Stifle Diseases

Question 1

what is the MOST common cause of hind limb lameness in dogs?

Answer 1

cranial cruciate ligament rupture

Question 2

what are the 3 types of cranial cruciate ligament injury?

Answer 2

complete tears
partial tears
avulsion

Question 3

what is the origin and insertion of the cranial cruciate ligament?

Answer 3

Origin: caudomedial aspect of the lateral femoral condyle

Courses in craniomedial direction to

Insertion: cranial intercondyloid area of the tibia

Question 4

T/F: cranial cruciate ligament injury occurs as a result of a traumatic event

Answer 4

false – this is true in people, but in dogs, its associated with a degenerative process and is a bilateral disease.

Question 5

The stifle joint is not a simple hinge joint. What are the 4 movements of the stifle joint?

Answer 5

1. flexion
2. extension
3. internal rotation
4. hyperextension

Question 6

What are the functions of the CCL?

Answer 6

1. limit cranial translation of the tibia with respect to the femur
2. prevents hyperextension of stifle joint
3. limits internal rotation of tibia
4. has mechanoreceptors for proprioceptive feedback
5. limited degree of valgus-varus support to flexed stifle

Question 7

why is the medial meniscus more likely to be involved in the cranial cruciate ligament injury rather than the lateral?

Answer 7

The medial meniscus is firmly attached to the tibial plateau and has no femoral attachment. The caudal pole gets wedged between the medial femoral condyle and the tibial plateau.

Question 8

what is the external rotator of the tibia?

Answer 8

biceps femoris which inserts on the lateral aspect of the tibia

Question 9

which muscles insert on the medial aspect of the tibia and function in stifle flexion and internal rotation?

Answer 9

caudal belly of the sartorius
gracilis
semitendinosus

Question 10

what are the active restraints of the stifle?

Answer 10

all of the muscles surrounding the stifle:
caudal belly of the sartorius
gracilis
semitendinosus, biceps femoris, quadriceps, semimembranosus, etc.

Question 11

What are the passive restraints of the stifle?

Answer 11

cranial cruciate ligament
caudal cruciate ligament
lateral collateral ligament
medial collateral ligament

Question 12

T/F: there is a higher incidence of cranial cruciate ligament injury in female dogs.

Answer 12

true

Question 13

what is the typical signalment for CCL injury?

Answer 13

• young-middle-aged
• active
• large breed
• straight-legged breeds (mastiffs, chows, akits, labs, rottweilers, st bernards, newfie)

Question 14

what are the etiologies of CCL injury?

Answer 14

1. chronic degenerative changes
2. conformation causes (obesity, hyperextention, etc.)
3. acute trauma (small % of cases)

Question 15

What are conformation-related factors that can lead to excessive stress on the CCL, chronic deterioration, and eventual CCL rupture? (there are 6)

Answer 15

1. postural arthrosis
2. stifle hyperextension (straight pelvic limbs)
3. narrowing of the femoral intercondylar notch
4. internal rotation of the tibia
5. abnormal slope of tibial plateau angle (increased TPA)
6. obesity

Question 16

How does muscle mass to bone ratio play a role in CCL chronic deterioration?

Answer 16

The more muscle surrounding the stifle, the stronger the active restraint is.
Dogs who have smaller muscle masses will be more at risk for deteriorative changes to the CCL compared to dogs with more muscle/active restraint.

Question 17

What would be the history associated with each of the following CCL injuries:

a. acute injury
b. chronic injury
c. partial tear

Answer 17

a. acute injury – sudden onset of NWB lameness followed by improvements (unless concurrent meniscal injury)
b. chronic injury – prolonged WB lameness, difficulty rising/sitting, sits with affected limb out to side of body
c. partial tear – mild WB lameness associated with exercise, resolves with rest and lasts for months

Question 18

What physical exam findings are associated with CCL injury?

Answer 18

1. pain
2. cranial drawer
3. tibial compression
4. joint effusion
5. periarticular fibrosis
6. posture during sitting
7. weight shifting when standing
8. thigh muscle atrophy
9. crepitus during jt flexion and extension

Question 19

What physical exam finding is suggestive of concurrent meniscal injury, but can NOT rule out meniscal injury?

Answer 19

clicking during walking or on stifle flexion and extension

Question 20

how can we diagnose CCL injuries?

Answer 20

1. hx and physical exam findings
2. imaging – xray, MRI, u/s

others (not req to dg):
arthroscopy, arthrocentesis

Question 21

What would be considered the appearance of an ‘abnormal sit test’ associated with CCL injury?

