Introduction: This prospective cohort study involved 781 elective primary inguinal hernia operations performed on 736 patients at the Hernia Centre of Reinbek Hospital from April 2000 to April 2002.
Material and Methods: Small hernias were fixed by the Shouldice repair, and large defects by the Lichtenstein repair with conventional polypropylene mesh. Pain was assessed before the operation, on day 0, 1, 2, 7, 6 months and 5 years after the operation by the visual analogue scale (VAS). The follow-up was 90.1% after 6 months and 82.6% after 5 years. Chronic pain (CP) was assessed in relation to preoperative pain, nerve anatomy and intraoperative nerve management. The anatomy of the iliohypogastric nerve (IHN), ilioinguinal nerve (IIN), and genital branch of the genitofemoral nerve (GB) before and after surgery was recorded in every operation.
Results: The preoperative pain rate was 41.0%. The CP and sensory disorder rate after 6 months were 16.4% and 15.9, respectively. The only independent significant parameters for CP after 6 months were preoperative pain (P < 0.002) and sensory disorder of the groin after 6 months (P < 0.0001).
After 5 years 16.1% of patients reported pain and 20.3% sensory disorder of the groin. Independent significant predictors of CP were: Preoperative pain (P < 0.024), IIN neurolysis in Lichtenstein repair (=IIN mobilization from its natural bed and nerve preservation; P < 0.002), CP after 6 months (P < 0.006) and a sensory disorder after 5 years (P < 0.0001). Eleven of 12 patients with relevant CP (VAS > 3) after 5 years had had a Lichtenstein repair with IIN neurolysis.
The CP population of preoperative pain free patients changed with time: 65% of the patients with CP after 6 months were pain free after 5 years, and 69% of the patients with CP after 5 years were asymptomatic after 6 months.
Conclusion: Mesh contact with a nerve removed from its natural bed may cause chronic long-term pain. The combination of IIN neurolysis and the Lichtenstein repair should be avoided.