|Year : 2015 | Volume
| Issue : 1 | Page : 124-128
Comparison between effects of adductor canal block and femoral nerve block on early postoperative course in total knee arthroplasty: A prospective double-blind, randomized controlled study
Nasr A Hegazy, Sherif S Sultan
Department of Anesthesia and Intensive Care, Faculty of Medicine, Ain Shams University, Cairo, Egypt
|Date of Submission||05-Sep-2014|
|Date of Acceptance||19-Oct-2014|
|Date of Web Publication||25-Mar-2015|
Nasr A Hegazy
119 Abd El Aziz Fahmy St, Apt 5, Heliopolis, Cairo
Source of Support: None, Conflict of Interest: None
Femoral nerve block (FNB) provides effective analgesia after total knee arthroplasty (TKA) but has been associated with delayed ambulation due to quadriceps muscle weakness. Adductor canal block (ACB) may be a promising alternative, with less effect on the quadriceps muscle and comparable analgesic efficacy.
The aim of the study was to compare ACB with FNB regarding the quadriceps muscle strength and its analgesic efficacy in patients following TKA.
Settings and design
This was a prospective, randomized, controlled, double-blinded study.
Patients and methods
The patients were randomized to receive either ACB or FNB. The primary outcome was the effect on quadriceps muscle and early ambulation as determined by the timed up and go test and 10-min walk test. The secondary outcome was to compare the analgesic efficacy as determined by numeric rating scale, opioid consumption, and hospital length of stay.
We enrolled 110 patients, of whom 107 were analyzed. The timed up and go test and the 10-m walk test were significantly shorter in the ACB group than in the FNB group on the postoperative day 1 with P-value of 0.002 and 0.005, respectively, whereas the difference between both study groups was statistically nonsignificant on the postoperative day 2. There was no significant difference between the study groups regarding the numeric rating scale, morphine consumption, or length of stay.
ACB may promote early ambulation after TKA without a reduction in analgesia when compared with FNB.
Keywords: adductor canal block, analgesia, early ambulance, femoral nerve block, knee arthroplasty
|How to cite this article:|
Hegazy NA, Sultan SS. Comparison between effects of adductor canal block and femoral nerve block on early postoperative course in total knee arthroplasty: A prospective double-blind, randomized controlled study. Ain-Shams J Anaesthesiol 2015;8:124-8
|How to cite this URL:|
Hegazy NA, Sultan SS. Comparison between effects of adductor canal block and femoral nerve block on early postoperative course in total knee arthroplasty: A prospective double-blind, randomized controlled study. Ain-Shams J Anaesthesiol [serial online] 2015 [cited 2018 May 22];8:124-8. Available from: http://www.asja.eg.net/text.asp?2015/8/1/124/153953
| Introduction|| |
Total knee arthroplasty (TKA) is a common surgery that is associated with moderate to severe pain  . Early ambulation and physical therapy are essential for functional recovery and long-term functional outcome after TKA as well as for reducing the immobility related complications , . Hence, optimal pain relief while maintaining the motor function remains the mainstay in postoperative pain management after TKA.
Analgesia after TKA can be achieved by integrated multimodal analgesic protocols using two or more analgesic modalities that work by different mechanisms that will optimize the analgesia and minimize the potential risks and side effects  . In addition to the preemptive analgesia such as NSAIDs, analgesia after knee surgery can be provided by multiple nonsystemic methods such as local anesthetic infiltration and peripheral nerve block, which is commonly used to relieve postoperative pain and decrease opioid requirement and its adverse effects.
Femoral nerve block (FNB) is commonly used in TKA to control postoperative pain. However, as the FNB is invariably associated with reduced quadriceps muscle strength  , increased risk for fall is estimated to be 2% , . Consequently, with the FNB, the goal of pain relief will compromise the goal of preserving the muscle strength. The ideal nerve block for TKA should provide effective analgesia while preserving the muscle power to expedite the recovery.
The introduction of ultrasonography and its use in different nerve blocks was the key of inventing the adductor canal block (ACB), which is relatively new block with high success rate  . In contrast to FNB, ACB is predominantly a sensory block that preserves the quadriceps muscle strength with the favorable earlier mobilization than the FNB  . ACB blocks the main sensory contributions from the femoral nerve to the knee, namely the saphenous nerve and the nerve to vastus medialis while they pass through the adductor canal  . Because of the small size and the absence of motor component, the conventional nerve localization techniques such as nerve stimulation have inconsistent success  .
The aim of this prospective study was to compare two different nerve blocks, FNB and ACB, in patients following TKA considering early postoperative ambulation (primary outcome) and analgesic efficacy (secondary outcome).
