Cutting errors in total knee replacement

Abstract

INTRODUCTION: The observed errors in the implanted prosthesis in TKR can be due to a number of causes. One of these is the potential error during execution of the bone cuts. However, information concerning this item is minimal in the literature. MATERIALS AND METHODS: The amount of cutting errors in forty consecutive TKRs was reported. The execution of the bone cuts were done either through the cutting slot (slotted-cutting) or on the surface of the cutting guide (open-cutting). The amount of cutting error after the firstcut was measured by the use of computer navigation system. It was hypothesized that there was no difference in the error between slotted-cutting and open-cutting. This was examined using Mann-Whitney U Test. RESULTS: It was found that the average cutting error was 1 degree in the coronal plane and 1.4 degrees in the sagittal plane. Significantly more outlier (>3 degrees) was observed in the errors in the sagittal plane (p=0.014). 58 cuts were done through the cutting slot and 22 cuts were done on the surface of the cutting guide. Open-cutting resulted in less error in the sagittal plane of the tibial cut when compared with slotted-cutting (p=0.031). DISCUSSION AND CONCLUSION: The magnitude of the error in the execution of bone cut in TKR was around 1 degree. Open-cutting resulted in less error. This was attributed by the use of a thicker saw blade with higher stiffness in the open-cutting method.