Femoral Triangle Block With Popliteal Plexus Block Versus Femoral Triangle Block Versus Adductor Canal Block for TKA

Femoral Triangle Block With Popliteal Plexus Block Versus Femoral Triangle Block Versus Adductor Canal Block for TKA

The Effect of the Popliteal Plexus Block on Postoperative Opioid Consumption, Pain, Muscle Strength and Mobilization After Total Knee Arthroplasty - a Randomized, Controlled, Blinded Study

In this study we wish to investigate the analgesic effect 3 different nerve block regimes in patients following primary total knee arthroplasty (TKA). All nerve blocks were performed as single shot blocks with the administration of Marcain 5 mg/ml. Regime A: proximal Femoral Triangle Block (FTB) with 10 ml including Intermediate Femoral Cutaneous Nerve Block (IFCNB) with 5 ml + Popliteal Plexus Block (PPB) with 10 ml. Regime B: proximal FTB with 10 ml including IFCNB with 5 ml. Regime C: Adductor Canal Block (ACB) with 25 ml.

The Adductor Canal Block (ACB) is frequently used after TKA, but it is limited to provide anesthesia from the anteromedial part of the knee region. The proximal Femoral Triangle Block (FTB) is also used for TKA, and also limited to provide anesthesia from the anterior medial part of the knee joint. The FTB anesthetize the saphenus nerve, the nerve to vastus medialis, and may anesthetize the medial femoral cutaneous nerve which innervates the distal medial thigh as well as the anteromedial knee region. We included the Intermediate Femoral Cutaneous Nerve block (IFCNB) in the FTB, as the nerves can be targeted in the subcutis on the anterior thigh and easily be anesthetized during the same procedure as FTB. IFCNB anesthetize the distal anterior thigh, which may include the proximal part of the surgical incision for TKA. In the following text the proximal FTB including IFCNB will be refered as "FTB" and the dose of 15 ml will refer to 10 ml for the proximal FTB and 5 ml used for the IFCNB. A new nerve block technique, called Popliteal Plexus Block (PPB), is specifically designed to anaesthetize nerves involved in innervation of the back of the knee joint. The analgesic effect of PPB has not yet been evaluated in randomized, controlled, blinded trials. In order to optimize pain treatment for primary TKA by improving the pain-relieving effect of peripheral nerve blocks, we aim to evaluate the analgesic effects of three different nerve block regimens (FTB + PPB versus FTB versus ACB) after primary unilateral TKA. Our outcomes include postoperative pain scores, opioid consumption, muscle strength and mobilization. Our hypothesis is that the combination of FTB + PPB provides superior postoperative pain treatment after TKA in comparison to both FTB or ACB. The combination of FTB + PPB will reduce opioid consumption (primary outcome) and postoperative pain scores without reducing muscle strength or impairing mobilization.

Patients assigned for total knee arthroplasty are randomized into one of the three study groups in accordance to a computer-generated block randomization list in a 1:1:1 ratio (each block containing 15 numbers). Prior to surgery the patients receive the peripheral nerve blocks allocated to the group/arm they belong to: Group A: FTB (active) + ACB (sham) + PPB (active) Group B: FTB (active) + ACB (sham) + PPB (sham) Group C: FTB (sham) + ACB (active) + PPB (sham)

Three unblinded anesthesiologists, including the sponsor, are responsible for performing the peripheral nerve block and will not be involved in any clinical assessments, data collection or interpretation of adverse events. During the nerve block procedure, an opaque cloth hung over the stomach level, prevents the patient for monitoring block procedure and the ultrasound monitor. All patients experience three needle insertions in the skin (one for PPB, one for FTB incl. IFCN and one for ACB). The same time is used for each needle insertion, regardless of injection of active drug (active nerve block) or simulation of injection (sham block). Most patient are sensible to the needle insertion but are not able to feel the injection of local anesthetics. All this will ensure that the patient is blinded. None of the blinded outcome assessors, including primary investigator, are present during the opening of the randomization or during the nerve block procedure.

