**5.6 Postoperative pain**

Postoperative pain is acute pain that occurs following tissue injury associated with surgery and should resolve during the healing process. This normally takes up to 3 months, after which the pain is considered to be chronic or persistent [77]. Armstrong et al. found a significant correlation between increased preoperative and postoperative pain scores and anxiety, current smoking, psychological conditions, and current opioid use. Additionally, Armstrong et al. recommended for a multimodal approach to postoperative pain management and developed a pain sequence to help providers [78]. Multimodal analgesia is an essential component of such care. Further, there has been a recent renewal of interest in non-opioid alternatives or adjuncts in controlling postoperative pain, often in the context of multimodal analgesia [79]. Intravenous acetaminophen, non-steroidal anti-inflammatory drugs (NSAIDs), magnesium, ketamine, dexmedetomidine, liposomal bupivacaine, and newer neuraxial and peripheral regional techniques, as well as patient-controlled modalities, are gaining importance. Acupuncture and transcutaneous electrical nerve stimulation may be useful as adjuncts in multimodal analgesia packages [79]. Acupuncture is a well-known and widely used treatment for pain and other conditions. There have been increasing numbers of clinical trials evaluating the efficacy of acupuncture and related techniques for postoperative analgesia. Sun et al. [80] evaluated 15 studies on the efficacy of acupuncture and related techniques for acute postoperative pain management in surgery: abdominal, maxillofacial, knee, hemorrhoidectomy, back, thoracotomy, hip arthroplasty, and molar extraction. They suggested that perioperative administration of acupuncture might be useful as an adjunct to postoperative analgesia [80].
