A genicular nerve block added nothing meaningful to adductor canal block plus IPACK after knee replacement

Design

Retrospective propensity-score-matched cohort, single high-volume centre

Population

2803 inpatient and 1102 outpatient matched pairs having primary unilateral knee replacement

Primary outcome

Pain scores, opioid consumption, physiotherapy clearance and 90-day opioid refills

Effect

No clinically meaningful difference on any outcome

A retrospective propensity-matched cohort from a high-volume US arthroplasty centre, published in April, compared primary knee replacements done with adductor canal block and IPACK infiltration, with or without an added genicular nerve block. After matching, 2803 inpatient and 1102 outpatient pairs were analysed, all on the same multimodal protocol.

There was no difference in highest or median pain in hospital. Opioid consumption differed by a few milligrams of oral morphine equivalent, below the 10 mg threshold set as meaningful. Time to physiotherapy clearance differed by about an hour, and 90-day opioid refills did not differ.

Where a good motor-sparing block and multimodal analgesia are already in place, a third block adds time, cost and risk without measurable benefit for the average patient. The authors suggest some subgroups might benefit, but those have not been identified.

• Do not add a routine genicular nerve block when adductor canal block, IPACK and multimodal analgesia are already used.
• Invest effort in the multimodal protocol itself — paracetamol, an anti-inflammatory where safe, and early mobilisation.
• Reserve additional blocks for patients with uncontrolled pain despite the standard protocol, and audit the result.
• Count block time and theatre turnover when weighing extra regional techniques.

Why it matters

It removes a step many units have been adding by default, with no measurable gain.

Don't overread it

This was a single-centre observational comparison; a small benefit in particular subgroups cannot be excluded.

The statistics, in plain English

With thousands of patients, even tiny differences become statistically significant — a P value below 0.001 here reflects a few milligrams of morphine. The authors set thresholds for a clinically meaningful difference in advance, and none was reached.

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