Single shot bolus of 10 ml Marcain 5 mg/ml is used for FTB, 5 ml Marcain 5 mg/ml for IFCN + 10 ml Marcain 5 mg/ml is used for PPB

Total volumes of Marcain differs in each arm, depending on which nerve blocks the patients is randomized to receive. Sham block does not include injection of placebo saline, due to the risk of hydrodissection between the anatomical sections which may erase the isolation of the different nerve blocks. Instead the sham block include imitation of the real nerve block, including correct placement of the needle on the target for the block.

Total opioid consumption is the aggregate of the opioid administered by the Patient Controlled Analgesia (PCA) pump and any potential rescue opioids administered, calculated as IV morphine equivalents

Total opioid consumption is the aggregate of the opioid administered by the PCA pump and any potential rescue opioids administered, calculated as IV morphine equivalents

Post-block Maximum Voluntary Isometric Contraction (MVIC) by knee extension, calculated as a percentage of the Pre-block baseline value

Grade 3: Able to extend the knee in active Range of Motion (ROM) against gravity, Grade 2: Patient is lying on the side, with knee resting on the bed, able to extend the knee in active ROM with minimal assistance from the investigator, Grade 1: Muscle contraction of the quadriceps muscle is palpable or observable but the knee does not extend, Grade 0: No muscle contraction of the quadriceps muscle is palpable or observable

Assessed pre-block, post-block (60 minutes after pre-block) and postoperative 5 hours after time of skin closure (end of surgery)

Grade 3: Able to plantarflex in active ROM, Grade 2: Patient is lying on the side, with ankle resting on the bed, able to plantarflex the ankle in active ROM with minimal assistance from the investigator, Grade 1: Muscle contraction of the gastrocnemius muscle is palpable or observable but the ankle does not plantarflex, Grade 0: No muscle contraction of the gastrocnemius muscle is palpable or observable

Assessed pre-block, post-block (60 minutes after pre-block) and postoperative 5 hours after time of skin closure (end of surgery)

Grade 3: Able to dorsiflex in active ROM Grade 2: Patient is lying on the side, with ankle resting on the bed, able to dorsiflex the ankle in active ROM with minimal assistance from the investigator, Grade 1: Muscle contraction of the tibialis anterior muscle is palpable or observable but the ankle does not dorsiflex, Grade 0: No muscle contraction of the tibialis anterior muscle is palpable or observable

Assessed pre-block, post-block (60 minutes after pre-block) and postoperative 5 hours after time of skin closure (end of surgery)

Measure of seconds it takes a patient to get up from a chair with armrest, walk a distance of three meters, turn around, walk back and sit down again. All patients must use crutches for the test. If patient cannot mobilize with crutches, the test will not be performed.

Patient will be asked to indicate worst pain, Numeric Rating Scale (NRS), 0-10, experienced during the TUG test

preoperative (preblock baseline), 2, 5 (prior to TUG test), 7, 20 and 24 hours after time of skin closure (end of surgery)

Patient will be asked to indicate worst pain intensity during active flexion of the knee towards 90 degrees (NRS, 0-10)

preoperative (preblock baseline), 2, 5 (prior to TUG test), 7, 20 and 24 hours after time of skin closure (end of surgery)

Inclusion Criteria: Scheduled to undergo primary total knee arthroplasty in spinal anesthesia Able to perform a Timed Up and Go (TUG) test Age > 50 years old Ability to give their written informed consent to participating in the study after having fully understood the contents of the study American Society of Anesthesiologists (ASA) physical status 1, 2, or 3 Exclusion Criteria: Patients who cannot cooperate Patients who cannot understand or speak Danish. Patients with allergy or intolerance to the medicines used in the study Patients with a daily intake of strong opioids (morphine, oxycodone, ketobemidone, methadone, fentanyl) Patients suffering from alcohol and/or drug abuse - based on the investigator's assessment BMI > 40 Diagnosed with chronic central or peripheral neurodegenerative disorders