Abstract
Background and Aims:
Postoperative analgesia for Total Knee Arthroplasty (TKA) is paramount for early mobilisation and rehabilitation. The newer motor sparing peripheral nerve blocks for analgesia for TKA are 4 in 1 block, modified 4 in 1 block, infiltration between popliteal artery and capsule of the knee (IPACK) block along with adductor canal block (ACB). We hypothesised that Modified 4 in 1 block is as efficient as the already proven technique of combined IPACK and ACB in providing post-operative analgesia to the patients of TKA.
Methods:
Seventy patients fulfilling the inclusion criteria posted for TKA surgery were randomised into two groups: Modified 4 in 1 block group (Group - M) and combined IPACK + ACB group (Group - I). After thorough preoperative evaluation and with mimimum standard monitoring the patients received sub-arachnoid block followed by the desired peripheral nerve block as per the group. After the surgery the visual analog scale (VAS) pain score was compared at 3, 6, 12, 24 hours postoperatively and tabulated.
Results:
The mean pain scores between both the groups was comparable at 3 hours, 6 hours and 24 hours. But at 12 hours after the surgery, VAS was less in Group-M in comparison to Group-I, Haemodynamic parameters were comparable between both the groups. None of the patients in both the groups showed any complications like muscle weakness in the post-operative period.
Conclusion:
Modified 4 in 1 block is a new and novel technique for the TKA surgeries and is comparable with already established combined IPACK+ACB technique for providing adequate postoperative analgesia after TKA.
Key words: 4 in 1 block, adductor canal block, analgesia, ERAS, knee replacement, pain free surgery, post-operative pain
INTRODUCTION
The advanced technological world demands better quality of life for the geriatric population. The commonest hindrance is the restriction of their movements, the commonest cause being knee osteoarthritis (OA), which is also associated with chronic refractory pain.[1] Total knee arthroplasty (TKA)/Total knee replacement (TKR) is the commonly performed treatment for the same.[2]
Adequate analgesia for TKA or TKR has become eminent, as inadequacy increases morbidity.[2-5] Management of pain for TKA has been challenging,[4] where various methods like epidural, peripheral nerve block (PNB), Local Infiltration Analgesia (LIA), intravenous (IV) analgesics like opioids, non-steroidal anti-inflammatory drugs (NSAIDs) and intra-articular (IA) injections, have been used.[2] Complications to epidural like autonomic disturbances, urinary retention and motor blockade can be debilitating.[6] Opioids may cause post-operative nausea and vomiting (PONV), respiratory depression, pruritus, etc.[7,8] PNB has emerged as an important addition to multimodal regimen in providing adequate pain relief with reduced complications.[7-10]
Analgesia for TKA needs blockade of the joint structure and dermatomes.[10,11] The PNBs used for analgesia for TKA are adductor canal block (ACB), femoral nerve block (FNB), and popliteal sciatic nerve block (PSNB).[12] The newer motor sparing peripheral nerve blocks for analgesia for TKA are 4 in 1 block, modified 4 in 1 block, ultrasound-guided local anaesthetic infiltration of the interspace between popliteal artery and the capsule of posterior knee (IPACK) block along with adductor canal block (ACB).[9,12,13] These blocks have been used in isolation and combinations for post-operative analgesia in TKA, and combined IPACK+ACB is a proven most promising technique for providing adequate post-operative analgesia in patients of TKA and is considered superior to other block techniques like FNB, PSNB, combined FNB+PSNB and combined ACB+PSNB.[5,7,12,14]
Modified 4 in 1 block is the modification of 4 in 1 block, where four nerves supplying the knee are blocked by single injection technique.[15] IPACK blocks the popliteal plexus.[14,16] Adductor canal block (ACB) blocks the saphenous nerve.[17] We hypothesised that modified 4 in 1 block is as efficient as the already proven technique of combined IPACK+ACB in providing post-operative analgesia to the patients of TKA. In this study, we compared the modified 4 in 1 block with combined IPACK+ACB with respect to quality of post-operative analgesia using visual analog scale (VAS) score and any associated complications in TKA surgery. The primary objective was evaluation of the quality of post-operative pain relief using VAS over first 24 hours and the secondary objective was to assess post-operative haemodynamic parameters and post-operative complication, if any.
