A NEW EXTRAMEDULLARY FEMORAL ALIGNMENT SYSTEM FOR TOTAL KNEE ARTHROPLASTY

Abstract

Several reports suggest that the clinical transepicondyle axis which is known as the transverse flexion axis of knee rotation most consistently recreates a balanced flexion space and normal patella-femoral tracking. However the problem is that it is difficult to find the exact location of both femoral epicondyles intraoperatively. We suggest a method to determine femoral external rotation which parallel to the T-E axis using the femoral extramedullary(EM) system.

By definition, T-E axis is the line across each epicondyle and knee center, which is perpendicular to the mechanical axis of the femur in the coronal plane. Mechanical coronal plane perpendicular to mechanical sagittal plane is represented by the plane made of three points; femoral head center, lateral femoral epicondyle and knee center. T-E axis is parallel to the coronal plane, therefore if we position the distal femoral block parallel to the mechanical coronal plane, the position of distal femoral block should be parallel to the T-E axis. If the EM system is in its correct position sagittally and coronally, the T-E axis can be traced automatically.

Determination of femoral external rotation which parallel to the transepicondylar axis using the EM system could be one of the useful method to determine the external rotation of the femoral component and it will also imrove the patello-femoral tracking.