|Year : 2017 | Volume
| Issue : 11 | Page : 903-909
Adductor canal block for post-operative analgesia after simultaneous bilateral total knee replacement: A randomised controlled trial to study the effect of addition of dexmedetomidine to ropivacaine
Rakhee Goyal1, Gaurav Mittal2, Arun Kumar Yadav3, Rishab Sethi1, Animesh Chattopadhyay1
1 Department of Anaesthesia and Critical Care, Army Hospital (Research and Referral), New Delhi, India
2 Department of Orthopaedics, Army Hospital (Research and Referral), New Delhi, India
3 Department of Community Medicine, All India Institute of Medical Sciences, New Delhi, India
|Date of Web Publication||13-Nov-2017|
Department of Anaesthesia and Critical Care, Army Hospital (Research and Referral), New Delhi
Source of Support: None, Conflict of Interest: None
Background and Aims: Knee replacement surgery causes tremendous post-operative pain and adductor canal block (ACB) is used for post-operative analgesia. This is a randomised, controlled, three-arm parallel group study using different doses of dexmedetomidine added to ropiavcaine for ACB. Methods: A total of 150 patients aged 18–75 years, scheduled for simultaneous bilateral total knee replacement, received ultrasound-guided ACB. They were randomised into three groups -Group A received ACB with plain ropivacaine; Groups B and C received ACB with ropivacaine and addition of dexmedetomidine 0.25 μg/kg and 0.50 μg/kg, respectively, on each side of ACB. The primary outcome was the duration of analgesia. Total opioid consumption, success of early ambulation, and level of patient satisfaction were also assessed. Results: The patient characteristics and block success rates were comparable in all groups. Group C patients had longer duration of analgesia (Group C 18.4 h ± 7.4; Group B 14.6 ± 7.1; Group A 10.8 ± 7; P < 0.001); lesser tramadol consumption (Group C 43.8 mg ± 53.2; Group B 76.4 ± 49.6; Group A 93.9 mg ± 58.3; P < 0.001) and lesser pain on movement (P < 0.001). The patients in Group B and C walked more steps than in Group A (P < 0.002). The level of patient satisfaction was highest in Group C (P < 0.001). Conclusions: The addition of dexmedetomidine to ropivacaine resulted in longer duration of analgesia after adductor canal block for simultaneous bilateral total knee replacement surgery.
Keywords: Arthroplasty, replacement, knee, dexmedetomidine, diagnostic imaging, nerve block, ropivacaine
|How to cite this article:|
Goyal R, Mittal G, Yadav AK, Sethi R, Chattopadhyay A. Adductor canal block for post-operative analgesia after simultaneous bilateral total knee replacement: A randomised controlled trial to study the effect of addition of dexmedetomidine to ropivacaine. Indian J Anaesth 2017;61:903-9
|How to cite this URL:|
Goyal R, Mittal G, Yadav AK, Sethi R, Chattopadhyay A. Adductor canal block for post-operative analgesia after simultaneous bilateral total knee replacement: A randomised controlled trial to study the effect of addition of dexmedetomidine to ropivacaine. Indian J Anaesth [serial online] 2017 [cited 2019 Apr 18];61:903-9. Available from: http://www.ijaweb.org/text.asp?2017/61/11/903/218092
| Introduction|| |
Total knee replacement (TKR) surgery is associated with severe post-operative pain. Multimodal analgesia facilitates early ambulation and rehabilitation, reduced hospital stay and cost of treatment and increased patient satisfaction. Studies in the recent past have shown promising results of adductor canal block (ACB) in volunteers, and in patients after various surgeries on the knee., They have demonstrated good post-operative analgesia and significantly better quadriceps muscle strength compared to femoral nerve block and psoas compartment block.
The present study was designed to evaluate the duration of analgesia after ACB for simultaneous bilateral TKR (SBTKR) surgery.
| Methods|| |
The study was a randomised, controlled, three-arm parallel group study and conducted in a high volume joint replacement centre in New Delhi, India. The institutional ethics committee of the hospital approved it. The study was conducted from April 2016 to March 2017 and was compiled in accordance with the consolidated standards of reporting trials CONSORT guidelines.
