Dexmedetomidine as an Adjunct to Periarticular Ropivacaine in Total Knee Replacement: A Pilot Randomised Controlled Trial

A Pilot Randomized Controlled Trial Assessing the Impact of Dexmedetomidine as an Adjunct to Periarticular Ropivacaine Infiltration on Postoperative Pain and Recovery in Patients Undergoing Total Knee Replacement

This study aims to evaluate whether adding dexmedetomidine to ropivacaine-based periarticular infiltration (PAI) improves postoperative pain control in patients undergoing total knee replacement (TKR). Despite standard pain management, many patients continue to experience moderate-to-severe pain after surgery. Dexmedetomidine, a sedative and analgesic agent, may help prolong the effect of local anaesthetics. A total of 60 patients will be randomly assigned to receive either ropivacaine alone or ropivacaine with dexmedetomidine. Pain scores, opioid use, side effects, and recovery time will be monitored for 24 hours. The goal is to determine if this method is more effective and safer for improving recovery after knee surgery.

Study Overview

• Status: Not yet recruiting
• Conditions: Postoperative Pain Management in Total Knee Arthroplasty
• Intervention / Treatment: Drug: Ropivacaine + saline solution; Drug: Ropivacaine + Dexmedetomidine

Detailed Description

Total knee replacement is associated with significant postoperative pain despite the use of multimodal analgesia. Periarticular infiltration (PAI) using local anaesthetics such as ropivacaine has become a common component of pain control protocols but offers a limited duration of relief. Dexmedetomidine, a selective α2-adrenergic agonist, has demonstrated analgesic benefits as an adjuvant in peripheral nerve blocks, but its role in PAI remains underexplored.

This double-blind randomised controlled trial will recruit 60 adult patients undergoing unilateral total knee replacement at Universiti Malaya Medical Centre. Patients will be randomly assigned to receive either PAI with 0.5% ropivacaine alone (control group) or ropivacaine combined with 100 µg dexmedetomidine (intervention group). All patients will receive spinal anaesthesia and an adductor canal block before surgery.

Pain scores will be recorded using the Numerical Rating Scale (NRS) at 1, 6, 12, and 24 hours postoperatively. Secondary outcomes include 24-hour opioid consumption (morphine milligram equivalents), patient satisfaction (5-point Likert scale), adverse effects (sedation, bradycardia, hypotension, PONV), and time to first ambulation. This study will provide important feasibility data and inform the design of a future multicentre trial, particularly within the Malaysian population.

• Study Type: Interventional
• Enrollment (Estimated): 60
• Phase: Phase 4

Contacts and Locations

• Study Contact: Name: Ahmad Fariz Elias, MD; Phone Number: +60194062520; Email: fariz_elias@ummc.edu.my
• Study Contact Backup: Name: Ahmad Abid Amin, MBBS; Phone Number: +60133131064; Email: abid.amin@ummc.edu.my

Study Locations

• Malaysia
  • Kuala Lumpur
    • Kuala Lumpur, Kuala Lumpur, Malaysia, 59100
      • Universiti Malaya Medical Centre
      • Contact: Ahmad Abid Amin, MBBS; Phone Number: +60133131064; Email: abid.amin@ummc.edu.my
      • Principal Investigator: Ahmad Fariz Elias, MD
      • Sub-Investigator: Nabilah Abdul Ghani, MD

Participation Criteria

Eligibility Criteria

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

Description

Inclusion Criteria:

• Aged ≥18 years
• Undergoing elective unilateral total knee replacement
• ASA physical status I-III
• No known allergy to local anaesthetics or dexmedetomidine
• No opioid use >24 hours preoperatively
• Provided informed consent

Exclusion Criteria:

• Known allergy to study drugs
• Chronic pain or neurological conditions
• Bilateral or revision TKR
• Significant deformity affecting function
• Substance abuse history
• Day-case surgery

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Treatment
• Allocation: Randomized
• Interventional Model: Single Group Assignment
• Masking: Triple

