IN-VIVO KINEMATICS OF CRUCIATE-RETAINING AND CRUCIATE-SUBSTITUTING KNEE ARTHROPLASTIES

A fluoroscopic measurement technique has been used to provide detailed three-dimensional kinematic assessment of knee arthroplasty function during a step-up activity. Three groups of knee arthroplasty subjects with excellent clinical outcomes and similar ranges of motion were eva luated. Each group received different prosthetic components and surgic al treatments of the posterior cruciate ligament (PCL). Group 1 had re latively flat articular surfaces with retention of the bony insertion of the PCL, group 2 had similar articular geometry but recessed the PC L without retaining the bony insertion, and group 3 had prostheses wit h greater sagittal conformity and post/cam substitution of the sacrifi ced PCL. Although none of the knees exhibited normal knee kinematics, the ranges of axial rotation and condylar translation for group 1 were similar to ranges previously reported for normal and anterior cruciat e-deficient knees. Axial rotations and condylar translations decreased when the PCL was surgically recessed or substituted. The smallest kin ematic ranges were observed in group 3. The results indicate that both prosthetic component selection and surgical technique have a signific ant effect on prosthetic knee kinematics during functional activities.