Luxation & Patellar Groove Replacement (PGR)

Question 1

Which of the following statements correctly matches with Grade I patellar luxation?

A. A knee cap that can be luxating with manual pressure but is otherwise is within the groove.
B. The knee cap spontaneously luxates, is typically associated with a skipping lameness when the knee cap moves.
C. The knee cap is permanently luxated but can be manually replaced in the groove.
D. The knee cap is permanently luxated and cannot be manually replaced in the groove.

Answer 1

A. A knee cap that can be luxating with manual pressure but is otherwise is within the groove.

Question 2

Which of the following statements correctly matches with Grade II patellar luxation?

A. A knee cap that can be luxating with manual pressure but is otherwise is within the groove.
B. The knee cap is permanently luxated but can be manually replaced in the groove.
C. The knee cap is permanently luxated and cannot be manually replaced in the groove.
D. The knee cap spontaneously luxates, is typically associated with a skipping lameness when the knee cap moves.

Answer 2

D. The knee cap spontaneously luxates, is typically associated with a skipping lameness when the knee cap moves.

Question 3

T/F: patellar luxation is a clinial manifestation of an underlying disease, it is not a disease itself.

Answer 3

true
limb deformity –> misaligned quadriceps mechanism

Question 4

Of the 4 quadriceps muscles (rectus femoris, vastus medialis, vastus lateralis, and vastus intermedius.), which is the only one that does not originate from the proximal femur?

Answer 4

rectus femoris

Question 5

T/f: lateral patellar luxation is most common

Answer 5

false – medial

if its lateral, its most likely in a large breed dog.

Question 6

What would make a dog a poor candidate for trochleoplasty and better candidate for PGR?

Answer 6

significant cartilage erosion on the articular surface of the patella.

Question 7

what is the goal of an en-bloc trochleoplasty?

Answer 7

To remove articular cartilage and subchondral bone from the trochlear sulcus, thereby deepening the sulcus.

Question 8

why is chronic patellar luxation bad?

Answer 8

causes erosion, flattening, and fibrosis of the patella and results in incongruency with the trochlear groove.

Question 9

what is the goal of patelloplasty?

Answer 9

adapt the patellar shape to the trochler groove by removing osteophytes and patellar cartilage. Done with a bone rasp or osteotome.

Question 10

T/F: tibial tuberosity transposition is only indicated in skeletally immature dogs.

Answer 10

false – it is controversial in immature patients because it will arrest the physis and result in distally displaced patella increasing risk for patellar luxation.

Question 11

T/F: surgery to correct patellar luxation only improves a patient by ONE lameness and ONE luxation grade.

Answer 11

true

Question 12

what is the purpose of patellar groove replacement?

Answer 12

to improve the standard of care for severe patellofemoral degenerative joint disease, a frequent consequence of patellar luxation or CCL degen/rupture.

Question 13

T/F: bad joints get hot from friction

Answer 13

true and this is bad because heat drives degenerative changes. Inflammation –> pain –> decreased of function/use –>muscle wasting –> cartilage degeneration –> repeat cycle.

normal hip = 2 deg C
arthritic = 4 deg C

Question 14

what are contraindications for trochleoplasty and indications to perform PGR?

Answer 14

1. chronic and severe patellar luxation
2. severe osteophytosis
3. severe loss of joint cartilage
4. revisions of failed previous surgeries
5. severe malformations of ht trochlea
6. trochlear ridge fracture
7. convex trochlear groove with congenital patellar luxation

Question 15

T/F: patellar groove replacement should only be performed in mature dogs.

Answer 15

true
young animals are not good candidates. they rarely have degenerative changes this early and will have good outcomes with trochleoplasty.

Question 16

In cases of agenesis of the trochlear ridge, it is best to wait until what age to perform PGR?

Answer 16

skeletal maturity.

Question 17

T/F: PGR alone is able to correct mild to moderate quadriceps malalignment, however severe alignment needs to be addressed with other techniques.

Answer 17

true