How Precise is the Determination of Rotational Alignment of the Femoral Prosthesis in Total Knee Arthroplasty. An In Vivo Study

Abstract

Correct rotation of the femoral component is critical in avoiding patellar instability in total knee arthroplasty. This study attempted to compare the precision of 4 commonly used methods (transepicondylar axis [TEA], 3° external rotation [ER] from posterior condylar line [PCL], perpendicular cut to Leo Whiteside line [WSL], and balanced flexion gap [GAP]) in determining the rotational alignment of the femoral prosthesis in an in vivo setting. The ranges of error were as follows: (1) TEA, 28° (17° internal rotation [IR] to 11° ER); (2) PCL, 27° (13° IR to 14° ER); (3) WSL, 32° (17° IR to 15° ER); (4) GAP, 26° (14° IR to 12° ER). If an error of more than 5° from neutral alignment is defined as an outlier, 56% in TEA, 72% in PCL, 60% in WSL, and 20% in GAP methods would fall in the outlier zone. © 2007 Elsevier Inc. All rights reserved.