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For the last 15 years, plenty single-center/multicenter or nationwide studies have shown that persistent postsurgical pain (PPP) is an important negative outcome of an otherwise successful operation, and may negatively affect daily life activities. These data have come after almost all procedures. In this book, several aspects of the pathogenesis and possibilities for prevention/treatment will be covered and this chapter only provides a short summary of recent reviews/large series emphasizing the PPP problem and the open questions, with a focus on the most common and relevant operations like groin hernia surgery, breast cancer surgery, thoracic surgery and major joint arthroplasty [3,6–8,10,14,16–18,20–22,34]. Although there is a general agreement about the clinical relevance of PPP, several issues remain to be better evaluated in order to understand the relative role of pre-, intra- and postoperative risk factors or in another way patient- vs. surgery-related factors. Finally, suggestions for future research are outlined with a focus on preoperative risk factors and new surgical technology (minimal invasive surgery).
Despite the many publications, there has unfortunately not been general agreement about a uniform assessment of pain and its clinical consequences. A plea was made more than 10 years ago in order to facilitate interpretation of the different studies . Most importantly, persistent postsurgical pain must be assessed during well-defined function and probably also in more detail during the day regarding spontaneous versus more persistent pain patterns . Since different procedures are performed in different patient characteristics, there is a need for procedure-specific assessment of PPP. However, a procedure-specific evaluation on the consequences of PPP for daily life functions have so far only been validated for groin hernia surgery  and thoracic surgery  and to some extent after breast cancer surgery [12,28]. Although the need for preoperative procedure-specific assessments have recently been questioned, taking knee replacement and breast cancer surgery as an example , more detailed evaluation is required before the procedure-specific assessment strategy is refuted.
Since the main question remains to be answered as to the “neuropathic” vs. the “inflammatory” component in persistent postsurgical pain [16,20], some type of neurophysiological assessment is required, since the neuropathic component probably is dominant [16,20]. Although quantitative sensory testing is a well-documented technique for assessing the “neuropathic” component , studies in PPP, especially from groin hernia , breast cancer [15,31] and thoracic surgery [35,36], have demonstrated that although “positive” QST phenomena may be more frequent in PPP patients, many QST abnormalities are found in pain free patients. The same applies to different “neuropathic” pain questionnaires [25,29]. Despite these limitations, assessment of PPP should be supplemented by adding the most relevant QST assessment and “neuropathic” pain questionnaires to improve our understanding of PPP. Finally, it must be described whether PPP patients were pain free preoperatively or whether the preoperative pain was the same character and localization or different from PPP or whether other chronic pain syndromes were apparent preoperatively (low back pain, migraine, fibromyalgia, etc.).
It is well-established from the many reviews and large studies that several preoperative factors are important as predictors of PPP. This includes young age, preoperative pain, psycho-social factors (anxiety, pain catastrophizing, etc.) [3,6–8,10,14,16,18,20–22,30,34]. Also, the preoperative function of the nociceptive system may be important and where several studies have shown a variable predictive value of different preoperative nociceptive tests [2,23,26,32]. However, the ideal tests remain to be established and, again, probably on a procedure-specific basis. The exact role of genetic mechanisms also remains to be established although an increasing number of genetic characterization studies are available including in PPP (see chapter by Maixner).
Since nerve injury is the most important pathogenic factor for PPP [16,20], details on nerve handling in different operations where major nerves are involved are extremely important, but usually not well-described [3,33,34