Biomechanics of Patellofemoral Joint Prostheses

Patellofemoral joint forces

“…Without this lateral reaction force the patella would be subject to subluxation laterally. Several authors have examined this force in the normal knee and in implanted knees (Amis et al, 2005;Heim and Postak, 1993;Miller et al, 1995;Singerman et al, 1994Singerman et al, , 1995aSingerman et al, , b, 1999Steubben et al, 1993;Pelker et al, 1991). There can be considerable scatter in the medial/lateral force (Singerman et al, 1995a) making it difficult to determine which force to expect.…”

Aseptic loosening of the patellar component at the cement–implant interface

“…There is a fourfold increase in the joint reaction force during flexion when compared to extension [9]. Further, the joint reaction force at the sagittal plane passes through proximal patellar articulation when the knee is flexed and this point of contact changes to distal edge of the patella as the knee is extended [8,9]. As a result of these changes in point of contact and the magnitude of these forces, a cyclic rocking effect is set up on the patellar button in a proximal distal fashion.…”

“…The magnitude of joint reaction force increases as the knee flexes to maintain equilibrium against rising quadriceps force and patellar tension [8]. There is a fourfold increase in the joint reaction force during flexion when compared to extension [9].…”

In Vivo Kinematics of the Extensor Mechanism of the Knee During Deep Flexion

“…In contemporary TKA components, while the patellofemoral contact locations have been measured using various techniques [31,32], the effect of the TKA on the function of the quadriceps-patellar tendon-patella complex has not been reported. Further, the patellofemoral contact biomechanics of the knee were not reproduced by the TKAs during flexion [20,[33][34][35]. It is unknown if a physiological quadriceps and patellar tendon ratio could be reproduced in the knee after a TKA implantation.…”

“…. A line connecting this intersection and the contact point was considered as the direction of the joint reaction force [11,20,21]. An angle between the quadriceps and the direction of the patellofemoral joint reaction force was defined as the quadriceps angle (OQ-F), and that between the patellar tendon and the direction of the patellofemoral joint reaction force was deflned as the patellar tendon angle (Op^f).…”