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Postoperative continuous adductor canal block for total knee arthroplasty improves pain and functional recovery: A randomized controlled clinical trial
Journal of Clinical Anesthesia 49 (2018) 46–52
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Journal of Clinical Anesthesia journal homepage: www.elsevier.com/locate/jclinane
Original contribution
Postoperative continuous adductor canal block for total knee arthroplasty improves pain and functional recovery: A randomized controlled clinical trial
T
Patrick Leung, MDa, David M. Dickerson, MDb, Sahitya K. Denduluri, MDa, ⁎ Maryam K. Mohammed, MDa, Min Lu, MDa, Magdalena Anitescu, MD, PhDb, Hue H. Luu, MDa, a b
University of Chicago Medical Center, Department of Orthopaedic Surgery and Rehabilitation, 5841 S. Maryland Ave, M/C 3079, Chicago, IL 60637, United States University of Chicago Medical Center, Department of Anesthesia and Critical Care, 5841 S. Maryland Ave, M/C 4028, Chicago, IL 60637, United States
A R T I C LE I N FO
A B S T R A C T
Keywords: Continuous adductor canal block Total knee arthroplasty
Study objective: Investigate the use of a postoperative continuous adductor canal block (cACB) after epidural analgesia to decreases opioid consumption and improve visual analog scale (VAS) scores compared to a sham catheter. Design: Double-blinded randomized placebo-controlled trial. Setting: Inpatient setting in tertiary care teaching hospital with outpatient follow-up. Patients: One-hundred and sixty-five subjects (cACB n = 82 and sham catheter n = 83) with end-stage degenerative joint disease undergoing elective unilateral total knee arthroplasty. Interventions: Patients were block randomized to receive a cACB or sham catheter. An epidural catheter was placed preoperatively and discontinued on postoperative day 1. Patients then received a cACB with bupivacaine or sham catheter which remained for the duration of the hospitalization. Measurements: Primary outcome was total opioid consumption. Secondary outcomes included VAS scores, knee range of motion (ROM), ambulation distance, and WOMAC scores. Main results: Seventy patients completed the study (cACB n = 38 and sham catheter n = 32). Compared to sham catheter, in the first 20 h after placement of a cACB, patients used 22.5 mg less opioid (95% CI: −43.1 to −1.94 mg, P = 0.03). VAS score area under the curve decreased 7.8 mm (95% CI: −15.5 – −0.058 mm, P = 0.04) with a cACB. At 3-week follow-up, WOMAC scores were significantly improved with the cACB with a mean difference of 8.72 (95% CI: −17.3 to −0.11, P = 0.04). There were no statistically significant differences in secondary outcomes on postoperative day 2. Paired outcomes at 6 weeks compared to baseline ROM, showed significant improvement in knee ROM with a cACB (mean difference 11.77°, 95% CI: 3.1–20.5°, P = 0.01). Conclusion: A postoperative cACB after total knee arthroplasty significantly reduces total opioid consumption and pain scores compared to sham catheter. Ambulatory ability was not affected and patients recovered function earlier. ClinicalTrials.gov NCT02121392.
1. Introduction Knee replacement surgery is projected to increase in the United States [1]. Total knee arthroplasty (TKA) is associated with significant postoperative pain. The need for effective analgesia without compromising function is a priority. Currently there is no consensus on the best pain control regimen after TKA. An ideal postoperative analgesic facilitates early knee range of motion (ROM) and ambulation, reduces overall narcotic consumption, improves patient satisfaction, and
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reduces chronic post-surgical pain. Pain management after TKA encompasses a wide variety of interventions. Neuraxial anesthesia with epidurals is frequently utilized in TKA as it is associated with decreased morbidity and mortality compared to general anesthesia [2]. Although epidural analgesia is superior to systemic analgesia in controlling early postoperative pain, there is no statistical difference by 18–24 h [3]. Epidural analgesia can be titrated for minimal motor blockade however the theoretical risk of intra-spinal hematoma formation after anticoagulation often leads to catheter
Corresponding author. E-mail addresses: [email protected] (P. Leung), [email protected] (D.M. Dickerson), [email protected] (M. Anitescu), [email protected] (H.H. Luu). https://doi.org/10.1016/j.jclinane.2018.06.004 Received 1 February 2018; Received in revised form 28 May 2018; Accepted 1 June 2018 0952-8180/ © 2018 Elsevier Inc. All rights reserved.
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subject's waist to obscure their view of the procedure. An ultrasound transducer (SonoSite M-Turbo, Bothell, WA) was used to identify the adductor canal at the mid-thigh. Under ultrasound guidance, a 17gauge Tuohy needle with a closed tip catheter (B Braun, Melsungen, Germany) was introduced into the adductor canal and 1% lidocaine and 5% dextrose was used to hydrodissect the space lateral to the superficial femoral artery. A non-stimulating epidural catheter was then placed within the adductor canal, bolused with 10 mL of 0.25% bupivacaine and connected to an infusion pump. The catheter site and electronic infusion pump (CADD®-Solis, Smiths Medical, St. Paul, MN) were covered with an opaque dressing and bag, respectively. Bupivacaine 0.125% was infused at 8 cm3/h via the cACB catheter. In the control group, patients were prepared in an identical manner. An ultrasound transducer was used to identify the adductor canal. To minimize the risk to the patients in this group, the skin was not punctured during placement of the sham catheter. Catheter placement was simulated with a wooden stick applicator applied to the skin with pressure for 10 s. The catheter was secured to the skin, covered with an opaque dressing, and connected to an identical pump. Saline was flushed through the tubing to give the appearance of a functioning catheter. The pump and medication bag were covered with an opaque bag. A supplemental pain regimen was prescribed for all patients which included intravenous morphine 1–2 mg every 2 h as needed, oxycodone controlled-release 10 mg twice daily, tramadol 50 mg every 6 h, and 1–2 tabs of hydrocodone/acetaminophen 5–325 mg every 4–6 h as needed. VAS scores were recorded at least every 4 h and documented in the electronic medical records. Ambulation distance and ROM were measured twice daily during physical therapy. Immediately prior to discharge, infusion pumps were discontinued and the catheters were withdrawn. For patients with the cACB catheter, a sterile dressing was applied over the area.
removal within 24 h of initiation of anticoagulation. A femoral nerve blockade does not carry such limitation and has gained popularity for postoperative analgesia in patients undergoing TKA. Compared to opioid analgesia, femoral nerve blocks reduce total opioid consumption, pain scores on the visual analog scale (VAS), shorten recovery times, and decrease postoperative adverse events [4–7]. Femoral nerve blocks, however, are not without adverse effects. In healthy human volunteers undergoing a continuous femoral nerve block, quadriceps femoris strength decreased up to 84% of baseline [8]. Loss of quadriceps strength limits rehabilitation and potentially poses a fall risk [9, 10]. To address this limitation, peripheral nerve blocks have been performed within the adductor canal where the femoral nerve has given off the majority of its motor branches to the quadriceps femoris muscle. The femoral, obturator, and sciatic nerves contribute to the sensory innervation of the knee. Within the adductor canal, anatomic studies identify several nerves, primarily sensory. Adductor canal block (ACB) spares the majority of motor contributions to the lower extremity and infusion of local anesthetics into this space provides effective analgesia after TKA [11–13]. The primary objective of this prospective, randomized, doubleblinded, sham-controlled trial was to evaluate opioid consumption after TKA with epidural analgesia and continuous adductor canal block (cACB). Secondary end points included VAS scores, ambulation distance, knee ROM, WOMAC scores, and length of stay (LOS). We hypothesized that epidural analgesia with cACB would decrease opioid consumption and improve pain control compared to control. 2. Materials and methods This trial was registered at ClinicalTrials.gov in April 2014 with the identifier NCT02121392, and approved by the Institutional Review Board of the University of Chicago. All patients provided informed written consent. Patients scheduled for unilateral TKA from September 2014 to January 2017 at the University of Chicago Medical Center were enrolled. All participants were allocated preoperatively via a computergenerated block randomizer (4 numbers per block) to receive either the continuous adductor canal block or sham catheter by an investigator not involved in patient enrollment, data collection, or analysis. The surgeon, study participants, and research staff were blinded to the assignment except for the anesthesiologists performing the interventions. The anesthesiologists were not involved in post-intervention evaluation of the patients. Eligibility criteria included patients with end-stage degenerative joint disease undergoing elective unilateral TKA, age < 85 years, and the ability to follow the study protocol. Exclusion criteria included American Society of Anesthesiologist physical class > 3, allergy to the study medications, coagulopathy, and platelet count < 105/μL. Patients with contraindications to the insertion of an epidural or cACB were also excluded, including severe anatomic abnormalities, or a history of previous surgery at the site of catheter placement.
