Design: Randomised, triple-blind controlled trial
Population: 80 adults 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), P = 0.073

A triple-blind randomised trial in 80 patients having anterior cruciate ligament reconstruction under general anaesthesia with a femoral triangle block compared IPACK (20 ml ropivacaine 0.2%) with a selective tibial nerve block (5 ml ropivacaine 0.75%) for posterior knee pain.

Median morphine use at 24 hours was 12 mg with IPACK and 16 mg with tibial block (P = 0.073). Pain scores, range of motion, quadriceps strength, walking distance and function at four and eight months did not differ. No complications were reported.

Either block is reasonable; choice can rest on operator skill and theatre efficiency. The trial was small and may have missed a modest difference.

Use whichever posterior knee block — IPACK or selective tibial — your team performs most reliably.
Combine it with a femoral triangle block and regular paracetamol and an anti-inflammatory where safe.
Check motor function of the foot after a tibial nerve block before mobilising.
Expect similar recovery and later function with either approach.

Why it matters

It removes the pressure to adopt one posterior block over the other for this operation.

The statistics, in plain English

A P value of 0.073 means the morphine difference could plausibly be chance. With 80 patients the trial had limited power to find small differences, so 'similar' means no large difference rather than proof of equivalence.