Comparative Evaluation of Analgesic Efficacy of Adductor Canal Block Versus Intravenous Diclofenac in Patients Undergoing Knee Arthroscopic Surgery.

Background: Adductor canal block is a new and promising approach for providing postoperative pain relief in arthroscopic knee surgery. Aim: The aim is to compare the postoperative analgesic efficacy of adductor canal block and intravenous (i.v.) diclofenac in patients undergoing knee arthroscopic surgeries. Set and Design: This was a prospective, randomized double-blinded comparative study comprising 60 American Society of Anesthesiologists Physical status Classes I and II patients posted for unilateral knee arthroscopic surgery. Materials and
Methods: Patients were randomized into two groups of 30 patients each. Patients were given general anaesthesia with fentanyl, propofol, and vecuronium. Ultrasound (USG) guided adductor canal block with 30 ml of 0.5% ropivacaine was given in Group A patients and patients in Group B received i.v. diclofenac before extubation. After adequate recovery, patients were shifted to postanesthetic care unit. Visual Analogue Scale score was assessed at rest, on standing and on walking 3 m. Statistical Analysis: Student's independent t-test was employed for comparing continuous variables. Chi-square test or Fisher's exact test, whichever is appropriate, was applied for comparing categorical variables.
Results: The mean duration of analgesia was longer in Group A as compared to Group B and mean consumption of rescue analgesic was lower in Group A. Both were statistically significant. No significant postoperative complications or local side effects related to the block were noted. Conclusions: Adductor canal block provides a longer duration of postoperative analgesia promotes early mobilization and has a good safety profile in unilateral knee arthroscopic surgeries. Copyright:

INTRODUCTION

Arthroscopic knee surgeries have become commonly performed orthopedic surgeries. They cause minimal tissue trauma through very small surgical exposure.[1] General anesthesia is most frequently used for lower limb orthopedic daycare surgeries because of good pharmacokinetic profile of newer inhalational and intravenous (i.v.) agents, thus improving the discharge time. Postoperative pain is a significant consequence that can affect early mobilization, joint range of movement and length of stay.[2] Inadequate pain control can lead to complications such as venous thromboembolic and cardiac events. Adequate pain control is therefore paramount to a successful outcome and patient satisfaction. With advancement in nerve stimulation and ultrasound (USG) guidance there is improved overall block success.[3] The femoral nerve block was commonly used before, but it has disadvantages i.e., reduction in muscle strength, which is associated with risk of falling and thereby potentially compromising mobilization.[4] The adductor-canal-blockade is a good alternative method for pain management after knee arthroscopy. The only potentially affected muscle function is that of the vastus medialis, which makes this adductor canal block an almost pure sensory blockade.[5]

This study is therefore designed to compare the analgesic efficacy of USG guided adductor canal block using 30 ml of 0.5% ropivacaine with conventional analgesic in the form of i.v. diclofenac.

MATERIALS AND METHODS

After obtaining institutional ethics committee approval, registration at clinical trials registry of India (CTRI/2018/05/013800, Registered on May 09, 2018) and obtaining written informed consent, American Society of Anesthesiologists (ASA) Physical status classes I–II patients of age 18–65 years of both gender with normal range of body mass index (BMI) undergoing elective unilateral arthroscopic knee surgery. This study was conducted in the Department of Anesthesia and Intensive Care from November 2014 to January 2016. A prospective, randomized, comparative, parallel-group, double-blinded, clinical trial study was conducted. Patients with a history of allergy to local anaesthetic, coagulopathy, previous neurological deficit, infection at the site of block, BMI >35, difficult airway, history of chronic obstructive pulmonary disease, hepatobiliary diseases, renal disease, cardiovascular diseases and mental deficit that hinders the comprehension of the scale of pain used in this study were excluded.

