Novel patient-specific navigational template for total knee arthroplasty

Current techniques for total knee arthroplasty have certain drawbacks, including violation of the intramedullary canals and limited accuracy. The aim of this research was to develop and validate the accuracy of a new computer-assisted preoperative planning concept for the creation of patient-specific navigational templates to replace conventional instruments. Volumetric computerized tomography (CT) scanning was performed on 30 cadaveric knees, and a three-dimensional reconstruction model of each knee was generated from the scan data. Using a reverse-engineering technique, optimal lower-limb alignment and rotational alignment were determined. A navigational template was also designed with a surface that matched the distal femur and proximal tibia. This template, with its corresponding femur and tibia, was manufactured using a rapid-prototyping technique and tested for violations. The navigational template was then used intraoperatively to assist with an arthroplasty in each of the 30 cadaveric knees. Following surgery, the positions of the prostheses were evaluated with X-rays and CT scans. The method showed a high degree of accuracy and reproducibility. In all cases, placing the template manually on the lamina of the femur and tibia was relatively easy. Twenty-eight prostheses were considered to be positioned entirely accurately, whereas two prostheses were considered to have a 1-2 degrees malpositioning. This study thus introduces a novel navigational template for total knee arthroplasty. Preliminary cadaveric trials have demonstrated that this design can improve the accuracy of osteotomy in the surgical procedure.