METHODS
After institutional ethics committee approval and clinical trial regiatry of India, this comparative, randomised controlled trial was conducted on patients of American Society of Anaesthesiologists (ASA) physical status I, II, III posted for TKA surgery aged 40–85 years of either gender in the Department of Anaesthesiology, in a tertiary care hospital. Written and informed consent was obtained American Society of Anesthesiologists (ASA). Patients with bleeding disorders, allergy to drugs used, infection or wound at the site of injection, cognitive and psychiatric illness, contraindications for neuraxial blockade, history of substance abuse, peripheral neuropathy or neurologic deficit, patients on recent oral opioids in the last 3 months, pregnant patients, bilateral TKA, patients with severe cardiovascular, respiratory, renal and hepatic disease and patients posted for any other combined procedures were excluded from the study. Materials required for peripheral nerve blocks were 22G hypodermic needle (Dispovan single-use hypodermic needle, Hindustan syringes and Medical Devices, India), 0.2% ropivacaine, dexmedetomidine, 20 ml syringe (Dispovan single-use hypodermic needle, Hindustan syringes and Medical Devices, India), 10 cm and 22G stimuplex needle (Bbraun™ Stimuplex®, ultra 360®, Bbraun™, Japan), portable ultrasonography (USG) machine (Sonosite™ Edge II™, Fujifilm Sonosite™, USA), sterile drapes and sterile USG probe cover.
The sample size calculation was done with reference from previous studies which have established the efficacy of IPACK block.[7,14] A pilot institutional study gave an effect size difference of 0.35. Using the OpenEpi (version 3) sample size calculator, with power at 80% with confidence interval at 95%, we derived a minimum of 58 participants (29 participants in each group). Considering 10% drop-outs, we required 64 participants (32 in each group), to have an effective trial objective.
Seventy patients fulfilling all the inclusion criteria posted for TKA surgery were randomly (using computer generated random number) divided into two groups. Group M (n = 35) – modified 4 in 1 block group and Group I (n = 35) – combined IPACK+ACB group, during the pre-operative evaluation [Figure 1]. Preoperatively, a thorough pre-anaesthetic check-up was done along with in detail general, physical, and systemic examination of the patients. Following investigations were advised and checked—complete blood counts, liver function test, kidney function test, 12 lead electrocardiogram, 2D echocardiography, serum electrolytes, coagulation parameters and high-resolution computed tomography scan of thorax, Corona virus disease (COVID) reverse transcriptase - polymerase chain reaction as per the existing COVID-19 safety protocol during the period of study. All the patients were explained about the procedure and the importance of VAS score in the post-operative period. The patients were advised to take oral alprazolam 0.25 mg and pantoprazole 40 mg, the previous night. Patients were kept nil by mouth for 6 hours for solid and 2 hours for clear fluids prior to surgery. In the preoperative room, an 18gauge venous cannula was secured and intravenous fluid (Ringer’s lactate or balanced salt solution) was started at 2 ml/kg/h. They were advised to take oral pantoprazole 40 mg, domperidone 10 mg, and paracetamol 500 mg, orally, 2 hours before the surgery with sips of water.
Figure 1.
Consolidated Standards of Reporting Trials (CONSORT) flow diagram of patient enrolment
Intraoperatively, electrocardiography, pulse rate, automated non-invasive intermittent blood pressure and pulse oximeter were attached. In the sitting position, subarachnoid block was given at L4–L5 interspinous space with injection hyperbaric bupivacaine 0.5%, 3 ml along with injection fentanyl 25 mg using 25gauge Quincke Babcock needle. Immediately the patient was made supine, and desired level of block was assessed. In supine position, the PNB, as per the randomised group, was given, by a senior qualified anaesthesiologist. For both the groups, a drug mixture of ropivacaine (0.2%) 40 mL with dexmedetomidine (1 mg/kg body weight) was prepared.
