Why can surgery cause chronic pain?
- Michele Curatolo
- Nov 6
- 4 min read
Most people expect pain after surgery to fade as healing occurs. However, for millions worldwide, it doesn’t. Chronic post-surgical pain can last months or even years, affecting daily life, sleep, and emotional well-being. It can be more than discomfort; it can become a significant health issue that leads to disability and reduced quality of life. Understanding why this happens is the first step toward effective prevention and treatment.
What is chronic post-surgical pain?
Chronic post-surgical pain refers to pain that persists for more than three months after an operation, even though the surgical wound has healed. It can occur after many types of procedures, from hernia repairs and breast surgeries to knee replacements and amputations. Frequently, the pain changes in character from the initial pain experience in the first few days after surgery, sometimes evolving into a burning sensation accompanied by tingling or prickling. Patients may also experience pain with simple touch, as well as pain spreading beyond the area of surgery.
Why does it happen?
Several processes can explain why pain continues long after tissues have healed, and these mechanisms can interact.
One reason is that nerves near the surgical site may remain irritated or damaged, which can happen when nerves are stretched, cut, or compressed during surgery. Think, for example, of lung surgery, during which the nerves between the ribs (intercostal nerves) can be severely and unavoidably damaged. Damaged nerves can behave abnormally, sending pain signals. Immune cells play a crucial role in tissue repair and healing after surgery. However, they can also cause nerve pain by creating a chemical environment that keeps pain-sensitive nerves in an active state.
Another factor is increased sensitivity within the central nervous system. After surgery, the spinal cord and brain can become “over-tuned,” amplifying pain signals. This phenomenon, known as central sensitization, means that even mild stimuli can be perceived as intensely painful. Read more here.
Related to the previous point, the body has natural systems that dampen pain, but for reasons that are not clear these systems can be less effective in certain individuals.
Finally, chronic pain can lead to lasting changes in the brain. Changes in brain chemistry may weaken protective mechanisms or amplify pain signals. Regions that process pain may reorganize, making pain feel stronger or more widespread. Emotional factors such as anxiety, depression, and negative expectations can further reinforce these changes. In fact, regions of the brain related with pain perception are connected with regions of the brain that process emotions, creating a cycle between pain and emotion.
What don't we know?
We have a minimal understanding of why some patients develop such a distressful condition, whereas others with the same surgery remain pain-free.
The molecular mechanisms underlying chronic post-surgical pain are largely unknown.
These knowledge gaps hamper the development of effective preventive and therapeutic strategies.
Frequently Asked Questions
How common is chronic post-surgical pain?
Studies suggest that 10–50% of patients experience some level of persistent pain after surgery, and 2–10% have severe pain that affects daily life. These numbers, however, depend significantly on the type of surgery and the definition of post-surgical pain severity.
Who is at most risk?
Research shows that certain factors increase the likelihood of chronic pain after surgery. These include, among others, severe pain in the frist few days after the operation, younger age, female sex, pre-existing pain conditions, and psychological traits such as anxiety or catastrophizing. The type of surgery also matters: procedures involving nerve injury, such as thoracotomy or mastectomy, carry a higher risk.
What does chronic post-surgical pain feel like?
It can vary. Some describe burning, stabbing, or electric shock-like sensations. Others experience aching or hypersensitivity around the surgical site.
Can chronic pain after surgery go away on its own?
In some cases, pain gradually improves over time. However, for many, it persists without treatment or, unfortunately, despite treatment.
Can chronic pain after surgery be prevented?
The literature is sparse and inconsistent regarding preventive interventions. Adequate pain control during the few days after surgery, nerve-sparing techniques, and addressing psychological factors may reduce risk, but despite these measures, a significant proportion of patients will develop chronic pain.
When to seek help?
Persistent pain after surgery should never be ignored. If pain lasts beyond a few weeks and interferes with daily activities, professional evaluation is essential.
What treatments are available?
Options include medications for nerve pain, physical therapy, nerve blocks, and psychological treatments. Because chronic post-surgical pain manifests in many different ways, a personalized approach is mandatory. While many patients experience relief, treatments are unfortunately of limited efficacy and do not work in all patients.
Why are so many patients suffering despite treatment?
There are many potential reasons, but one stands out. Because we have a very limited understanding of the molecular mechanisms that drive persistent pain after surgery, the current treatments do not target the mechanisms specifically involved in chronic post-surgical pain, and therefore fail to work in many patients.
Research into the mechanisms that explain chronic postoperative pain will be essential to develop more effective preventive and therapeutic strategies.
Some of the many good review articles
Allen, C., et al., Preventing persistent postsurgical pain: A systematic review and component network meta-analysis. European Journal of Pain, 2022. 26(4): p. 771-785. https://onlinelibrary.wiley.com/doi/abs/10.1002/ejp.1915
Carley, M.E., et al., Pharmacotherapy for the Prevention of Chronic Pain after Surgery in Adults: An Updated Systematic Review and Meta-analysis. Anesthesiology, 2021. 135(2): p. 304-325.
Chapman, C.R. and C.J. Vierck, The Transition of Acute Postoperative Pain to Chronic Pain: An Integrative Overview of Research on Mechanisms. The Journal of Pain, 2017. 18(4): p. 359.e1-359.e38.
