ATTENTION TO DETAILSurgeons must operate carefully during open hernia repairs to prevent chronic pain from occurring.

Discomfort after hernia surgery is expected. But when the pain persists past 30 days, it becomes a source of dismay for patients and frustration for surgeons, who are often unaware of the scope of the issue. There are upwards of 1 million hernia repairs done each year. If an estimated 15% to 35% of those patients experience post-op chronic pain, hundreds of thousands of individuals are in discomfort following surgery. But understanding the many factors that contribute to the problem can prevent it from happening in the first place.

• Patients. Experts agree that laparoscopic repair is best for patients with previous complicated open mesh repairs or bilateral hernias. Research has shown that male patients younger than 40 years old who show pain symptoms out of proportion with pre-op physical exams typically don't do well with mesh repair. Additionally, patients undergoing recurrent hernia repair and patients who experience high levels of pre-op pain are more likely to suffer from post-op chronic pain.
• Technique. Very few surgeons are attentive to avoiding hernia surgery's "blue line" — the internal spermatic vein and the genital branch of the genitofemoral nerve — that leads to the significant number of patients who suffer post-op chronic pain.

Most chronic pain occurs after open surgery dissection that requires surgeons to carefully move tissue and the spermatic cord. They show varying attention to detail in identifying the 3 sensory nerves found in the groin: the ilioinguinal, genito-femoral and iliohypogastric. Exaggerated scarification responses or the surgeon's lack of meticulous dissection while operating (injuring the nerves with suture or compressing them with mesh) can damage one or more of these nerves.

The laparoscopic approach results in fewer overall nerve issues because the anatomical location of the sensory nerves in the preperitoneal space is predictable. If no dissection is done inferior to the iliopubic tract, and no mesh affixation is performed with devices such as tacks or staples below the tract, the operation likely won't result in significant chronic pain. However, surgeons can still injure the lateral femoral cutaneous nerve during laparoscopic procedures, leaving patients with pain on the anterior lateral side of the thigh.

PAINFUL PATCH Heavyweight microporous mesh increases risk of inflammatory response.

DEFINING DISCOMFORT
What Is Chronic Pain?

Chronic pain, which occurs after 15% to 35% of hernia repairs, is defined as pain measuring 4 or higher on a 1-to-10 scale and lasting longer than a month after surgery. It prohibits patients from returning to normal life routines and activities.

Somatic pain is experienced most often. It's the result of scarification issues, previous ligament or mesh injury, or new ligament or mesh injury caused by surgery. Neuropathic pain involves direct nerve damage or injury, or incorporation of sensory nerves with suture, tacks, staples or mesh. Finally, visceral pain related to hernia repair can occur when implanted mesh compromises peritoneal tissue.

Prevention is of course the best solution to post-op chronic pain. But when inguinodynia does occur, surgeons must first rule out other causes of the pain. Is the patient suffering from back problems or urologic complications? Is the patient dealing with psychological issues? Has there been recurrence of the hernia?

Legitimate chronic post-op pain is first treated with the least invasive intervention: anti-inflammatories, ice therapy and restriction of activity. Injections with a local anesthetic and steroid have been shown to reduce pain to tolerable levels 50% of the time.

If those attempts fail to work, pain specialists may get involved, offering alcohol blocks, radiofrequency ablation, dorsal column stimulators that send block pain sensations at the spinal cord and implantable morphine pumps.

The ultimate cure, of course, is re-operating to remove the affected nerves or mesh that are the offending problems.

— Jeffrey B. Mazin, MD, FACS

• Mesh. Surgeons are increasingly worried about inflammatory responses caused by mesh as well as mesh shrinkage. A polypropylene mesh can shrink up to 46%, meaning it pulls away from the tissue junction and disengages from the body wall, causing pain and hernia recurrence.

Many surgeons opt for lightweight macroporous mesh instead of heavyweight microporous mesh because breakage (prevented by high-tensile strength material) isn't as big a concern as previously thought. Lightweight macroporous mesh helps prevent chronic post-op pain by letting the body more easily grow (incorporate) through the crosshatches of the material.

To limit risks of inflammation and related chronic pain, synthetic mesh shouldn't be placed in patients who are allergic to the materials, and mesh shouldn't be used in patients who've been infected by MRSA. Additionally, prosthetic mesh shouldn't be placed in areas contaminated by spillage of bowel contents or pus. Biological mesh can be used in areas of previous (but not gross) infection or contamination.

Surgeons should attach meshes using techniques they're most comfortable with during laparoscopic surgeries. However, absorbable fixation devices are better options than non-absorbable spiral or titanium tacks. Absorbable devices might initially irritate nerves around the repair, but the discomfort will theoretically subside as the devices dissolve and time passes.

Surgeons can also use a biologic liquid affixation product, which effectively replaces the need to use tacking devices. An available self-adherent mesh solves the mechanical attachment issues, but is technically difficult to apply because it acts like Velcro in the body, sticking to nearly everything in the anatomical space as the surgeon tries to place it in the defect. It's challenging to align properly and place exactly. (I use this mesh most often in slender patients with clean anatomical structures.)

Myth busting
Surgeons need to grasp the seriousness of this issue and understand that chronic post-op pain creates a financial burden on the healthcare system because of the multiple treatments needed to address it. They must understand that operating carefully around the neurological nerve base and moving exquisitely around sensory nerves when repairing defects are of paramount importance. Hernia repair is not a one-size-fits-all surgery; the procedure must be tailored to the unique anatomy and risk factors of individual patients. Above all, surgeons must dispel the myth that hernia repairs are easy fixes. In fact, hernia surgery is technically challenging and very difficult to do correctly.