Popliteal Plexus Block for Total Knee Arthroplasty

Study Overview
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Brief Summary
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This study aims to assess the analgesic effect of the popliteal plexus block as a supplement to a femoral triangle block in patients undergoing total knee arthroplasty

Detailed Description
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A femoral triangle block (FTB) effectively anesthetizes the anterior group of nerves innervating the knee (infrapatellar branch of the saphenous nerve, the medial femoral cutaneous nerve and the terminal branch of the medial vastus muscle nerve). However, the posterior group of nerves innervating the knee joint is not covered with an FTB, and therefore most patients complain of significant, opioid-requiring pain despite a successful FTB. The posterior group consists of the popliteal plexus, which is derived from the tibial nerve and the posterior branch of the obturator nerve. The popliteal plexus is located in the popliteal fossa, where it entwines the popliteal artery and vein. Recent cadaver studies have suggested that an injection into the distal part of the adductor canal will spread to the popliteal fossa (PubMed Identifier (ID): 28937534; PubMed ID: 27442773). This study aims to assess the analgesic effect of the popliteal plexus block (PPB) as a supplement to a femoral triangle block (FTB) after total knee arthroplasty (TKA). In the study all patients will receive an FTB with 10 ml bupivacaine-epinephrine (0.5%-1:200,000) with the addition of 0.5 ml Dexamethasone (4 mg/ml). All patients are postoperatively observed for the development of significant pain (NRS > 3) in the primary observation period (POP) defined as: a 3-hour observation period starting at the return of completely normal cutaneous sensation (lateral thigh and lateral side of the lower leg) after spinal anesthesia. If the patient reports pain (NRS > 3) in the POP, the patient will be randomized to the study treatment - a PPB with 10 ml bupivacaine-epinephrine or 10 ml saline.

Official Title
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The Effect of the Popliteal Plexus Block on Postoperative Pain After Total Knee Arthroplasty - a Randomized, Controlled, Double-blinded Study

Conditions
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Pain, Postoperative

Intervention / Treatment
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* Drug: Bupivacaine-EPINEPHrine 0.5%-1:200,000 Injectable Solution
* Other: Sodium Chloride 0.9 %


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Male or female at least 50 years of age at screening Scheduled to undergo primary total knee arthroplasty in spinal anesthesia Normal sensory function at the lateral part of the thigh and lower leg American Society of Anesthesiologists (ASA) physical status 1, 2, or 3 Able to provide informed consent Exclusion Criteria: Unable to cooperate and follow the study protocol Communication problems Allergic towards any medical product administered in the study Diabetes requiring medical treatment Pregnancy (a pregnancy test will be conducted on all women of childbearing potential prior to inclusion in the study. A positive test result will result in exclusion from the study) Preoperative opioid treatment (dosed > once daily)

Ages Eligible for Study
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Minimum Age: 50 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Treatment
Allocation: Randomized
Intervention Model: Parallel Assignment
Interventional Model Description: Randomized, placebo-controlled, double-blinded design
Masking: Quadruple


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Active Comparator: Active Popliteal Plexus Block<br>10 ml Bupivacaine-Epinephrine 0.5%-1:200,000 Injectable Solution | Drug: Bupivacaine-EPINEPHrine 0.5%-1:200,000 Injectable Solution<br>* 10 ml<br>* Other names: Marcain-adrenaline;|
| Placebo Comparator: Placebo Popliteal Plexus Block<br>10 ml Sodium Chloride 0.9 % | Other: Sodium Chloride 0.9 %<br>* 10 ml<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Success of the popliteal plexus block (PPB) | Success of the PPB is defined as the proportion of patients with significant postoperative pain (NRS > 3) after FTB, who drop in pain score to NRS ≤ 3 after PPB and maintain NRS ≤ 3 without any opioids until 60 minutes after PPB | 60 minutes after placement of the PPB | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Onset time of the PPB | The onset time is defined as the time from withdrawal of the block needle and until the patient reports NRS ≤ 3. The maximal onset time is defined as 60 minutes | The pain scores after PPB are evaluated every 5 minutes until 15 minutes after PPB and hereafter every 15 minutes until 60 minutes after PPB | 
| The effect of the PPB on cutaneous sensation | Performed as a pinprick test on the lateral aspect of the lower leg. Sensation to pinprick is graded on a 3-point scale: 0 = no sensation, 1 = reduced sensation and 2 = normal sensation to pinprick compared to the contralateral side | Baseline and 2 hours after the placement of the PPB | 
| The effect of PPB on isometric muscle strength of the he dorso- and plantar flexors of the ankle joint | Dorsal and plantar flexion of the foot is measured as the maximum voluntary isometric contraction (MVIC). During the test, a handheld dynamometer is kept immobile and the patient is asked to push against the dynamometer with maximal force and maintain this maximal pressure for 5 seconds. The MVIC is measured three times, separated by a 30-second pause, and the highest of the three MVIC values is registered | Baseline and 2 hours after the placement of the PPB | 
| Opioid consumption from 0-4 hours | Registered from the electronic patient record | Subjects receiving PPB: From after PPB placement and up until 4 hours after PPB. Subjects not receiving PPB: From the end of the primary observation period (POP) and up until 4 hours after the end of the POP | 
| Opioid consumption from 4-24 hours | Registered from the electronic patient record | Subjects receiving PPB: From 4 hours after PPB placement and up until 24 hours after PPB. Subjects not receiving PPB: From 4 hours after the end of the POP and up until 24 hours after the end of the POP | 
| Pain scores (Numerical Rating Scale, NRS, 0-10 where 0 is no pain and 10 is worst pain imaginable | The patient is asked about the worst pain since last test time | For subjects receiving a PPB, pain scores will be performed 2, 4 and 24 hours after PPB. For subjects not receiving a PPB, final pain scores will be made at the 24 hrs follow-up visit | 
| Pain localization | Evaluated using a systematic questionnaire | Subjects with NRS > 3: when significant pain is reported during the POP; 15 and 60 min after PPB; at any increase in NRS score at any time during the 60 min after PPB; 2, 4 and 24 hrs after PPB. For subjects with NRS ≤ 3: at the 24 hrs follow-up visit | 
| The number of patients requiring a PPB | The number of patients experiencing NRS > 3 as a proportion of all patients with femoral triangle block (FTB) | All patients receive an FTB and are observed postoperatively for the development of NRS > 3 during the primary observation period (POP) defined as: A 3-hour observation period starting at the return of normal cutaneous sensation after spinal anesthesia | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Arthroplasty, Replacement, Knee, Anesthetics, Local, Pain, Postoperative, Nerve Block, Bupivacaine, Epinephrine