2.2. Outcomes Patients were followed at weeks 3, 6, 12, 24, and 52. Scores from the Western Ontario and McMaster University Arthritis Index (WOMAC) were obtained at 3 and 6 weeks. The primary endpoint was total opioid consumption in morphine equivalents. Secondary endpoints included VAS area under the curve (AUC), inpatient LOS, knee ROM, ambulation distance, WOMAC scores, and use of anti-emetic medications. Data collection and analysis was performed by a blinded research assistant. 2.3. Statistical analysis Based on previous studies, we estimated a mean opioid consumption of 50 mg of morphine (SD ± 25 mg) during the first two day postoperatively after the use of an epidural catheter which was discontinued on the first postoperative day. A reduction of 20 mg in opioid consumption was considered clinically relevant. With α = 0.05 and a power of 90%, 35 subjects were needed in each group for a total of 70 patients. To compensate for anticipated dropouts from the study, we planned for an inclusion of 80 patients. Data was reported for all primary and secondary endpoints as the mean, standard deviation (SD), and 95% confidence intervals (CI). For VAS pain scores, AUC was calculated for the first 12 hour postoperatively and for 20 h after cACB catheter placement. For these same time intervals, cumulative opioid consumption, ambulation distance, and ROM were compared using the independent samples t-test. WOMAC questionnaires were converted to numerical values, and a comparison of arithmetic mean scores was performed using the independent samples t-test. Additionally, paired t-tests were used to investigate improvements in ROM and WOMAC scores within each study group. All hypothesis testing was two-tailed and conducted with an assumption of unequal variance when applicable. Statistical analyses
2.1. Administration of epidural anesthesia and adductor canal block Patients were evaluated preoperatively by an anesthesiologist and assessed for eligibility for epidural anesthesia, and a lumbar epidural or a combined spinal-epidural, which was placed according to standard protocol. If an epidural catheter could not be placed or neuraxial anesthesia was deemed inadequate for surgery, the patient received general anesthesia and was removed from the study. All surgeries were performed by the senior author (HHL). Patient controlled epidural analgesia was managed by the Acute Pain Service immediately postoperatively through the first postoperative morning. The epidural catheter was removed on postoperative day (POD) 1. After resolution of the epidural's effects, subjects in the treatment group received a cACB catheter placed by a board-certified pain specialist. An opaque blanket was hung above the 47
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(P = 0.28), mean ambulation distance, and day-to-day changes in ambulation distance (Table 2). There were no significant differences in absolute and day-to-day percent change in ROM measurements with the exception of ROM on POD 1 (51.4° ± 17° in control group vs. 40.6° ± 14° in cACB group, 95% CI: −18.5 to −3.2°, P = 0.006).
Table 1 Baseline characteristics of study patients. Patient baseline characteristics
Sample size Age (years) Gender ASAb classification BMIc (kg/m2) WOMACd Knee extension (°) Knee flexion (°) Knee ROMe (°) a b c d e
Control
cACBa
P-value
32 63.3 (9.8) 7 male | 25 female 2.66 (0.48) 33.9 (6.0) 50.1 (13) 3.34 (6.0) 105 (18) 102 (18)
39 64.6 (8.7) 9 male | 30 female 2.79 (0.41) 33.3 (7.4) 53.8 (20) 4.56 (6.4) 97.3 (25) 92.7 (26)
– 0.59 – 0.22 0.79 0.37 0.42 0.13 0.10
3.4. Postoperative functional status Likert-type 5-point WOMAC questionnaire was used to assess functional outcomes at 3 and 6 week postoperatively. At 3 weeks, a significant improvement from baseline function was observed in both control and cACB groups (P = 0.002 and P = 0.0001 respectively). Functional status was greater for patients in the cACB group compared to those in the control group at 3 weeks (37.8 ± 13 vs. 29.1 ± 15, mean difference 8.7, 95% CI: −17.3 to −0.11, P = 0.04). WOMAC scores were similar between control and cACB at 6-week follow-up (32.9 ± 14 vs. 27.9 ± 17, 95% CI: −16.2–6.3, P = 0.38). ROM was comparable between the groups at both 3 and 6-week follow-up. Paired outcomes at 3 and 6 weeks compared to baseline ROM, showed significant improvement in ROM of the surgical knee at 6 week postoperatively with a cACB (mean difference 11.77°, 95% CI: 3.1–20.5°, P = 0.01) (Tables 3 and 4). There were no adverse events associated with catheter placement.
cACB: continuous adductor canal block. ASA: American Society of Anesthesiologists. BMI: Body Mass Index. WOMAC: Western Ontario and McMaster Universities Arthritis Index. ROM: range of motion.
were performed with GraphPad Prism V7 (La Jolla, CA, USA). A value of P < 0.05 was considered statistically significant. 3. Results
4. Discussion
3.1. Participant flow and recruitment
After TKA, adequate pain control facilitates early rehabilitation and prevents adverse events associated with prolonged immobilization. The ideal postoperative analgesic reduces opioid consumption and adverse events, encourages early ambulation, and facilitates knee ROM. For our primary outcome, we demonstrated with a cACB there is a clinically significant 23.4% decrease in opioid consumption compared to control. Additionally, VAS AUC decreased by 21.4% and WOMAC scores demonstrated an improvement in functional status in the cACB group compared to those in the control group at 3 weeks. The reduction in opioid consumption is consistent with prior studies using adductor canal blocks yet is unique in that the block and catheter placement was performed on the first postoperative day and a sham catheter was used for comparison [12, 13]. Because selectively blocking all afferent nociceptive fibers from the knee is limited by potential weakness, additional adjuvant treatments will play a role in pain control after TKA. There are numerous additional modalities to control pain in patients undergoing TKA. Common interventions can include intraoperative measures such as local infiltration analgesia (LIA) and pre-postoperative non-opioid adjuvants such as selective cyclooxygenase (COX)-2 inhibitors. LIA has been demonstrated to reduce pain scores, morphine consumption, and postoperative nausea and vomiting while improving ROM at 24 hour postoperatively compared to placebo [14]. Numerous groups have investigated LIA versus peripheral nerve blocks and also the use of peripheral nerve blocks as an adjuvant to LIA with mixed results [15–17]. Non-opioid enteral medications can reduce pain after TKA. Selective COX-2 inhibitors administered preoperatively decreases postoperative pain scores, opioid consumption, nausea and vomiting without leading to increased blood loss [18]. Each intervention has its own unique pros and cons and thus must be weighed individually by each surgeon. In our situation, we believed the increased risk of GI bleeding with simultaneous administration of warfarin and selective COX-2 inhibitors precluded its use [19]. The duration of a single shot LIA can be variable, with some authors demonstrating an effective period of approximately 24 h [20, 21]. The benefit of subsequent intra-articular infusions has not been firmly established and thus supplemental analgesia maybe required [22–24]. The knee receives multiple sources of innervation and it is likely a combination of interventions that will result in adequate pain control and the minimization of opioids.
