Chronic postoperative pain is defined as chronic pain that intensifies after surgery and persists for at least three months¹. Chronic postoperative pain is estimated to affect 5% to 75% of surgical patients, with certain surgeries carrying higher risk². Understanding these risks and associated mechanisms is critical for preventing it and improving postoperative outcomes.

Chronic postoperative pain arises primarily from peripheral and central sensitization. Peripheral sensitization involves heightened nociceptor responses due to ion channel and inflammatory mediator upregulation. Central sensitization occurs in the spinal cord and brain, where prolonged noxious stimuli result in long-term synaptic changes and amplified pain signals. These mechanisms involve microglia activation, cytokine release, and neurotransmitter alterations, contributing to the transition from acute to chronic pain³. Surgeries involving significant nerve damage, such as amputations, thoracotomies, and mastectomies, often lead to central sensitization. Conversely, surgeries causing localized tissue damage, such as hernia repairs, primarily involve peripheral sensitization⁴.

In many patients, chronic postoperative pain manifests as neuropathic pain due to nerve or sensory system injury. Neuropathic pain is significant, challenging to treat, and marked by amplified pain sensitivity and neuroplastic changes. Common surgeries with a higher risk of neuropathic chronic postoperative pain include amputations, thoracotomies, mastectomies, and inguinal herniotomies⁵. Non-neuropathic cases can stem from inflammatory or visceral pain, typical of knee, hip, or abdominal surgeries. Early identification of pain mechanisms is essential for effective treatment: COX inhibitors and NSAIDs for inflammatory pain, opioids for visceral pain, and gabapentin for neuropathic pain^{3, 4}.

The extent of surgical trauma and the duration of surgery are key predictors of risk; however, the type of tissue injured also influences the type of chronic postoperative pain and its appropriate treatment³. Surgeries with the highest incidence include amputations, thoracotomies, and mastectomies. Amputations have the highest reported incidence, with up to 85% of patients experiencing chronic pain, often manifesting as phantom limb pain.⁶. Thoracotomies also carry a high risk, with incidence rates reaching 70%, typically caused by intercostal nerve damage^{6, 7}. Similarly, mastectomies have an incidence as high as 60%, with approximately 65% of cases involving neuropathic pain due to injury to the intercostobrachial nerve^{3, 4, 6}.

Other surgeries associated with high risk of chronic postoperative pain include cardiac surgeries with sternotomy, inguinal herniotomy, and orthopedic procedures. Cardiac surgeries, such as coronary artery bypass, have a 40% incidence, likely due to intercostal nerve or brachial plexus injury^{5, 8}. Inguinal herniotomies report rates of up to 60% at one year post-surgery, with 80% of cases involving neuropathic pain due to injury to nerves like the ilioinguinal and genitofemoral nerves^{5, 9}. Orthopedic procedures, including hip and knee arthroplasty, have reported rates of up to 45%, attributed to significant trauma to musculoskeletal structures, prolonged inflammation, and tissue damage^{3, 6}.

Risk factors for chronic postoperative pain can extend beyond just the type of surgery. Other factors include the presence of preoperative pain, psychological distress, acute postoperative pain, poor postoperative pain control, younger age, female sex, and higher body mass index⁶. Preventive strategies include optimizing the management of acute postoperative pain, using multimodal analgesia, and addressing psychological factors preoperatively¹⁰.

References

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2. Lopes A, Seligman Menezes M, Antonio Moreira de Barros G. Chronic postoperative pain: ubiquitous and scarcely appraised: narrative review. Braz J Anesthesiol. 2021;71(6):649-55. Epub 20210218. doi: 10.1016/j.bjane.2020.10.014. PubMed PMID: 34715995; PMCID: PMC9373680.

3. Rosenberger DC, Pogatzki-Zahn EM. Chronic post-surgical pain – update on incidence, risk factors and preventive treatment options. BJA Educ. 2022;22(5):190-6. Epub 20220224. doi: 10.1016/j.bjae.2021.11.008. PubMed PMID: 35496645; PMCID: PMC9039436.

4. Kehlet H, Jensen TS, Woolf CJ. Persistent postsurgical pain: risk factors and prevention. Lancet. 2006;367(9522):1618-25. doi: 10.1016/S0140-6736(06)68700-X. PubMed PMID: 16698416.

5. Xiao MZX, Khan JS, Dana E, Rao V, Djaiani G, Richebe P, Katz J, Wong D, Clarke H. Prevalence and Risk Factors for Chronic Postsurgical Pain after Cardiac Surgery: A Single-center Prospective Cohort Study. Anesthesiology. 2023;139(3):309-20. doi: 10.1097/ALN.0000000000004621. PubMed PMID: 37192204.

6. Correll D. Chronic postoperative pain: recent findings in understanding and management. F1000Res. 2017;6:1054. Epub 20170704. doi: 10.12688/f1000research.11101.1. PubMed PMID: 28713565; PMCID: PMC5499782.

7. Geil D, Thomas C, Zimmer A, Meissner W. Chronified Pain Following Operative Procedures. Dtsch Arztebl Int. 2019;116(15):261-6. doi: 10.3238/arztebl.2019.0261. PubMed PMID: 31130157; PMCID: PMC6546858.

8. Bordoni B, Marelli F, Morabito B, Sacconi B, Severino P. Post-sternotomy pain syndrome following cardiac surgery: case report. J Pain Res. 2017;10:1163-9. Epub 20170515. doi: 10.2147/JPR.S129394. PubMed PMID: 28553137; PMCID: PMC5439996.

9. Reinpold W. Risk factors of chronic pain after inguinal hernia repair: a systematic review. Innov Surg Sci. 2017;2(2):61-8. Epub 20170512. doi: 10.1515/iss-2017-0017. PubMed PMID: 31579738; PMCID: PMC6754000.

10. Edwards DA, Hedrick TL, Jayaram J, Argoff C, Gulur P, Holubar SD, Gan TJ, Mythen MG, Miller TE, Shaw AD, Thacker JKM, McEvoy MD, Group P-W. American Society for Enhanced Recovery and Perioperative Quality Initiative Joint Consensus Statement on Perioperative Management of Patients on Preoperative Opioid Therapy. Anesth Analg. 2019;129(2):553-66. doi: 10.1213/ANE.0000000000004018. PubMed PMID: 30768461.