Investigating intraoperative joint capsule using a pressure sensor tensor in posterior stabilized TKA

Knowledge of the biomechanical behavior of the knee prosthesis can have an important influence on balance, stabilization and lifetime of total knee prosthesis. A ligament tensioning device with pressure sensor was used to measure the torque versus rotation between the tibia and femur during total knee arthroplasties. The measurements were performed with the knee flexed, after balance in extension. We followed the testing of a mathematical model description, evaluation of the force / torque accumulated in the capsular ligament structures during balancing and at 5 ° of knee deviation. Statistical tests have validated the model. The force balance was influenced by the inclination of the tibial surface, the extension deficit, the size of the tibial plateau, the deviation of HKA axis and slice thickness of tibial osteotomy. These data help to establish the force necessary for joint replacement. They demonstrate that the force required during prosthesis balancing is determined by many factors and thus it´s incalculable preoperatively. This requires the use of devices that indicate equilibration intraoperatively.