Over the study period, 258 patients were eligible for the study and 165 consented to be enrolled. There were no significant differences in baseline characteristics (Table 1). In the perioperative period prior to cACB placement, 89 patients (54%) were un-enrolled (see Fig. 1 CONSORT diagram for details). Of these patients, 41 had been allocated to receive a cACB and 35 to receive a SC. A total of 76 patients underwent successful placement of a cACB or SC. After exclusion of 5 patients whose catheters were inadvertently dislodged, there were 32 patients in the control group and 39 received a cACB. One patient in the control arm was lost to follow-up after discharge and was thus excluded from analysis of all follow-up variables. Per our IRB protocol, the study was terminated upon successful enrollment and data analysis of 70 patients. 3.2. Total opioid consumption At 12 hour postoperatively with the epidural catheter in place, there was no difference in morphine equivalents between control and cACB (11.9 ± 14 mg vs. 12.5 ± 15 mg, 95% CI: −6.6–7.6 mg, P = 0.89). At 20 h after catheter placement, the control group required significantly more morphine equivalents than the cACB group (96.5 ± 47 mg vs. 73.9 ± 38 mg, 95% CI: −43.1 to −1.94 mg, P = 0.03) (Fig. 2). Patients were discharged on POD 2, around 24 h after catheter placement resulting in pain scores and medications frequently being documented only up to the 20-hour time point. 3.3. Secondary outcomes Secondary outcomes included VAS AUC, length of stay, ambulation distance and knee range of motion. At 12 hour postoperatively, with the epidural catheter in place, there were no significant differences between control and cACB with respect to pain scores (VAS AUC for the interval 0–12 h/12 h 27.9 ± 16 mm vs. 26.9 ± 19 mm, 95% CI: −9.6–7.6 mm, P = 0.82) After discontinuation of the epidural catheter on POD 1, patients received either a sham catheter or cACB. Compared to the control group, there was a significant decrease in the pain scores 20 h after cACB placement (VAS AUC for the interval 0–20 h/20 h 36.4 ± 18 mm vs. 28.6 ± 14 mm, 95% CI: −15.5 to −0.058 mm, P = 0.04) (Fig. 3). Placement of a cACB did not affect the LOS 48
Journal of Clinical Anesthesia 49 (2018) 46–52
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Assessed for eligibility (n=258)
Enrollment
Excluded from enrollment (n=93) Declined enrollment (n=49) Cancelled/rescheduled (n=9) Age > 85 years (n=2) Anticipated lack of local follow-up care (n=1) ASA > 3 (n=2) Chronic opiate use (n=7) Contraindications to epidural placement - Cardiac valvular abnormalities (n=2) - Coagulopathy (n=4) - Previous lumbar spinal surgery (n=4) Femoral or peripheral neuropathy (n=5) History of alcohol or substance abuse (n=2) Language barrier (n=4) Prior operations on surgical knee (n=2)
Randomized (n=165) Excluded pre- or peri-operatively (n=89)
Surgery cancelled (n=16) Withdrew consent preoperatively (n=8) Required GETA on DOS (n=4) Epidural placement failed (n=19) Epidural analgesia inadequate postoperatively (n=15) Withdrew consent postoperatively (n=20) Unable to consent for cACB placement on POD 1 (n=1) Elevated INR on POD 1, contraindication to cACB (n=1) cACB not placed due to miscommunication (n=5)
Allocation Treatment Group (n=41)
Control Group (n=35)
Follow-Up Accidental withdrawal of catheter (n=2) Lost to outpatient follow-up (n=1)
Patient unblinded (n=1) Accidental transection of catheter (n=1) Catheter removed: hip flexion weakness (n=1)
Analysis
Included in analysis (n=38)
Included in analysis (n=32)
Fig. 1. Consolidated standards of reporting trials (CONSORT) diagram shows flow of patients through the study protocol.
100
160
120
Control cACB
Control
P = 0.03
80
100
AUC (mm)
Morphine Equivalents (mg)
140
80
60
P= 0.89
40
60
cACB
P= 0.82
P = 0.04
40
20
20 0
12hr
0
20hr
12hr
20hr
Fig. 3. VAS AUC (0–100 mm, mean ± SD) was calculated for the interval 0–12 hour postoperative and 0–20 h after placement of cACB. From 0 to 20 h after catheter placement, VAS AUC significantly decreased compared to control (P = 0.04).
Fig. 2. Total opioid consumption was measured for 0–12 hour postoperative and 0–20 h after placement of cACB. Data are expressed as mean ± SD. From 0 to 20 h after catheter placement, cumulative morphine equivalent consumption significantly decreased compared to control (P = 0.03).
49
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Table 2 Length of stay, and inpatient functional outcomes including knee ROM and ambulation distance were evaluated daily until POD 2. In addition to daily absolute measurements, the percent change from the previous day was also calculated. Of these variables, only absolute knee ROM was significantly greater in the control group vs. cACB (P = 0.006) on POD 1. Inpatient functional outcomes
Length of stay (days) ROMc POD 1 ROM (°) POD 0–1 percent increase in ROM POD 2 ROM (°) POD 1–2 percent increase in ROM Ambulation distance POD 1 ambulation distance (m) POD 0–1 increase in ambulation distance (m) POD 2 ambulation distance (m) POD 1–2 increase in ambulation distance (m) a b c
Control
cACBa
P-value
2.42 (0.86)
2.67 (1.1)
0.28
51.4 35.5 71.3 35.9
(17) (91) (19) (89)
40.6 22.4 62.5 61.1
(14) (52) (21) (72)
0.006 0.58 0.09 0.24
−10.85 (−18.52 to −3.18) – −8.8 (−19.3–1.71) –
13.8 12.6 32.5 16.7
(15.6) (15.9) (26.2) (20.8)
17.6 15.7 39.4 14.1
(21) (19.8) (31.8) (33.6)
0.39 0.5 0.35 0.71
3.8 (−5.10–12.7) – 6.85 (−7.76–21.5) –
cACB: continuous adductor canal block. CI: Confidence Interval. ROM: range of motion.
In our study, no difference in ambulation distance was detected between control and cACB, demonstrating minimal handicap from cACB. Another study showed a 2–6 fold increase in ambulatory distance in patients receiving an adductor canal block compared to those receiving a femoral nerve block [25]. In healthy volunteers, cACB decreased strength 5%–48%, as compared to a 82%–95% decrease with a femoral nerve block [26, 27]. In our study, there was no clinically relevant motor weakness as seen by the equivalent ambulation distance. The lack of discrete sensorimotor testing was a limitation of this study. Given that up to 64% loss of quadriceps strength has been reported after TKA even without a femoral nerve block, it is important not to further inhibit lower extremity motor function via motor nerve blockade [28]. Accelerating rehabilitation and maximizing ROM prevents arthrofibrosis after TKA. Both goals can be facilitated by postoperative pain control. At six weeks, when compared to baseline, postoperative ROM was significantly improved with the cACB. In general, studies show that peripheral nerve blocks after TKA show small but significant improvements in ROM in the immediate postoperative period and at long-term follow-up [29–31]. A significant functional improvement was observed 3 weeks postoperatively in the cACB group, which equalized by 6 weeks. This suggests the cACB group potentially recovered function sooner. Some studies demonstrated improved functional recovery with an ACB when utilizing the Timed Up and Go test and dynamic measurement of quadriceps strength [12, 32]. This study is unique in its demonstration of postoperative improvement in WOMAC scores with a cACB. Given the findings of comparable ROM and improved physical function, it is reasonable to anticipate that with cACB after TKA, patients will resume their preoperative activities earlier. Although the decrease in opioid usage and improved pain scores with cACB were clinically significant, there was no statistical difference in total anti-emetic use between the two groups. A meta-analysis of several randomized controlled trials that reviewed femoral nerve blocks demonstrated lower risk of nausea or vomiting and greater patient satisfaction when compared to patient-controlled analgesia [33]. In a randomized double-blinded study comparing ACB to femoral nerve block, there was no difference between groups in morphine-related adverse effects, including nausea, vomiting, sedation and need for antiemetics [27]. The pathophysiology of opioid-induced nausea and vomiting is complex. Although a dose-dependent relationship exists, the concentration at which opioids produce adverse events is patient-specific. Thus, even though total opioid consumption was significantly reduced with cACB, it may not have been reduced enough to minimize adverse events [34].
