Design: Randomised, triple-blind, single-centre trial
Population: 80 adults having ACL reconstruction with a femoral triangle block
Primary outcome: Cumulative IV morphine at 24 hours
Effect: Median 12 mg vs 16 mg, P = 0.073

This single-centre, triple-blind trial randomised 80 adults having ACL reconstruction under general anaesthesia with a femoral triangle block to either IPACK (20 ml ropivacaine 0.2%) or a selective tibial nerve block (5 ml ropivacaine 0.75%) for posterior knee pain.

Median morphine use over 24 hours was 12 mg after IPACK and 16 mg after the tibial nerve block (P = 0.07). Pain scores, range of motion, quadriceps strength and walking distance did not differ, nor did quadriceps strength and hop testing at four and eight months. No complications were reported.

Both blocks cover the posterior knee. The choice can follow operator familiarity and theatre flow. The trial was designed to show IPACK superior, not to show equivalence, so small differences cannot be excluded.

Use whichever posterior knee block your team performs reliably; outcomes were similar.
Pair either block with a femoral triangle block and regular paracetamol and NSAID.
Check foot plantarflexion before discharge after a tibial nerve block.
Count local anaesthetic dose across all blocks given in the same patient.

Why it matters

It removes a reason to insist on one posterior knee technique over another.

The statistics, in plain English

The P value of 0.07 means the 4 mg difference could easily be chance. A trial of 80 patients powered for superiority cannot prove the two are equivalent, only that a large difference is unlikely.