- Design
- Single-centre randomised controlled trial, assessor-blinded
- Population
- 60 adults having total knee arthroplasty
- Primary outcome
- Resting pain score at 24 hours
- Effect
- 2.4 vs 2.9; difference -0.52 (-1.01 to -0.02)
This single-centre trial randomised 60 patients having total knee replacement to adductor canal plus iPACK blocks with either liposomal bupivacaine plus plain bupivacaine, or plain bupivacaine plus dexamethasone. Outcome assessors were blinded.
Resting pain at 24 hours was 2.4 vs 2.9 on a 10-point scale, a difference of 0.52 points (95% CI 0.02 to 1.01). Rescue analgesia was needed less often in the liposomal group (RR 2.40 for dexamethasone), and quadriceps strength was better at 12 hours. Patient-controlled analgesia use was nearly identical.
A half-point difference is below what most patients would notice, and the trial was small. Liposomal bupivacaine is expensive and not widely stocked in India, whereas dexamethasone as an adjuvant is cheap and familiar. This trial does not make a strong case for switching.
- Keep plain bupivacaine with dexamethasone as a reasonable block regimen; the difference was small.
- Consider liposomal bupivacaine only where cost is not a barrier and rescue analgesia is a recurrent problem.
- Record rescue analgesia use in your own audit to judge whether a change would help.
- Check quadriceps strength before early mobilisation after any adductor canal block.
Why it matters
It frames an expensive product against a cheap adjuvant, which is the real choice most units face.
Don't overread it
A single small trial with a difference below the usual threshold for a clinically meaningful change in pain.
The statistics, in plain English
The confidence interval for the pain difference runs from 0.02 to 1.01 points; the lower end is almost no difference at all. Most studies treat about 1 to 1.5 points as the smallest change a patient notices.
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