Abstract
Change in the joint line in TKA has been recognized as an important parameter in association with post-operative soft tissue tension, range of motion, and knee kinematics. In general, the joint line has been assessed only in tibial side based on the bony reference point of tibia. However, the joint line should also be assessed in the femoral side. This is because a replaced femoral condyle often does not accurately restore the geometry of the original condyle, depending on the alignment, the size, or the design of the component. This discrepancy, especially in the geometry of the distal and posterior condyle will greatly affect the knee kinetics in association with the soft tissue tension. Objective of this study was to investigate how joint line was changed in femoral and tibial condyle by TKA.
We have developed a method to assess the femoral-joint line and the tibial joint line three-dimensionally and quantitatively by the 3D model image matching to biplanar computed radiography. Twenty-knees underwent TKA and 3D joint line examination.
Most of the knees demonstrated the significant proximal movement of the medial joint line in tibia, while the lateral joint line was restored. The significant distal movement of the distal femoral joint line was demonstrated in most of the knees, and it was demonstrated more frequently in medial condyle. Most of the knees demonstrated the significant anterior movement of posterior femoral joint line while no knee demonstrated the significant posterior movement.
From the results of this report, it was proved that the joint line can be changed by TKA procedure not only in tibial condyle but also in distal and posterior femoral condyles with considerable variations. In addition, it was also proved that there can be a difference in the change in the joint line between medial and lateral condyle.
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Award for the best student biomaterials paper (US$ 2,000); a proper certificate
Correspondence should be addressed to Richard Komistek, PhD, International Society for Technology in Arthroplasty, PO Box 6564, Auburn, CA 95604, USA. E-mail: ista@pacbell.net
