- Design
- Randomised, triple-blinded trial
- Population
- 80 patients having ACL reconstruction under general anaesthesia with femoral triangle block
- Primary outcome
- Cumulative intravenous morphine at 24 hours
- Effect
- Median 12 mg (IPACK) vs 16 mg (tibial block), p = 0.073
In this triple-blinded randomised trial, 80 patients having anterior cruciate ligament reconstruction under general anaesthesia with a femoral triangle block received either IPACK (20 ml ropivacaine 0.2%) or a selective tibial nerve block (5 ml ropivacaine 0.75%). All had paracetamol, ibuprofen and intravenous morphine patient-controlled analgesia. The hypothesis was that IPACK would be superior.
Median cumulative morphine at 24 hours was 12 mg (IQR 6 to 20) with IPACK and 16 mg (IQR 10 to 30) with the tibial block, a difference that did not reach significance (p = 0.073). Pain scores, early function (range of motion, quadriceps strength, walking distance) and late function at 4 and 8 months did not differ, and no complications were reported.
The trial was powered for superiority, so similar results do not prove equivalence, but they support choosing between the blocks on local skill, volume and preference.
- 24-hour morphine was similar: median 12 mg with IPACK and 16 mg with tibial block (p = 0.073).
- Pain scores and function to 8 months did not differ.
- No complications were reported in either group.
- Consider choosing by operator experience and local anatomy familiarity.
- Both were added to a femoral triangle block under general anaesthesia.
Why it matters
It removes a reason to prefer the more voluminous block when a smaller-volume option works as well.
Don't overread it
The trial was designed to test superiority and used a single multimodal regimen, so it does not prove the blocks are equivalent.
The statistics, in plain English
A p value of 0.073 means the morphine difference could plausibly be due to chance; with 80 patients the trial could still miss a modest true difference. The study aimed to prove IPACK better and did not.
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