%POD1) discharges, distance ambulated with physical therapy on postoperative day 1 (POD1), and postoperative inhospital narcotic use in morphine equivalents per hour (morphine Eq/h). The criteria for discharge after TKA at our institution include pain adequately controlled on oral medications, tolerating a diet, voiding, and being cleared by physical therapy. While nursing regularly encourages and assists patients out of bed on the day of surgery, formal physical therapy typically begins on POD1. Criteria for clearing physical therapy include ability to perform antigravity leg lifts to display sufficient quadriceps strength, bed mobility with at most 25% assist with joints coach, and ability to ambulate 50 feet independently. Nurses, therapists, and case managers had no knowledge of the use of ACB perioperatively and made all decisions on discharge criteria and pain medication administration. Analysis was performed on the 2 cohorts using independent sample t-tests, and chi-square analyses were used for categorical data where appropriate. P value of <.05 was set as the threshold to determine statistical significance of results. All statistical analyses were completed using SPSS version 21 (IBM corporation, Armonk, NY). Results The ACB þ PAI group consisted of 624 patients with a mean age of 64.5 years. There were 237 males (38%) and 387 females (62%) with a mean BMI of 32.6. The percentage of these patients requiring narcotics preoperatively was 29.7%. The PAI-alone group consisted of 69 patients with a mean age of 67.2 years. There were 28 males (41%) and 41 females (59%) with a mean BMI of 31.7. The percentage of these patients requiring narcotics preoperatively for pain control was 31.9%. The PAI group was slightly older (67.2 vs 64.5 years, P ¼ .024); otherwise, there were no statistical differences in gender, BMI, or percentage of patients requiring preoperative narcotics (Table 1). We observed no statistical difference in postoperative narcotic use between the ACB þ PAI group (mean, 2.36 morphine Eq/h; SD, 1.23) and the PAI-alone group (2.10; SD, 1.05) with a trend toward decreased use in the PAI-alone group (P ¼ .09). The ACB þ PAI group ambulated significantly farther with physical therapy on POD1 (mean, 75.8 ft; SD, 49.0) compared to PAI-alone group (mean, 59.9 ft; SD, 34.3, P ¼ .008). The ACB þ PAI group also was discharged from the hospital in a significantly shorter duration of time compared to the PAI-alone group when looked at in both hours (34.8 hours; SD, 16.9 vs 40.6 hours; SD, 17.4; P ¼ .01) and percentage of patients discharged on POD1 (83% vs 66.6%, P ¼ .01; Table 2). In the subcohort of patients who had primary TKA where incision was made after 12 PM with ACB perioperatively (n ¼ 157), we observed no difference in LOS (35.3 hours vs 35.4 hours, P ¼ .924), distance ambulated with PT (76.6 ft vs 73.5 ft, P ¼ .479), or in hospital narcotic use postoperatively (2.34 vs 2.33 morphine eq/h) against those who had surgery in the morning (n ¼ 534) (Table 3). Table 1 Demographics of Included Patients. Demographic
ACB þ PAI
PAI Alone
P Value
N M/F (%) BMI Age (y) Preop narcotic use (%)
624 38/62 32.6 64.5 29.7
69 41/59 31.7 67.2 31.9
.59 .29 .02 .71
ACB þ PAI, adductor canal block combined with periarticular injection; BMI, body mass index; F, female; M, male; PAI, ¼ periarticular injection; Preop, preoperative.
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Table 2 Effects of Adductor Canal Block. Outcome
ACB þ PAI
PAI Alone
P Value
Postop narcotic use (morphine Eq/h) Distance ambulated with PT POD1 (ft) LOSdhospital hours LOSd%POD1 discharges %Requiring postoperative manipulation under anesthesia
2.36 75.8 34.8 83% 3.0%
2.10 (1.05) 59.9 (34.3) 40.6 (17.4) 66.6% 4.4% (3/69)
.09 .01 .01 .01 .47
(1.23) (49) (16.9) (19/624)
ACB þ PAI, adductor canal block combined with periarticular injection; LOS, length of stay; PAI, ¼ periarticular injection; Postop, postoperative; POD1, postoperative day 1.
