Design: Single-centre, randomised, placebo-controlled phase II trial
Population: 120 adults having arthroscopic rotator cuff repair with interscalene block
Primary outcome: Rebound pain within 24 hours
Effect: 23.3% vs 36.7%; RR 0.64 (95% CI 0.36-1.12); p = 0.163

In a single-centre phase II trial (Drug Design, Development and Therapy, 5 October 2026), 120 adults having arthroscopic rotator cuff repair under interscalene block and general anaesthesia were randomised to intravenous lidocaine (1 mg/kg bolus then 2 mg/kg/h to closure) or saline.

Rebound pain within 24 hours occurred in 23.3% with lidocaine and 36.7% with saline (relative risk 0.64, 95% CI 0.36-1.12; p = 0.163). Peak movement pain scores were the same. Intraoperative remifentanil use was lower with lidocaine. The authors note that a corrected calculation showed about 82 patients per group were needed, so the trial was underpowered.

The result neither supports nor rules out lidocaine for rebound pain. Until a larger trial reports, planning oral analgesia around the block's offset matters more.

Do not add intravenous lidocaine solely to prevent rebound pain on this evidence.
Expect rebound pain in about a third of patients after a single-shot interscalene block.
Plan oral analgesia to be on board before the block wears off.
Watch for a larger trial before changing protocol.

Why it matters

Rebound pain is the main thing that spoils a good block, and there is still no proven drug to prevent it.

The statistics, in plain English

A relative risk of 0.64 with a CI crossing 1.0 means the result could be a real benefit or chance. Underpowered trials miss true effects, so 'not significant' here is not the same as 'no effect'.