Applying the proper amount of tension to knees collateral ligaments during surgery is a prerequisite to achieve optimal performance after TKA. It must be taken into account that lower values of ligament tension could lead to an instable joint while higher values could induce over-tensioning thus leading to problems at later follow-up: a “functional stability” must then be defined and achieved to guarantee the best results. In this study, an experimental cadaveric activity was performed to measure the minimum tension required to achieve functional stability in the knee joint. Ten cadaveric knee specimens were investigated; each femur and tibia was fixed with polyurethane foam in specific designed 3D-printed fixtures and clamped to a loading frame. A constant displacement rate of 0.05 mm/s was applied to the femoral clamp in order to achieve joint stability and the relative force was measured by the machine: the lowest force guaranteeing joint stability was then determined to be the one corresponding to the slope change in the force/displacement curve, representing the activation of the elastic region of both collateral ligaments. The force span between the slack region and the found point was considered to be the tension required to reach the functional stability of the joint. This methodology was applied on intact knee, after ACL-resection and after further PCL-resection in order to simulate the knee behavior in CR and PS implants. The test was performed at 0, 30, 60 and 90° of flexion using a specifically designed device. Each configuration was analyzed three times for the sake of repeatability.INTRODUCTION
METHODS
Functional stability is a new concept stating that lower tensions than expected are enough to achieve joint stability leading to proper function after TKA. To check this rationale clinically, a new electronic device (DLB bicon sensorplate) was used intraoperatively to measure ligament tension and allow the surgeon to proper balance the knee after TKA insertion. In this study a controlled clinical analysis at 1 YR follow-up is reported. A cohort of 25 patients was treated in a single centre, single surgeon study to quantify the influence of the use of this electronic device in the short- and midterm results (DLB Group). A control cohort of 25 patients were treated without the device (Control Group). All patients were monitored by the use of OKS, AKSS and FJS; beside that, the muscle function before and after the surgery was tested and a load distribution analysis was performed. The FU examinations were done after 6 weeks, 3 months, 6 months and 1 yr. All the patients finished the study and could be included.Introduction
Methods