Discussion Poorly controlled pain following TKA can result in diminished function with physical therapy, decreased mobilization, prolonged hospitalization, and reduced patient satisfaction. PAI and ACB have both been implicated as important components in multimodal pain management regimens but the role of ACB remains controversial. To our knowledge, this is the largest retrospective study exploring the role of ACB. We demonstrated improved function with physical therapy and decreased length of hospitalization when ACB was added to our standard PAI; however, we showed no significant difference in postoperative in hospital narcotic use between the 2 groups. Prior studies that have explored the efficacy of ACB in TKA have had mixed outcomes, and an ideal perioperative pain management strategy has yet to be elucidated. In a retrospective study, Gwam et al [20] looked at ACB alone vs ACB þ PAI and found no significant improvements in postoperative narcotic use or LOS between the 2 cohorts, concluding ACB alone may be sufficient. Conversely, Grosso et al [19] showed in a randomized, controlled trial no significant differences in pain control or opiate consumption between PAI alone and ACB with PAI and significantly worse pain control in ACB without PAI. Furthermore, Sawhney et al [21] demonstrated improved pain control in patients receiving ACB and PAI rather than either in isolation, postulating that the addition of the PAI provides anesthetic effect to the lateral and posterior aspects of the knee while the ACB provides analgesia for the anterior and medial aspects. The results of our retrospective study were similar to those found in a recent meta-analysis by Ma et al [22], where combined ACB with PAI was associated with improved postoperative mobilization on POD1 but that did not translate to decreased narcotic utilization or hospital LOS. Finally, Sardena et al [23] performed a separate meta-analysis using randomized, controlled trials looking at PAI vs ACB in isolation concluded PAI had significantly improved postoperative pain and decreased opiate consumption when compared with ACB. The results of our study along with the inconclusive nature of the current literature reviewed above have led the senior authors to a more selective use of ACB after TKA. It is an expense that has failed to definitively demonstrate a clinically relevant difference in Table 3 Adductor Canal Block Results Stratified Based on Time of Surgery. Outcome
After 12 PM Case þ ACB
All Other Primary TKA
N Distance ambulated with PT POD1 (ft) LOSdhospital hours Postop narcotic use (Morphine Eq/h)
157 76.6 (49.2) 35.3 (19.0) 2.34 (1.29)
534 73.5 (47.3) 35.4 (16.4) 2.33 (1.20)
P Value
.48 .92 .95
ACB, adductor canal block; LOS, length of stay; PT, physical therapy; POD1, postoperative day 1; TKA, total knee arthroplasty.
perioperative pain control or outcomes we are now selectively using in patients known to have preoperative issues with pain control or stiffness. Our study is not without limitations. First, these results are from a single, high-volume, arthroplasty fellowshipetrained surgeon practicing in a large, tertiary referral center with the availability of regional anesthesiologists and may not translate to a lower-volume practice. Additionally, our study is retrospective in nature and we were unable to collect consistent Visual Analog Scale pain scores in the postoperative period were inconsistently recorded at varying time intervals. We believe that morphine equivalent narcotic dosing and postoperative function with physical therapy serve as sufficient proxies for pain scores. Our study was aimed largely at the immediate postoperative period and thus fails to include data after discharge from the hospital. Furthermore, despite statistically significant differences in LOS (34.8 vs 40.6 hours, P ¼ .01) and distance ambulated with PT (75.8 ft vs 59.9 ft, P ¼ .008), the sustained clinical relevance of these differences is unclear. We are unaware of literature citing minimal clinically important differences for these values but this is an area of future study. While there were some variables introduced late in the course of collection period (ie, cementation and tourniquet use), we believe the effects of these were minimized by the way our cohorts were formed. Finally, given the retrospective nature of the study, we did not have an “ACB-alone” cohort to include as all patients received a PAI. One hypothesis of failure of ACB to decrease narcotic use postoperatively is the rebound phenomenon that has been described following regional anesthesia [24]. This would likely be reflected as a substantial increase in narcotic use on the morning of POD1. In this study, we did not differentiate the timing of narcotic dosing postoperatively but would be an interesting area of future study. We currently have a prospective, randomized, controlled trial underway to explore this cohort using wearable devices to record pain scores postoperatively. Given the recent emphasis on responsible healthcare spending, it should be mentioned that at our institution the provider fees of an ultrasound-guided ACB are approximately $600 with actual CMS provider reimbursement of $67.75. When considering the addition of ACB to multimodal pain regimens, this increased cost needs to be weighed against the modest improvements in distance ambulated with physical therapy and LOS.
