Abstract
Background:
The safety implications of achieving high flexion after TKA and the use of high flexion prostheses remain issues of concern. It is possible that different designs have different clinical and radiological results and complications, such as, early aseptic loosening. However, little information is available on the clinical results of TKAs performed using single-radius, high-flex posterior stabilized design. Accordingly, this study was undertaken to document results of single-radius, high-flex posterior stabilized TKAs with minimum 7-year follow-up.
Methods:
From April 2003 to February 2006, 308 patients (455 knees) underwent TKA using single-radius, high-flex posterior stabilized design and among those patients, 251 patients (388 knees) included in this study who were able to be followed up for a minimum 7 year. Clinical results were evaluated using Knee Society Knee scores (KSKS) and Knee Society Function scores (KSFS) at last follow-up. The passive knee flexion was measured using a goniometer before and after surgery. The survival rate of the implants and implant-specific complications such as osteolysis or loosening were investigated. The osteolysis or loosening around the components was recorded according to the Knee Society Radiological scoring System.
Results:
Mean Knee Society Knee score improved from 48.2 preoperatively to 96.8 postoperatively and mean Function score improved from 49.7 preoperatively to 74.2 postoperatively, respectively. The average range of motion (ROM) improved from 112.7° preoperatively to 131.5° postoperatively. Postoperative mechanical axis deviation (MAD) was within −3° to 3°, in 316 knees (81.4%).
Non-progressive osteolysis was observed at zone 4 of the femoral component in eight knees (2.06%), at zone 3 of the tibial component in one knee (0.26%), at zone 2 of the tibial component in two knees (0.52%), and at zone 1 of the tibial component in thirteen knees (3.35%) in anteroposterior view. Two cases were revised due to infection and recurrent hemarthrosis. However, no complications, like early aseptic loosening, that have been associated with high flexion designs were observed.
Conclusions:
Clinical results for TKAs conducted using a single-radius, high-flex posterior stabilized design with a minimum 7-year follow-up were favorable. Furthermore, no high flexion implant-specific complications such as early aseptic loosening were encountered.
