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

Phase 4

• Conditions: Total Knee Arthroplasty; Regional Anesthesia; Multimodal Analgesic Approach; Postoperative Opioid-related Complications
• Interventions: Drug: Bupivacaine

• Registration Number: NCT06908837
• Lead Sponsor: Regionshospitalet Silkeborg

Brief Summary

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.

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 Timeline

• Study First Submitted: 2025-03-26
• Status Verified: 2025-04
• Study First Submitted QC: 2025-04-02
• Study First Posted: 2025-04-03
• Study Start: 2025-04-07
• Last Update Submitted: 2025-04-08
• Last Update Posted: 2025-04-11
• Primary Completion: 2026-02-28
• Study Completion: 2026-03-01

Recruitment & Eligibility

• Status: ENROLLING_BY_INVITATION
• Sex: All
• Target Recruitment: 120

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 & Design

• Study Type: INTERVENTIONAL
• Study Design: PARALLEL

Arm && Interventions

Group	Intervention	Description
Popliteal Plexus Block with 20 mL of bupivacaine	Bupivacaine	-
Popliteal Plexus Block with 10 mL of bupivacaine	Bupivacaine	-

Primary Outcome Measures

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

Secondary Outcome Measures

Name	Time	Method
No opioid requirement	From T0 (end-of-surgery time) to T24 (24 hours after end-of-surgery time)	The frequency of patients with no opioid consumption
Pain at rest	Assessed preoperatively, at T6 (6±1 hours after end-of-surgery time), and at T24 (24 hours after end-of-surgery time).	Registered using the Numeric Rating Scale (0 = no pain and 10 = worst imaginable pain)
Pain during 10 meters walk assisted only by crutches	Assessed preoperatively, at T6 (6±1 hours after end-of-surgery time), and at T24 (24 hours after end-of-surgery time).	Registered using the Numeric Rating Scale (0 = no pain and 10 = worst imaginable pain)
Early postoperative walking ability	Assessed at T6 (6±1 end-of-surgery time)	The frequency of patients unable to walk 10 meters with crutches at T6
Quality of Recovery 15	Assessed at T24 (24 hours after end-of-surgery time)	Patient reported outcome measure of the Quality of Recovery 15 survey.
Postoperative Manual Muscle Test	Assessed at T6 (6±1 end-of-surgery time)	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.

Trial Locations

Locations (1)

Elective Surgery Centre at Silkeborg Regional Hospital; 🇩🇰 Silkeborg, Denmark Central Region, Denmark