Table 3 The WOMAC questionnaire was used to assess functional recovery at 3 and 6 week postoperatively. Compared to baseline, both control and cACB showed significant improvement at 3 and 6 weeks. At 3 weeks, the mean WOMAC score in the cACB group was significantly improved (P = 0.04). WOMAC scores at 3 and 6 weeks follow-up Control
cACBa
P-value
Mean difference (CIb)
Preoperative WOMACc score (n = 70) WOMACc score at 3 weeks
50.1 (13)
53.8 (20)
0.37
–
37.8 (13)
29.1 (15)
0.04
WOMACc score at 6 weeks Paired outcome: Baseline → 3-week WOMACc score improvement Paired outcome: Baseline → 6-week WOMACc score improvement
32.9 (14) P = 0.002
27.9 (17) P = 0.0001
0.4 –
−8.72 (−17.3 to −0.11) – –
P = 0.0002
P = 0.0002
–
–
a b c
cACB: continuous adductor canal block. CI: Confidence Interval. WOMAC: Western Ontario and McMaster Universities Arthritis Index.
Table 4 Range of motion was assessed at 3 and 6 week postoperatively. There was no difference in ROM between the two groups at either 3 or 6 weeks. Compared to baseline, cACB group showed significant improvement at 6 weeks, (mean difference 11.77°, 95% CI: 3.1–20.5°, P = 0.01). Knee range of motion at 3 and 6 weeks follow-up
Preoperative ROMb (°) ROMb At 3 weeks (°) ROMb At 6 weeks (°) Paired outcome: Baseline → 3-week ROMb improvement Paired outcome: Baseline → 6-week ROMb improvement a b
Mean difference (CIb)
Control
cACBa
P-value
102 (18) 98.2 (11.5) 109 (14.0) P = 0.34
92.7 (26) 94.3 (13.0) 105 (10.2) P = 0.76
0.10 0.21 0.24 –
P = 0.06
P = 0.01
–
cACB: continuous adductor canal block. ROM: range of motion.
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Limitations of the study included the number of patients withdrawn (n = 89) after randomization. The majority withdrew due to an unsuccessful epidural catheterization (n = 34). In a retrospective study of an obstetric population, failure of epidural analgesia after initial success was reported to be 6.8% [35]. Thus, epidural failure is a potential shortcoming of the technique. Twenty patients withdrew consent after successful epidural placement. Common reasons were concerns about receiving a sham catheter or fear of pain associated with catheter placement. In peripheral nerve block studies involving sham catheters, withdrawal rates of 0–10% have been reported [13, 36]. We believe withdrawal of consent postoperatively can be partly attributed to the timing of peripheral nerve block placement. In some studies peripheral nerve blocks or catheters are placed preoperatively after spinal or epidural placement, intraoperatively under anesthesia, or postoperatively in the post-anesthesia care unit, reducing the potential for patient withdrawal [12, 13, 27, 37]. Sham and experimental catheters were placed on POD 1 after the epidural catheter was removed and after resolution of the epidural's effects. Preoperative catheter placement was not performed to avoid having a catheter in the surgical field and postoperative placement was avoided due to concerns for neural injury during catheter placement in the setting of residual neuraxial anesthesia. Some patients expressed unwillingness to proceed with the study as they were experiencing very little pain as a result of the epidural catheter and did not want to undergo another procedure. In the interest of preserving patient autonomy, these patients were withdrawn from the study. Despite the number of dropouts from the study, these patients were distributed evenly across the two groups having little effect on our patient cohort permitting generalization of these results to a larger, real-world TKA population. In designing the study, our power analysis called for 70 patients and we wrote our IRB protocol to enroll 80 subjects to account for patient drop outs. Per our IRB protocol, we terminated the study early once we reached our target number of 70 patient based on our power analysis. At this point, we had already achieved our primary outcome.
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A pre-emptive multimodal pathway featuring peripheral nerve block improves perioperative outcomes after major orthopedic surgery. Reg Anesth Pain Med 2008;33(6):510–7. [8] Charous MT, Madison SJ, Suresh PJ, et al. Continuous femoral nerve blocks varying local anesthetic delivery method (bolus versus basal) to minimize quadriceps motor block while maintaining sensory block. Anesthesiology 2011;115(4):774–81. [9] Ilfeld BM, Duke KB, Donohue MC. The association between lower extremity continuous peripheral nerve blocks and patient falls after knee and hip arthroplasty. Anesth Analg 2010;111(6):1552. [10] Sharma S, Iorio R, Specht LM, Davies-Lepie S, Healy WL. Complications of femoral nerve block for total knee arthroplasty. Clin Orthop Relat Res 2010;468(1):135–40. [11] Lund J, Jenstrup M, Jaeger P, Sørensen A, Dahl J. Continuous adductor-canalblockade for adjuvant post-operative analgesia after major knee surgery: preliminary results. Acta Anaesthesiol Scand 2011;55(1):14–9. [12] Jenstrup M, Jaeger P, Lund J, et al. Effects of adductor-canal-blockade on pain and ambulation after total knee arthroplasty: a randomized study. Acta Anaesthesiol Scand 2012;56(3):357–64. [13] Hanson NA, Allen CJ, Hostetter LS, et al. Continuous ultrasound-guided adductor canal block for total knee arthroplasty: a randomized, double-blind trial. Anesth Analg 2014;118(6):1370–7. [14] Seangleulur A, Vanasbodeekul P, Prapaitrakool S, et al. The efficacy of local infiltration analgesia in the early postoperative period after total knee arthroplasty: a systematic review and meta-analysis. Eur J Anaesthesiol 2016;33(11):816–31. [15] Andersen HL, Gyrn J, Moller L, Christensen B, Zaric D. Continuous saphenous nerve block as supplement to single-dose local infiltration analgesia for postoperative pain management after total knee arthroplasty. Reg Anesth Pain Med 2013;38(2):106–11. [16] Gudmundsdottir S, Franklin JL. Continuous adductor canal block added to local infiltration analgesia (LIA) after total knee arthroplasty has no additional benefits on pain and ambulation on postoperative day 1 and 2 compared with LIA alone. Acta Orthop. 2017;88(5):537–42. [17] Spangehl MJ, Clarke HD, Hentz JG, et al. The Chitranjan Ranawat Award: periarticular injections and femoral & sciatic blocks provide similar pain relief after TKA: a randomized clinical trial. Clin Orthop Relat Res 2015;473(1):45–53. [18] Lin J, Zhang L, Yang H. Perioperative administration of selective cyclooxygenase-2 inhibitors for postoperative pain management in patients after total knee arthroplasty. J Arthroplast 2013;28(2):207–13. [e2]. [19] Cheetham TC, Levy G, Niu F, Bixler F. Gastrointestinal safety of nonsteroidal antiinflammatory drugs and selective cyclooxygenase-2 inhibitors in patients on warfarin. Ann Pharmacother 2009;43(11):1765–73. [20] Zhang S, Wang F, Lu Z, et al. Effect of single-injection versus continuous local infiltration analgesia after total knee arthroplasty: a randomized, double-blind, placebo-controlled study. J Int Med Res 2011;39(4):1369–80. [21] Busch CA, Shore BJ, Bhandari R, et al. Efficacy of periarticular multimodal drug injection in total knee arthroplasty: a randomized trial. JBJS 2006;88(5):959–63. [22] Sun X-L, Zhao Z-H, Ma J-X, et al. Continuous local infiltration analgesia for pain control after total knee arthroplasty: a meta-analysis of randomized controlled trials. Medicine 2015;94(45). [23] Ali A, Sundberg M, Hansson U, Malmvik J, Flivik G. Doubtful effect of continuous intraarticular analgesia after total knee arthroplasty: a randomized, double-blind study of 200 patients. Acta Orthop 2015;86(3):373–7. [24] Keijsers R, van den Bekerom M, van Delft R, et al. Continuous local infiltration analgesia after TKA: a meta-analysis. J Knee Surg 2016;29(04):310–21. [25] Mudumbai SC, Kim TE, Howard SK, et al. Continuous adductor canal blocks are superior to continuous femoral nerve blocks in promoting early ambulation after TKA. Clin Orthop Relat Res 2014;472(5):1377–83. [26] Kwofie MK, Shastri UD, Gadsden JC, et al. The effects of ultrasound-guided adductor canal block versus femoral nerve block on quadriceps strength and fall risk: a blinded, randomized trial of volunteers. Reg Anesth Pain Med 2013;38(4):321–5. [27] Jæger P, Nielsen ZJ, Henningsen MH, et al. Adductor canal block versus femoral nerve block and quadriceps strength a randomized, double-blind, placebo-controlled, crossover study in healthy volunteers. Anesthesiology 2013;118(2):409–15. [28] Mizner RL, Stevens JE, Snyder-Mackler L. Voluntary activation and decreased force production of the quadriceps femoris muscle after total knee arthroplasty. Phys Ther 2003;83(4):359–65. [29] Nader A, Kendall MC, Wixson RL, et al. A randomized trial of epidural analgesia followed by continuous femoral analgesia compared with oral opioid analgesia on short-and long-term functional recovery after total knee replacement. Pain Med 2012;13(7):937–47. [30] YaDeau JT, Cahill JB, Zawadsky MW, et al. The effects of femoral nerve blockade in conjunction with epidural analgesia after total knee arthroplasty. Anesth Analg 2005;101(3):891–5. [31] Leach D, Bonfe M. The effectiveness of femoral/sciatic nerve blocks on