References [1] Cram P, Lu X, Kates SL, Singh JA, Li Y, Wolf BR. Total knee arthroplasty volume utilization, and outcomes among Medicare beneficiaries, 1991-2010. JAMA 2012;308:1227e36. [2] Kurtz S, Ong K, Lau E, Mowat F, Halpern M. Projections of primary and revision hip and knee arthroplasty in the United States from 2005 to 2030. J Bone Joint Surg Am 2007;89:780e5. [3] Husted H, Lunn TH, Troelsen A, Gaarn-Larsen L, Kristensen BB, Kehlet H. Why still in hospital after fast-track hip and knee arthroplasty? Acta Orthop 2011;82:679e84. [4] Korean Knee S. Guidelines for the management of postoperative pain after total knee arthroplasty. Knee Surg Relat Res 2012;24:201e7. [5] Capdevila X, Barthelet Y, Biboulet P, Ryckwaert Y, Rubenovitch J, d'Athis F. Effects of perioperative analgesic technique on the surgical outcome and duration of rehabilitation after major knee surgery. Anesthesiology 1999;91: 8e15. [6] Brokelman RB, van Loon CJ, Rijnberg WJ. Patient versus surgeon satisfaction after total hip arthroplasty. J Bone Joint Surg Br 2003;85:495e8. [7] Parvizi J, Miller AG, Gandhi K. Multimodal pain management after total joint arthroplasty. J Bone Joint Surg Am 2011;93:1075e84. https://doi.org/10.2106/ JBJS.J.01095. [8] 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 2008;79:174e83. [9] McGrory BJ, Weber KL, Jevsevar DS, Sevarino K. Surgical management of osteoarthritis of the knee. Evidence-based clinical practice guideline. J Am Acad Orthop Surg 2016;24:e87e93.
R.D. Rames et al. / The Journal of Arthroplasty 34 (2019) S164eS167 [10] Paul JE, Arya A, Hurlburt L, Cheng J. Femoral nerve block improves analgesia outcomes after total knee arthroplasty: a meta-analysis of randomized controlled trials. Anesthesiology 2010;113:1144e62. [11] Hadzic A, Houle TT, Capdevila X, Ilfeld BM. Femoral nerve block for analgesia in patients having knee arthroplasty. Anesthesiology 2010;113:1014e5. [12] Kandasami M, Kinninmonth AW, Sarungi M, Baines J, Scott NB. Femoral nerve block for total knee replacement - a word of caution. Knee 2009;16:98e100. [13] Jaeger P, Zaric D, Fomsgaard JS, Hilstd KL, Bjerregaard J, Gyrn J, et al. Adductor canal block versus femoral nerve block for analgesia after total knee arthroplasty: a randomized, double-blind study. Reg Anesth Pain Med 2013;38:526e32. [14] Grevstad U, Mathiesen O, Lind T, Dahl JB. Effect of adductor canal block on pain in patients with severe pain after total knee arthroplasty: a randomized study with individual patient analysis. Br J Anaesth 2014;112:912e9. [15] Hanson NA, Allen CJ, Hostetter LS, Nagy R, Derby RE, Slee AE, et al. Continuous ultrasound-guided adductor canal block for total knee arthroplasty: a randomized, double-blind trial. Anesth Analg 2014;118:1370e7. [16] Kim D, Lin Y, Goytizolo EA, Kahn RL, Maalouf DB, Manohar A, et al. Adductor canal block versus femoral nerve block for total knee arthroplasty: a prospective, randomized, controlled trial. Anesthesiology 2014;120:540e50. [17] Koniuch KL, Harris B, Buys MJ, Meier AW. Case report of a massive thigh hematoma after adductor canal block in a morbidly obese woman anticoagulated with apixaban. Case Rep Anesthesiol 2018;2018:7653202. https:// doi.org/10.1155/2018/7653202. [18] Chen J, Lesser JB, Hadzic A, Reiss W, Resta-Flarer F. Adductor canal block can result in motor block of the quadriceps muscle. Reg Anesth Pain Med 2014;39: 170e1.
