Postoperative Pain Management in Total Knee Arthroplasty
Conditions
Keywords
Total Knee Replacement, TKR, Periarticular Infiltration, Ropivacaine, Dexmedetomidine, Postoperative Pain, Opioid Consumption, Regional Anaesthesia, Adductor Canal Block
Brief summary
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.
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.
Interventions
0.5% ropivacaine (19 mL) + 1 mL normal saline administered intraoperatively via periarticular injection.
0.5% ropivacaine (19 mL) + dexmedetomidine 100 µg in 1 mL administered intraoperatively via periarticular injection.
Sponsors
University of Malaya
Study design
Allocation
RANDOMIZED
Intervention model
SINGLE_GROUP
Primary purpose
TREATMENT
Masking
TRIPLE (Subject, Caregiver, Outcomes Assessor)
Masking description
The study will be conducted in a quadruple-blinded manner. Group allocation will be concealed using computer-generated randomisation and sequentially numbered, opaque, sealed envelopes. A designated research team member, not involved in patient care or outcome assessment, will prepare the study drug (ropivacaine + saline or ropivacaine + dexmedetomidine) in identical, pre-labelled syringes. The operating surgeon, participant, and outcomes assessor will remain blinded to group allocation throughout the study period.
Intervention model description
This is a two-arm, parallel-group, quadruple-blinded randomised controlled trial. Sixty adult patients undergoing unilateral total knee replacement will be randomly assigned in a 1:1 ratio to receive periarticular infiltration with either ropivacaine alone (control group) or ropivacaine combined with 100 µg dexmedetomidine (intervention group). Allocation will be concealed using computer-generated block randomisation and sealed opaque envelopes. Blinding will be maintained for participants, care providers, investigators, and outcomes assessors. The intervention will be administered intraoperatively as a single dose.
Eligibility
Sex/Gender
ALL
Age
18 Years to 100 Years
Healthy volunteers
No
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
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| 24-hour postoperative pain score (NRS 0-10) at rest and during movement | 24 hours postoperatively (from time of skin closure) | 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. |
Secondary
| Measure | Time frame | Description |
|---|---|---|
| Total postoperative opioid consumption (MME) | 24 hours postoperatively | 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. |
| Patient satisfaction with pain management | Postoperative day 1 | Patient satisfaction will be measured on postoperative day 1 using a 5-point Likert scale, ranging from very dissatisfied to very satisfied. |
| Incidence of adverse effects (sedation, bradycardia, hypotension, PONV) | Within 24 hours postoperatively | 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) |
| Time to first ambulation | From end of surgery to first ambulation (within 24 hours) | Time from skin closure to the patient's first unsupported ambulation (\>5 metres) will be recorded in hours. |
Countries
Malaysia
Contacts
Primary ContactAhmad Fariz Elias, MD
Backup ContactAhmad Abid Amin, MBBS
Outcome results
None listed