The Posterior Tibial Slope Effect to Gap Difference on a Single Radius System for Total Knee Arthroplasty Based on the Computer-Aided Design Approach

Total knee arthroplasty (TKA) is one of the most successful ways of treating pain and functional limitations due to osteoarthritis. Asians and Middle Easterners need a large range of flexi angles for religious, social, and cultural activities. Prayer activities and seiza required flexible angle from 150° to 165°. To support these activities, a TKA high flexion (high-flex) type is required. The application of high-flex TKA causes a difference between extension gap and flexion gap, called gap difference. Gap difference is strongly influenced by posterior tibial slope (PTS) and single radius system, and it causes TKA instability. This study aims to analyze the stability of AKJ with GD measurement on a single radius system with a computer-aided design (CAD) approach to prayer, social, and cultural activities for Asians, especially in Indonesia. This study uses the CAD approach with stages that are implant scanning, surface processing, curve processing, components improvement, and gap difference measurement. This study has successfully tested the stability of the model against the difference between gap extension and gap flexion. TKA model with a maximum of PTS 6° can be recommended for the purposes of Asian activities, especially Indonesians in religious, social, and cultural activities. In the future, stability tests will be needed for the movement of anterior–posterior translation.