5. Conclusions Of the many modalities that deliver analgesia after TKA, each has distinct benefits and adverse effects. The best method for controlling pain after TKA is continuous and multimodal. This randomized controlled study demonstrates a cACB inserted on the first postoperative day decreases total opioid consumption, pain scores, and lead to an improvement in WOMAC scores at 3 weeks. Ambulatory ability was not affected, suggesting no clinically significant motor blockade with this technique. Continuous adductor canal blockade after epidural analgesia is a viable option for post-TKA pain control providing prolonged effective non-opioid based analgesia in the acute postoperative phase. Declarations of interest None. Funding The Kovler Family Foundation and The Barnett Family Trust. Acknowledgements We would like to thank The Kovler Family Foundation and The Barnett Family Trust for their funding of our research. References [1] 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
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Analg 2005;101(5):1343–8. [35] Pan P, Bogard T, Owen M. Incidence and characteristics of failures in obstetric neuraxial analgesia and anesthesia: a retrospective analysis of 19,259 deliveries. Int J Obstet Anesth 2004;13(4):227–33. [36] Mulroy MF, Larkin KL, Batra MS, Hodgson PS, Owens BD. Femoral nerve block with 0.25% or 0.5% bupivacaine improves postoperative analgesia following outpatient arthroscopic anterior cruciate ligament repair. Reg Anesth Pain Med 2001;26(1):24–9. [37] Hunt KJ, Bourne MH, Mariani EM. Single-injection femoral and sciatic nerve blocks for pain control after total knee arthroplasty. J Arthroplast 2009;24(4):533–8.
postoperative pain management in total knee arthroplasty. Orthop Nurs 2009;28(5):257–62. [32] Sørensen JK, Jæger P, Dahl JB, et al. The isolated effect of adductor canal block on quadriceps femoris muscle strength after total knee arthroplasty: a triple-blinded, randomized, placebo-controlled trial with individual patient analysis. Anesth Analg Feb. 2016;122(2):553–8. [33] Chan EY, Fransen M, Parker DA, Assam PN, Chua N. Femoral nerve blocks for acute postoperative pain after knee replacement surgery. Cochrane Database Syst Rev 2014;5. [34] Roberts GW, Bekker TB, Carlsen HH, et al. Postoperative nausea and vomiting are strongly influenced by postoperative opioid use in a dose-related manner. Anesth
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Contents lists available at ScienceDirect
Journal of Clinical Anesthesia journal homepage: www.elsevier.com/locate/jclinane
Original contribution
Postoperative continuous adductor canal block for total knee arthroplasty improves pain and functional recovery: A randomized controlled clinical trial
T
Patrick Leung, MDa, David M. Dickerson, MDb, Sahitya K. Denduluri, MDa, ⁎ Maryam K. Mohammed, MDa, Min Lu, MDa, Magdalena Anitescu, MD, PhDb, Hue H. Luu, MDa, a b
University of Chicago Medical Center, Department of Orthopaedic Surgery and Rehabilitation, 5841 S. Maryland Ave, M/C 3079, Chicago, IL 60637, United States University of Chicago Medical Center, Department of Anesthesia and Critical Care, 5841 S. Maryland Ave, M/C 4028, Chicago, IL 60637, United States
A R T I C LE I N FO
A B S T R A C T
Keywords: Continuous adductor canal block Total knee arthroplasty
Study objective: Investigate the use of a postoperative continuous adductor canal block (cACB) after epidural analgesia to decreases opioid consumption and improve visual analog scale (VAS) scores compared to a sham catheter. Design: Double-blinded randomized placebo-controlled trial. Setting: Inpatient setting in tertiary care teaching hospital with outpatient follow-up. Patients: One-hundred and sixty-five subjects (cACB n = 82 and sham catheter n = 83) with end-stage degenerative joint disease undergoing elective unilateral total knee arthroplasty. Interventions: Patients were block randomized to receive a cACB or sham catheter. An epidural catheter was placed preoperatively and discontinued on postoperative day 1. Patients then received a cACB with bupivacaine or sham catheter which remained for the duration of the hospitalization. Measurements: Primary outcome was total opioid consumption. Secondary outcomes included VAS scores, knee range of motion (ROM), ambulation distance, and WOMAC scores. Main results: Seventy patients completed the study (cACB n = 38 and sham catheter n = 32). Compared to sham catheter, in the first 20 h after placement of a cACB, patients used 22.5 mg less opioid (95% CI: −43.1 to −1.94 mg, P = 0.03). VAS score area under the curve decreased 7.8 mm (95% CI: −15.5 – −0.058 mm, P = 0.04) with a cACB. At 3-week follow-up, WOMAC scores were significantly improved with the cACB with a mean difference of 8.72 (95% CI: −17.3 to −0.11, P = 0.04). There were no statistically significant differences in secondary outcomes on postoperative day 2. Paired outcomes at 6 weeks compared to baseline ROM, showed significant improvement in knee ROM with a cACB (mean difference 11.77°, 95% CI: 3.1–20.5°, P = 0.01). Conclusion: A postoperative cACB after total knee arthroplasty significantly reduces total opioid consumption and pain scores compared to sham catheter. Ambulatory ability was not affected and patients recovered function earlier. ClinicalTrials.gov NCT02121392.
1. Introduction Knee replacement surgery is projected to increase in the United States [1]. Total knee arthroplasty (TKA) is associated with significant postoperative pain. The need for effective analgesia without compromising function is a priority. Currently there is no consensus on the best pain control regimen after TKA. An ideal postoperative analgesic facilitates early knee range of motion (ROM) and ambulation, reduces overall narcotic consumption, improves patient satisfaction, and
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reduces chronic post-surgical pain. Pain management after TKA encompasses a wide variety of interventions. Neuraxial anesthesia with epidurals is frequently utilized in TKA as it is associated with decreased morbidity and mortality compared to general anesthesia [2]. Although epidural analgesia is superior to systemic analgesia in controlling early postoperative pain, there is no statistical difference by 18–24 h [3]. Epidural analgesia can be titrated for minimal motor blockade however the theoretical risk of intra-spinal hematoma formation after anticoagulation often leads to catheter
Corresponding author. E-mail addresses: [email protected] (P. Leung), [email protected] (D.M. Dickerson), [email protected] (M. Anitescu), [email protected] (H.H. Luu). https://doi.org/10.1016/j.jclinane.2018.06.004 Received 1 February 2018; Received in revised form 28 May 2018; Accepted 1 June 2018 0952-8180/ © 2018 Elsevier Inc. All rights reserved.
