Both posterior stabilized (PS) and cruciate retaining (CR) total knee replacement systems have demonstrated high rates of survivorship, high clinical knee scores and high patient satisfaction scores over the last few decades. However, CR total knees sometimes exhibit more varied kinematics and diminished range of motion (ROM) than similar PS knees. One known cause of this is a posterior cruciate ligament (PCL) that does not optimally work with the tibial insert, allowing for paradoxical femoral anterior translation in flexion and impingement between the posterior lip of the tibial insert and the posterior femur. This appears to be related to difficulty obtaining optimal postoperative PCL function.
To achieve full (or nearly full) PCL function, a number different surgical techniques have been suggested. These include increasing the slope of the proximal tibial resection, recession of the PCL along its tibial attachment, and resection of additional posterior femoral bone. Each of these approaches can have negative consequences for PCL function and CR total knee replacement performance.
For example, if the PCL is found to be too tight, the surgeon can reduce its tension by re-cutting the proximal tibia with an increased posterior tibial slope. Increasing the slope of the proximal tibial resection can damage the PCL (and/or the tibial PCL attachment), because the re-cut can be distal to the tibial PCL attachment (see FIG. 6).
Among those benefits and improvements that have been disclosed, other objects and advantages of this invention will become apparent from the following description taken in conjunction with the accompanying figures. The figures constitute a part of this specification and include illustrative embodiments of the present invention and illustrate various objects and features thereof. Further, the same reference numerals represent similar elements in the Figures.
USPTO Backgrounds
USPTO Backgrounds