Ketamine and nefopam has been documented to decrease pain intensity and improve rehabilitation after total knee arthroplasty (TKA). We conducted a follow-up study of a previously randomized clinical trial to determine the prevalence and risk factors of chronic pain 1 year after TKA and to assess the role of perioperative administration of ketamine and nefopam.
The original randomized, double-blind trial evaluated postoperative pain in 75 patients scheduled for TKA who received either a 48-hour infusion of ketamine or nefopam compared with placebo. The current study has evaluated patients at 6 and 12 months for the presence of chronic pain defined as a visual analogue scale ≥40 mm during a stair-climbing test. Other outcomes were incidence of neuropathic pain evaluated (DN4 score), active flexion of the knee, and functional outcome (KOOS-PS score).
A total of 69 patients completed the trial. The prevalence of chronic pain at 12 months was 17.4% (95% confidence interval [CI], 10.2%-27.9%) without difference between the ketamine (12.5%), nefopam (13.7%), and placebo groups (26.1%). Prevalence of neuropathic pain was 10.2% (95% CI, 3%-17.3%). Ketamine reduced DN4 scores (P=0.02), increased knee flexion (P=0.0007), and KOOS-PS scores (P<0.0001) compared with placebo. A visual analogue scale score ≥60 mm in the postoperative period was the only risk factor associated with the occurrence of chronic pain (odds ratio 4.54; 95% CI, 1.17-17.67).
After TKA, the intensity of postoperative pain is a risk factor of chronic pain on movement. Intraoperative ketamine seems to improve long-term results of rehabilitation in this setting.
*Department of Anesthesiology and Intensive Care, Centre Hospitalier Privé Sévigné, Cesson-Sévigné
†Department of Anesthesiology and Intensive Care, Tenon University Hospital, Université Pierre & Marie Curie Paris VI, Paris, France
Presented in part (scientific abstract) at the 54th meeting of French Society of Anesthesiology and Intensive Care, September 19-22, 2012, Paris, France.
The authors declare no conflict of interest.
Reprints: Christophe Aveline, MD, Department of Anesthesiology and Surgical Intensive Care, Centre Hospitalier Privé Sévigné, 8 rue du Chêne Germain, Cesson-Sévigné 35517, France (e-mail: email@example.com).
Received April 9, 2013
Received in revised form December 2, 2013
Accepted September 7, 2013