SA: Stifle

Question 1

What is the most common signalment for cranial cruciate ligament disease?

Answer 1

Middle aged, medium to large breed dog with normal activity = ligament tear OR
Young (skeletally immature) athletic dogs = acute avulsion injury

Question 2

What is a risk factor for early rupture of the cranial cruciate ligament?

Answer 2

Early-neutered or straight-legged conformation
Higher TPA

Question 3

How do small breeds present with cranial cruciate disease?

Answer 3

Older, overweight
Usually acute complete rupture
May be secondary to medial patellar luxation

Question 4

What is the pattern of lameness for a partial cranial cruciate ligament tear?

Answer 4

Prolonged, intermittent, mild

Question 5

What is the pattern of lameness for a complete cranial cruciate ligament tear?

Answer 5

Acute, severe

Question 6

What is the pattern of lameness for secondary meniscal injury?

Answer 6

Lameness may partially improve, then becomes and stays severe

Question 7

In general, what are patterns of lameness for cranial cruciate ligament injury? (When are they worse/when do they improve?)

Answer 7

Worse after prolonged rest
Worse after strenuous exercise
Improves with rest
Improves with NSAIDs

Question 8

What gait abnormalities are associated with cranial cruciate ligament injury?

Answer 8

Significant lameness (place sound leg down more heavily)
Positive sit test

Question 9

What standing exam abnormalities are associated with cranial cruciate ligament injury?

Answer 9

Muscle atrophy/asymmetry (quadriceps mm)
Medical buttress

Question 10

What stifle manipulation abnormalities are associated with cranial cruciate ligament injury?

Answer 10

Pain on ROM (full flexion and extension)
Crepitus/clicks
Instability

Question 11

What are signs of bilateral cranial cruciate ligament injury?

Answer 11

Gait with lower head carriage
Weight shifted forward when sitting

Question 12

Cranial Drawer Test

Question 13

Tibial Thrust Test

Question 14

Caudal cruciate ligament tear clinical signs

Answer 14

(some) Drawer instability
NO tibial thrust

Question 15

What can be seen on stifle radiographs that are indicative of cranial cruciate ligament injruy?

Answer 15

Effusion and osteoarthritis

Question 16

How is tibial plateau angle measured?

Answer 16

Compare angle of mechanical/functional axis with interchondylar eminence of the femur of the tibia to the angle across the tibial plateau

Question 17

What is average TPA?

Answer 17

25-30 degrees

Question 18

What is considered excessive TPA?

Answer 18

> 35 degrees

Question 19

Which procedures are dogs with TPA > 30 degree not good candidates for?

Answer 19

Conservative management
ExCap
TTA

Question 20

Which procedures are dogs with TPA > 30 degree good candidates for?

Answer 20

TPLO

Question 21

What is the function of the menisci?

Answer 21

Load bearing
Load distribution

Question 22

What other structure is prone to secondary damage due to cranial cruciate ligament injury?

Answer 22

Caudal pole of the medial meniscus
Isolated meniscal tear or lateral meniscal injuries are rare

Question 23

What is important about diagnosis of meniscal injury secondary to cranial cruciate ligament injury?

Answer 23

Must inspect first with arthroscopy or arthrotomy
Probing increases diagnostic accuracy by 8 times

Question 24

When is conservative cranial cruciate ligament stabilization successful?

Answer 24

Dogs < 15kg acceptable limb function
Reported success rates 84-90%
Weight loss improved results

Question 25

Why is surgery for cranial cruciate ligament injury indicated?

Answer 25

To address any concurrent meniscal injury Reestablish joint stability Mitigate secondary osteoarthritis

Question 26

Cranial cruciate ligament Extraarticular Stabilization (ExCap)

Answer 26

Replace intra-articular ligament with suture

Question 27

What are the long-term outcomes of ExCap Stabilization?

Answer 27

*Sub-optimal* Fails to maintain stability Progressive OA Does not prevent late meniscal damage No perfectly isometric suture

Question 28

Which tibial osteotomies work via decreasing the tibial plateau angle?

Answer 28

Tibial plateau leveling osteotomy (TPLO)

Question 29

Which tibial osteotomies work via altering alignment of the patellar tendon?

Answer 29

Tibial tuberosity advancement (TTA)

Question 30

Which tibial osteotomies work via decreasing the tibial plateau angle AND altering alignment of the patellar tendon?

Answer 30

Triple tibial osteotomy (TTO)

Question 31

What are the general goals of tibial osteotomies?

Answer 31

Alter conformation of the proximal tibia --> functional stability to tibial thrust

Question 32

How does a TPLO treat cranial cruciate ligament injury?

Answer 32

Takes away the need for an intact cranial cruciate ligament Joint reaction force perpendicular to tibial plateau *Creates functionally stable stifle joint reliably*

Question 33

How does a TTA treat cranial cruciate ligament injury?

Answer 33

Advances tuberosity forward Joint compressive force Patellar tendon perpendicular to tibial plateau, joint reaction force perpendicular to tibial plateau

Question 34

Rank the possible cranial cruciate ligament treatments in terms of return to comfortable function

Answer 34

TTA > TPLO > ExCap > Conservative

Question 35

What is the prognosis of cranial cruciate ligament repair?

Answer 35

All surgical techniques quote 80-90% return to 'normal' function *~50% contralateral cranial cruciate ligament rupture within 12-18 months*

Question 36

What is the pathophysiology of patellar luxation?

Answer 36

*Primary malalignment of extensor mechanism* due to (1) shallow trochlear groove (2) malpositioning of tibial tuberosity (3) distal femoral varus (4) excessive laxity and fibrosis of soft tissues

Question 37

Grade I Patellar Luxation

Answer 37

Subluxates with digital pressure, but spontaneously reduces Rare spontaneous luxation and lameness *Normal in cats*

Question 38

Grade II Patellar Luxation

Answer 38

Luxates manually and spontaneously Can be manually or spontaneously reduced "Spends most of its time in the groove" Intermittent lameness or "skipping lameness"

Question 39

Grade III Patellar Luxation

Answer 39

Patella is luxated, but can be manually reduced May walk crouched with stifle semi-flexed Patella spends more time out than in

Question 40

Grave IV Patellar Luxation

Answer 40

Permanently luxated and cannot be reduced May carry limb or walk crouched Severe gait changes (handstands)

Question 41

What is seen with patellar luxation on orthopedic exam?

Answer 41

Lameness (varies with grade) Standing exam most useful Slightly extend and internally rotate stifle (patella pops out)

Question 42

Surgical Considerations: Grade I and II MPL

Answer 42

Surgery only indicated if clinically significant

Question 43

Surgical Considerations: Grade II and III MPL

Answer 43

Surgery recommended to minimize arthritis and may avoid cranial cruciate disease

Question 44

Surgical Considerations: Grade IV MPL

Answer 44

Severe bony and ligamentous deformities may not be repairable if not corrected early

Question 45

What are the surgical options for MPL?

Answer 45

Shallow trochlear groove: trochleoplasty Malpositioning of tibial tuberosity: tibial tuberosity transposition (TTT) Distal femoral varus: distal femoral osteotomy (DFO) Excessive laxity and fibrosis: fascia imbrication +/- release, anti-rotation suture (ExCap)

Question 46

What are possible complications of MPL surgery?

Answer 46

Reluxation or overcorrection (MPL --> LPL) Forewarn owners of potential surgery