All the patients, aged 18–75 years, body mass index 20–35 kg/m 2, in the American Society of Anesthesiologists' I–II, scheduled for SBTKR were enrolled in the study. The exclusion criteria included known allergy to any of the study drugs; patients on recent oral opioids in the last 3 months; pregnancy; patients in whom the nerve block could not be performed as per the methodology; and any cognitive dysfunction. After explaining the study preoperatively in detail, a research assistant took written consent from all the patients.
The patients received oral paracetamol 500 mg, pregabalin 75 mg and etoricoxib 90 mg, on the night before surgery. After overnight fasting, all the patients were given a subarachnoid block for the surgery with 2.5 ml 0.5% hyperbaric bupivacaine and 25 μg fentanyl. They received 8 mg intravenous (IV) dexamethasone as per institutional protocol. General anaesthesia was given in those patients where subarachnoid block was contraindicated, or who either had the inadequate effect of subarachnoid block or the surgery extended beyond the duration of the block. Fentanyl 2 μg/kg IV was used for analgesia in these cases. The same team of orthopaedic surgeons performed all the surgeries. IV paracetamol 15 mg/kg was given at the end of the surgery and then orally, thrice a day postoperatively. After the completion of surgery, the patients were shifted to the block-procedure room. The attending anaesthesiologist who had an experience of minimum 25 such blocks gave the ACB.
An independent researcher generated the randomisation code on the basis of a computer-generated randomisation table using www.graphpad.com. Each patient allocation was put in a serially numbered opaque sealed envelope and handed over by the research assistant to the procedure room anaesthesiologist. The anaesthesiologist incharge of the case who performed the block was blinded to the group allocated. The assessor was the nurse and the physiotherapist of the ward, both blinded to the study groups. The patient and the surgeon were also blinded to the study group allocation. Data analysis was independent of treatment allocation.
The block solution was made in a 20 ml syringe for each group. Each syringe had 10 ml ropivacaine 7.5 mg/ml. In addition, in Group A, the syringe contained 10 ml saline; Group B and Group C had 0.25 μg/kg DEX and 0.5 μg/kg DEX, respectively. The required amount of saline was added in Group B and C syringes to make the volume of 20 ml. One syringe was used for each side. The anaesthesiologist incharge of the procedure room was given the study group allocation in a sealed envelope, and he or she prepared the drugs according to the study protocol. Each 20 ml syringe was labelled with the patient number, date and surgery, but not the designated group.
The patient was positioned with both lower limbs slightly abducted at the hips and flexed at the knees. At the level of mid-thigh, an ultrasound-guided ACB was performed successively on both operated sites. The block sites were prepped with chlorhexidine. Local lignocaine infiltration was used for surgeries that were done under general anaesthesia. A linear ultrasound probe (7 L4P, 5–10 MHz; Mindray Z 6, Shenzhen Mindray Biomedical Electronics Ltd, Shenzhen, China), covered in a sterile dressing was transversely placed to visualise the adductor canal. As shown in [Figure 1], these structures were identified on the ultrasound-boat shaped sartorius muscle, femoral artery (pulsatile) and femoral vein (compressible by the probe), the latter two also confirmed on Doppler mode. A 21-gauge 10 cm short bevel needle (Stimuplex, B Braun Medical Inc., USA) was used in plane with the transducer, from lateral to medial, with the needle tip targeted anterolateral to the femoral artery and below the sartorius. A bolus of 2 ml of normal saline was used to confirm the location of needle tip. A volume of 20 ml of block solution was injected in 5 ml aliquots through the injection port of the needle after a careful negative aspiration. The spread of the drug between the sartorius and the femoral artery was seen real time on ultrasound [Figure 2].
|Figure 1: Ultrasound image showing important landmarks for the adductor canal block. FA – Femoral artery; FV – Femoral vein|
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|Figure 2: Ultrasound image showing the spread of drug below the sartorius and lateral to femoral vessels|
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The patients were observed by the anaesthesia resident for 60 min in the procedure room. Heart rate (HR), arterial blood pressure (BP) and SpO2 were monitored continuously and noted at 15 min interval for the 1st h after the block, and then 6-hourly for the next 24 h.
