Effect of total knee arthroplasty on sagittal and frontal dynamics in osteoarthritis subjects Chénier F. 1 , Lavoie F. 1,3 , Clément J. 1,2 , Hagemeister N. 1,2 , De Guise J.A. 1,2 , Aissaoui R. 1,2, 1 Laboratoire de recherche en imagerie et orthopédie, Centre de Recherche du Centre Hospitalier de l’Université de de Montréal. 2 Dépt. de génie de la production automatisée. École de technologie supérieure. (rachid.aissaoui@etsmtl.ca) 3 Service de chirurgie orthopédique, Centre Hospitalier de l’Université de Montréal Abstract- There is still no consensus about the benefits of a postero-stabilized prosthesis (PS) versus a bicruciate preserving prosthesis (2C) following a total knee arthroplasty (TKA). Whereas clinical outcome parameters could not conclude on each prosthesis advantages, little is known on the knee dynamics using both prostheses. In this work, six TKA candidates walked at self-selected speed, once before the TKA, then one year after. Three had a PS and three had a 2C. Five control subjects were also evaluated. Knee moments in the sagittal and frontal planes were computed. In the frontal plane, external adduction moments generally decreased between pre-op and post-op. In the sagittal plane, external knee flexion moments were strongly reduced for one PS subject and for two 2C subjects between pre-op and post-op evaluations. In the frontal plane, external adduction moments were reduced for two PS subjects and one P2C subject between pre-op and post-op evaluations. Keywords- Total knee arthroplasty, Knee osteoarthritis, Gait analysis, Inverse dynamics 1 INTRODUCTION Many factors affect postoperative motion in total knee arthroplasty (TKA): component design, ligament and muscle tension, component alignment, and the change in joint line before and after component implantation [1]. In normal knees, it has been suggested that the so-called screw-home mechanism occurs as a result of the function of active stabilizers, in combination with geometric and ligamentous restraints [2]. Clinical outcome parameters such as the American Knee Society Scores cannot provide a consensus on the benefits of posterior- stabilized (PS) versus bicruciate-preserving (2C) TKA [3]. On the other hand, knee joints dynamics in the sagittal and frontal planes remain unclear between pre and post-operation with respect to normal gait profiles [4], [5]. Dynamic knee adduction moments have been reported to be reduced after TKA using a posterior- stabilized prosthesis. It was found in [6] that peak adduction moment was reduced to 85% of the preoperative level at 6 months but increased to 94% of the preoperative level at 1 year. The authors concluded that the posterior-stabilized TKA reduces knee adduction moment at 6 months, but this effect is lost with time i.e. after one year [6]. The purpose of this study is to test the effect of two types of prosthesis: a posterior-stabilized prosthesis (PS) and a bicruciate-preserving prosthesis (2C), in the progression of the sagittal and frontal patterns of knee joint moment one year after total knee arthroplasty. In this work, the six first subjects of a large-scale study were evaluated before and one year after TKA. Sagittal and frontal knee moment patterns are reported. 2 MATERIAL AND METHODS 2.1 Subjects Six patients with knee osteoarthritis who underwent TKA and five healthy control subjects participated in this study. TKA patients were separated in two groups: three patients received a posterior-stabilized prosthesis (PS) and three received a bicruciate-preserving prosthesis (2C). Both PS and 2C were Ceraver Osteal total knee replacement prostheses. This study was addressed to any eligible TKA patient being candidate to a prosthesis that preserves both cruciate ligaments. The subjects must present a disabling knee osteoarthritis with failure of the conservative treatment; must be 70 years old or less; have intact cruciate ligaments; present a coronal knee misalignment of 10 degrees or less; have a knee flexion contracture of 10 degrees or less and a minimal flexion of 90 degrees; and surgical exposure of their knee must be sufficient to allow preservation of both cruciate ligaments. The excluding criteria included morbid obesity, and the incapacity to walk on a treadmill or to squat.