The following secondary outcome measures were not significantly different between the @W and the @W series with regard to residual symptoms ( @ vs @ % ; P = @ ) , rate of complications ( @ vs @ % ; P = @ ) , need for synchronous robot-assisted pyelolithotomy ( @ vs @ % ; P = @ ) , improvement in split renal function ( @ vs @ % ; P = @ ) and duration of surgery ( @ vs @min ; P = @ ) .