Small Ani. Sx- Ortho- Patellar luxation

drraythe's version from 2016-04-29 14:52

who needs kneecaps anyway

Question Answer
which is more common- Medial or lateral patellar luxation?MEDIAL (75%)
rads of medial vs lateral patellar luxation-- how to the conformation of the legs change based on these problems?in medial luxation, femurs are like an "O" but in lateral luxation, femurs are like an "X"
who gets medial patellar luxation versus lateral patellar luxation?(1) MEDIAL: usually Small & miniature breeds get this, like Poodle, Yorkshires, Pomeranian, Pekingese, Chihuahuas, Boston Terriers (however, possible for large breeds to get it too) (2) LATERAL: ONLY LARGE BREEDS seem to ge this one
explain what the extensor mechanism of the leg is (What it is composed of) and how it plays a role in patellar luxationincludes: Quadriceps, Patella, Trochlea, Ligamentum rectum patellae, Tuberositas tibiae. These should all be in a single line, in alignment, and should stay like that as the dog grows. Problems with this extensor mech mean that the luxation starts congenitally or very young
pathophysiology--> what are the two major players in the pathophys of the luxation?(1) Conformation of rear limb (2) Tension of m. rectus femoris
explain how Tension of m. rectus femoris plays a role in patellar luxationmost important factor to consider! more tension or fibrosis of rectus= more problems. Bc tighter is it, more medially patella is pulled (it is "a" in the diagram)
what is the concept of this pic explaining? The red is the line of quadriceps and rectus femoris. yellow is growth plates. bone will grow more or less depending on how much pressure is put on it. More pressure on the growth plate= less growing, so if the quads/rectus are out of line and causing undue pressure on the growth plate medially, the bone will start to bow laterally.
what is another dz which can be caused by patellar luxation?cr cruciate ligament rupture due to the pulling forces
why do you wanna tx PL early?progresses until leg is really deformed, bc this is happening as the animal is still growing!
when you are taking rads to try to dx PL, where should you focus?NOT JUST ON STIFLE, get the whole leg in the view (assess state of the femur and tibia)
which has a better prog- medial or lateral PL?medial better prog
what does a dog with patellar luxation look like when walking?skipping legs, intermittent lameness
GRADING--> what is grade 1?you can move it fully out of position but it'll pop back in (can be in normal position and skip out intermittently)
GRADING--> what is grade 2?luxate patella, then flex and extend leg then it goes back (can be in normal position and skip out intermittently)
GRADING--> what is grade 3?normally luxated, if apply pressure (manually reduce), can bring it back
GRADING--> what is grade 4?cannot reduce patella unless you do sx
why do you start with dxing PL while they stand, and then move them to lateral recumb?WHEN STANDING, you are able to diff 1+2 from 3+4.....1+2 the patella is in situ, and 3+4 the patella is out when just standing there. Then when you put them in lateral recumbency you can try to differentiate 1 from 2 and 3 from 4
what should you NOT do when assessing PL?DONT SEDATE-- relaxes all the ligaments and crap
what are you doing with the pt in lateral recumbency to try to differentiate each specific grade of PL?gentle manipulation--> flex, extend, internal and external rotat
lateral recumbency: what will a grade 1 be like? if rotate and jump back, grade 1
lateral recumbency: what will a grade 2 be like?will go back after some rotation, flex and extension of leg
lateral recumbency: what will a grade 3 be like?reduce by applying pressure
lateral recumbency: what will a grade 4 be like?wont be reduced with pressure
what problems must you address with surgical repair in order to restore joint function? (2 options to restore alignment are..)in order to restore joint function, you must correct extensor order to do this, you must: (1) reconstruct the bones (2) reconstruct the soft tissues
what are the two bone reconstruction techniques you can do to try to fix the extensor mechanism--> restore joint fxn?(1) Tibial tuberosity transposition (2) Trochleoplasty
explain what you are doing in a Tibial tuberosity transposition, and whyyou perform an Osteotomy where you cut the tibial tuberosity and displace it laterally...this pulls the patella over with it. **careful not to cut into medial meniscus!
why would we do a trochleaplasty? what is this?usually the sulcus the patella/patellar lig sits in is not deep enough. with this procedure we can make it deeper
**how does the method/type of trochleoplasty change depend on age? what ages??(1) > 5 months of age: Wedge resection sulcoplasty (2) < 5 months of age: Subchondral sulcoplasty (cartilage flap)
what are the 3 kinds of Trochleoplasties you can do?Wedge resection sulcoplasty (greater than than 5mo), Subchondral sulcoplasty (cartilage flap) (less than 5mo), Patellar grove replacement
how do you do a Wedge resection sulcoplasty? (what age?)(greater than 5mo) cut cart in a wedge, take piece of bone under, and replace wedge of cart underneath-- makes it a bit deeper. can try to raise up medial ridge too. (so take wege, make deeper cut, then push wedge back in under pressure. now have deeper trochlea. its subchondral bone-- stable under pressure- dont need to fix it down. Dont forget to keep wedge moist when you aren't manipulating it)
how do you do a Subchondral Sulcoplasty? (what age?)(less than 5mo) cartilage is thick when they are young- so take blade, do one cut on one side, one on other, cut it on top, elevate it, take rongeurs, remove some subchondral bone, and then replace the flap.
what are you doing in a Patellar grove replacement?literally slice everything off and replace it with a prosthesis
what are 4 options of Soft Tissue Reconstruction Techniques to fix PL?Fascia lata overlap, Antirotational sutures, Desmotomy (retinaculum), Quadriceps release (cut medial part to release some of the tension)
**what should you know about performing the soft tissue recon. techniques?NEVER do THESE ALONE!! ALWAYS WITH THE BONE RECON. TECHNIQUES~!
how should you position pt when prepping for sx?dorsal recumb, at end of table, need to be able to flex all joints
if you have osteotomized the tibial tuberosity, how do you fix it back into place?tension band!
if you have PL AND CrCruLR which technique is esp desireable?TTA
what should you do post-operatively for the animal? for how long?Mod Robert Jones for a few days (reduce inflammaton, but important animal moves leg so only there for a few days max), and Physiotherapy to help reduce fibrosis
summary: #1 CS of PL?INTERMITTENT LAMENESS (usually if 1-2 grade)
summary: when is it essential to correct PL? when is it not so much?If young and still growing, should DEF treat bc chronic PL can cause deformities... if older dog with grade 1-2, prolly dont have to tx bc not growing any more. if 3-4 prolly still gotta do sthing
summary: how should you fix PL?need BONE RECON TECHNIQUES!! soft tissue recon is good to ADD to bone, but alone it is not enough and probs will recur