As a part of multimodal analgesia, pregabalin 75 mg, etoricoxib 90 mg, and ranitidine 150 mg were given orally to all the patients on the evening after surgery and then repeated twice a day for the next two days. Numeric Rating Scale (1–10, 1 being the least and 10 being the worst pain described by the patient) was used to assess pain at 6, 12, 18 and 24 h during the post-operative period. If the patient complained of pain and demanded relief, IV tramadol 100 mg was administered. Ondansetron 4 mg was added intravenously if tramadol was used. Time to first rescue analgesia and the total tramadol consumption in 24 h were noted.
The ward nurse collected the data in the post-operative period such as HR, BP and SpO2. Bradycardia and hypotension were defined as 20% decreases from the baseline HR and mean arterial pressure and were treated with atropine and IV fluids, respectively. Any adverse event such as nausea, vomiting, shivering, giddiness, local pain, paraesthesia, or signs of local anaesthetic systemic toxicity were noted. A physiotherapist assessed quadriceps motor strength by straight leg raise on a 0–5 scale pre-operatively and then at 24 h after the block as per the Medical Research Council Scale  (0 = no voluntary contraction possible, 1 = muscle flicker, but no movement of limb, 2 = active movement only with gravity eliminated, 3 = movement against gravity but without resistance, 4 = movement possible against some resistance and 5 = normal motor strength against resistance). The patients were assisted to ambulate with support by the physiotherapist when motor strength was ≥ 2 at 24 h. The ward nurse noted the time of ambulation and the number of steps that the patient could walk. She also noted the patient satisfaction score at 72 h postoperatively; 1 - not satisfied, 2 – satisfied and 3 - better than expected. At this time, the patients were also asked about any paraesthesia, numbness or pain in the thigh. Both the nurse and the physiotherapist were blinded to the study groups.
The primary outcome of the study was the duration of analgesia. The secondary outcomes included total 24 h opioid consumption, success of early ambulation, level of patient satisfaction and any adverse effects following the study intervention.
The sample size was calculated on the assumption that addition of dexmedetomidine (DEX) will increase the duration of analgesia by 50%, level of significance as 0.05, power as 80% and error (within-group variance) as 70 for a mean contrast comparing means of the first two groups, assuming equal group sizes. Total sample size was calculated as 135 i.e. 45 in each group. However, 200 cases were enrolled to cover for any dropouts. The results were analysed using STATA version 13 IC (StataCorp. 2013. Stata Statistical Software: Release 13. College Station, TX: StataCorp LP). The level of statistical significance was taken at 0.05.
Baseline difference among three groups was analysed by univariate analysis of variance (ANOVA) for a continuous variable, Kruskal–Wallis test for non-parametric data, or by Chi-square test for a categorical variable. Intention to treat was used to analyse efficacy parameters. ANOVA was done to assess the difference between the duration of analgesia and average step walked after 24 h, and Bonferroni test was applied for the difference between two groups if ANOVA was significant.
| Results|| |
Enrolment of participants was carried out between April 2016 and March 2017. A detail of flow of the participants is shown in [Figure 3]. The basic characteristics of the parameters of the participants are shown in [Table 1]. A subarachnoid block was given to all patients except in two cases (patient refusal) in Group A, three cases (two-patient refusal; one-general anaesthesia given because subarachnoid block was inadequate during surgery) in Group B, and one patient (patient refusal) in Group C. The duration of surgery was 97 ± 15 min. ACB was successfully given as per protocol in all the cases. The duration of analgesia (time between the block and rescue analgesia) was highest in Group C (mean 18.4 h ± 7.4). Bonferroni test showed a statistically significant difference between Group A and C (P< 0.001) and comparable results between Group A and B (P< 0.023); and B and C groups (P< 0.028). The number of patients who required rescue analgesic [Table 1] and the total amount of opioid consumed in 24 h was lowest in Group C.
|Table 1: Basic characteristics of the participants and post-operative outcomes|
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Patients in Group C experienced lesser pain both at rest and on movement as compared to the other groups during the first 24 h in the post-operative period [Table 2]. There was statistically significant difference among three groups for pain rest (left) and pain movement (right and left) (P = 0.002, <0.001 and <0.001, respectively). The pain score was consistently higher in Group A as compared to Group B and Group C.
