115 patients (90 followed up included in this secondary follow-up) were randomized to receive computer assisted or conventional total knee arthroplasty (TKA). At 6 weeks, there was a significantly greater proportion of patients in the computer assisted group who had a coronal alignment within 3 degrees of neutral compared to those who received conventional TKA. At 5 years, International Knee Society and Short Form-12 (SF-12) scores were significantly better in the patients with a coronal alignment within 3 degrees of neutral than in those with a less accurate alignment.