Comparing Local Anesthetic Injections to Nerve Blocks for Pain Control After Total Knee Replacement

Summary

Why are we doing this study? People who have knee replacement surgery often feel pain afterward. Doctors use different methods to control this pain. One method is an injection of numbing medicine directly into the knee during surgery, called local infiltration analgesia (LIA). Another method uses a thin tube (catheter) placed near nerves in the leg to continuously deliver numbing medicine, called a nerve block. This study compares these two pain control methods after knee replacement surgery, to find out whether the injection method (LIA) works at least as well as the nerve block method for controlling pain.

Who can take part in this study? Adults aged 18 to 90 years who need a first-time (primary) knee replacement because of knee arthritis can take part. Participants must be able to walk before surgery, be in generally stable health, and be able to give informed consent. People with a knee injury (rather than arthritis), people who use a wheelchair, and people unable to give consent were not included.

What happens during this study? 78 participants were randomly assigned, like a coin flip, to receive either the injection into the knee (LIA) or the nerve block through a catheter for pain relief after surgery. Both groups also received the same standard pain medicines by mouth or vein as needed. Researchers measured pain levels using a 0-10 pain scale before surgery and at 24, 48, 72, and 96 hours afterward. They also measured knee movement (range of motion), how much extra pain medicine was needed, and how satisfied participants were with their pain control. The study took place at one hospital, the Elisabethinen Hospital in Klagenfurt, Austria, between June 2025 and January 2026.

Conditions

• Pain, Postoperative
• Osteoarthritis, Knee
• Arthroplasty, Replacement, Knee

Interventions

DRUG

Continuous Femoral and Sciatic Nerve Block (Ropivacaine)

Continuous peripheral regional anesthesia via ultrasound-guided femoral and sciatic nerve catheters, placed intraoperatively. Under general anesthesia, each catheter received an initial bolus of 15 mL mepivacaine 1.5% plus 10 mL ropivacaine 0.375%; under spinal anesthesia, an initial 15 mL normal saline (0.9%) test bolus confirmed catheter position, followed by 10 mL ropivacaine 0.375% once sensory block began to wear off. A continuous perineural infusion of ropivacaine 0.2% was then maintained via infusion pump for 48 hours postoperatively: 5 mL/h for the first 24 hours, reduced to 3 mL/h thereafter. Patients could additionally self-administer a 5 mL bolus every 30 minutes as needed. Catheters and the infusion pump were removed at 48 hours postoperatively.

DRUG

Local Infiltration Analgesia (Ropivacaine, Ketorolac, Epinephrine)

Periarticular local infiltration analgesia administered intraoperatively during total knee arthroplasty, comprising 150 mL ropivacaine 2 mg/mL (from a 200 mL preparation, first 50 mL discarded), 30 mg ketorolac (1 mL of 30 mg/mL solution), and 0.5 mg epinephrine hydrochloride (0.5 mL of 1 mg/mL solution). The combined solution was injected periarticularly by the operating surgeon as a single intraoperative dose during wound closure. Total ropivacaine dose did not exceed the maximum recommended dose of 300 mg. No repeat dosing was administered postoperatively for this arm.

Sponsors & Collaborators

• Elisabethinen Hospital

  collaborator OTHER

• Christopher Male

  lead OTHER

Study Design

Allocation

RANDOMIZED

Purpose

SUPPORTIVE_CARE

Masking

NONE

Model

PARALLEL

Eligibility

Min Age

18 Years

Max Age

90 Years

Sex

ALL

Healthy Volunteers

No

Timeline & Regulatory

Start

2025-06-01

Primary Completion

2026-01-31

Completion

2026-01-31

Countries

• Austria

Study Locations