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[19] Grosso MJ, Murtaugh T, Lakra A, Brown AR, Maniker RB, Cooper HJ, et al. Adductor canal block compared with periarticular bupivacaine injection for total knee arthroplasty: a prospective randomized trial. J Bone Joint Surg Am 2018;100:1141e6. [20] Gwam CU, Mistry JB, Khlopas A, Chughtai M, Thomas M, Mont MA, et al. Does addition of multimodal periarticular analgesia to adductor canal block improve lengths of stay, pain, discharge status, and opioid use after total knee arthroplasty? J Arthroplasty 2017;32:1470e3. [21] Sawhney M, Mehdian H, Kashin B, Ip G, Bent M, Choy J, et al. Pain after unilateral total knee arthroplasty: a prospective randomized controlled trial examining the analgesic effectiveness of a combined adductor canal peripheral nerve block with periarticular infiltration versus adductor canal nerve block alone versus periarticular infiltration alone. Anesth Analg 2016;122: 2040e6. [22] Ma J, Gao F, Sun W, Guo W, Li Z, Wang W. Combined adductor canal block with periarticular infiltration versus periarticular infiltration for analgesia after total knee arthroplasty. Medicine (Baltimore) 2016;95: e5701. [23] Sardena V, Burzynski JM, Scuderi GR. Adductor canal block or local infiltrate analgesia for pain control after total knee arthroplasty? A systematic review and meta-analysis of randomized controlled trials. J Arthroplasty 2019;34: 183e9. [24] Williams BA, Bottegal MT, Kentor ML, Irrgang JJ, Williams JP. Rebound pain scores as a function of femoral nerve block duration after anterior cruciate ligament reconstruction: retrospective analysis of a prospective, randomized clinical trial. Reg Anesth Pain Med 2007;32:186e92.
