C hronic pain is a major health problem and the leading cause of years lived with disability. 57 In the absence of disease-modifying therapies and adequate symptomatic treatment, prevention is important. In recent years, there has been a focus on "transition of acute to chronic pain" or "pain chronification." It has been postulated that some forms of chronic pain might be regarded as a continuum of acute pain, possibly with a transition point or period where acute pain progresses into chronic pain, sometimes also referred to as the shift from physiological to pathological pain 14,45,55,67 (Fig. 1A). Such terminology implies that one mechanistic type of pain transforms into another pain, for example, that acute pain caused by tissue damage and inflammation changes into a neuropathic pain, which is unlikely or at least not proven. In the following, we challenge the concept of "transition" of pain.
Transition of pain or development of pain?For many years, there has been a focus on the phenomena of central sensitization, spinal amplification, and altered descending pain modulation as underlying mechanisms of chronic pain. 6,23,24,34 In an editorial in PAIN from 1988, Patrick Wall speculated that acute and chronic pain after surgery could be prevented by treatments, for example, nerve blocks or opioids, that would block nerve discharges caused by injury or preexisting pain, thereby reducing central sensitization. 68 Although there is ample evidence from preclinical and clinical studies that excessive afferent discharges consequential to tissue injury evoke a peripheral and central sensitization resulting in sensory hypersensitivity, 12,16,70 it has never been proven in humans that central sensitization is sustained after the tissue has healed and the afferent input has ceased and that it drives chronic pain. 24 Similarly, studies addressing clinical signs of central sensitization before surgery show some evidence for a link to chronic pain only for total joint arthroplasty, and with conflicting results. 52,54 Nevertheless, the association between severe acute and persistent postsurgical