Neutral alignment leads to higher knee society scores after total knee arthroplasty in preoperatively non-varus patients: a prospective clinical study using 3D-CT

• Published in: Knee surgery, sports traumatology, arthroscopy : official journal of the ESSKA sports traumatology, arthroscopy : official journal of the ESSKA, 2018-06, Vol.26 (6), p.1602-1609
• Main Authors: Slevin, Omer, Hirschmann, Anna, Schiapparelli, Filippo F., Amsler, Felix, Huegli, Rolf W., Hirschmann, Michael T.
• Format: Article
• Language: English
• Subjects: Alignment; Arthroplasty (knee); Biomedical materials; Correlation analysis; Deformation; Diagnostic systems; Femur; Joint surgery; Knee; Medicine; Medicine & Public Health; Orthopedics; Patients; Position measurement; Radiographs; Radiography; Regression models; Surgical implants
• ISSN: 0942-2056; 1433-7347
• DOI: 10.1007/s00167-017-4744-y

Purpose The optimal coronal alignment is still under debate. However, in most of the studies, alignment was only assessed using radiographs, which are not accurate enough for assessment of tibial and femoral TKA position. The primary purpose of this study was to assess the relationship between coronal TKA alignment using 3D-reconstructed CTs and clinical outcome in patients with preoperative varus in comparison with patients with natural or valgus deformity. It was the hypothesis that neutral limb alignment shows a better outcome after TKA. Methods Prospectively collected data of 38 patients were included. The clinical and radiological follow-up was 24 months. The patients were grouped into two groups with regard to their preoperative limb alignment. Group A (varus) consisted of 21 patients with preoperative varus of 3° or more, while group B (non-varus) consisted of 17 patients with neutral (− 3  + 3) or valgus alignment (> + 3). For assessment of TKA component position and orientation, 3D-reconstructed CT was used. The measurements of the deviation from the whole limb mechanical axis (HKA angle) and the joint line alignment in the femoral (mLDFA) and the tibial side (MPTA) were assessed in the preoperative leg as well as during follow-up after TKA. For clinical outcome assessment, the Knee Society Score (KSS) was used at 1 and 2 years postoperatively. Correlation between KSS score and each variable was done using a linear and quadratic regression model ( p