PURPOSE: Inguinal hernia repairs should have few complications and a short learning curve. A new operation called Onstep has promising results, but still some recurrences. The aim of the study was to find reasons for recurrence, by studying the re-operations.

METHODS: The study is a case series, where 565 patients operated with Onstep at six hospitals between December 2011 and April 2015 were identified. If a recurrence had occurred, the description of the re-operation was studied and compared to the primary Onstep operation.

RESULTS: We found 26 inguinal hernia recurrences, giving a recurrence rate of 4.6 %. The reasons for recurrence were a cranial displacement of the mesh in five patients, a caudal displacement in three patients, a folded mesh in one patient, and broken sutures in the mesh laterally in six patients. We found indications of a learning curve, since 70 % of the recurrences had their primary operation among the first half of the total Onstep procedures. Another finding was that 30 patients had complaints from the ring in the mesh, and most of these patients were slender. Fifteen patients have had the ring removed, and for six patients with a follow-up, the complaints have been reduced or disappeared.

CONCLUSIONS: The main reasons for recurrence may be broken sutures in the mesh laterally or a suboptimal size of the opening in fascia transversalis medially, enabling the mesh to displace. Furthermore, the results suggest a learning curve. These findings may guide further improvement in the Onstep method for inguinal hernia repair.