Assessing the accuracy of patient-specific guides for total knee arthroplasty

Patient-specific guides have been introduced recently as a means of making accurate bone cuts through custom cutting blocks constructed based on pre-operative three-dimensional imaging. However, the controversy concerning the improved results of patient-specific guides have not been resolved yet; in addition, there have been no studies to investigate the causes of variable with inconsistent results and solutions for the causes. Thirty eight patients (38 knees) underwent total knee arthroplasty with patient-specific guides. The mean age of the patients was 68 years (SD +/- 6.3), and all patients had a minimum 2-year follow-up. An intra-operative alignment using navigation and the causes of outliers were evaluated. An average coronal alignment of PSI jigs was 0.5A degrees (SD +/- 0.9A degrees) in femur and 0.1A degrees (SD +/- 0.8A degrees) in tibia, and the number of outliers was two and three cases, respectively. An average sagittal alignment was 0.6A degrees (SD +/- 0.9A degrees) in femur and 5.5A degrees (SD +/- 1.1A degrees) in tibia, and the number of outliers was three and five cases, respectively. All outliers resulted from large osteophytes near the contact point of patient-specific guides which disturb sitting of the guide. It was suggested that patient-specific guides were an effective and safe method to achieve accurate alignments, with no additional intra-operative complication. It is important to note that surgeons need to be precautious using the patient-specific instrumentation in patients with severe varus deformity. In addition, existing osteophytes which disturb sitting of the guides should be carefully evaluated pre-operatively and intra-operatively. IV.