Contents lists available at ScienceDirect
The Journal of Arthroplasty journal homepage: www.arthroplastyjournal.org
Primary Arthroplasty
Effect of Adductor Canal Block on Acute Perioperative Pain and Function in Total Knee Arthroplasty Richard D. Rames, MD *, Toby N. Barrack, Robert L. Barrack, MD, Ryan M. Nunley, MD Department of Orthopaedic Surgery, Washington University in St. Louis, Barnes-Jewish Hospital, St. Louis, MO
a r t i c l e i n f o
a b s t r a c t
Article history: Received 7 December 2018 Received in revised form 14 February 2019 Accepted 21 February 2019 Available online 25 February 2019
Background: Multimodal pain management strategies are commonplace in perioperative management of total knee arthroplasty (TKA), although controversy remains regarding the role of adductor canal blocks (ACB) in this algorithm. The purpose of this study is to independently evaluate the effect of ACB on shortterm postoperative outcomes including (1) length of stay (LOS), (2) postoperative narcotic utilization, and (3) function with physical therapy in the era of modern TKA. Methods: We retrospectively identified a cohort of consecutive patients from January 2014 to January 2018 who had undergone unilateral primary TKA using a single-shot ACB in addition to a standardized multimodal pain regimen vs those who only received a multimodal pain regimen. These 2 groups were compared using independent sample t-tests with primary end points of interest being LOS, distance ambulated with therapy, and inpatient narcotic use. Results: There were 624 patients in the ACB group, with a mean age of 64.5 years. The group without ACB consisted of 69 patients, with a mean age of 67.2 years. We observed no significant difference in narcotic utilization postoperatively (2.361 vs 2.097, P ¼ .088). The ACB group ambulated significantly further with therapy (75.8 vs 59.9 ft, P ¼ .008) and had a shorter LOS in both total hours and percentage of postoperative day 1 (%POD1) discharges (34.8 vs 40.6 hours, P ¼ .01, 83% vs 66.6%, P ¼ .01). Conclusion: ACB did not decrease postoperative pain medication utilization. The modest improvement in distance ambulated with therapy on POD1 (16 ft) and LOS (16% greater POD1 discharges) may not support the cost-effectiveness of this intervention. Level of Evidence: III, Retrospective Cohort. © 2019 Elsevier Inc. All rights reserved.
Keywords: primary TKA adductor canal block periarticular injection opiates multimodal pain regimen
Over 600,000 total knee arthroplasties (TKAs) are performed each year in the United States, and it is projected that the demand for TKA is anticipated to increase by greater than 600% by the year 2030 [1,2]. Despite the increasing number of procedures performed, studies suggest that a significant amount of these patients experience moderate to severe pain in the immediate postoperative period [3]. Poorly controlled pain can result in poor function with physical therapy, prolonged hospitalization, and
One or more of the authors of this paper have disclosed potential or pertinent conflicts of interest, which may include receipt of payment, either direct or indirect, institutional support, or association with an entity in the biomedical field which may be perceived to have potential conflict of interest with this work. For full disclosure statements refer to https://doi.org/10.1016/j.arth.2019.02.049. Source of funding: No outside sources of funding were used for this study. * Reprint requests: Richard D. Rames, MD, Department of Orthopaedic Surgery, Washington University in St. Louis, Barnes-Jewish Hospital, 660 S. Euclid Avenue, Campus Box 8233, St. Louis, MO 63110. https://doi.org/10.1016/j.arth.2019.02.049 0883-5403/© 2019 Elsevier Inc. All rights reserved.
