Effects of 10 Versus 20 mL Local Anesthetic for Popliteal Plexus Block on Opioid Consumption, Pain, and Patient-Reported Outcomes After Total Knee Arthroplasty

Effects of 10 Versus 20 mL Local Anesthetic for Popliteal Plexus Block on Opioid Consumption, Pain, and Patient-Reported Outcomes After Total Knee Arthroplasty - a Randomized, Controlled, Blinded Study

This trial aims to assess the analgesic effect of Popliteal Plexus Block (PPB) with 10 mL versus 20 mL of Bupivacain 5 mg/mL, when applied as an adjunct treatment to a multimodal analgesic regimen following primary total knee arthroplasty. We hypothesize that PPB with 20 mL of local anesthetic reduces 24-hour postoperative opioid consumption (= primary outcome) compared to 10 mL after TKA.

Secondary outcome include

• the frequency of 24-hour opioid-free analgesia
• pain intensity at rest and during mobilization
• Manual Muscle Tests and ability to mobilize with crutches six hours after end-of-surgery
• and patients reported outcomes using the Quality of Recovery 15 survey 24 hours after end-of-surgery.

Participant will:

• undergo primary total knee arthroplasty in spinal anesthesia.
• recieve a PPB with either 10 mL of Bupivacaine or 20 mL.
• recieve a multimodal analgesic regime including a Femoral Triangle Block.
• Have 10 scored morphine tablets available for self-administration within the first 24 postoperative hours after end-of-surgery.
• be examined by a physiotherapist 6 hours (±1 hour) after end-of-surgery to assess pain scores, manual muscle testing of ankle and knee function, and the ability to mobilize with crutches.
• complete a survey 24 hours after end-of-surgery to assess self-administered morphine intake, pain scores, and Quality of Recovery-15.

Study Overview

• Status: Completed
• Conditions: Total Knee Arthroplasty; Regional Anesthesia; Multimodal Analgesic Approach; Postoperative Opioid-related Complications
• Intervention / Treatment: Drug: Bupivacaine

Detailed Description

Patients will undergo primary unilateral total knee arthroplasty with insertion of non-cruciate retaining standard cemented prosthesis by a parapatellar medial approach, without use of tourniquet or Local Infiltration Analgesia.

For the spinal anesthesia, 3 mL of Ropivacaine 5 mg/ml will be applied.

All patients will receive a femoral triangle block in combination with the PPB, both administered immediately after surgery in the post-anesthesia care unit.

Description of the PPB procedure:

The superficial femoral artery is identified at mid-thigh level and traced caudally until it deviates from sartorius muscle and is positioned adjacent to the posteromedial margin of the vastus medialis muscle, close to the adductor hiatus. The needle will be inserted medially to the transducer and advanced in-plane through the sartorius muscle targeting the endpoint of injection in the distal part of the adductor canal, on the top of the superficial femoral artery, posteromedial to the fascia of the vastus medialis muscle. We will inject the allocated volume of bupivacaine 5 mg/mL, ensuring anterolaterally spread to the artery

The Femoral Triangle Block uses 15 mL of Bupivacaine 5 mg/mL (10 mL applied in the femoral triangle to target the saphenous nerve and nerve to vastus medialis and 5 mL applied to target the intermediate femoral cutaneous nerve located at the superficial side of the sartorius muscle).

The multimodal analgesic regime also consists of a Dexamethasone 12 mg IV (administered perioperatively), Paracetamol (1000 mg) x 4 daily + NSAID (400 mg) x 3 times daily postoperatively, inclusing preoperatively administration of Paracetamol 1000 mg and Ibuprofen 400 mg.

The scored morphine tablets allows the patients to take 5 mg morphine at a time, with a maximum oral dose of 100 mg within the first 24 hours after end-of-surgery time. If needed, hospital staff can administer rescue doses of intravenous morphine, which will be recorded in the patient file. Total opioid consumption will be reported as oral morphine milligram equivalents (MME), combining hospital-administered opioid doses from the patient file and self-reported intake of dispensed morphine tablets.

• Study Type: Interventional
• Enrollment (Actual): 120
• Phase: Phase 4

Contacts and Locations

Study Locations

• Denmark
  • Denmark Central Region
    • Silkeborg, Denmark Central Region, Denmark, 8600
      • Elective Surgery Centre at Silkeborg Regional Hospital

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult; Older Adult
• Accepts Healthy Volunteers: No

Description

Inclusion Criteria:

• Scheduled to undergo primary total knee arthroplasty in spinal anesthesia.
• Ability to give their written informed consent 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 read or speak Danish.
• Patients who cannot operate or have access to a smartphone with internet connectivity (required for patient-reported outcome assessment).
• Patients with allergies or intolerance to the medicines used in the study.
• Patients with a consistent daily intake of opioids preoperatively.
• Patients who are dependent on walking aid devices preoperatively.
• Patients suffering from alcohol and/or drug abuse - based on the investigator's assessment.
• BMI > 40.
• Diagnosed with chronic neurodegenerative disorders.