For Group M patients: In supine position, the leg to be operated upon was externally rotated with slight abduction and knee slightly flexed. The medial femoral condyle was marked. A linear high-frequency ultrasound probe (6–13 Hz) was used. The probe was placed at the femoral condyle, and vastus medialis was identified. Scanning proximally, intersection of vastus and sartorius (anteromedial intermuscular septum) was identified. The probe was slid proximally till the superficial femoral artery appeared in the adductor hiatus and further proximally till the descending genicular artery branching from superficial femoral artery was visualised. This point was the point of interest which is roughly 8–10 cm above the femoral condyle. The stimuplex needle was then attached to peripheral nerve stimulator (PNS) was guided in-plane from lateral to medial in the vastus medialis muscle. The PNS was set at 1 mA current to stimulate the nerve to vastus medialis, in the vaso-adductor membrane. When the contractions of the vastus medialis was observed even at the threshold current of 0.4 mA, 5 to 7 ml of the drug mixture of ropivacaine (0.2%) and dexmedetomidine was injected. The needle was then redirected from lateral to medial to reach the perivascular area and further 20-25 ml of the drug mixture was injected.[15]
For Group I patients: In supine position, the knee was slightly flexed and the thigh was externally rotated, the transducer was placed at the medial aspect of the knee joint to identify the femoral condyle. The area was scanned proximally to identify the popliteal artery and femoral shaft. When the femoral condyle was initially visualised, transducer was slid proximally until the condyle disappeared and the femoral shaft was identified. At this point, the needle was inserted in-plane at the anterior aspect of the transducer and advanced in a medial to lateral direction parallel to the posterior border of the femoral condyle until the needle tip would be located between the femur and popliteal artery.[18,19] After confirmation of needle placement 15–20 ml of the drug mixture of ropivacaine (0.2%) and dexmedetomidine was injected in small aliquots, between the popliteal artery and femur.[12,20]
For USG-guided ACB, the probe was placed at the medial part of the thigh and, the superficial femoral artery was identified underneath the sartorius muscle, with the vein just inferior and the saphenous nerve just lateral to the artery. Needle was inserted in-plane in a lateral-to-medial direction and advanced towards the superficial femoral artery and the saphenous nerve.[7,18] After negative aspiration, 1–2 mL of the drug mixture of ropivacaine (0.2%) and dexmedetomidine was injected to verify correct placement of the needle in the vicinity of the saphenous nerve in the adductor canal.[7,18,19,21] Then 15–20 ml of the drug mixture of ropivacaine (0.2%) and dexmedetomidine was injected to complete the block.[12]
After giving the blocks, the surgery was started as proposed, and intraoperatively the patients were given a single dose of paracetamol 15 mg/kg intravenous (IV) along with tramadol 1 mg/kg IV.
Post-operatively all these patients received paracetamol 15 mg/kg along with tramadol 1 mg/kg IV every 8 hourly, along with diclofenac (aqueous preparation) 1.5 mg/kg IV every 12 h. The parameters recorded in the postoperaative period were VAS scores and haemodynamic parameters at 3, 6, 12 and 24 hours post surgery. The VAS pain score was compared at 3, 6, 12 and 24 h post-operatively and tabulated. When the VAS score was more than 5, then injection butorphanol 1 mg slow IV was given as rescue analgesic.[15]
Statistical analysis was done by using descriptive statistic, i.e., mean, standard deviation, standard error of mean. Quantitative data was analyzed by the student’s t-test, and qualitative data was analysed by Chi-square test. P < 0.05 was considered statistically significant. The statistical software, namely SPSS (statistical package for social sciences) 20.0, MedCalc and GraphPad Prism 6.0 version, were used for the analysis of the data.
RESULT
The demographic data (age, gender, weight and height) and duration of surgery were comparable between the two groups (P value > 0.05) [Table 1].
Table 1.
Patient demographic data
| Parameters | Mean ± Standard Deviation (SD) | P | |
|---|---|---|---|
|
| |||
| Group-M (n=35) | Group- I (n=35) | ||
| Age (years) | 64.25±7.85 | 62.71±7.74 | 0.4115 |
| Height (cm) | 162.14±10.52 | 158.6±10.40 | 0.1613 |
| Weight (kg) | 74.02±11.96 | 68.65±11.76 | 0.0625 |
| Gender (females:males) (n) | 21:14 | 24:11 | 0.4576 |
| Duration of surgery (min) | 126.43±37.52 | 131.64±41.96 | 0.5848 |
The mean VAS scores between both the groups was comparable at between the groups at 3, 6 and 24 h. But at 12 h after the surgery, VAS score were significantly less in group M compared to group I (p < 0.05) [Table 2].
Table 2.
VAS data
| Time (Hours) | Group-M (n=35) | Group- I (n=35) | P |
|---|---|---|---|
| 3 | 0.0285±0.169 | 0.0571±0.2355 | 0.5617 |
| 6 | 0.5142±0.7017 | 0.6±0.6945 | 0.6092 |
| 12 | 1±0.6859 | 1.3714±0.7702 | 0.0368 |
| 24 | 1.4571±1.0939 | 1.8857±0.9000 | 0.0819 |
Vas=visual analog score, data as mean±standard deviation (sd)
The haemodynamic data were comparable between both the groups, at all time point (P value > 0.05).