reduced patient satisfaction [4e6]. Secondary to concerns associated with side effects and addiction profiles of opioids, a majority of high-volume arthroplasty surgeons have adopted a multimodal pain management strategy [7]. Periarticular injections (PAI) have been described as a component and are commonly used intraoperatively as a combination of local anesthetic with epinephrine and nonsteroidal anti-inflammatory drugs infiltrated locally into exposed tissue [8]. Despite widespread use of multimodal pain strategies, and support from recent Clinical Practice Guidelines published by the AAOS [9], controversy remains regarding the role of peripheral nerve blockade in this algorithm. Femoral nerve blocks (FNB) have been shown to reduce opiate consumption and decrease postoperative pain scores [10,11]. Unfortunately, FNB are associated with motor blockade of the quadriceps muscle which can impair postoperative mobilization and increase risks of early falls [12]. Adductor canal blocks (ACB) provide a more distal nerve blockade, at the mid-thigh, ideally providing sensory blockade in the distribution of the saphenous nerve, posterior branch of the obturator nerve and vastus medialis
R.D. Rames et al. / The Journal of Arthroplasty 34 (2019) S164eS167
nerve while sparing quadriceps function. Literature has supported improved motor function with similar pain control when comparing ACB to FNB [13e16]. Despite the evidence above, concerns exist regarding the widespread adoption of ACB. Those opposed cite the increased cost, the potential for neurovascular injury [17] or inadvertent motor blockade [18], and lack of increased analgesic effect when combined with PAI [19]. The purpose of this study is to independently evaluate the effect of ACB on short-term postoperative outcomes including (1) length of stay (LOS), (2) postoperative narcotic utilization, and (3) function with physical therapy. Methods After institutional review board approval was obtained, our institutional database was used to retrospectively identify 2 cohorts of consecutive patients who had undergone unilateral TKA with a single surgeon. Patients who underwent surgery from January 2014 through January 2018 were included, as this time frame captures patients treated with our current TKA perioperative protocol, including use of tranexamic acid (1 g at incision and 1 g at closure), pericapsular injection (0.5% Marcaine with epinephrine, ketorolac) regional anesthetic, and day of surgery inpatient physical therapy. Patients undergoing single-sided primary TKA were included. Exclusion criteria included simultaneous bilateral TKA, revision surgery, second-stage treatment for infection, or incomplete data recorded postoperatively. All 693 patients in the retrospective study received a standard multimodal pain regimen including 650 mg preoperative oral Tylenol, 100 or 200 mg celecoxib twice daily based on age, 15 or 30 mg intraoperative and postoperative intravenous ketorolac based on age and creatinine clearance, 1-2 tablets of 5/325 mg Percocet titrated to pain, and intravenous Dilaudid for breakthrough. All patients received an intraoperative PAI consisting of 60 cc 0.5% Marcaine with epinephrine and ketorolac injected into the joint capsule, synovium, periosteum, and surrounding soft tissue immediately before implantation of final implants. As a supplement to our standard multimodal pain regimen and PAI mentioned above, one cohort of patients (ACB þ PAI) received a perioperative single-shot ACB consisting of 0.5% bupivacaine with epinephrine performed by our regional anesthetists with an attending anesthesiologist performing or directly overseeing all blocks. Blocks were performed under ultrasound guidance at the midlevel of the medial thigh. Anesthetic doses were based on patient body mass index (BMI) and age. The majority of blocks were performed postoperatively in the post-anesthesia care unit. The patients who did not receive an ACB formed a second cohort of PAI-alone patients. This group did not receive blocks for the following reasons: lack of regional availability, systemic anticoagulation, or patient refusal. These cohorts did not statistically differ in terms of gender, BMI, or percentage requiring preoperative narcotics. To control for time of discharge and hours in the hospital, a subcohort of patients with ACB was then selected based on time of surgery to attempt to isolate the effect of the ACB. During the collection period of this longitudinal study, the surgeon transitioned his practice from all long tourniquet, cemented components to tourniquetless surgery with or without cementation. During the period of study, 42 patients were enrolled in a separate randomized, controlled trial and were excluded from this study. Patients deemed to have inadequate bone stock to support a cementless prosthesis received cement fixation. Retrospective chart review was then conducted to collect perioperative data on each cohort. The data points of interest were LOS