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Active Comparator: Ropivacaine + Saline; Patients will receive 20 mL of periarticular infiltration consisting of 19 mL of 0.5% ropivacaine and 1 mL of normal saline during total knee replacement.	Drug: Ropivacaine + saline solution; 0.5% ropivacaine (19 mL) + 1 mL normal saline administered intraoperatively via periarticular injection.
Experimental: Ropivacaine + Dexmedetomidine; Patients will receive 20 mL of periarticular infiltration consisting of 19 mL of 0.5% ropivacaine and 100 µg dexmedetomidine in 1 mL during total knee replacement.	Drug: Ropivacaine + Dexmedetomidine; 0.5% ropivacaine (19 mL) + dexmedetomidine 100 µg in 1 mL administered intraoperatively via periarticular injection.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
24-hour postoperative pain score (NRS 0-10) at rest and during movement	Pain intensity will be assessed using the Numerical Rating Scale (NRS), where 0 indicates no pain and 10 indicates worst possible pain. Measurements will be taken at rest and during passive knee flexion to 90°, at 1, 6, 12, and 24 hours postoperatively. The primary endpoint is the NRS score at 24 hours.	24 hours postoperatively (from time of skin closure)

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Total postoperative opioid consumption (MME)	Total opioid use in the first 24 hours postoperatively will be recorded from the PCA pump. All opioids will be converted into morphine milligram equivalents (MME) for standardisation.	24 hours postoperatively
Patient satisfaction with pain management	Patient satisfaction will be measured on postoperative day 1 using a 5-point Likert scale, ranging from "very dissatisfied" to "very satisfied."	Postoperative day 1
Incidence of adverse effects (sedation, bradycardia, hypotension, PONV)	Adverse effects will be monitored and recorded within 24 hours postoperatively: Sedation (RASS ≤ -2) Bradycardia (HR < 50 bpm) Hypotension (MAP < 65 mmHg or SBP < 90 mmHg) PONV (score ≥1 on 0-4 scale)	Within 24 hours postoperatively
Time to first ambulation	Time from skin closure to the patient's first unsupported ambulation (>5 metres) will be recorded in hours.	From end of surgery to first ambulation (within 24 hours)

Collaborators and Investigators

• Sponsor: University of Malaya

Publications and helpful links

Helpful Links

• We also register our research protocol to national medical research registration Malaysia

Study record dates

Study Major Dates

• Study Start (Estimated): October 1, 2025
• Primary Completion (Estimated): December 1, 2027
• Study Completion (Estimated): December 1, 2028

Study Registration Dates

• First Submitted: September 8, 2025
• First Submitted That Met QC Criteria: September 8, 2025
• First Posted (Estimated): September 16, 2025

Study Record Updates

• Last Update Posted (Estimated): September 16, 2025
• Last Update Submitted That Met QC Criteria: September 8, 2025
• Last Verified: May 1, 2025

More Information

Terms related to this study

• Keywords: Postoperative Pain; Dexmedetomidine; Ropivacaine; Opioid Consumption; Total Knee Replacement; Adductor Canal Block; Regional Anaesthesia; TKR; Periarticular Infiltration
• Additional Relevant MeSH Terms: Pain; Neurologic Manifestations; Postoperative Complications; Pathologic Processes; Pathological Conditions, Signs and Symptoms; Signs and Symptoms; Pain, Postoperative; Organic Chemicals; Heterocyclic Compounds, 1-Ring; Heterocyclic Compounds; Pharmaceutical Preparations; Azoles; Imidazoles; Anilides; Amides; Aniline Compounds; Amines; Crystalloid Solutions; Isotonic Solutions; Solutions; Ropivacaine; Dexmedetomidine; Saline Solution
• Other Study ID Numbers: 2025429-15014

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: YES

IPD Plan Description

Protocol and statistical analysis plan

Data collected from the study limited to demographic data, numerical rating scale and adverse event

• IPD Sharing Time Frame: 2 years after completing of study

IPD Sharing Access Criteria

Editorial board that reviews my article for publication

They will have assess to our data collection, as we will keep the data in redcap server

• IPD Sharing Supporting Information Type: STUDY_PROTOCOL; SAP

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