All patients underwent thorough preanesthetic checkup and airway assessment by Mallampati grading and were kept fasting overnight. Randomization was performed using computer-generated random numbers and allocation concealment was done using the sealed envelope technique. All patients received oral tablet Alprazolam 0.25 mg the night before surgery and 2 h before surgery. After securing 18G intravenous line, i.v. metoclopramide 10 mg and i.v. ranitidine 50 mg were given 45 min before the surgery. In the operating room, standard monitors such as pulse oximetry, electrocardiography, noninvasive blood pressure, and EtCo2 were monitored. The patients were given i.v. fentanyl 2 μg.kg−1 and general anesthesia was induced with propofol (2–2.5 mg.kg−1) i. v. and the neuromuscular block was achieved with vecuronium 0.1 mg.kg−1 i. v. Airway was secured with proseal laryngeal mask airway and all patients were mechanically ventilated. Anesthesia was maintained by O2, N2O, isoflurane (0.5%–1%). At the end of surgery patients in Group A received single shot USG-guided adductor canal block with 30 ml of 0.5% ropivacaine and in Group B patients received i.v. diclofenac in the dose of 1 mg.kg−1 bodyweight.

At the end of the surgery, residual neuromuscular blockade was reversed by injection neostigmine 0.05 mg.kg−1 body weight and injection glycopyrolate 0.01 mg.kg−1 bodyweight. Postoperative nausea vomiting (PONV) was treated with injection ondansetron 0.1 mg.kg−1 bodyweight. Postoperatively, all the patients were shifted to postanesthetist care unit (PACU) for monitoring and observation for any side effects. Heart rate (HR), mean arterial pressure (MAP), SpO2, and respiratory rate (RR) were recorded at intervals of 30 min, 60 min, 90 min, 2 h, 4 h, 6 h, 12 h, and 24 h. Postoperative pain was evaluated at rest by using a Visual Analog Scale (VAS) scoring from zero (total absence of pain) to 10 cm (the worst pain possible) over the time intervals of 30 min, 2 h, 6 h, 12 h and 24 h. VAS score on standing and on walking for three meters was assessed at 6 h, 12 h and 24 h of the postoperative period. Rescue analgesia in the form of injection tramadol 50 mg i. v. was administered when the VAS score was more than four. The number of rescue analgesic injections received by the patient in 24 h was noted and the total consumption of rescue analgesia was calculated. Any side effect or complication was also documented.

Statistical analysis

Statistical tests and analysis were performed using the Statistical Package for Social Sciences (IBM Corp., Chicago, IL, USA) for windows version 17.0. Normally distributed continuous data were analyzed using the student t-test. Nonnormally distributed continuous data and ordinal data were analysed using Mann–Whitney test. Categorical data were analyzed using Chi-square or Fischer Exact whichever is appropriate. A P < 0.05 was considered to be significant.

RESULTS

Both the groups were comparable in terms of clinical and demographic parameters such as age, gender, height, weight, BMI, ASA physical status, and duration of surgery [Table 1] (P > 0.05).

Table 1

Demographic parameters

Variable	Group A (n=30)	Group B (n=30)	P
ASA I/II (n)	20/5	22/3	>0.05
Gender (male/female)	28/2	28/2	>0.05
BMI	26.35±1.96	27±2.51	0.264
Age (years)	27.83±9.12	30.8±11.72	0.362
Weight (kg)	74.07±6.06	75.3±8.23	0.504
Height (cm)	168.33±4.53	166.87±5.68	0.273
Duration of surgery	110.5±17.78	114.5±17.19	0.379

BMI=Body mass index, ASA=American Society of Anesthesiologists

Intraoperative and postoperative monitoring of parameters such as HR, systolic blood pressure, diastolic blood pressure, MAP, RR, and SpO2 showed no significant difference between the groups.

In Group A, the mean VAS score (on rest) at 30 min was 1.13 ± 0.51, at 2 h was 1.27 ± 0.52, at 6 h was1.2 ± 0.48, at 12 h was 1.3 ± 0.47 and 1.13 ± 0.35 at 24 h. In Group B, the mean VAS score at rest, at 30 min was 1.47 ± 0.68, at 2 h was 1.87 ± 0.78, at 6 h was 1.87 ± 0.63, at 12 h was 1.57 ± 0.57 and at 24 h was 1.7 ± 0.6. This result showed a consistently lower VAS score in Group A throughout the study period as compared to Group B and these differences are statistically significant (<0.05) at all intervals [Table 2].

