Another question concerns the effects of NOA on postoperative hyperalgesia. This hyperalgesia, which results from surgery-related inflammation, is increased by consumption of morphine and not only contributes to the overall experience of postoperative pain but also to the chronicisation of postoperative pain. Since in clinical practice, hyperalgesia can be measured using specific tools (Von Frey filament type), our study will evaluate the anti-hyperalgesic effects of NOA on a subgroup of patients enrolled in the centers used to evaluate nociceptive thresholds.