Answer 21

tuber calcaneous is lateral to the tuber ischii when sitting. This lateralization is due to synovitis and an inability to flex.

In a normal patient, the tuber ischii and tuber calcaneous would sit directly under eachother.

Question 22

Which test is considered more sensitive because it can detect PARTIAL CCL tears?

Answer 22

cranial drawer motion test

excessive craniocaudal movement of the tibia relative to the femur as a result of cruciate ligament injury
partial tear – CD in flexion
complete tear – CD in flexion and extension

Question 23

Why might a cranial drawer motion be difficult to elicit in cases of partial tears?

Answer 23

periarticular fibrosis

you can use sedation or anesthesia to more easily elicit cranial drawer motion if it is present.

Question 24

T/F: there is normal stifle movement in immature dogs.

Answer 24

true 4-5 mm of movement can occur in normal stifles of immature dogs.

Question 25

Which of the following statements is FALSE about partial vs complete CCL tears? A. partial tears have no cranial drawer in extension B. complete tears have drawer in extension and flexion C. partial tears only have drawer in extension

Answer 25

C. partial tears only have drawer in extension partial tears have NO cranial drawer in extension, but they DO have drawer in flexion.

Question 26

Which of the following statements about cranial tibial thrust is FALSE? A. only elicited for complete tears B. mimics dog walking C. a positive tibial thrust and negative cranial drawer indicates complete tear

Answer 26

C. a positive tibial thrust and negative cranial drawer indicates complete tear this combination is not possible (positive tibial thrust and a negative cranial drawer) You can, however, have a negative tibial thrust and a positive cranial drawer. This is because cranial tibial thrust ONLY detects complete tears, whereas cranial drawer can detect partial tears. So if you have a partial injury, it would be possible to have a negative tibial thrust but a positive cranial drawer, but not the other way around.

Question 27

What is indicative of CCL injury when performing a tibial compression test?

Answer 27

cranial advancement of the tibial crest as the hock is flexed.

Question 28

what radiographic findings would be associated with CCL injury? (6 things)

Answer 28

1. articular cartilage degeneration 2. periarticular osteophyte development (trochlear ridge, caudal tibial plateau, distal pole of patella) 3. capsular fibrosis 4. joint effusion 5. subchondral sclerosis 6. thickening of medial fibrous joint capsule

Question 29

Arthroscopy isn't necessarily used to diagnose CCL tears, but rather is used to determine if _______ pathology is present.

Answer 29

meniscal. it can confirm presence of CCL injury too (any gross tears, fibrillation, discoloration, or rupture) and be used to take culture or biopsy samples. it can also be therapeutic as a tool to remove CCL remnants, assist in CCL reconstruction, treat meniscal injury, or lavage the joint.

Question 30

why is medial meniscal injury common?

Answer 30

because the medial meniscus is firmly attached to the tibial plateau (less mobile) and has no femoral attachment. It is wedged between the medial femoral condyle and the tibial plateau. whereas the lateral meniscus is more mobile and has a femoral attachment.

Question 31

what are the 5 functions of the menisci?

Answer 31

1. load transmission across stifle 2. energy absorption 3. rotation and varus-valgus stability 4. lubricate the joint 5. joint congruity

Question 32

what history would align with meniscal injury?

Answer 32

Acute lameness followed by improvement, then worsening lameness after the initial improvements. this can occur prior to or after surgery.

Question 33

T/F: only 20% of patients with CCL tears have concurrent meniscal tears

Answer 33

false -- 50-75% patients do. isolated meniscal tears are uncommon

Question 34

which type of meniscal tear is most common?

Answer 34

bucket-handle tear (longitudinal tear in caudal body of medial meniscus)

Question 35

why is primary repair of meniscal tears not feasible usually?

Answer 35

- chronic injuries - the central portion is poorly vascularized.

Question 36

How does meniscal release possibly prevent subsequent meniscal injury from occuring?

Answer 36

allows the caudal pole of the meniscus to slide out of the way of the medial femoral condyle during cranial tibial thrust.

Question 37

why would meniscal release not be considered the best idea?

Answer 37

it causes abnormal areas of pressure between articular surfaces and can lead to osteoarthritis and further damages.

Question 38

You should inform your clients that ______% of dogs with CCL rupture will rupture the other ligament within 2 years. *how does this % change if there are already radiographic changes present?*

Answer 38

30-40 increases to 60% if there are already radiographic changes.

Question 39

T/F: progressive osteoarthritis occurs after CCL rupture regardless of the treatment method

Answer 39

true