Table 2

Mean visual analogue scale scores at rest

Mean VAS scores	Group A	Group B	P
30 min	1.13±0.51	1.47±0.68	0.029
2 h	1.27±0.52	1.87±0.78	<0.0005
6 h	1.2±0.48	1.87±0.63	<0.0005
12 h	1.3±0.47	1.57±0.57	0.059
24 h	1.13±0.35	1.7±0.6	<0.0005

VAS=Visual analogue scale

In Group A, on standing, the mean VAS score at 6 h was 2.57 ± 0.82, at 12 h was 2.13 ± 0.35 and at 24 h was 2.1 ± 0.71. In Group B, the mean VAS at 6 h was 3.07 ± 1.36, at 12 h was 2.8 ± 0.92 and at 24 h was 2.67 ± 1.12. The VAS score on standing was lower in Group A when compared to Group B throughout 24 h. These differences were statistically significant [Table 3] (P < 0.05).

Table 3

Mean visual analogue scale scores at standing

Mean VAS scores	Group A	Group B	P
6 h	2.57±0.82	3.07±1.36	0.077
12 h	2.13±0.35	2.8±0.92	0.001
24 h	2.1±0.71	2.67±1.12	0.019

VAS=Visual analogue scale

The mean VAS score on walking for three meters is shown in Table 4 which shows a considerably lower VAS score in Group A as compared to Group B. These differences were statistically significant (P < 0.05).

Table 4

Mean visual analog scale scores at walking

Mean VAS scores	Group A	Group B	P
6 h	3.33±1.09	4.5±1.41	0.002
12 h	2.57±0.73	4.2±1.47	<0.0005
24 h	2.43±0.86	3.9±1.63	<0.0005

VAS=Visual analog scale

The analysis of the above data shows that in the adductor canal group in 67% of cases did not require rescue analgesic in 24 h postoperative period as compared to the diclofenac group in which only in 20% of cases rescue analgesic was not needed. This difference was found to be statistically significant with a P < 0.005 [Table 5].

Table 5

Number of patients needed rescue analgesics

Rescue analgesic	Group		Total, n (%)	P
	A, n (%)	B, n (%)
Not needed	20 (67)	6 (20.00)	26 (43)	<0.005
Needed	10 (33)	24 (80.00)	34 (57)
Total	30 (100)	30 (100)	60 (100)

The time taken for the first analgesic requirement in Group A was longer18.6 ± 8.39 h when compared to Group B 10.13 ± 7.45 h. This difference was statistically significant with a P < 0.05. The analysis of the above data suggests that the mean total consumption of rescue analgesic tramadol in Group A was lower 20 ± 33.73 mg, whereas it was80 ± 46.6 mg in Group B and this difference was statistically significant P < 0.005 [Table 6].

Table 6

First analgesic request and total consumption of tramadol

Variable	Group A (n=30)	Group B (n=30)	P
First analgesic request (h)	18.6±8.39	10.13±7.45	<0.05
Total tramadol consumption in 24 h (mg)	20±33.73	80±46.6	<0.05

P<0.05 is considered a significant, data are expressed as mean±SD. SD=Standard deviation

Regarding postoperative side effects Group A had a lower incidence of PONV compared to Group B which was statistically insignificant P > 0.05 [Table 7].

