Total knee arthroplasty is a commonly performed orthopaedic surgery for the treatment of end-stage osteoarthritis when conservative management becomes ineffective. TKA is associated with significant acute postoperative pain and many patients experience severe postoperative pain despite the use of multimodal analgesia. Poor acute postoperative pain control impacts rehabilitation, prolongs recovery and increases opioid consumption and chronic post-surgical pain.
Liposomal bupivacaine (Exparel, Pacira Pharmaceuticals Inc, Parsippany, New Jersey, USA) is a multivesicular formulation of bupivacaine that prolongs drug release and can extend the duration of analgesia. The adductor canal block (ACB) has been shown to reduce pain intensity and opioid consumption after total knee arthroplasty. The use of liposomal bupivacaine in the adductor canal block has recently been FDA-approved. However, the results of its efficacy from existing clinical trials have been mixed. In addition, the doses in the clinical trials have been different, and the optimal dose for perineural application of liposomal bupivacaine is unclear, including for the adductor canal block.
In this project, the investigators propose to conduct a randomized controlled trial to investigate the effect of different doses of liposomal bupivacaine in the adductor canal block on acute postoperative pain intensity and opioid consumption after robotic assisted total knee arthroplasty. The investigators will also assess secondary outcomes including knee functional scores, chronic pain and quality of recovery.
ASA I-III
Age 18-80 years old
Scheduled for elective primary unilateral total knee arthroplasty (TKA) with robotic surgery
Able to speak and understand Cantonese or Mandarin or English
Revision TKA
Single-stage bilateral TKA
Complex primary TKA requiring use of stem/augment/constrained liner
Surgeries with significant intraoperative complications which may alter rehabilitation protocol eg collateral ligament injury, fracture requiring fixation
Parallel
0.5% standard bupivacaine only
Drug20ml 0.5% standard bupivacaine only
1.33% liposomal bupivacaine with 0.5% standard bupivacaine
Drug10ml 1.33% liposomal bupivacaine (133mg) plus 10ml 0.5% standard bupivacaine
1.33% liposomal bupivacaine only
Drug20ml 1.33% liposomal bupivacaine (266mg)
Weighted area under curve (AUC) pain score
Pain severity would be rated at rest after surgery using numerical rating scale (NRS) with 0 to 10 where 0=no pain and 10=the worst possible pain
NRS pain scores
NRS pain scores at rest and with movement (active knee flexion) from after surgery to postoperative day (POD) 7, ranging 0-10, with higher scores indicating more severe pain.
Oxynorm consumption
Oxynorm consumption from postoperative day (POD) 1-7
Overall Benefit of Analgesic Score (OBAS)
Overall Benefit of Analgesic Score (OBAS) from postoperative day (POD) 1-7 (range, 0 \[best\] to 28 \[worst\])
Plasma level of bupivacaine and ropivacaine
Plasma level of bupivacaine and ropivacaine before and after surgery
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