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in both hours and percentage of postoperative day 1 (%POD1) discharges, distance ambulated with physical therapy on postoperative day 1 (POD1), and postoperative inhospital narcotic use in morphine equivalents per hour (morphine Eq/h). The criteria for discharge after TKA at our institution include pain adequately controlled on oral medications, tolerating a diet, voiding, and being cleared by physical therapy. While nursing regularly encourages and assists patients out of bed on the day of surgery, formal physical therapy typically begins on POD1. Criteria for clearing physical therapy include ability to perform antigravity leg lifts to display sufficient quadriceps strength, bed mobility with at most 25% assist with joints coach, and ability to ambulate 50 feet independently. Nurses, therapists, and case managers had no knowledge of the use of ACB perioperatively and made all decisions on discharge criteria and pain medication administration. Analysis was performed on the 2 cohorts using independent sample t-tests, and chi-square analyses were used for categorical data where appropriate. P value of <.05 was set as the threshold to determine statistical significance of results. All statistical analyses were completed using SPSS version 21 (IBM corporation, Armonk, NY). Results The ACB þ PAI group consisted of 624 patients with a mean age of 64.5 years. There were 237 males (38%) and 387 females (62%) with a mean BMI of 32.6. The percentage of these patients requiring narcotics preoperatively was 29.7%. The PAI-alone group consisted of 69 patients with a mean age of 67.2 years. There were 28 males (41%) and 41 females (59%) with a mean BMI of 31.7. The percentage of these patients requiring narcotics preoperatively for pain control was 31.9%. The PAI group was slightly older (67.2 vs 64.5 years, P ¼ .024); otherwise, there were no statistical differences in gender, BMI, or percentage of patients requiring preoperative narcotics (Table 1). We observed no statistical difference in postoperative narcotic use between the ACB þ PAI group (mean, 2.36 morphine Eq/h; SD, 1.23) and the PAI-alone group (2.10; SD, 1.05) with a trend toward decreased use in the PAI-alone group (P ¼ .09). The ACB þ PAI group ambulated significantly farther with physical therapy on POD1 (mean, 75.8 ft; SD, 49.0) compared to PAI-alone group (mean, 59.9 ft; SD, 34.3, P ¼ .008). The ACB þ PAI group also was discharged from the hospital in a significantly shorter duration of time compared to the PAI-alone group when looked at in both hours (34.8 hours; SD, 16.9 vs 40.6 hours; SD, 17.4; P ¼ .01) and percentage of patients discharged on POD1 (83% vs 66.6%, P ¼ .01; Table 2). In the subcohort of patients who had primary TKA where incision was made after 12 PM with ACB perioperatively (n ¼ 157), we observed no difference in LOS (35.3 hours vs 35.4 hours, P ¼ .924), distance ambulated with PT (76.6 ft vs 73.5 ft, P ¼ .479), or in hospital narcotic use postoperatively (2.34 vs 2.33 morphine eq/h) against those who had surgery in the morning (n ¼ 534) (Table 3). Table 1 Demographics of Included Patients. Demographic
ACB þ PAI
PAI Alone
P Value
N M/F (%) BMI Age (y) Preop narcotic use (%)
624 38/62 32.6 64.5 29.7
69 41/59 31.7 67.2 31.9
.59 .29 .02 .71
ACB þ PAI, adductor canal block combined with periarticular injection; BMI, body mass index; F, female; M, male; PAI, ¼ periarticular injection; Preop, preoperative.
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Table 2 Effects of Adductor Canal Block. Outcome
ACB þ PAI
PAI Alone
P Value
Postop narcotic use (morphine Eq/h) Distance ambulated with PT POD1 (ft) LOSdhospital hours LOSd%POD1 discharges %Requiring postoperative manipulation under anesthesia
2.36 75.8 34.8 83% 3.0%
2.10 (1.05) 59.9 (34.3) 40.6 (17.4) 66.6% 4.4% (3/69)
.09 .01 .01 .01 .47
(1.23) (49) (16.9) (19/624)
ACB þ PAI, adductor canal block combined with periarticular injection; LOS, length of stay; PAI, ¼ periarticular injection; Postop, postoperative; POD1, postoperative day 1.
