The persistence of pain long after a surgical wound has closed is a common experience. This discomfort is known as chronic post-surgical pain (CPSP), defined as pain that continues for at least three to six months following an operation, after the expected healing period has passed. Scar tissue is a living, dynamic tissue that undergoes constant remodeling and can change in density and structure over time. This biological process can lead to the delayed onset or worsening of pain years after the initial surgery, often related to how the scar tissue interacts with surrounding nerves, muscles, and organs.
Nerve Entrapment and Neuropathic Pain
Surgery involves making an incision that cuts through layers of tissue, which can damage or sever small peripheral nerves. While immediate post-operative pain subsides, long-term discomfort can develop as these injured nerve endings attempt to regenerate. This is called neuropathic pain, and it is distinct from the typical aching of healing tissue.
One common mechanism is nerve entrapment, where the surrounding scar tissue, or fibrosis, develops thickly and compresses a nerve. The dense collagen fibers squeeze the nerve, causing it to send abnormal pain signals. This compression often results in sharp, shooting, or burning pain, and sometimes an intense sensitivity to light touch, known as allodynia.
Another specific nerve issue is the formation of a neuroma, which is a disorganized, non-cancerous growth of nerve tissue at the site where a nerve was cut. This tangled mass of nerve fibers becomes highly sensitive, sometimes feeling like a painful knot under the skin. Pressure on a neuroma, such as from clothing or movement, can trigger severe, electrical shock-like pain.
Adhesions and Deep Tissue Fibrosis
Healing from surgery involves multiple layers of tissue, and scarring is not limited to the visible skin surface. Deep internal scarring, known as adhesions, are fibrous bands that form between internal organs, muscles, fascia, or other tissues that are normally separate. These adhesions form as the body’s repair mechanism, but they can cause internal structures to stick together.
These internal bands of scar tissue restrict the natural movement and gliding of organs and muscles against one another. When the body moves, the restricted tissues are pulled, which can cause a deep, chronic, aching pain or a sensation of internal tightness. Adhesions are common, occurring in over 90% of abdominal surgeries, and can cause chronic abdominal or pelvic pain that may manifest months or years later. The pain is typically mechanical, described as a tugging or pulling sensation that worsens with certain movements or positions.
Abnormal Scar Tissue Structures
Sometimes, the visible scar tissue itself is the source of persistent discomfort due to an overzealous healing response. Two forms of pathological scarring, hypertrophic scars and keloids, are characterized by excessive collagen deposition and prolonged, localized inflammation. Hypertrophic scars are raised, red, and remain confined to the original wound boundaries, often improving over time.
Keloids are more aggressive, growing outward and spreading beyond the initial incision site. Both types of scars can cause chronic pain and significant itching (pruritus), because the increased tension and prolonged inflammation within the scar tissue irritate nearby nerve endings. Pain can also be caused by a foreign body reaction, which is a localized inflammatory response to non-dissolvable materials left in the body, such as certain sutures or surgical mesh.
Identifying Serious Symptoms
While some mild, intermittent discomfort is an expected part of long-term healing, certain symptoms require prompt medical attention. A sudden, sharp increase in pain, especially if accompanied by new swelling, warmth, or discharge from the scar, could indicate a late-onset infection. Any new or rapidly growing mass under the scar, or a sudden change in its texture or color, should be evaluated immediately by a healthcare provider.
The appearance of new numbness, tingling, or weakness in a limb or area near the scar may signal nerve compression or damage that needs urgent assessment. Chronic pain that significantly interferes with daily life, sleep, or mobility should be discussed with a doctor. Seeking professional evaluation rules out serious complications and allows for accurate diagnosis and management planning.