From the previous studies , , we estimated that the FNB will cause weakness in the quadriceps muscle at least twice as that caused by the ACB. With a of 0.05 and a power of 80%, 42 patients would be required in each group. To compensate for dropouts, we planned to recruit 110 patients.
| Patients and methods|| |
After obtaining approval from Institutional Research Ethics Board of King Fahd Hospital, KSA, all patients who were scheduled to undergo elective unilateral primary TKA received written information about the study at their consultation at the Orthopedic Outpatient Clinic. During the period between June 2013 and March 2014, patients were enrolled in the study after evaluation at the preoperative anesthesia clinic, and patients who accepted to participate in the study gave informed written consent. They were assigned to either the ACB group or the FNB group (1 : 1 allocation, parallel trial design), on the basis of a computer-generated randomization list created by independent researcher. Group assignment was concealed by opaque envelopes that were opened only after enrollment. Eligibility criteria included elective unilateral primary TKA under spinal anesthesia, age 50-75 years, with an American Society of Anesthesiologists (ASA) physical status classification I-III, a BMI of 18-35, and ability to follow the study protocol. Exclusion criteria included contraindication for neuroaxial anesthesia or nerve block (bleeding diathesis, pre-existing lower extremity neuromuscular disorder, local infection, or sepsis), allergy or contraindication to the drugs used in the study (local anesthetic, NSAIDs, opioids), chronic opioid use (defined as daily use of narcotic analgesic equivalent to oral morphine 60 mg for >1 month), alcohol or drug abuse, renal impairment, or obstructive sleep apnea.
Patients were randomized to receive either an ACB or FNB; both were performed under ultrasound guidance. The two anesthesiologists performing the block were expert in ultrasound-guided nerve blocks and aware of the treatment but not involved in any other aspect of the study including data collection, but both patients and research assistant were blinded to the group assignment and the type of the block. The surgery was performed in all patients by three surgeons using the same type of prostheses, a standard medial parapatellar approach, and a femoral tourniquet. A research assistant recorded the patient's demographic data (age, sex, height, weight, BMI, ASA physical status classification) preoperatively. In addition, all patients were tutored in the numeric rate scale (NRS) for pain score assessment, as well as trained in the timed up and go (TUG) test  and in the use of intravenous patient-controlled analgesia. Routine noninvasive monitoring, including electrocardiogram, noninvasive blood pressure, and pulse oximetry, was applied. Sedation was obtained using 1-3 mg of midazolam and 25-50 mcg of fentanyl. After spinal neuroaxial block, nerve blocks were performed under aseptic technique with guidance of ultrasound (SonoSite, Bothell, Washington, USA), using a high-frequency linear transducer. Saphenous nerve (in the ACB group) was localized at medial side of the mid-thigh just deep to the sartorius muscle, usually lateral to the femoral artery, as a hyperechoic structure. The femoral nerve was visualized just under the fascia iliaca and lateral to the femoral artery. For both groups, ropivacaine 0.5% 20 ml was the local anesthetic injected through an 80-mm, 22-G, short-bevelled echogenic needle (SonoPlexStim Cannula; SonoPlexStim, Bethlehem, Pa, USA), and ultrasound picture was captured to ensure local anesthetic distribution by showing an inverted U-shaped distribution of local anesthetic. Standardized preemptive oral systemic analgesics included acetaminophen 1 g, celecoxib 100-200 mg, and gabapentin 100-200 mg. All patients received a standard spinal anesthesia with bupivacaine 0.75% (Heavy Marcaine 0.75%) 12-15 mg, fentanyl 10 mcg, and preservative-free morphine 100 mcg injected through a 25-G Whitacre needle at L2-L3 or L3-L4 interspace. Intraoperative sedation with propofol infusion and intraoperative fluid therapy were administered at the discretion of the attending anesthetist. Postoperative systemic oral analgesics were prescribed for 72 h postoperatively and included acetaminophen 3-4 g/day, celecoxib 100-200 mg twice daily, and gabapentin 100-200 mg every 8 h. Patient-controlled analgesia (intravenous and then oral) using hydromorphone was prescribed to be used only if NRS for pain score assessment is more than 4, despite the oral analgesics.
On postoperative day 1 (POD1), a standard regimen of physiotherapy in our institution was applied twice daily until discharge; patients were assessed and encouraged to ambulate using a high walker with arm support, as an assisted walking aid. Mobilization ability was assessed with validated ambulation tests, the TUG test  and the 10-min walk test  . The TUG test measures the time it takes the patient to get up from a chair, walk 3 m, turn, walk back to the chair, and sit down, whereas the 10-min walk test measures the time it takes to walk 10 m as quickly as possible. These tests were only performed if the patient feels that it is possible to rise and walk without the risk for falling.
Postoperative analgesia was assessed (12 h, POD1 at 24 h, POD2 at 48 h postoperatively) by both pain evaluation using NRS pain score (0-10; 0 = no pain, 10 = worst imaginable pain) on 45° passive flexion of the knee and opioid consumption (converting the oral and intravenous opioid to morphine equivalent) for the first 48 h postoperatively. Postoperative nausea, vomiting, and pruritus (present or absent) were also recorded. Hospital length of stay (LOS) in days and incidence of complications (if any), including falls, local anesthetic toxicity, or neurological complications, were recorded for both groups. Criteria for home discharge included:
- Ability to rise from bed and ambulate to bathroom independently,
- Walk along the hallway either independently or with a walker, and
- Ability to climb stairs safely as per their home environment.