The motor strength of quadriceps was comparable on both sides in all the groups 24 h after the block. All the patients were able to walk on the post-operative day 1 morning. The number of steps walked by the patients was more in Group C as compared to Group A (P = 0.002). The difference between Group A and B was also statistically significant but not between Group B and C (P = 0.9). [Figure 4] shows a graphical representation of the duration of analgesia, amount of tramadol used and number of steps walked in Group A, B and C.
|Figure 4: Bar diagrams showing duration of analgesia, amount of opioid (tramadol) administered and number of steps walked on first postoperative day|
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The HR, BP, SpO2 and post-operative adverse effects were comparable among all the three groups. There was no local anaesthetic systemic toxicity in any of the groups.
No patient reported any paraesthesia or pain in the thigh following ACB during 72 h postoperatively. Post hoc analysis showed statistically significant number of patients with a level of satisfaction 1 (P = 0.002) in Group A, and level of satisfaction 3 in Group C (P = 0.005) as shown in [Table 1].
| Discussion|| |
The study shows that first, ACB could be successfully given in all cases with technical ease using ultrasound guidance; second, early ambulation is possible with ACB after bilateral TKR surgery; and third, ambulation is better with better pain relief (Group C > B > A). The study also shows that the addition of DEX to ropivacaine in ACB up to 1 μg/kg does not affect the HR, blood pressure and SpO2.
The patients who require bilateral knee replacement either undergo staged surgery i.e. two surgeries, one in each knee, at two separate occasions in one hospital admission; or simultaneous bilateral surgery under one anaesthesia. The SBTKR involves single anaesthesia exposure, single rehabilitation period, single hospital stay and reduced overall cost. This is likely to lead to better patient satisfaction and lower treatment costs, therefore, better outcome.,,
In a multi-centric feasibility study to assess the clinical and functional outcomes of SBTKR, 123 patients who were operated in five different centres over a period of 7 years. There was no increased risk established for unilateral TKR as compared to the rates published in the literature. However, in another study a number of patient-related risk factors were identified for major morbidity and mortality following bilateral TKR and it was suggested that these factors be used as criteria for patient selection. Several studies have shown good analgesia and better quadriceps strength with ACB for unilateral TKR.,,,,,, Unlike the previous studies, the present study was designed to assess the duration of analgesia with ACB following SBTKR using ropivacaine and two different doses of dexmedetomidine.
The saphenous nerve, primarily a sensory nerve, is the main nerve that is blocked in the adductor canal at the level of mid-thigh. It is postulated that some other nerves such as nerve to vastus medialis, medial femoral cutaneous nerve, obturator nerve (articular branches) and medial retinacular nerve also traverse through the adductor canal and will have a motor component. Ropivacaine is less lipophilic than bupivacaine and less likely to penetrate large myelinated motor fibres. Theoretically, ropivacaine will have a lesser motor blockade in ACB, and therefore, we hypothesised that there would be better ambulation after surgery. In a similar study, 100 mg ropivacaine was used in ACB along with local infiltration analgesia (300 mg ropivacaine) for unilateral TKR. They found better analgesia and greater distance walked as compared to the continuous femoral nerve block. The rate of home discharge was also higher in the patients who received ACB.
DEX has been used in many studies as an additive to local anaesthetics for peripheral nerve blocks with good results.,, In this study, longer duration of analgesia and lesser opioid consumption was seen with DEX. Better analgesia, lower opioid consumption, better ambulation and minimal adverse effects are the possible contributory factors for higher satisfaction. Further studies with larger sample size may be required to establish the safety of ACB with additives like DEX for bilateral blocks.
It is likely that the haemodynamic parameters and pain in the early post-operative period may have been affected in cases where general anaesthesia was given. This may be considered as a limitation of the study.
| Conclusions|| |
The addition of dexmedetomidine to ropivacaine results in longer duration of analgesia after adductor canal block for simultaneous bilateral total knee replacement surgery.
Declaration of patient consent
The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2], [Figure 3], [Figure 4]
[Table 1], [Table 2]