Cranial Cruciate Ligament Rupture

Question 1

When is pain felt in the stifle if the cranial cruciate ligament ruptures? What are the 3 options for repair?

Answer 1

on extension

1. extracapsular repair
2. TPLO
3. TTA

Question 2

What results are seen upon manipulating the stifle after a TPLO or TTA

Answer 2

cranial drawer will still be present and tibial thrust will be eliminated

Question 3

Where does the cranial cruciate ligament originate and insert?

Answer 3

ORIGIN = medial surface of the lateral femoral condyle

INSERTION = craniomedial surface of the tibial plateau beneath the intermeniscal ligament

Question 4

What are the 3 functions of the cranial cruciate ligament?

Answer 4

1. prevent cranial drawer
2. prevent excessive hyperextension
3. prevent excessive internal rotation

Question 5

What breeds are predisposed to cranial cruciate ligament ruptures?

Answer 5

straight-legged dogs - Boxers, GSDs, Labradors, Golden Retrievers, Newfoundlands, Mastiffs, Akitas

• most commonly middle-aged to older

Question 6

What history is commonly seen in CCL ruptures?

Answer 6

acute or chronic lameness which does not improve with rest +/- mild improvement with NSAID therapy

Question 7

What are 8 possible findings consistent with CCL ruptures?

Answer 7

1. sitting with knee rotated outward (positive sit test)
2. positive cranial drawer (may not be appreciable with a partial tear or if the animal is fighting palpation)
3. positive tibial compression test
4. presence of medial buttress
5. palpable joint effusion
6. meniscal click
7. muscle atrophy
8. painful on extension

Question 8

What are 2 major signs of a chronic CCL tear?

Answer 8

1. medial buttress - accumulation of fibrous tissue the body deposits in an effort to stabilize the knee
2. muscle atrophy

Question 9

What are 2 major radiographic signs of CCL tears?

Answer 9

1. osteophytes - especially along femoral trochlear ridge, tibial plateau, and patella
2. joint effusion

Question 10

What is an extracapsular repair in regard to CCL ruptures? When is this preferred?

Answer 10

heavy suture is placed around fabella on lateral aspect and then through the hole in the tibia, running in similar orientation as the original CCL

smaller dogs <20 kg

Question 11

What is a major disadvantage to extracapsular repair for CCL ruptures?

Answer 11

can cycle, stretch, and break, resulting in instability

Question 12

What is a TPLO? What results after manipulating the stifle following surgery?

Answer 12

osteotomy performed at the proximal tibia and tibial plateau and is rotated then stabilized with a bone plate = more load on the caudal cruciate ligament

cranial cruciate is not fixed –> cranial drawer still present, but no tibial thrust

Question 13

What is a TTA? What is the goal? What results?

Answer 13

a cut is made along the cranial aspect of the proximal tibia and a cage is inserted between the tibia to advance it

to make the patellar tendon perpendicular to the tibial plateau

elimination of tibial thrust

Question 14

What does any repair of of a CCL result in?

Answer 14

osteoarthritis –> progresses slower than not doing anything

Question 15

How should patients be handled following CCL rupture repair?

Answer 15

CAGE REST - 8-12 weeks

• can be used to treat CCL tears in smaller dogs, waiting for fibrosis to help stabilize the leg –> greater progression of arthritis!