Angular limb deformity Flashcards
Define anatomic axis
line that passes through the center, or mid-diaphysis, of the bone in the frontal or sagittal plane. Best used with straight bones. If the bone is curved more than one line may be used to resolve the curved anatomic axis (think radius pro-curvatum)
Define mechanical axis
A straight line connecting the center points of the joints proximal and distal to the bone in the frontal or sagittal plane. It is always a straight line and represents the weight bearing axis of the bone
Define joint orientation angle
The intersection of a joint orientation line and a bone axis
How are joint orientation angles named (labeled)
Axis first (so a or m), then cranial/caudal or medial/lateral, then proximal or distal and finally the bone. mMPTA
Define inclination angle
Measured in the frontal plane. Its the intersection of the proximal femoral anatomic axis and a line originating at the center of the femoral head that bisects the femoral neck
Define coxa vara using inclination angle
This is a deceased angle of inclination
Define coxa valga using the inclination angle
This an increased angle of inclination
Anteversion angle
Measured in the transverse plane and is the angle between the femoral neck and the frontal plane of the femur as described by the caudal aspect of the femoral condyles
Define CORA
Center of rotation of angulation (essentially the apex of the deformity). A bone can have more than one
What three things does every CORA posses
A location, a magnitude and a plane. The plane is always directed opposite the way the bone is deviated
What is meant by an opening CORA
A CORA on the convex side of the transverse bisecting line with respect to the neutral CORA
What is meant by a closing CORA
A CORA on the concave side of the transverse bisecting line with respect to the neutral CORA
Angular limb deformity with a single CORA (the anatomic axes of the bone intersect within the cortical confines of the bone)
Uniapical deformity
Angular limb deformity with two CORA
biapical deformity
Angular limb deformity with more than 2 CORA
multiapical deformity
Angular limb deformity with 2 CORA whose planes lie in opposite directions
Biapical partially compensated
Angular limb deformity with 2 CORA whose planes lie in the same direction
Biapical non-compensated
What happens if your osteotomy and the ACA (angular correction axis) is placed at the CORA
Angular correction and co-linearity of the axis are achieved
What happens when your ACA (angular correction axis) is based at the CORA and the osteotomy is located somewhere other than the CORA
Appropriate realignment occurs through angulation AND translation
What happens when the osteotomy and the ACA occur at a level different from the CORA
Co-linearity of the segments does not occur and iatrogenic translation results (avoid this)
