In vivo patellofemoral forces in high flexion total knee arthroplasty

Abstract This study compares the in vivo patellofemoral contact forces generated in high flexion fixed bearing posterior cruciate retaining Nexgen CR-Flex (PCR) and high flexion posterior stabilized Nexgen LPS-Flex (LPS) TKAs with that of normal knees from full knee extension to maximum weight beari...

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Bibliographic Details
Published in:Journal of biomechanics 2008-01, Vol.41 (3), p.642-648
Main Authors: Sharma, Adrija, Leszko, Filip, Komistek, Richard D, Scuderi, Giles R, Cates, Harold E, Liu, Fei
Format: Article
Language:English
Subjects:
Arthroplasty, Replacement, Knee
Biomechanical Phenomena
Bones
CAD
Computer aided design
Femur - diagnostic imaging
Fluoroscopy
High flexion TKA
Humans
Inverse dynamics
Joint replacement surgery
Kinematics
Knee
Knee Prosthesis
Ligaments
Models, Biological
Patella - diagnostic imaging
Patellar Ligament - diagnostic imaging
Patellofemoral force
Physical Medicine and Rehabilitation
Quadriceps Muscle - diagnostic imaging
Range of Motion, Articular
Stress, Mechanical
Surgeons
Tibia - diagnostic imaging
Transplants & implants
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Summary:Abstract This study compares the in vivo patellofemoral contact forces generated in high flexion fixed bearing posterior cruciate retaining Nexgen CR-Flex (PCR) and high flexion posterior stabilized Nexgen LPS-Flex (LPS) TKAs with that of normal knees from full knee extension to maximum weight bearing flexion. Ten patients with the PCR total knee arthroplasty (TKA), ten with the LPS TKA and seven patients having normal knees were fluoroscoped while performing a deep knee bend activity. In vivo femorotibial kinematics, obtained from 3D-to-2D registration technique, and patellar kinematics obtained by direct measurements from the fluoroscopic images were entered into a 3D inverse dynamics mathematical model to determine the in vivo contact forces at the knee. The variation in the patellofemoral and quadriceps forces with flexion were found to be similar across the three groups—increasing from full extension to 90° of flexion, reaching a maximum between 90° and 120° of flexion and then decreasing until maximum flexion. At maximum knee flexion, these forces were found to be significantly lower in the normal knees than in the TKAs. The patellar ligament to quadriceps force ratio decreased with the increase in knee flexion while the patellofemoral to quadriceps force ratio increased. A strong correlation was found to exist between the patellofemoral forces, the femorotibial contact forces and the forces in the extensor mechanism. The PCR TKA in this study exhibited greater resemblance to the normal patients with respect to the patellofemoral forces than the LPS TKA though significant differences in the two implant types were not observed.
ISSN:0021-9290
1873-2380
DOI:10.1016/j.jbiomech.2007.09.027