Validation of three-dimensional total knee replacement kinematics measurement using single-plane fluoroscopy

Instability of the knee after total knee arthroplasty (TKA) is today the number one reason for aseptic revision surgery. In vivo evaluation of knee kinematics using single-plane fluoroscopy has become an important method to investigate knee stability and compare dierent implant designs. A validation experiment was performed to assess the accuracy of this method. A total knee implant was installed on sawbones and a flexion extension movement was performed with the sagittal plane parallel to the detector panel of the fluoroscope. Simultaneously, the sawbones were tracked using a conventional motion tracking system and rigidly attached markers. That measurement can be seen as a golden standard and is therefore believed to represent the real positions. The results indicate that knee rotations can be measured with an accuracy of approximately 0.6 and sagittal plane translations can be measured with an accuracy of approximately 0.4 mm. These results prove that the method is sufficiently accurate for clinical use.