Although there was a significant reduction of the duration of surgery in both patient-specific instrumentation groups in comparison to conventional instrumentation ( MRI versus conventional , 58 minutes [ range , 53-67 minutes ] versus 76 minutes [ range , 57-83 minutes ] , p < 0.001 ; CT versus conventional , 63 minutes [ range , 59-69 minutes ] versus 76 minutes [ range , 57-83 minutes ] , p < .001 ) , there were no differences in the postoperative Knee Society pain and function and WOMAC scores among the groups .