None of the patients in both the groups showed any complications like muscle weakness in the post-operative period due to regional analgesia techniques.
DISCUSSION
Pain management for TKA patients in post-operative period will lead to early mobilisation and early rehabilitation leading to decreased incidences of deep vein thrombosis, early surgical recovery, early discharge and patient satisfaction.
It is already discussed and observed by Enneking FK et al.[22] that PNB is superior to epidural analgesia, which provides complete analgesia. The established PNB used for analgesia for TKA, FNB and PSNB are associated with muscle weakness in the lower limb which lead to decreased mobility.[5,9,12] Studies show ACB is superior to FNB, by sparing quadriceps weakness.[12,17,23,24] Posterior knee is supplied by branches from the sciatic nerve, and ACB alone will be inadequate.[15,16] ACB + PSNB has the disadvantage of performing both the blocks in different positions and also some unwanted motor weakness with sciatic nerve block limiting the mobilisation and delay in rehabilitation.[7,9,10,14]
The newer motor sparing IPACK injection, blocks the popliteal plexus thereby blocking genicular branches of sciatic and obturator nerve and providing analgesia to the posterior compartment of the knee.[16] Various authors have successfully used the IPACK + ACB to provide complete analgesia for TKA.[5,12] IPACK block targets terminal branches of the sciatic nerve, i.e., genicular branch of the tibial nerve which prevents the complications associated with sciatic nerve block like foot drop.[5,14,16] ACB in combination with IPACK has been shown to be superior to FNB, FNB + IPACK, PSNB, FNB + PSNB, ACB + PSNB in TKR for analgesia, early mobilisation, rehabilitation, opioid sparing, patient satisfaction and early discharge.[5,7,12,14]
The study by Amin MA-A et al.[7] in 2021 concluded that the IPACK + ACB is better than ACB alone. Sankineani et al.[12] in 2018 concluded that IPACK along with ACB provides adequate and effective pain relief after TKA without affecting the motor function of the lower limb leading to early ambulation and better range of motion around the knee. Vijay M[5] in 2020 concluded that IPACK with ACB is the best mode of analgesia in treating post-operative pain after TKA. IPACK + ACB blocks only the sensory nerves of anterior, medial and posterior knee, preserving the motor function to encourage early ambulation and expedited rehabilitation.[9,12,13]
Runge et al.[25] in 2017 observed the spread of 10 ml of dye injected in the distal adductor canal to popliteal fossa staining saphenous nerve, the genicular branches of the posterior division of the obturator nerve, sciatic nerve and the nerve to vastus medialis in adductor canal. In 2018, Roy et al.[10] described a new and novel single injection technique called as 4 in 1 block for blocking all four nerves supplying knee joint (saphenous nerve, nerve to vastus medialis, genicular branches of sciatic and obturator nerve) through a single injection. They came up with a new technique called modified 4 in 1 block,where PNS was used to ensure the blockade of NVM. They performed the block in 10 patients posted for TKA; all patients had a VAS below 5 except 1 patient whose VAS was more than 5 at 36 hours in postoperative period and required rescue analgesic.[15]
In 2019, Srinivasan et al.[6] used the technique of 4 in 1 block on arthroscopic knee surgery for managing postoperative pain. He concluded that 4 in 1 block is a safe and easy block can be done in supine position with single injection.
We compared the modified 4 in 1 block with IPACK + ACB and found comparable postoperative pain scores as seen by Goyal et al.[21] The haemodynamics remained stable in the postoperative period and was comparable between both the tehniques. No neurological complications were recorded
Limitations
Very limited studies and articles are available for modified 4 in 1 block. The limitation of this study was the duration of the observation was limited to 24 hours postoperatively. Extensive and larger studies are needed to validate the findings of our study, and also study the other important parameters such as, duration of the block performance, total analgesic requirements including time to first rescue analgesic, objective evaluation of motor functions and benefits of the block in terms of early mobilisation and rehabilitation.
CONCLUSION
Modified 4 in 1 block is a new and novel technique for the TKR surgeries and is comparable with already established IPACK + ACB technique for providing adequate post-operative analgesia after TKA. Modified 4 in 1 also overcomes the technical and positional difficulty, which are associated with IPACK+ ACB technique, by using a single injection technique in the supine position.
Financial support and sponsorship
Nil.
Conflicts of interest
There are no conflicts of interest.
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