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subject's waist to obscure their view of the procedure. An ultrasound transducer (SonoSite M-Turbo, Bothell, WA) was used to identify the adductor canal at the mid-thigh. Under ultrasound guidance, a 17gauge Tuohy needle with a closed tip catheter (B Braun, Melsungen, Germany) was introduced into the adductor canal and 1% lidocaine and 5% dextrose was used to hydrodissect the space lateral to the superficial femoral artery. A non-stimulating epidural catheter was then placed within the adductor canal, bolused with 10 mL of 0.25% bupivacaine and connected to an infusion pump. The catheter site and electronic infusion pump (CADD®-Solis, Smiths Medical, St. Paul, MN) were covered with an opaque dressing and bag, respectively. Bupivacaine 0.125% was infused at 8 cm3/h via the cACB catheter. In the control group, patients were prepared in an identical manner. An ultrasound transducer was used to identify the adductor canal. To minimize the risk to the patients in this group, the skin was not punctured during placement of the sham catheter. Catheter placement was simulated with a wooden stick applicator applied to the skin with pressure for 10 s. The catheter was secured to the skin, covered with an opaque dressing, and connected to an identical pump. Saline was flushed through the tubing to give the appearance of a functioning catheter. The pump and medication bag were covered with an opaque bag. A supplemental pain regimen was prescribed for all patients which included intravenous morphine 1–2 mg every 2 h as needed, oxycodone controlled-release 10 mg twice daily, tramadol 50 mg every 6 h, and 1–2 tabs of hydrocodone/acetaminophen 5–325 mg every 4–6 h as needed. VAS scores were recorded at least every 4 h and documented in the electronic medical records. Ambulation distance and ROM were measured twice daily during physical therapy. Immediately prior to discharge, infusion pumps were discontinued and the catheters were withdrawn. For patients with the cACB catheter, a sterile dressing was applied over the area.
removal within 24 h of initiation of anticoagulation. A femoral nerve blockade does not carry such limitation and has gained popularity for postoperative analgesia in patients undergoing TKA. Compared to opioid analgesia, femoral nerve blocks reduce total opioid consumption, pain scores on the visual analog scale (VAS), shorten recovery times, and decrease postoperative adverse events [4–7]. Femoral nerve blocks, however, are not without adverse effects. In healthy human volunteers undergoing a continuous femoral nerve block, quadriceps femoris strength decreased up to 84% of baseline [8]. Loss of quadriceps strength limits rehabilitation and potentially poses a fall risk [9, 10]. To address this limitation, peripheral nerve blocks have been performed within the adductor canal where the femoral nerve has given off the majority of its motor branches to the quadriceps femoris muscle. The femoral, obturator, and sciatic nerves contribute to the sensory innervation of the knee. Within the adductor canal, anatomic studies identify several nerves, primarily sensory. Adductor canal block (ACB) spares the majority of motor contributions to the lower extremity and infusion of local anesthetics into this space provides effective analgesia after TKA [11–13]. The primary objective of this prospective, randomized, doubleblinded, sham-controlled trial was to evaluate opioid consumption after TKA with epidural analgesia and continuous adductor canal block (cACB). Secondary end points included VAS scores, ambulation distance, knee ROM, WOMAC scores, and length of stay (LOS). We hypothesized that epidural analgesia with cACB would decrease opioid consumption and improve pain control compared to control. 2. Materials and methods This trial was registered at ClinicalTrials.gov in April 2014 with the identifier NCT02121392, and approved by the Institutional Review Board of the University of Chicago. All patients provided informed written consent. Patients scheduled for unilateral TKA from September 2014 to January 2017 at the University of Chicago Medical Center were enrolled. All participants were allocated preoperatively via a computergenerated block randomizer (4 numbers per block) to receive either the continuous adductor canal block or sham catheter by an investigator not involved in patient enrollment, data collection, or analysis. The surgeon, study participants, and research staff were blinded to the assignment except for the anesthesiologists performing the interventions. The anesthesiologists were not involved in post-intervention evaluation of the patients. Eligibility criteria included patients with end-stage degenerative joint disease undergoing elective unilateral TKA, age < 85 years, and the ability to follow the study protocol. Exclusion criteria included American Society of Anesthesiologist physical class > 3, allergy to the study medications, coagulopathy, and platelet count < 105/μL. Patients with contraindications to the insertion of an epidural or cACB were also excluded, including severe anatomic abnormalities, or a history of previous surgery at the site of catheter placement.
2.2. Outcomes Patients were followed at weeks 3, 6, 12, 24, and 52. Scores from the Western Ontario and McMaster University Arthritis Index (WOMAC) were obtained at 3 and 6 weeks. The primary endpoint was total opioid consumption in morphine equivalents. Secondary endpoints included VAS area under the curve (AUC), inpatient LOS, knee ROM, ambulation distance, WOMAC scores, and use of anti-emetic medications. Data collection and analysis was performed by a blinded research assistant. 2.3. Statistical analysis Based on previous studies, we estimated a mean opioid consumption of 50 mg of morphine (SD ± 25 mg) during the first two day postoperatively after the use of an epidural catheter which was discontinued on the first postoperative day. A reduction of 20 mg in opioid consumption was considered clinically relevant. With α = 0.05 and a power of 90%, 35 subjects were needed in each group for a total of 70 patients. To compensate for anticipated dropouts from the study, we planned for an inclusion of 80 patients. Data was reported for all primary and secondary endpoints as the mean, standard deviation (SD), and 95% confidence intervals (CI). For VAS pain scores, AUC was calculated for the first 12 hour postoperatively and for 20 h after cACB catheter placement. For these same time intervals, cumulative opioid consumption, ambulation distance, and ROM were compared using the independent samples t-test. WOMAC questionnaires were converted to numerical values, and a comparison of arithmetic mean scores was performed using the independent samples t-test. Additionally, paired t-tests were used to investigate improvements in ROM and WOMAC scores within each study group. All hypothesis testing was two-tailed and conducted with an assumption of unequal variance when applicable. Statistical analyses
2.1. Administration of epidural anesthesia and adductor canal block Patients were evaluated preoperatively by an anesthesiologist and assessed for eligibility for epidural anesthesia, and a lumbar epidural or a combined spinal-epidural, which was placed according to standard protocol. If an epidural catheter could not be placed or neuraxial anesthesia was deemed inadequate for surgery, the patient received general anesthesia and was removed from the study. All surgeries were performed by the senior author (HHL). Patient controlled epidural analgesia was managed by the Acute Pain Service immediately postoperatively through the first postoperative morning. The epidural catheter was removed on postoperative day (POD) 1. After resolution of the epidural's effects, subjects in the treatment group received a cACB catheter placed by a board-certified pain specialist. An opaque blanket was hung above the 47
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(P = 0.28), mean ambulation distance, and day-to-day changes in ambulation distance (Table 2). There were no significant differences in absolute and day-to-day percent change in ROM measurements with the exception of ROM on POD 1 (51.4° ± 17° in control group vs. 40.6° ± 14° in cACB group, 95% CI: −18.5 to −3.2°, P = 0.006).
Table 1 Baseline characteristics of study patients. Patient baseline characteristics
Sample size Age (years) Gender ASAb classification BMIc (kg/m2) WOMACd Knee extension (°) Knee flexion (°) Knee ROMe (°) a b c d e
Control
cACBa
P-value
32 63.3 (9.8) 7 male | 25 female 2.66 (0.48) 33.9 (6.0) 50.1 (13) 3.34 (6.0) 105 (18) 102 (18)
39 64.6 (8.7) 9 male | 30 female 2.79 (0.41) 33.3 (7.4) 53.8 (20) 4.56 (6.4) 97.3 (25) 92.7 (26)
– 0.59 – 0.22 0.79 0.37 0.42 0.13 0.10
3.4. Postoperative functional status Likert-type 5-point WOMAC questionnaire was used to assess functional outcomes at 3 and 6 week postoperatively. At 3 weeks, a significant improvement from baseline function was observed in both control and cACB groups (P = 0.002 and P = 0.0001 respectively). Functional status was greater for patients in the cACB group compared to those in the control group at 3 weeks (37.8 ± 13 vs. 29.1 ± 15, mean difference 8.7, 95% CI: −17.3 to −0.11, P = 0.04). WOMAC scores were similar between control and cACB at 6-week follow-up (32.9 ± 14 vs. 27.9 ± 17, 95% CI: −16.2–6.3, P = 0.38). ROM was comparable between the groups at both 3 and 6-week follow-up. Paired outcomes at 3 and 6 weeks compared to baseline ROM, showed significant improvement in ROM of the surgical knee at 6 week postoperatively with a cACB (mean difference 11.77°, 95% CI: 3.1–20.5°, P = 0.01) (Tables 3 and 4). There were no adverse events associated with catheter placement.