Table 7

Adverse event rates

Adverse event	Group A (n=30), n (%)	Group B (n=30), n (%)	P
Nausea and vomiting	2 (6.6)	5 (17)	>0.05
Other side effects	Nil	Nil

DISCUSSION

Arthroscopic knee surgery is emerging as a commonly performed daycare surgery. It causes minimal tissue trauma as it is done through small surgical incision, but early postoperative pain is a major problem in most of these cases making early discharge difficult.[6]

Currently, diclofenac sodium is commonly used by intramuscular route at the end of surgery for postoperative pain relief. Kostamovaara et al.,[7] conducted a double-blind randomized study, in which supplementary analgesia was administered during postoperative period with three different nonsteroidal anti-inflammatory drugs (NSAIDs) groups, ketorolac, diclofenac and ketoprofen group. Median VAS scores were low in all groups with no significant difference between the groups. NSAIDs have potential side effects on platelet and renal functions, there are always a risk of major haemorrhage, and can cause renal failure. This shows that NSAIDs produce inconsistent analgesia as evidenced by the breakthrough pain experienced by the patient, thus increasing the demand of rescue analgesics. These results comply with our observation of the requirement of more rescue analgesics in the diclofenac group which can be explained by the higher VAS in this group. NSAIDs not provide continuous analgesia and patient may complain of breakthrough pain till the next dose is administered. Peripheral nerve blocks provide a longer duration of analgesia without breakthrough pain.[6]

Femoral nerve block was used previously for providing postoperative analgesia in arthroscopic procedures.[8] Adductor canal block has been advocated as an alternate for femoral nerve block with perhaps lesser risk of motor weakness. In healthy volunteers adductor canal block, the reduction in quadriceps strength was only 8% as compared to 49% with femoral nerve block. The risk of weakness and falling after performing a given peripheral nerve blockade might be reduced when adductor canal block was chosen.[9]

Jaeger et al.[10] performed a randomized study in 42 patients scheduled for elective total knee arthroplasty (TKA) and concluded that in the postoperative pain management adductor canal blockade was promising, with a significant reduction in pain during knee flexion in the early postoperative period compared with placebo. These findings correlate with our study. However, the study was not sufficiently powered to permit conclusions. Jenstrup et al.[5] did a randomized trial in patients aged 50–85 years scheduled for TKA and patients were allocated to receive continuous adductor canal block with ropivacaine 0.75% or placebo and results indicated that adductor canal block significantly reduced morphine consumption and pain during 45° flexion of the knee as compared with placebo and also enhanced ambulation ability.

Our study result was supported by Hanson et al.[11] who did a randomized double-blind trial in 50 patients undergoing ambulatory arthroscopic medial meniscectomy under general anaesthesia and one group received an USG-guided adductor canal block with 0.5% ropivacaine while the other group received a subcutaneous injection of sterile saline. This study concluded that an USG-guided block at the adductor canal as part of a combined multimodal analgesic regimen significantly reduces resting pain scores in the PACU following arthroscopic medial meniscectomy. Furthermore, 24-h postoperative opioid consumption and pain scores were also reduced. Armanious et al.[12] reported a favourable effect of the adductor canal block on pain during activity and morphine consumption as compared to the femoral nerve block. This study confirms that the Adductor canal block is mainly a sensory block, which is a useful analgesic adjuvant for acute pain management after knee surgery. We chose to ambulate the patient at 6 h as Adductor canal block is a pure sensory nerve block which preserves the muscle strength and does not cause much quadriceps weakness.

Our study thus concludes that adductor canal block provides consistently better analgesia for prolonged duration, facilitating early ambulation which ensures early readiness for discharge. It also decreases the requirement of rescue analgesics in the form of opioids. Hence, it is suggested that a further large study is needed, to establish the utility of USG guided adductor canal block, as a postoperative analgesic modality, in patients undergoing knee arthroscopy surgeries, in which early ambulation is desired.

CONCLUSIONS

The adductor canal block provides effective and adequate postoperative pain relief in patients undergoing elective knee arthroscopic surgeries. Adductor canal block can be incorporated as a part of analgesic regimen in knee arthroscopic surgeries as it is easy to perform, it provides adequate and long duration of postoperative analgesia and promotes early mobilization.

Financial support and sponsorship

Safdurjung Hospital, New Delhi, India

Sri Lakshmi Narayana Institute of Medical Sciences, Puducherry, India.

Conflicts of interest

There are no conflicts of interest.