2.4 Ethical statement and registration of clinical trial This observational study was performed under the approval of the medical ethical committee of the region Arnhem-Nijmegen. All patients, after extensive pre-operative information, gave written informed consent due to the experimental nature of this treatment at that time. This clinical trial was not registered in 2003 due to the fact that, in The Netherlands, MCS was not an experimental method at that moment. The authors confirm that all ongoing and related trials for this intervention are registered