Groin Pain After Hernia Repair

Pain persisting beyond the first few days after groin hernia repair is recognized to affect small numbers of patients, generally estimated to be 10–15% of hernias repaired. In nearly all of these patients, the pain subsides postoperatively over the early months. Chronic, disabling pain persisting at and beyond 1 year is thought to be real but rare, affecting less than 1% of patients undergoing inguino-femoral hernia repair. Indeed, Devlin indicates that every year “some 400,000 inguinal hernias are repaired, and yet even the biggest series of reports of pain after inguino-femoral hernia repair from the United States are of only 17 or 23 cases. Therefore, this must be a remote hazard… .”1 Severe chronic pain following hernia repair is usually due to ischemia or to neuropathy. Ischemia induced in musculofascial tissues by a repair done under tension is the most common cause of undue postoperative pain. In this situation, the sutures slowly cut through the tissues, relieving the pain but setting the stage for recurrence. The other major cause of ischemia-induced pain is tight closure of either the deep or superficial inguinal ring during repair. Most often, ischemia in the ring is partly due to edema following operative dissection, and resorption of edema postoperatively leads to gradual resolution of pain; rarely does testicular atrophy supervene. Neuropathy is widely recognized as a cause of chronic postoperative pain. It can be induced by nerve trauma during dissection, neuroma formation after partial or complete transection, entrapment by sutures, or by postoperative adhesions. The implantation of mesh, which induces scar formation through increased inflammation, also has been suggested as a cause of neuropathic pain. 2 More than a decade ago it was true that chronic disabling pain was rare after hernia repair. It is also true that the reported incidence of this problem has been increasing in recent years, 3 although the reasons for this change are not entirely settled. It is important to know the true incidence of chronic, disabling pain after hernia repair so that patients can make an informed choice of whether or not to undergo repair, and so they can receive an acceptable informed consent. Generally, problems with an incidence of less than 1% are thought not to need specific mention in discussing with patients the potential complications of an operation. The report from the Danish Hernia Data Base group 4 suggests that in current practice, the incidence of chronic pain 1 year after groin hernia repair may be approximately 29%. That number is unexpectedly high, and certainly will gain the attention of all surgeons who repair hernias. It is important to know if the incidence is truly so high and, if so, to learn what causes the pain. If the incidence truly exceeds 1 percent, then pain will need to be specifically mentioned in preoperative discussions with patients. The Danish report is based on two questionnaires mailed 1 year postoperatively to 1,443 patients having a hernia repair during a 2 month period in 1998. More than 80% of patients responded to each questionnaire. The first time around, patients were asked whether or not they had pain; 29% said they had pain, and 11% indicated that their pain was disabling to some degree. The second questionnaire was sent to those reporting pain, asking about specific pain characteristics; 58% of those experiencing pain now indicated that their pain impaired specific activities. There was no correlation of postoperative pain with the type of hernia or the method used for repair. These data need to be interpreted in terms of the limitations of the study methodology. Self-reporting, especially of the severity of such a subjective matter as pain, is confounded by variable perceptions of pain between patients, varying definitions of impairment, and similar limitations. In essence, the severity data from this study are not completely reliable. And, there was no evaluation by a physician, preferably a blinded one, of the patient’s complaints. I am not trying to denigrate the study, for it reports important data and raises important questions. But it does not provide final answers. This study suggests that something in the currently employed methods of groin hernia repair is associated with an increase in postoperative pain, and it provides a hypothesis for future investigation. These provocative results should stimulate additional effort and prospective clinical trials by the Danish Data Base Group and others to elucidate the exact causes in current surgical practices of postoperative groin pain. Could it be that the major change in the technique of hernia repair that has evolved over the most recent two decades—the widespread use of implanted prosthetic mesh, whether needed or not—is a cause?