47.ALD Flashcards
what does CORA stand for
Center of rotation of angulation
how is bone alignment objectively assessed
through examination of bone axes (mechanical and anatomical) and joint orientation
what is the joint orientation angle
the intersection of a bone axis and a joint orientation line
front vs sagittal vs transverse planes
frontal–evaluated on Cr Cd rad–valgus, varussagittal–evaluated on M-L rad–procurvatum, recurvatumtransverse–evaluated axially–torsional malformations6 possible deformities can be presentdeformity is defined by DISTAL portion in relationship to proximal portion
define anatomic vs mechanic bone axis
anatomic–line that passes through CENTER or middiaphysis of the bonemechanical–line connecting the center points of the joints proximal and distal to the bone–may be more helpful for sigmoid shape bones (ie. tibia, humerus)–represent weight bearing axis
normal mLDHA for large breed nonchondrodystrophic skeletally mature dogs
87 +/- 3 degrees
landmarks for proxial radial joint orientation line
proximolateral—radial headproximomedial–medial portion of coronoid process
normal procurvatum of the radius
27(study in labradors–sagitttal plane)
other joint orientation angles (in frontal and sagittal planes) for proximal and distal radius
proximal close to 90MP (frontal) 83LD (frontal) 86CdP (sagittal) 85CdD (sagittal) 77**procurvatum 27
formulation to determine degrees of procurvatum
(90-aCdPRA) + (90-aCdDRA) + thetaTheta is angle creative on sagittal film from intersection of both proximal and distal bone axes
difference btwn rotation and torsion
torsion is within the bonerotation refers to motion about a joint
proximal joint orientation line of proximal femur landmarks
center of femoral head to the dorsal most aspect of the greater trochanter
anatomic bone axis of the femur
determined by a line that connects the points selected at 33% and 50% below the proximal aspect of the femoral neck in the middle of the femur
T/Fthe anatomic bone axis will deviate from the center of the bone in the femur
TRUEthe anatomic bone axis will deviate from the center of the bone in the femur because NORMAL femoral VARUS (ends just lateral to the intercondylar notch)
mechanical axis of the femur
line from center of femoral head to center of the distal femoral joint orientation line
angle of anteversion
measured on CT or axial radiographangle btwn the neck and the frontal plane described by the caudal aspect of the femoral condyles~27 (range 16-31.3)
angle of inclination
measure on frontal radiographangle formed by the proximal femoral anatomic axis and a line that originates at the center of the femoral headcoxa vara—decreasedcoxa valgus–increasedN GSD 132N LABS, GOLDENS 134N ROTTS 137
proximal and distal, lateral anatomic and mechanical joint axes of the femur
> 90 but < 100 degrees
T/Fmechanical bone axis is used in the tibia
TRUE due to sigmoid shape
proximal tibial angle is reciprocal of what joint angle
proximal tibial angle is reciprocal ofmCdPTAnormal values vary 24-26
torsion of > 15 degrees results in how much miscalculation of a frontal plane deformity
torsion > 15 degrees will result in miscalculation of up to 5 degrees of a frontal plane deformity
surgical planning for CORA based corrections
–know normals axes and joint angles of good leg–rads, CT, stereolithography–locate CORA–define plane of deformity (uniplanar, biplanar)–define magnitude CORA–locate osteotomy–angulation correction axis
T/Fthe magnitude of the CORA equates to the degree of correction required to eliminate the deformity
TRUE
T/FThe plane of the CORA is ALWAYS in the direction OPPOSITE of how the bone is deviated
TRUE plane of the CORA is ALWAYS in the direction OPPOSITE of how the bone is deviatedpur frontal deformity with valgus (lateral deviation of dotal portion) then the plane of deformity is medial
partially compensated vs NONcompensated CORA
applies to BIAPICAL deformities (2 CORAs present)partially compensated–both CORAs with planes in the OPPOSITE directionnoncompensated–both CORAs with planes in the SAME direction
what is a translational deformity
when no angulation is present but the proximal and distal segments are NOT co-linear but rather shifted relative to one another
what is the angulation correction axis
the hinge point upon which rotation of two segments of bone can be madealways possesses a PERPENDICULAR relationship to the plane of the deformity
palsy’s three rules of osteotomies
- osteotomy and angular correction axis are co-linear with CORA–realignment occurs2. osteotomy is achieved at a different location than angular correction axis which is based on CORA–translation occurs (ex. TPLO, junta-articular corrections) but still co-linear3. osteotomy and angular correction axis is at a different spot from CORA–translation and NOT co-linear
types of osteotomies for correction of ALD
- opening wedge (osteotomy)2. closing wedge (ostectomy)3. radial (cylindrical)–match blade diameter to bone diameter3. true dome–size matched blade to widest dimension
on what side of the bone is an opening CORA vs a closing CORA
Neutral CORA is where intersecting axes are formedbut really the CORA is made up a infinite CORAs along the transverse bisecting lineconvex side CORA–opening CORAconcave side CORA–closing CORA
T/Ftrue dome osteotomies correct deformities in all three planes
TRUEtrue dome osteotomies correct deformities in all three planesradial(cylindrical) only corrects in one plane
types of fixation following ALD corrective osteotomies
–internal fix bone plate (often with closing wedge to have load sharing); compression vs locking plates–linear ESF (need robust designs for opening wedge)–circular, hybrids ESF (good for juxta-articular deformities)
