ACCURATE MEASUREMENT OF 3-DIMENSIONAL KNEE REPLACEMENT KINEMATICS USING SINGLE-PLANE FLUOROSCOPY

A simple extension of a previously reported object recognition techniq ue has been used to implement a six-degree-of-freedom position/orienta tion estimator for the measurement of knee replacement motion from two -dimensional (2-D) fluoroscopic images. Computer modeling studies and controlled mechanical tests were performed to assess the accuracy of t he technique. The results indicate that knee rotations can be measured with an accuracy of approximately one degree and that sagittal plane translations can be measured with an accuracy of approximately 0.5 mm. The measurement technique is uniquely well suited for performing dyna mic kinematic measurements on individuals with knee replacements, and for performing comparative studies among subjects with different desig ns of knee replacements.