Abstract
Background:
The literature is unclear about the optimal rotation of the femoral component during TKR. Measured resection techniques rely on the use of bony landmarks, while the balanced gap technique relies on soft tissue tensioning to guide the surgeon in rotating the femoral component. All these techniques still result in a wide range of component rotation. We compared the functional flexion axis (FFA) of 20 replaced knees to that of the contralateral normal knee to determine whether a balanced gap technique allowed us to recreate this normal anatomy.
Methods:
We reviewed the records of our TKR's from Jan 2008 to Dec 2010 and included all patients who had a normally functioning contralateral knee, tibial cut <3° from perpendicular to the mechanical axis performed by/under supervision of a single surgeon. These patients were contacted for follow up and axial flexed knee x-rays to measure femoral rotation and FFA (angle between clinical transepicondylar line and mechanical axis of tibia). These values were compared between replaced and normal knees using Students T-test.
Results:
20 patients were eligible for the study. Femoral component rotation ranged from 4° internal to 5° external rotation (mean of 0.6° external). Mean difference in functional flexion axis was 3.7°, ranging from 0 to 6° (p<0.05)
Conclusion:
The balanced gap technique is effective to restore the functional flexion axis of the replaced knee to that of the normal contralateral side.
