Comparison of custom cutting guides based on three-dimensional computerized CT-scan planning and a conventional ancillary system based on two-dimensional planning in total knee arthroplasty: a randomized controlled trial

Purpose Incorrect positioning of components during total knee arthroplasty (TKA) increases the risk of pain, instability, and early revision. The purpose of this study was to compare 3D planning-assisted and a conventional system for TKA positioning. We hypothesized that the use of three-dimensional CT-scan planning and custom cutting guides would increase the accuracy of component positioning. Methods A randomized, controlled, prospective study of two groups was performed. In one group, patient-specific custom cutting guides (PSCG) were used for component positioning based on 3D CT-scan planning. In the control group, TKA was performed with a conventional ancillary system. The components' positioning angles were measured on 3D reconstructions. The main evaluation criterion was the percentage of outliers outside of a target zone of +/- 3 degrees for the coronal positioning of the femoral component. Results Eighty patients were included. The percentage of outliers for the femoral component was significantly lower in the 3D-guided group (1 patient) compared to the control group (7 patients p = 0.02). The coronal femoral angle was restored with greater accuracy in the 3D-assisted group (- 0.1 degrees +/- 1.4 degrees) compared to the control group (1.6 degrees +/- 2.5 degrees). Surgery was significantly shorter in the 3D group. The clinical outcomes were better in the 3D group at the two year follow-up with fewer failures and a lower standard deviation in IKS scores. Conclusion The use of a 3D planning and custom guides can improve TKA component positioning by increasing the accuracy of implants alignment and reducing the percentage of outliers. The same benefit was not demonstrated for the global knee alignment and the clinical scores with no indisputable clinical advantage for the PSCG.