Descriptive statistics were performed using SPSS 18 (SPSS Inc., Chicago, Illinois, USA), and normality of the data distribution was assessed by the Kolmogorov-Smirnov test. Continuous variables were analyzed using Student's t-test (normal distributions) or the Wilcoxon rank-sum test (non-normal distributions). For the NRS, the Mann-Whitney U-test was performed. Categorical variables were compared using the χ2 -test or Fischer's exact test. Data were presented as mean ± SD except NRS, which was presented as median, and the patients' number in male/female and ASA I-III. All P-values were two-sided, and a P-value of less than 0.05 was considered statistically significant.
| Results|| |
A total of 240 patients were initially screened for inclusion criteria. In all, 171 patients met the inclusion criteria. A total of 110 patients were recruited and consented to participate in the study. Two patients were excluded from the study due to difficult spinal with necessity of general anesthesia. Another patient received Percocet, two tablets, at home on the morning of the surgery and also was excluded from the study. All of these three patients were excluded from the study before knowledge of which of the study groups they belonged to. The 107 patients were randomized to receive either FNB (n = 54) or ACB (n = 53). All patients completed the study and were included in the data analysis. Both groups were similar with respect to the patient demographic characteristics and perioperative data ([Table 1]).
When patients during the postoperative period were asked to perform the TUG and 10-min walk tests, all patients in the ACB group were able to perform it on POD1 and POD2, whereas in the FNB group, two patients were not able to complete the walk test (fall risk) on POD1 but all of the patients performed the test on POD2. Furthermore, patients in the ACB group performed both tests significantly faster than the FNB patients on POD1, but the difference was nonsignificant on POD2 as illustrated in [Table 2].
As shown in [Table 3], the difference between both study groups with respect to the Numeric rating scale (NRP) and the opioid consumption was statistically nonsignificant, suggesting that the ACB was not inferior to FNB with respect to the postoperative analgesia. Although the LOS was slightly shorter in the ACB group, this difference was statistically nonsignificant.
There were no differences between the two study groups in the rate of opioid-related adverse effects including nausea, vomiting, and no reported cases of respiratory depression. There was not any reported case of local anesthetic toxicity or postoperative neuropathy ([Figure 1]).
|Figure 1: The fl ow of the patients during the study protocol. ACB, adductor canal block; FNB, femoral nerve block .|
Click here to view
| Discussion|| |
Effective analgesic modalities are essential in TKA to facilitate early rehabilitation and postoperative recovery  . The ideal analgesic regimen after TKA should offer adequate analgesia with little or no effect on motor power to allow for safe early ambulation  . The local anesthetic that can selectively anesthetize sensory nerves while sparing motor nerves does not exist  .
Our results suggest that the use of the ACB was associated with improvement regarding early postoperative ambulation in patients with TKA surgery compared with patients who received FNB and this difference was significant on POD1 but nonsignificant on POD2. This was indicated by the difference in the TUG test and 10-min walk test between both groups. This finding was supported by other previous studies ,,, . However, Jaeger et al.  and Mudumbai et al.  studied the continuous catheter infusion technique, whereas we studied single-shot technique, and they collected data for 24 h postoperatively, whereas our data were for 48 h postoperatively. Worth to mention that Kim et al.  used dynamometer to measure the quadriceps strength and their anesthetic technique was combined spinal epidural neuroaxial block with postoperative epidural patient-controlled analgesia with continuous background epidural infusion.
In addition, a study performed on healthy volunteers showed that ACB preserved quadriceps strength and ability to ambulate better than what FNB did  . In addition to the positive effect of early ambulation on the surgical outcome of TKA, it helps to decrease the incidence of deep venous thrombosis of the legs  and enhance muscle strength and gait control  . Furthermore, there have been concerns raised regarding a potential risk for patient falling with FNB , ; we observed two patients who were not able to complete the walk test and considered at risk for falling.
Direct comparison between the pain scores and total opioid use did not demonstrate significant difference between both study groups on POD1 and POD2, which indicates that ACB is an effective analgesic modality when compared with FNB after TKA surgery. Other secondary outcomes such as nausea, vomiting, pruritus, LOS, and complications showed no significant difference between both groups, which may be attributed to the similar analgesic effects and narcotic use in both the study groups. Previous studies ,,, demonstrated the analgesic efficacy of ACB as well as decreased opioid consumption and subsequently less side effects after TKA. Grevstad et al.  studied the effect of postoperative ACB in patients with severe pain, despite systemic analgesics, after TKA and concluded that ACB is an effective analgesic modality in such patients, although some patients still have mild to moderate pain.
| Conclusion|| |
The perioperative inclusion of ACB in patients undergoing TKA surgery, as part of multimodal analgesic approach, is associated with earlier postoperative ambulation with good analgesic effect when compared with similar patients receiving FNB within the same clinical analgesic approach.
| Acknowledgements|| |
Conflicts of interest
There are no conflicts of interest.
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[Table 1], [Table 2], [Table 3]