Angle Accuracy of Intramedullary Bone Resection Guides for Total Knee Arthroplasty

The importance of proper prosthetic placement has been confirmed in numerous studies. The objective of this study was to compare the planned resection angles to the verified intraoperative angles of femoral and tibial varus/valgus, tibial slope, and femoral flexion for each total knee performed using intramedullary (IM) cut guides for both distal femur and proximal tibia cuts. A total of 1,000 total knee arthroplasties (TKAs) were evaluated for this study. Intraoperative cut-check technology was used to show real-time validation of these resection angles. Assuming an acceptable range of within 2° of the planned cuts, results show the femoral varus/valgus angles were 75% accurate, the femoral flexion angles were 50.8% accurate, the tibial cuts were 95.2% accurate in the coronal plane, and the tibial slope was the least accurate with only 50.3% within the acceptable range. This showed that IM guides are reasonably accurate in producing desired angles in the coronal plane but less accurate in the sagittal plane, with a greater number of outliers in femoral flexion and posterior slope. Surgeons need to be aware of potential cutting errors when using IM guides as they affect the overall alignment of the implant, and real-time verification technology is available to verify the accuracy of the cuts.