Appropriately planned resection depth can impact outcomes after robotic total knee arthroplasty

Introduction

There are many factors to consider while planning and executing a successful total knee arthroplasty. One of these, the amount of bony resection, is determined in part based on the patients’ anatomy and preoperative deformity. Utilizing intraoperative technology such as robotics allows for resection to be done accurately. Therefore, the goal of this study was to investigate the relationship between tibial & femoral resection depths and postoperative outcomes. Additionally, a quantitative method for preoperatively determining the level of resection depth needed was developed.

Methods

A de-identified dataset containing 107 robotic total knee arthroplasty cases was reviewed. Preoperative demographics, preoperative planning details, and sub-scale scores from the Knee Society Scoring System were reviewed. Analysis was performed to find significant associations with the sub-scale scores. Additionally, multiple regression models were developed to predict resection depth values.

Results

Associations were found between femoral resection depth and Satisfaction & Function scores three months postoperatively. Additionally, Satisfaction and Function were 6 % and 16 % higher respectively when the native alignment strategy was used rather than mechanical alignment of the lower limb. Three-month Function scores were also 6 % higher for males than females. The models to predict resection depth included alignment strategy, preoperative knee deformity, and gender as the significant contributors.

Conclusion

Tibial and femoral resection depth can influence postoperative outcomes. Therefore, it is important to understand what factors contribute to the determination of how much bone should be resected. With that information, patient-specific preoperative plans can be developed with the intent of optimizing postoperative outcomes.