Randomisation is 1:1 between Strattice® mesh vs. standard closure. The sample size for the trial is 560 (80% power, 10% dropout/crossover, 40% proportional reduction - 25% to 15%) and recruitment will be over 2 years from at least 30 centres. ROCSS will be a double blind (observer blind) randomised controlled trial with a CT scan at one year and clinical follow up at 2 years. Cost benefit analysis and quality of life analysis will be performed at 2 years. The sample size will be reviewed prior to reaching target and may be increased 790 (90% power, 20% dropout/crossover, 40% proportional reduction - 25% to 15%).