Decreased collagen type I/III ratio in patients with recurring hernia after implantation of alloplastic prostheses

Background. Abnormal collagen metabolism is suspected to play an important role in the pathogenesis of recurring inguinal and incisional hernias. Whereas alloplastic prostheses are nowadays routinely used, the quantity and quality of collagen formation after repair in humans has not been analysed in a large cohort. Method. Seventy-eight prostheses (Prolene, Atrium, Marlex, Vypro, Mersilene, Gore-Tex) implanted for inguinal and incisional hernia repair were explanted because of recurrence, chronic pain or infection. The mean implantation period was 17.9+/-11.2 (range 0.5-48) months. Collagen formation was investigated quantitatively (collagen-protein ratio) and qualitatively (collagen type I/III ratio). Results were related to clinical data that included gender, age, implantation period, indication for implantation/explantation, type and location of prosthesis. Results. Mean collagen-protein ratio was 45.3+/-8.5 mug/mg, with significant differences between male (43.8+/-9.1 mug/mg) and female tissue samples (48.1+/-6.8 mug/mg, P=0.033). The mean collagen type I/III ratio of all samples investigated was 2.1+/-1.4. Samples explanted for recurring hernias exhibited a significantly decreased ratio (1.3+/-0.7, P<0.05) compared to samples explanted because of pain (3.4+/-1.2) or infection (2.9+/-1.6). Multivariate analysis excluded independent effects of age, gender, indication for implantation of prostheses, location and implantation period on collagen type I/III ratio. Conclusion. The present study confirms the importance of a biological approach, next to technical aspects, to the understanding of the pathogenesis of recurrent hernia formation and underscores the presence of a disturbed scarring process. The composition of scar tissue with a lowered collagen type I/III ratio and, therefore, reduced tensile strength may be a major contribution to hernia recurrence.