Ketamine is a phencyclidine intravenous anaesthetic that blocks N-methyl-d-aspartate receptors and HCN channels in the CNS.

Lately it has gained acceptance in a low-dose form, with studies showing an analgesic benefit in orthopaedic surgery.

Our goal was to critically appraise and synthesise current evidence regarding use of low-dose ketamine in major, painful orthopaedic surgeries.

We conducted searches in Medline, Embase, Cochrane, and specialty journals for randomised controlled trials (RCTs) that compared low-dose ketamine to placebo. Primary outcomes included total opioid use, time to first opioid, and VAS pain scores.

Meta-analyses were undertaken in RevMan software using a random effects model. We rated the quality of the evidence using the GRADE Working Group criteria.

Low-dose ketamine is an effective adjuvant that decreases pain and opioid requirements in painful orthopaedic procedures, especially in the first 24 h after procedure.