Kinematic alignment total knee replacement with personalized instruments

There is a very wide variation in patients’ knee anatomy. The precise restoration of this anatomy during total knee arthroplasty (TKA) may improve knee balance, clinical function and patient satisfaction. In the early ages of TKA, implant sizes and surgical precision were limited. The amount of deviation from a patient’s anatomy that may impact on clinical results is not clear. However, in the era of personalized joint replacement, we believe that a precision of within 2 mm or 2° should be the goal. Performing a kinematically aligned (KA) TKA requires accurate planning of resections and precise tools to achieve the set goals. Patient-specific instrumentation is a very attractive solution. These patient-specific instruments (PSI) are constructed based upon preoperative planning using either tomographic or magnetic resonance imaging. 3D models of the patient’s knee, hip and ankle are reconstructed and anatomical landmarks are identified to set the parameters of tibia and femur resections according to the surgeon’s preferences. Compared to standard instruments, computer navigation or robotic surgery, PSI results in a shorter operating time and decreased instrumentation. PSI is a simple, standardised solution for a patient-specific restricted KA protocol in TKA, with many benefits to the surgeon and patient.