As far as I understand, the 3 degrees of external rotation needed for the correct femoral component placement stems from the fact that naturally there is a 3 degrees internal rotation of the posterior condylar axis relative to the epicondylar axis, which one needs to overcome in order to have a rectangular gap in flexion. I cannot understand how this concept has anything to do with the natural 3 degrees of varus in the tibia. Could you please explain how a change in rotation of the femoral component will afect varus-valgus alignment of the knee in flexion, as it is not clear to me at all. Thank you.
Dear Marius Tulbure...I can explain. The answer lies in your comment too. "naturally there is a 3 degrees internal rotation of the posterior condylar axis relative to the epicondylar axis". This is because the lateral condyle is small in AnteroPost diameter compared to medial condyle. And this is due to the 3 degree native varus of tibia. So now you understand that varus tibia and femur rotation are related.
Miller 7th edition, page 465. same concept is explained with diagram. native proximal tibia is 3 degrees varus,to compensate this femoral component is externally rotated.
yes i can explain u to there is a nice paper in jourrnal of arthroplasty 20 december 2017 chung kia et al , " distal femoral rotation correlates with proximal tibial joint line obliquity . pubmed.ncbi.nlm.nih.gov/29395720/ the zig that we dial 3 degrees external rotation is primarily due to the angle between posterior condylar axis and the tans epicondylar axis . and it has been found that this posterior condylar twist angle is mecahnically equal to the prioximal tibia coronal varus slope which is 3 degrees. and it has been proved . so to simplify things mahaluxmiwala sir tells that the zig angle s due to varus slope. we may have to read between the lines
You have said native tibia is 3 degree varus and the tibial cut is made at 90 degree to tibial shaft. And hence 3 degree external rotation is dialled while cutting posterior femoral condyle so as to achieve a rectangular flexion gap. Does the native 3 degree tibia and 90 degree to tibial shaft cut have an influence on extension gap too? How do we achieve a rectangular extension gap now?
Naturally the Medial Femoral condyle is elongated distally and posteriorly ... vis a vis lateral Femoral condyle ,...so 90 degree distal femur cut to the mechanical axis .. takes care of of extension gap
![ทุกครั้งที่หลับตา (Lucid Dream) - AYLA's [ Official MV ]](http://i.ytimg.com/vi/4i1OBAQyv58/mqdefault.jpg)
As far as I understand, the 3 degrees of external rotation needed for the correct femoral component placement stems from the fact that naturally there is a 3 degrees internal rotation of the posterior condylar axis relative to the epicondylar axis, which one needs to overcome in order to have a rectangular gap in flexion. I cannot understand how this concept has anything to do with the natural 3 degrees of varus in the tibia. Could you please explain how a change in rotation of the femoral component will afect varus-valgus alignment of the knee in flexion, as it is not clear to me at all. Thank you.
Dear Marius Tulbure...I can explain. The answer lies in your comment too. "naturally there is a 3 degrees internal rotation of the posterior condylar axis relative to the epicondylar axis". This is because the lateral condyle is small in AnteroPost diameter compared to medial condyle. And this is due to the 3 degree native varus of tibia. So now you understand that varus tibia and femur rotation are related.
Miller 7th edition, page 465. same concept is explained with diagram. native proximal tibia is 3 degrees varus,to compensate this femoral component is externally rotated.
yes i can explain u to there is a nice paper in jourrnal of arthroplasty 20 december 2017 chung kia et al , " distal femoral rotation correlates with proximal tibial joint line obliquity .
pubmed.ncbi.nlm.nih.gov/29395720/
the zig that we dial 3 degrees external rotation is primarily due to the angle between posterior condylar axis and the tans epicondylar axis . and it has been found that this posterior condylar twist angle is mecahnically equal to the prioximal tibia coronal varus slope which is 3 degrees. and it has been proved . so to simplify things mahaluxmiwala sir tells that the zig angle s due to varus slope. we may have to read between the lines
You have said native tibia is 3 degree varus and the tibial cut is made at 90 degree to tibial shaft. And hence 3 degree external rotation is dialled while cutting posterior femoral condyle so as to achieve a rectangular flexion gap.
Does the native 3 degree tibia and 90 degree to tibial shaft cut have an influence on extension gap too? How do we achieve a rectangular extension gap now?
Naturally the Medial Femoral condyle is elongated distally and posteriorly ... vis a vis lateral Femoral condyle ,...so 90 degree distal femur cut to the mechanical axis .. takes care of of extension gap
Thank you so much, please have this kind of grasp enabled pacing interactive sessions more..
Excellent sir,,,
So nice of you