Influence of the Rotational Alignment of the Femoral and Patellar Components on Patellar Tilt in Total Knee Arthroplasty

Abstract

PurposeThe purpose of this study was to analyze the influence of rotational alignment of the femoral and patellar components on patellar tilt after total knee arthroplasty (TKA).Materials and MethodsA total of 56 patients (76 knees) who underwent TKA using Advance Medial Pivot Knee system between May 2009 and April 2011 and were available for minimum 1-year follow-up were enrolled in this study. Whiteside's line and the transepicondylar line were used to determine the rotational alignment of the femoral component. Patella cut was aimed to be parallel to the anterior patellar cortex during surgery. Radiographic evaluation was performed using plain axial radiographs. The rotational alignment of the femoral component was measured as the angle between the anterior condylar axis and the surgical transepicondylar axis. The patellar resection angle was measured between the patellar resection axis and the anterior cortical line of the patella. Patellar tilt was evaluated to investigate the correlation with the rotation of the femoral component and patellar resection angle.ResultsThe mean rotation of the femoral component was 0.42°±3.18° of internal rotation. The mean patellar resection angle was 1.82°±3.44°, indicating medial overresection. The mean patellar tilt was 6.12°±4.31° of lateral tilt. The rotational angle of the femoral component showed a negative correlation with patellar tilt in the linear regression analysis (p=0.749), but the patellar resection angle showed a positive correlation with patellar tilt (p<0.001).ConclusionsAccurate patellar resection is recommended for proper patellar tracking in TKA.

Influence of Patellar Tilt Angle in Merchant View on Postoperative Range of Motion in Posterior Cruciate Ligament-Substituting Fixed-Bearing Total Knee Arthroplasty

“…Previous studies have reported on the correlation between patellar tilt and postoperative knee flexion in TKA. In a study by Kim et al,18) when TKA was performed without a release of the lateral retinaculum, the mean patellar tilt was 6.12°, which is similar to 6.78° obtained in our study despite release of the lateral retinaculum. Kawamura and Bourne16) reported that the postoperative tilt angle of the patella may be a factor that affects the postoperative range of flexion.…”

Does patellar tilt affect the outcome of total knee arthroplasty? a retrospective study

“…The same has been reported by Kim et al in a retrospective study on 56 patients (76 knees) who underwent TKA. 22 A complete tension free eversion of patella is essential to correctly place the patellar clamp for resection. In cases of tight knee, an essential step would be performing a lateral release before the patellar resection rather than doing it after the patellar implantation.…”

Agreement and Reliability of Lateral Patellar Tilt and Displacement following Total Knee Arthroplasty with Patellar Resurfacing

“…24 Other evidence is less supportive, Kim et al evaluated 45°M erchant radiographs following 76 primary TKAs and found no correlation between patellar tilt and femoral rotation. 25 Notably, these variables may be dependent as the anterior femoral condyles are used to measure lateral patellar tilt. Laughlin et al evaluated 45°Merchant view radiographs in 89 primary TKAs and found that lateral patellar tilt increased from 3 weeks to a mean 36 months of follow-up.…”