PAIN Opioid-induced hyperalgesia in a mice model of orthopaedic pain: preventive effect of ketamine

Postoperative pain management is a great challenge because it is a critical part of a patient’s recovery. 2 Bone injury is often accompanied by acute pain that can be clearly diminished by morphine use. 4 However, although opioids are among the most effective analgesics in humans, there is growing evidence showing that they also induce abnormal and prolonged pain states after acute or chronic administration. 6 It has been proposed that postoperative pain in patients receiving opioids during surgery could result not only from the nociceptive input related to tissue damage, but also from opioid-induced pain sensitization. 7 8 Recently, it was demonstrated that ketamine not only improves exaggerated postoperative incisional pain management, but also provides better postoperative rehabilitation. We recently described a model of fracture pain in mice that could mimic orthopaedic surgery. The aim of this study was to assess the preventative effect of ketamine on the exaggerated postoperative pain observed in sufentaniltreated mice and its ability to improve the analgesic effectiveness of morphine during the postoperative period.