Comparison of high-flex and conventional implants for bilateral total knee arthroplasty

Abstract

Clinical and radiographical outcomes of conventional versus high-flex implants were compared in a prospective study in twenty patients one year after bilateral total knee replacement. First, a conventional posterior stabilized total knee arthroplasty (TKA) was implanted in one limb. Six to eight months later, the contralateral knee of each patient was replaced with a high-flexion design TKA. Clinical and radiological parameters including Knee Society objective and functional Scores (KSS), range of motion, tibial slope, position of the femoral component, angles between the components and the anatomical axis of femur and tibia and final varus or valgus alignment were evaluated one year after the operation.One year after surgery, for PS implants mean knee score and mean functional score were 79 points (range 72 to 93 points) and 81 points (range 70 to 100 points), whereas for RPF knees they were 86 points (range 76 to 93 points) and 91 points (range 75 to 100 points) respectively. Mean maximal flexion 97o in the PS group and 118o in the RPF knees. These results were significantly better for the High flex implants. No differences were found in the radiological results.We conclude that the high flexion TKA is associated with a higher range of motion of the knee resulting in better functional outcomes.