cACB: continuous adductor canal block. ASA: American Society of Anesthesiologists. BMI: Body Mass Index. WOMAC: Western Ontario and McMaster Universities Arthritis Index. ROM: range of motion.
were performed with GraphPad Prism V7 (La Jolla, CA, USA). A value of P < 0.05 was considered statistically significant. 3. Results
4. Discussion
3.1. Participant flow and recruitment
After TKA, adequate pain control facilitates early rehabilitation and prevents adverse events associated with prolonged immobilization. The ideal postoperative analgesic reduces opioid consumption and adverse events, encourages early ambulation, and facilitates knee ROM. For our primary outcome, we demonstrated with a cACB there is a clinically significant 23.4% decrease in opioid consumption compared to control. Additionally, VAS AUC decreased by 21.4% and WOMAC scores demonstrated an improvement in functional status in the cACB group compared to those in the control group at 3 weeks. The reduction in opioid consumption is consistent with prior studies using adductor canal blocks yet is unique in that the block and catheter placement was performed on the first postoperative day and a sham catheter was used for comparison [12, 13]. Because selectively blocking all afferent nociceptive fibers from the knee is limited by potential weakness, additional adjuvant treatments will play a role in pain control after TKA. There are numerous additional modalities to control pain in patients undergoing TKA. Common interventions can include intraoperative measures such as local infiltration analgesia (LIA) and pre-postoperative non-opioid adjuvants such as selective cyclooxygenase (COX)-2 inhibitors. LIA has been demonstrated to reduce pain scores, morphine consumption, and postoperative nausea and vomiting while improving ROM at 24 hour postoperatively compared to placebo [14]. Numerous groups have investigated LIA versus peripheral nerve blocks and also the use of peripheral nerve blocks as an adjuvant to LIA with mixed results [15–17]. Non-opioid enteral medications can reduce pain after TKA. Selective COX-2 inhibitors administered preoperatively decreases postoperative pain scores, opioid consumption, nausea and vomiting without leading to increased blood loss [18]. Each intervention has its own unique pros and cons and thus must be weighed individually by each surgeon. In our situation, we believed the increased risk of GI bleeding with simultaneous administration of warfarin and selective COX-2 inhibitors precluded its use [19]. The duration of a single shot LIA can be variable, with some authors demonstrating an effective period of approximately 24 h [20, 21]. The benefit of subsequent intra-articular infusions has not been firmly established and thus supplemental analgesia maybe required [22–24]. The knee receives multiple sources of innervation and it is likely a combination of interventions that will result in adequate pain control and the minimization of opioids.
Over the study period, 258 patients were eligible for the study and 165 consented to be enrolled. There were no significant differences in baseline characteristics (Table 1). In the perioperative period prior to cACB placement, 89 patients (54%) were un-enrolled (see Fig. 1 CONSORT diagram for details). Of these patients, 41 had been allocated to receive a cACB and 35 to receive a SC. A total of 76 patients underwent successful placement of a cACB or SC. After exclusion of 5 patients whose catheters were inadvertently dislodged, there were 32 patients in the control group and 39 received a cACB. One patient in the control arm was lost to follow-up after discharge and was thus excluded from analysis of all follow-up variables. Per our IRB protocol, the study was terminated upon successful enrollment and data analysis of 70 patients. 3.2. Total opioid consumption At 12 hour postoperatively with the epidural catheter in place, there was no difference in morphine equivalents between control and cACB (11.9 ± 14 mg vs. 12.5 ± 15 mg, 95% CI: −6.6–7.6 mg, P = 0.89). At 20 h after catheter placement, the control group required significantly more morphine equivalents than the cACB group (96.5 ± 47 mg vs. 73.9 ± 38 mg, 95% CI: −43.1 to −1.94 mg, P = 0.03) (Fig. 2). Patients were discharged on POD 2, around 24 h after catheter placement resulting in pain scores and medications frequently being documented only up to the 20-hour time point. 3.3. Secondary outcomes Secondary outcomes included VAS AUC, length of stay, ambulation distance and knee range of motion. At 12 hour postoperatively, with the epidural catheter in place, there were no significant differences between control and cACB with respect to pain scores (VAS AUC for the interval 0–12 h/12 h 27.9 ± 16 mm vs. 26.9 ± 19 mm, 95% CI: −9.6–7.6 mm, P = 0.82) After discontinuation of the epidural catheter on POD 1, patients received either a sham catheter or cACB. Compared to the control group, there was a significant decrease in the pain scores 20 h after cACB placement (VAS AUC for the interval 0–20 h/20 h 36.4 ± 18 mm vs. 28.6 ± 14 mm, 95% CI: −15.5 to −0.058 mm, P = 0.04) (Fig. 3). Placement of a cACB did not affect the LOS 48
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Assessed for eligibility (n=258)
Enrollment
Excluded from enrollment (n=93) Declined enrollment (n=49) Cancelled/rescheduled (n=9) Age > 85 years (n=2) Anticipated lack of local follow-up care (n=1) ASA > 3 (n=2) Chronic opiate use (n=7) Contraindications to epidural placement - Cardiac valvular abnormalities (n=2) - Coagulopathy (n=4) - Previous lumbar spinal surgery (n=4) Femoral or peripheral neuropathy (n=5) History of alcohol or substance abuse (n=2) Language barrier (n=4) Prior operations on surgical knee (n=2)
Randomized (n=165) Excluded pre- or peri-operatively (n=89)
Surgery cancelled (n=16) Withdrew consent preoperatively (n=8) Required GETA on DOS (n=4) Epidural placement failed (n=19) Epidural analgesia inadequate postoperatively (n=15) Withdrew consent postoperatively (n=20) Unable to consent for cACB placement on POD 1 (n=1) Elevated INR on POD 1, contraindication to cACB (n=1) cACB not placed due to miscommunication (n=5)
Allocation Treatment Group (n=41)
Control Group (n=35)
Follow-Up Accidental withdrawal of catheter (n=2) Lost to outpatient follow-up (n=1)
Patient unblinded (n=1) Accidental transection of catheter (n=1) Catheter removed: hip flexion weakness (n=1)
Analysis
Included in analysis (n=38)
Included in analysis (n=32)
Fig. 1. Consolidated standards of reporting trials (CONSORT) diagram shows flow of patients through the study protocol.
100
160
120
Control cACB
Control
P = 0.03
80
100
AUC (mm)
Morphine Equivalents (mg)
140
80
60
P= 0.89
40
60
cACB
P= 0.82
P = 0.04
40
20
20 0
12hr
0
20hr
12hr
20hr
Fig. 3. VAS AUC (0–100 mm, mean ± SD) was calculated for the interval 0–12 hour postoperative and 0–20 h after placement of cACB. From 0 to 20 h after catheter placement, VAS AUC significantly decreased compared to control (P = 0.04).
Fig. 2. Total opioid consumption was measured for 0–12 hour postoperative and 0–20 h after placement of cACB. Data are expressed as mean ± SD. From 0 to 20 h after catheter placement, cumulative morphine equivalent consumption significantly decreased compared to control (P = 0.03).
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Table 2 Length of stay, and inpatient functional outcomes including knee ROM and ambulation distance were evaluated daily until POD 2. In addition to daily absolute measurements, the percent change from the previous day was also calculated. Of these variables, only absolute knee ROM was significantly greater in the control group vs. cACB (P = 0.006) on POD 1. Inpatient functional outcomes
Length of stay (days) ROMc POD 1 ROM (°) POD 0–1 percent increase in ROM POD 2 ROM (°) POD 1–2 percent increase in ROM Ambulation distance POD 1 ambulation distance (m) POD 0–1 increase in ambulation distance (m) POD 2 ambulation distance (m) POD 1–2 increase in ambulation distance (m) a b c
Control
cACBa
P-value
2.42 (0.86)
2.67 (1.1)
0.28
51.4 35.5 71.3 35.9
(17) (91) (19) (89)
40.6 22.4 62.5 61.1
(14) (52) (21) (72)
0.006 0.58 0.09 0.24
−10.85 (−18.52 to −3.18) – −8.8 (−19.3–1.71) –
13.8 12.6 32.5 16.7
(15.6) (15.9) (26.2) (20.8)
17.6 15.7 39.4 14.1
(21) (19.8) (31.8) (33.6)
0.39 0.5 0.35 0.71
3.8 (−5.10–12.7) – 6.85 (−7.76–21.5) –
cACB: continuous adductor canal block. CI: Confidence Interval. ROM: range of motion.
