Abstract
Historical studies in TKA suggest that 82–89% of patients are satisfied with TKA. Bourne et al. reviewed 1703 patients and reported that in newer designs that things have not improved much. Approximately one in five (19%) primary TKA patients were not satisfied with the outcome. Satisfaction with pain relief varied from 72–86% and with function from 70–84% for specific activities of daily living. The burden of OA is increasing in society and younger patients are undergoing TKA.
A customised, individually made (CIM) knee arthroplasty (iTotal, ConforMIS Inc., Bedford, MA USA) has been introduced by individualising component geometry; exact sizing- medial – lateral and anterior–posterior, restoring medial and lateral joint lines, and restoring individual “J Curves” of the patients’ native femur as it was prior to the arthritic condition. This is done by preoperative CT scanning to include hip-knee-ankle and software to CAD-CAM manufacture of the individualised implants, with accompanying individualised cutting jigs. The hypothesis is to restore form and ultimately function. Will this lead to improved patient satisfaction?
Cadaveric comparison on an “Off The Shelf ” (OTS) implant to CIM implant in 9 matched pair analyses before and after TKA demonstrated that the CIM implant motion was not different than their preoperative kinematics of the knee but the OTS implant was.
In vivo comparisons performed fluoroscopically of CIM implants versus OTS implants further demonstrated a more normal knee in terms of kinematics and stability in the CIM knee.
Follow up of 110 consecutive patients undergoing a CIM CR TKA revealed patient satisfaction of 98%. Patient average age was 56.1 years old, average follow up 20 months. Two patients required revision- (both dissatisfied)- one for tibial subsidence 18 months after TKA (osteoporosis and obesity) the other developed global laxity at 9 months postoperatively. Both revised with stabilised PS OTS implants. At this early average follow up of <2 years it appears that patient satisfaction improves over prior OTS implant satisfaction with a CIM TKA that restores native size and geometry.
