Liposomal Bupivacaine Improves 72-Hour TKA Pain
Key Takeaways
- Older adults undergoing unilateral total knee arthroplasty under spinal anesthesia who received a postoperative four-in-one nerve block had lower pain scores with liposomal bupivacaine than with ropivacaine mainly from 24 to 72 hours, while early differences were smaller.
- Oxycodone use was absent on postoperative day 1 in both groups, but consumption on postoperative days 2 and 3 was lower with liposomal bupivacaine.
- Early recovery favored liposomal bupivacaine, with better knee ROM and higher MRC muscle strength during the first 72 postoperative hours.
- Length of stay was unchanged, and prolonged numbness was reported in 8.3% of liposomal bupivacaine recipients versus none of the ropivacaine group without a statistically significant between-group difference.
Between September 2023 and July 2024, investigators conducted a randomized, single-blinded trial in 120 patients aged 65 to 80 years undergoing unilateral TKA under spinal anesthesia, with per-protocol efficacy analysis of 60 liposomal bupivacaine patients and 59 ropivacaine patients after one postrandomization deep vein thrombosis exclusion. Patients, postoperative assessors, and data analysts were blinded, while the anesthesiologist performing the block was not because the drugs differed in appearance.
The postoperative ultrasound-guided block used a single adductor canal approach to target the saphenous nerve, sciatic nerve, nerve to vastus medialis, and medial femoral cutaneous nerve, using liposomal bupivacaine 266 mg diluted to 40 mL or ropivacaine 97.5 mg diluted to 40 mL, with 10 mL per targeted nerve. The primary endpoint was visual analog scale (VAS) pain at rest at 72 hours, and secondary outcomes included pain during movement, oxycodone use on postoperative days 1 through 3, Medical Research Council (MRC) muscle strength, range of motion (ROM), satisfaction, adverse events, and length of stay (LOS).
VAS pain at rest at 72 hours was lower with liposomal bupivacaine than with ropivacaine, with median scores of 2.0 (1, 2) versus 3.0 (2, 4), median difference -1.3, 95% CI -2.0 to -0.6, adjusted P < 0.001. Pain trajectories at rest and during movement separated most clearly from 24 to 72 hours, with only small effects in the first 12 hours.
No oxycodone use occurred in either group on postoperative day 1, while consumption was lower with liposomal bupivacaine on postoperative days 2 and 3. Knee ROM on postoperative days 1 through 3 and MRC muscle strength from 2 to 72 hours also favored liposomal bupivacaine; muscle-strength area under the curve over 72 hours was 335.0 (317.3, 340.0) versus 252.0 (247.0, 264.0), median difference 77.0, 95% CI 69.0 to 83.0, P < 0.001. Patient and surgeon satisfaction were higher as well.
The anesthesiologist performing the block could not be blinded, efficacy analyses were per protocol after one postrandomization exclusion, follow-up for prespecified outcomes ended at 72 hours, dose selection reflected prior studies and clinical experience rather than pharmacologic equivalence, and motor assessment did not objectively test sciatic-innervated ankle movement. Prolonged numbness in the sciatic distribution was seen in 8.3% of liposomal bupivacaine recipients versus none with ropivacaine, resolved within 1 week, and was not followed by persistent sensory abnormality at 2 weeks, 4 weeks, or 3 months, leaving a signal rather than a confirmed between-group safety difference.
The investigators concluded that a single injection of liposomal bupivacaine in this four-in-one nerve block was associated with modestly better pain control between 24 and 72 hours after TKA, along with lower opioid use on postoperative days 2 and 3 and better early functional recovery, while the overall clinical significance remained uncertain.
Clinician Questions
Which total knee arthroplasty patients were represented in the liposomal bupivacaine four-in-one block trial?
The trial enrolled adults aged 65 to 80 years with American Society of Anesthesiologists physical status II or III and body mass index 18 to 27 kg/m² who underwent unilateral TKA under spinal anesthesia at a single center in China, so the findings come from that specific perioperative setting rather than from broader TKA populations.
How was the four-in-one nerve block performed after total knee arthroplasty in this trial?
Investigators performed the block postoperatively in the post-anesthesia care unit under ultrasound guidance through a single adductor canal approach targeting the saphenous nerve, sciatic nerve, nerve to vastus medialis, and medial femoral cutaneous nerve, with 10 mL injected per targeted nerve.
Why did the authors describe the liposomal bupivacaine benefit after TKA as modest rather than definitive?
The authors bounded their interpretation because early pain effects within 12 hours were small, no opioid advantage appeared on postoperative day 1, length of stay did not differ, and the overall clinical significance of the observed differences remained uncertain in this setting.
Recommended Reading
- For more on extending postoperative nerve-block analgesia: The Expanding Role of Peripheral Nerve Stimulation in Acute Pain Control
- For more on perioperative management before orthopedic surgery: 4F-PCC Enables Faster VKA Reversal Before Urgent Orthopedic Surgery