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Treatment
• Allocation: Randomized
• Interventional Model: Parallel Assignment
• Masking: Quadruple

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Popliteal Plexus Block with 20 mL of bupivacaine	Drug: Bupivacaine; Applied perineurally using a 22-gauge, 80-mm block needle (Temena, Felsberg, Germany) under ultrasound guidance.
Active Comparator: Popliteal Plexus Block with 10 mL of bupivacaine	Drug: Bupivacaine; Applied perineurally using a 22-gauge, 80-mm block needle (Temena, Felsberg, Germany) under ultrasound guidance.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Total opioid consumption, expressed in oral morphine milligram equivalents (MME).	Combining hospital-administered opioid doses from the patient file and self-reported intake of dispensed morphine tablets.	From T0 (end-of-surgery time) to T24 (24 hours after end-of-surgery time)

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
No opioid requirement	The frequency of patients with no opioid consumption	From T0 (end-of-surgery time) to T24 (24 hours after end-of-surgery time)
Pain at rest	Registered using the Numeric Rating Scale (0 = no pain and 10 = worst imaginable pain)	Assessed preoperatively, at T6 (6±1 hours after end-of-surgery time), and at T24 (24 hours after end-of-surgery time).
Pain during 10 meters walk assisted only by crutches	Registered using the Numeric Rating Scale (0 = no pain and 10 = worst imaginable pain)	Assessed preoperatively, at T6 (6±1 hours after end-of-surgery time), and at T24 (24 hours after end-of-surgery time).
Early postoperative walking ability	The frequency of patients unable to walk 10 meters with crutches at T6	Assessed at T6 (6±1 end-of-surgery time)
Postoperative Manual Muscle Test	Frequency of patients with Manual Muscle Test results < Grade 3 in evaluations of dorsiflexion and plantarflexion of the ankle and knee extension. Grade 5: Patient can move the limb in the intended direction against gravity and maximum manual resistance. Grade 4: Patient can move the limb in the intended direction against gravity and moderate manual resistance. Grade 3: Patient can move the limb in the intended direction against gravity without resistance. Grade 2: Patient can move the limb in the intended direction only by elimination of the gravity or with minimal assistance from the investigator. Grade 1: Patient is unable to move the limb in the intended direction, but muscle contraction of the respective muscle is palpable or observable. Grade 0: No muscle contraction of the respective muscle is palpable or observable.	Assessed at T6 (6±1 end-of-surgery time)
Quality of Recovery 15	Patient reported outcome measure of the Quality of Recovery 15 survey.	Assessed at T24 (24 hours after end-of-surgery time)

Collaborators and Investigators

• Sponsor: Regionshospitalet Silkeborg
• Investigators: Principal Investigator: Johan K Sørensen, MD, Elective Surgery Centre at Silkeborg Regional Hospital, Denmark

Publications and helpful links

General Publications

• Sorensen JK, Jensen MSH, Grevstad U, Nikolajsen L, Runge C. Optimal Analgesic Volume for Popliteal Plexus Block After Total Knee Arthroplasty: A Blinded RCT Protocol. Acta Anaesthesiol Scand. 2025 Jul;69(6):e70057. doi: 10.1111/aas.70057.

Study record dates

Study Major Dates

• Study Start (Actual): April 7, 2025
• Primary Completion (Actual): November 26, 2025
• Study Completion (Actual): November 26, 2025

Study Registration Dates

• First Submitted: March 26, 2025
• First Submitted That Met QC Criteria: April 2, 2025
• First Posted (Actual): April 3, 2025

Study Record Updates

• Last Update Posted (Actual): January 22, 2026
• Last Update Submitted That Met QC Criteria: January 20, 2026
• Last Verified: January 1, 2026

More Information

Terms related to this study

• Keywords: Total knee arthroplasty; postoperative pain; regional anesthesia; Postoperative mobility; postoperative opioid consumption; Quality of Recovery 15; Popliteal Plexus Block; optimal analgesic volume; Manual Muscle Test
• Additional Relevant MeSH Terms: Pain; Neurologic Manifestations; Postoperative Complications; Pathologic Processes; Pathological Conditions, Signs and Symptoms; Signs and Symptoms; Pain, Postoperative; Organic Chemicals; Anilides; Amides; Aniline Compounds; Amines; Bupivacaine
• Other Study ID Numbers: 2024-520204-26-00

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: UNDECIDED
• IPD Plan Description: Data is available upon reasonable request.

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No
• product manufactured in and exported from the U.S.: No