SECTION I SYMPOSIUM: Symposium: Knee Kinematics and Total Knee Replacement Design

In Vivo Fluoroscopic Analysis Of Fixed-Bearing Total Knee Replacements

Dennis, Douglas A. MD^*,**; Komistek, Richard D. PhD^*,**; Mahfouz, Mohamed R. PhD^*

From the *Rocky Mountain Musculoskeletal Research Laboratory, Denver, CO; and the **Colorado School of Mines, Division of Engineering, Golden, CO.

Reprint requests to Richard D. Komistek, PhD, 2425 S. Colorado Blvd., Suite 280, Denver, CO 80222. Phone: 303-759-1464; Fax: 303-759-2316; E-mail: [email protected].

Clinical Orthopaedics and Related Research 410():p 114-130, May 2003. | DOI: 10.1097/01.blo.0000062385.79828.72

Abstract

In vivo kinematic patterns were determined for subjects (patients participating in the study), having either a fixed-bearing posterior-stabilized or posterior cruciate-retaining total knee arthroplasty. While under fluoroscopic surveillance, subjects did normal gait and a deep knee bend. Video images were downloaded to a workstation computer and analyzed in three dimensions using an iterative model-fitting approach. Femorotibial contact paths for the medial and lateral condyles, axial rotation, and condylar lift-off were determined. During a deep knee bend, subjects having a posterior-stabilized total knee arthroplasty routinely experienced posterior femoral rollback of their lateral condyle and normal axial rotational patterns, whereas random subjects having a posterior cruciate-retaining total knee arthroplasty experienced paradoxical anterior sliding and opposite axial rotational patterns. During gait, posterior-stabilized and posterior cruciate-retaining total knee arthroplasties experienced similar kinematic patterns, with the presence of paradoxical sliding and opposite axial rotational patterns. Subjects having posterior-stabilized and posterior cruciate-retaining total knee arthroplasties experienced condylar lift-off. Subjects having a posterior cruciate-retaining total knee arthroplasty predominantly experienced lateral condylar lift-off whereas subjects with posterior-stabilized total knee arthroplasties experienced either medial or lateral condylar lift-off. Subjects having a posterior-stabilized total knee arthroplasty experienced significantly greater weightbearing range of motion.