In our study, no difference in ambulation distance was detected between control and cACB, demonstrating minimal handicap from cACB. Another study showed a 2–6 fold increase in ambulatory distance in patients receiving an adductor canal block compared to those receiving a femoral nerve block [25]. In healthy volunteers, cACB decreased strength 5%–48%, as compared to a 82%–95% decrease with a femoral nerve block [26, 27]. In our study, there was no clinically relevant motor weakness as seen by the equivalent ambulation distance. The lack of discrete sensorimotor testing was a limitation of this study. Given that up to 64% loss of quadriceps strength has been reported after TKA even without a femoral nerve block, it is important not to further inhibit lower extremity motor function via motor nerve blockade [28]. Accelerating rehabilitation and maximizing ROM prevents arthrofibrosis after TKA. Both goals can be facilitated by postoperative pain control. At six weeks, when compared to baseline, postoperative ROM was significantly improved with the cACB. In general, studies show that peripheral nerve blocks after TKA show small but significant improvements in ROM in the immediate postoperative period and at long-term follow-up [29–31]. A significant functional improvement was observed 3 weeks postoperatively in the cACB group, which equalized by 6 weeks. This suggests the cACB group potentially recovered function sooner. Some studies demonstrated improved functional recovery with an ACB when utilizing the Timed Up and Go test and dynamic measurement of quadriceps strength [12, 32]. This study is unique in its demonstration of postoperative improvement in WOMAC scores with a cACB. Given the findings of comparable ROM and improved physical function, it is reasonable to anticipate that with cACB after TKA, patients will resume their preoperative activities earlier. Although the decrease in opioid usage and improved pain scores with cACB were clinically significant, there was no statistical difference in total anti-emetic use between the two groups. A meta-analysis of several randomized controlled trials that reviewed femoral nerve blocks demonstrated lower risk of nausea or vomiting and greater patient satisfaction when compared to patient-controlled analgesia [33]. In a randomized double-blinded study comparing ACB to femoral nerve block, there was no difference between groups in morphine-related adverse effects, including nausea, vomiting, sedation and need for antiemetics [27]. The pathophysiology of opioid-induced nausea and vomiting is complex. Although a dose-dependent relationship exists, the concentration at which opioids produce adverse events is patient-specific. Thus, even though total opioid consumption was significantly reduced with cACB, it may not have been reduced enough to minimize adverse events [34].
Table 3 The WOMAC questionnaire was used to assess functional recovery at 3 and 6 week postoperatively. Compared to baseline, both control and cACB showed significant improvement at 3 and 6 weeks. At 3 weeks, the mean WOMAC score in the cACB group was significantly improved (P = 0.04). WOMAC scores at 3 and 6 weeks follow-up Control
cACBa
P-value
Mean difference (CIb)
Preoperative WOMACc score (n = 70) WOMACc score at 3 weeks
50.1 (13)
53.8 (20)
0.37
–
37.8 (13)
29.1 (15)
0.04
WOMACc score at 6 weeks Paired outcome: Baseline → 3-week WOMACc score improvement Paired outcome: Baseline → 6-week WOMACc score improvement
32.9 (14) P = 0.002
27.9 (17) P = 0.0001
0.4 –
−8.72 (−17.3 to −0.11) – –
P = 0.0002
P = 0.0002
–
–
a b c
cACB: continuous adductor canal block. CI: Confidence Interval. WOMAC: Western Ontario and McMaster Universities Arthritis Index.
Table 4 Range of motion was assessed at 3 and 6 week postoperatively. There was no difference in ROM between the two groups at either 3 or 6 weeks. Compared to baseline, cACB group showed significant improvement at 6 weeks, (mean difference 11.77°, 95% CI: 3.1–20.5°, P = 0.01). Knee range of motion at 3 and 6 weeks follow-up
Preoperative ROMb (°) ROMb At 3 weeks (°) ROMb At 6 weeks (°) Paired outcome: Baseline → 3-week ROMb improvement Paired outcome: Baseline → 6-week ROMb improvement a b
Mean difference (CIb)
Control
cACBa
P-value
102 (18) 98.2 (11.5) 109 (14.0) P = 0.34
92.7 (26) 94.3 (13.0) 105 (10.2) P = 0.76
0.10 0.21 0.24 –
P = 0.06
P = 0.01
–
cACB: continuous adductor canal block. ROM: range of motion.
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Limitations of the study included the number of patients withdrawn (n = 89) after randomization. The majority withdrew due to an unsuccessful epidural catheterization (n = 34). In a retrospective study of an obstetric population, failure of epidural analgesia after initial success was reported to be 6.8% [35]. Thus, epidural failure is a potential shortcoming of the technique. Twenty patients withdrew consent after successful epidural placement. Common reasons were concerns about receiving a sham catheter or fear of pain associated with catheter placement. In peripheral nerve block studies involving sham catheters, withdrawal rates of 0–10% have been reported [13, 36]. We believe withdrawal of consent postoperatively can be partly attributed to the timing of peripheral nerve block placement. In some studies peripheral nerve blocks or catheters are placed preoperatively after spinal or epidural placement, intraoperatively under anesthesia, or postoperatively in the post-anesthesia care unit, reducing the potential for patient withdrawal [12, 13, 27, 37]. Sham and experimental catheters were placed on POD 1 after the epidural catheter was removed and after resolution of the epidural's effects. Preoperative catheter placement was not performed to avoid having a catheter in the surgical field and postoperative placement was avoided due to concerns for neural injury during catheter placement in the setting of residual neuraxial anesthesia. Some patients expressed unwillingness to proceed with the study as they were experiencing very little pain as a result of the epidural catheter and did not want to undergo another procedure. In the interest of preserving patient autonomy, these patients were withdrawn from the study. Despite the number of dropouts from the study, these patients were distributed evenly across the two groups having little effect on our patient cohort permitting generalization of these results to a larger, real-world TKA population. In designing the study, our power analysis called for 70 patients and we wrote our IRB protocol to enroll 80 subjects to account for patient drop outs. Per our IRB protocol, we terminated the study early once we reached our target number of 70 patient based on our power analysis. At this point, we had already achieved our primary outcome.
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5. Conclusions Of the many modalities that deliver analgesia after TKA, each has distinct benefits and adverse effects. The best method for controlling pain after TKA is continuous and multimodal. This randomized controlled study demonstrates a cACB inserted on the first postoperative day decreases total opioid consumption, pain scores, and lead to an improvement in WOMAC scores at 3 weeks. Ambulatory ability was not affected, suggesting no clinically significant motor blockade with this technique. Continuous adductor canal blockade after epidural analgesia is a viable option for post-TKA pain control providing prolonged effective non-opioid based analgesia in the acute postoperative phase. Declarations of interest None. Funding The Kovler Family Foundation and The Barnett Family Trust. Acknowledgements We would like to thank The Kovler Family Foundation and The Barnett Family Trust for their funding of our research. References [1] 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
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postoperative pain management in total knee arthroplasty. Orthop Nurs 2009;28(5):257–62. [32] Sørensen JK, Jæger P, Dahl JB, et al. The isolated effect of adductor canal block on quadriceps femoris muscle strength after total knee arthroplasty: a triple-blinded, randomized, placebo-controlled trial with individual patient analysis. Anesth Analg Feb. 2016;122(2):553–8. [33] Chan EY, Fransen M, Parker DA, Assam PN, Chua N. Femoral nerve blocks for acute postoperative pain after knee replacement surgery. Cochrane Database Syst Rev 2014;5. [34] Roberts GW, Bekker TB, Carlsen HH, et al. Postoperative nausea and vomiting are strongly influenced by postoperative opioid use in a dose-related manner. Anesth
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