Ortho cruciate disease

Question 1

WHat is the aetiology of cranial cruciate ligament disease in dogs vs cats

Answer 1

In dogs tends to be young, healthy dogs with no trauma

Cats tend to be older, overweight or with trauma to pelvic limb; less common

Question 2

Why should we always check for CCL failure in pelvic limb lameness cases

Answer 2

Often missed; i.e 1/3 of dogs referred for hip dysplasia actually had CCL failure as main reason for lameness

Question 3

Origin and insertion of cranial cruciate

Answer 3

Caudo-medial part of lateral femoral condyle
Travels across stifle craniomedially to intercondylar fossa of tibia

Question 4

3 functions of the cranial cruciate ligament

Answer 4

1) Prevents cranial translation of the tibia relative to the femur
2) Prevents internal rotation of the tibia
3) Prevents hyperextension

Question 5

What are the two functional bands of the CCL and when are they taut

Answer 5

Cranio-medial bend: taut in flexion and extension
Caudo-lateral band: taut in extension only

Question 6

WHat do we see with partial tear just rupturing caudo-lateral band

Answer 6

Dog is lame
But may not feel any instability because the other band is taut in flexion and extension still

Question 7

What do we see with partial tear of the craniomedial band of CLL

Answer 7

Lameness
Instability during flexion i.e cranial draw

Question 8

Why must we test the stifle in flexion and extension for instability

Answer 8

Because if there is a partial rupture, just tearing craniomedial band will just see draw during flexion

Question 9

What is the meniscus of the joint and what is their function

Answer 9

C shaped cartilages sitting on top of tibia to act as shock absorbers for femoral condyle
- Absorb energy and transmit load
- Functional in lubrication
- Allows joint congruity

Question 10

What is the difference between the medial and lateral meniscus of the stifle and what implication does this have for damage

Answer 10

Medial meniscus is held in place on medial and cranial aspect (i.e around periphery)
vs lateral only held in place on cranial aspect

when femur/tibia move independently in CCL rupture, femoral condyles slide across the menisci
- On the lateral side, lateral meniscus pushed out the way so not damaged
- vs on medial side, stuck in place so get damage

Question 11

What is the most common cause of cranial cruciate disease

Answer 11

Progressive degeneration of unknown cause
i.e in dogs it is relatively normal forces across an ABNORMAL ligament

[can also get traumatic causes but rarer]

Question 12

Characteristics of CCL disease in dogs

Answer 12

Degenerative
Mostly middle aged; typically large breed e.g lab, golden retriver, boxer, rotties etc also westies
~10% bilateral
Often already have some osteoarthritis present

May just be a partial tear so can present as very lame and painful but stable

Question 13

Why are westies prone to CCL disease despite not being a large breed

Answer 13

Because they are have a very steep tibial plateau which puts abnormal strain on the joint

Question 14

What happens to those which are only unilateral CCL disease at presentation

Answer 14

~ half of them have rupture of the other one in 6 months after

Question 15

Presenting signs of CCL disease

Answer 15

Pelvic limb lameness
Can be chronic variable or acute in onset because after long period of degeneration, a mild trauma causes rupture
Difficulty sitting/rising
Initially improve with rest and NSAIDs but then lameness returns with exercise

= Pain and mechanical lameness

Question 16

WHat is the sit test for CCL failure

Answer 16

Where an animal sits with one leg tucked under normally but the other out to the side

Question 17

Physical exam findings with CCL disease

Answer 17

Lameness
Sitting with one leg out to side
Medial buttress
Stifle effusion
Quardiceps atrophy
Joint pain during tests
Failure of cranial draw/tibial thrust

Question 18

What is a medial buttress in CCL disease

Answer 18

Where there is development of fibrous tissue on the medial aspect of the joint in an attempt to stabilise it
Feel thickening + see on radiograph

Question 19

Where do we feel stifle effusion

Answer 19

Along patellar ligament; will no longer be able to get fingers around it

Question 20

Cranial draw test basic

Answer 20

Hold femur still and attempt to move tibia cranially; should NOT be able to do this

Question 21

Out of cranial draw and tibial thrust which is easier to feel in conscious dogs

Answer 21

Cranial draw

Question 22

Tibial thrust test basic

Answer 22

Compressing tibia against stifle and flexing tarsus
If ligament is intact, the tibial tuberosity should not move but with CCL rupture, will move forward

more subtle

Question 23

What two radiographic views do we use for CCL evaluation

Answer 23

Mediolateral stifle
Dorsopalmar

Question 24

Radiographic signs with CCL disease

Answer 24

Stifle effusion; fat pad displacement, disruption of caudal fascial plane
Osteophytes in typical locations; poles of patella, caudal tibial plateau, fabellae, CCL insertion

[may notice cranial displacement of tibia]

Question 25

Why is meniscal injury bad and how often do we see in with CCL disease

Answer 25

Because meniscus cannot heal so get impact on shock absorption system forever
~1/3 of dogs show this (almost always medial meniscus affected)

Question 26

Presentation with a secondary meniscal injury after CCL disease

Answer 26

Chronic history of lameness then sudden deterioration
More lame than the average CCL patient
Large stible effusion
Owners may report hearing clicking/popping sound as meniscus released

NB: can happen after CCL surgery

Question 27

Risk factors for medial meniscal injury

Answer 27

much more likely with complete rupture i.e more instability
More likely with more weeks of lameness i.e left unresolved
More likely if overweight

Question 28

What does conservative CCL treatment mean

Answer 28

Strict rest for 6-8 weeks + rehab
Want to let body form a scar around the damaged joint which can help stabilise it

Much more successful for small dogs but still poor

Question 29

Broad categories of surgery for CCL

Answer 29

Intra-articular; to replace ligament
Extra-capsular; to stabilise stifle
Osteotomy; to change joint shape

Question 30

How does the lateral (febello-tibial retinacular) suture work for CCL

Answer 30

= an extra-capsular method of stifle stabilisation

Use strong permanent suture i.e strong nylon anchored at most isometric points possible to maintain tension throughout range of motion

Want to hold joint still for long enough to get tight periarticular fibrosis

Question 31

What are some complications/limitations with lateral suture technique

Answer 31

No point combos give constant suture tension; if tightening it in flexion can get instability on extension etc

Ideally perform tightening with stifle in slight extension

Question 32

What are the main types of osteotomy for CCL

Answer 32

Tibial plateau levelling osteotomy TPLO
Tibial tuberosity advancement TTA
[others are cranial closing wedge osteotomy, triple tibial osteotomt)

Question 33

How does a TPLO work basic

Answer 33

Cut prox tibia, rotate and secure to change slope angle from 24 degrees to 6 degress i.e flatten it

This will reduce tibial thrust instability
[NB: still have cranial draw since joint unstable; get DYNAMIC stability during movement]

Question 34

How does TTA work basic

Answer 34

Advance the tibial tuberosity cranially
This makes the force of the patella tendon parallel to loading force of joint; counteracts tibial thrust

i.e slope the same but force has changed

Potential issue = underadvancement of tuberosity

Question 35

When is TPLO particularly a good idea

Answer 35

Boisterous large dog
Bilateral disease
Steep anlge

Question 36

POst-op care for TPLO/TTA

Answer 36

6 weeks strict rest
No runningjumping etc
Radiographs at 6 weeks
Gradual return to exercise and physio