Discussion Poorly controlled pain following TKA can result in diminished function with physical therapy, decreased mobilization, prolonged hospitalization, and reduced patient satisfaction. PAI and ACB have both been implicated as important components in multimodal pain management regimens but the role of ACB remains controversial. To our knowledge, this is the largest retrospective study exploring the role of ACB. We demonstrated improved function with physical therapy and decreased length of hospitalization when ACB was added to our standard PAI; however, we showed no significant difference in postoperative in hospital narcotic use between the 2 groups. Prior studies that have explored the efficacy of ACB in TKA have had mixed outcomes, and an ideal perioperative pain management strategy has yet to be elucidated. In a retrospective study, Gwam et al [20] looked at ACB alone vs ACB þ PAI and found no significant improvements in postoperative narcotic use or LOS between the 2 cohorts, concluding ACB alone may be sufficient. Conversely, Grosso et al [19] showed in a randomized, controlled trial no significant differences in pain control or opiate consumption between PAI alone and ACB with PAI and significantly worse pain control in ACB without PAI. Furthermore, Sawhney et al [21] demonstrated improved pain control in patients receiving ACB and PAI rather than either in isolation, postulating that the addition of the PAI provides anesthetic effect to the lateral and posterior aspects of the knee while the ACB provides analgesia for the anterior and medial aspects. The results of our retrospective study were similar to those found in a recent meta-analysis by Ma et al [22], where combined ACB with PAI was associated with improved postoperative mobilization on POD1 but that did not translate to decreased narcotic utilization or hospital LOS. Finally, Sardena et al [23] performed a separate meta-analysis using randomized, controlled trials looking at PAI vs ACB in isolation concluded PAI had significantly improved postoperative pain and decreased opiate consumption when compared with ACB. The results of our study along with the inconclusive nature of the current literature reviewed above have led the senior authors to a more selective use of ACB after TKA. It is an expense that has failed to definitively demonstrate a clinically relevant difference in Table 3 Adductor Canal Block Results Stratified Based on Time of Surgery. Outcome
After 12 PM Case þ ACB
All Other Primary TKA
N Distance ambulated with PT POD1 (ft) LOSdhospital hours Postop narcotic use (Morphine Eq/h)
157 76.6 (49.2) 35.3 (19.0) 2.34 (1.29)
534 73.5 (47.3) 35.4 (16.4) 2.33 (1.20)
P Value
.48 .92 .95
ACB, adductor canal block; LOS, length of stay; PT, physical therapy; POD1, postoperative day 1; TKA, total knee arthroplasty.
perioperative pain control or outcomes we are now selectively using in patients known to have preoperative issues with pain control or stiffness. Our study is not without limitations. First, these results are from a single, high-volume, arthroplasty fellowshipetrained surgeon practicing in a large, tertiary referral center with the availability of regional anesthesiologists and may not translate to a lower-volume practice. Additionally, our study is retrospective in nature and we were unable to collect consistent Visual Analog Scale pain scores in the postoperative period were inconsistently recorded at varying time intervals. We believe that morphine equivalent narcotic dosing and postoperative function with physical therapy serve as sufficient proxies for pain scores. Our study was aimed largely at the immediate postoperative period and thus fails to include data after discharge from the hospital. Furthermore, despite statistically significant differences in LOS (34.8 vs 40.6 hours, P ¼ .01) and distance ambulated with PT (75.8 ft vs 59.9 ft, P ¼ .008), the sustained clinical relevance of these differences is unclear. We are unaware of literature citing minimal clinically important differences for these values but this is an area of future study. While there were some variables introduced late in the course of collection period (ie, cementation and tourniquet use), we believe the effects of these were minimized by the way our cohorts were formed. Finally, given the retrospective nature of the study, we did not have an “ACB-alone” cohort to include as all patients received a PAI. One hypothesis of failure of ACB to decrease narcotic use postoperatively is the rebound phenomenon that has been described following regional anesthesia [24]. This would likely be reflected as a substantial increase in narcotic use on the morning of POD1. In this study, we did not differentiate the timing of narcotic dosing postoperatively but would be an interesting area of future study. We currently have a prospective, randomized, controlled trial underway to explore this cohort using wearable devices to record pain scores postoperatively. Given the recent emphasis on responsible healthcare spending, it should be mentioned that at our institution the provider fees of an ultrasound-guided ACB are approximately $600 with actual CMS provider reimbursement of $67.75. When considering the addition of ACB to multimodal pain regimens, this increased cost needs to be weighed against the modest improvements in distance ambulated with physical therapy and LOS.
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