Lecture 15 & 16 - Common Hindlimb Disorders

Question 1

what are the 6 possible reasons for a negative Ortolani test?

Answer 1

1. normal
2. capsular fibrosis has eliminated laxity
3. irreducible luxation of the femoral head
4. acetabular infilling with bone
5. insufficient force or subluxate the femoral head
6. inadequate muscle relaxation

Question 2

triple pelvic osteotomy - what is it? and how old are the patients that get it?

Answer 2

osteotomy of the Ilium, Ischium and pubis - the pelvis is cut to allow for rotation of the acetabulum

patients have to have minimal to no DJD and are no more than 10 months of age

Question 3

what is juvenile pubic symphysiodesis and what is the key to its success?

Answer 3

cauterization of pubic symphyseal growth plate causes premature closure allowing unopposed dorsal growth causing the acetabulum to rotate outward

key: do while patient is growing –> 12-16 weeks

Question 4

total hip replacements are reserved for what type of patients?

Answer 4

clinically affected animals that have failed medical management

Question 5

what is the difference between a total hip replacement and a femoral head osteotomy?

Answer 5

they both result in a pain free joint, but a total hip replacement results in a normal or near normal gait, muscle mass, and range of motion, a femoral head osteotomy does not, it results in poor function.

Question 6

which classification of traumatic hip luxation is most common and how is it detected?

Answer 6

cranio-dorsal

palpate: wing of ileum, greater trochanter, ischial tuberosity. they should form a triangle. if you palpate them in a single line = suspicious of cranio-dorsal hip luxation

Question 7

treatments for traumatic hip luxations - open reductions (there are 5)

Answer 7

toggle pin (indicated if: multiple limb injuries)
capsulorraphy (indicated if: intact joint capsule)
extra-capsular prosthesis (indicated if non-repair capsule tears)
de-vita pin (sciatic n. injury)
transarticular pin

Question 8

what are the primary restraints in the stifle?

Answer 8

the cranial and caudal cruciate ligaments

Question 9

what is the most important force in the stifle?

Answer 9

cranial tibial translation - where the tibia wants to thrust forward - the cranial cruciate ligament is what prevents that

Question 10

what is the primary function of the cranial cruciate ligament? what does it also contribute control of?

Answer 10

primary function:

• cranial tibial translation - resists cranial displacement of the tibia relative to the femur
• stifle hyperextension

also contributes to the control of internal tibial rotation (along with the caudal cruciate ligament)

Question 11

what does the caudal crucial ligament protect against?

Answer 11

caudal displacement of the tibia relative to the femur.

Question 12

if you have a CCL rupture and stifle derangement it can be injury to which soft tissues?

Answer 12

the medial collateral ligament and caudal cruciate ligament

Question 13

what is the most common meniscal injry we see?

Answer 13

a bucket handle heart of the CAUDAL 3rd of the MEDIAL meniscus secondary to injury of the CCL

Question 14

how does the caudal medial meniscal injury occur?

Answer 14

with the shifting of the tibia in relation to the femur when a dog steps forward, the caudal horn of the meniscus can get caught between the femoral and tibial condyles and cause a tear

Question 15

why do we not see lateral meniscal tears?

Answer 15

the lateral meniscus is loosely attached to the tibia. the mensico-femoral ligament attaches it caudally to the femur so it will slide more with the femur than the tibia which protects it more.

Question 16

explain the mechanism of a meniscal tear

Answer 16

1. meniscus is normally a secondary restraint.
2. you get a CCL rupture, causing the meniscus to become the primary restraint.
3. as tibia slides forward the caudal pole of the meniscus gets caught
4. this creates a wedge phenomenon of the caudal pole of the meniscus which is responsible for the meniscus injury.

Question 17

describe the cranial drawer test? what motion are you testing of which bone?

Answer 17

1. index finger on tibial tuberosity
2. thumb on head of fabella
3. other index finger over head of patella
4. slide tibia cranially, if able.

if you detect motion or laxity, that is a positive test for a CCL injury.

–> testing for cranial movement of the tibia

Question 18

tibial thrust test - describe

Answer 18

more likely to detect instability even with lots of muscle mass

1. hold stifle in normal flexed (standing) position.
2. drape index finger over cranial femur with tip of finger on tibial tuberosity
3. with other hand, hold and hyperflex the hock
4. if there is instability, it will push the index finger over the tibial tuberosity out

Question 19

what is an essential premise of the tibial osteotomy

Answer 19

tibial osteotomy is a surgical correction of an CCL injury:
it does NOT replace the ligament - it changes the mechanics of the joint so that it no longer needs the ligament by changing the caudal slope of the tibia.

the idea is to neutralize the cranial tibial thrust.

Question 20

tibial plateau leveling osteotomy (TPLO) - describe the approach

Answer 20

TPLO is the most common surgical treatment for a CCL injury. you cut in the PROXIMAL aspect of hte TIBIA and rotate in order to minimize the need for the CCL.

Question 21

**patellar luxation grading **

Answer 21

grade 1 (IN/IN): nonclinical, can be manually luxated but will immediately return to normal when released
grade 2 (IN/OUT): may have clinical signs, USUALLY in normal position, but can be luxated and will remain luxated position until its spontaneously reduced.
grade 3 (OUT/IN): surgery recommended, luxated MOST of the time, but can be manually reduced. spontaneously luxates and remains luxated. 
grade 4 (OUT/OUT): associated with severe conformational abnormalities, luxated and CANNOT be reduced mannually.

Question 22

what are the surgical treatments for patellar luxation?

Answer 22

reconstructive procedures: alter anatomic abnormalities

1. deepen femoral trochlea
2. tibial tuberosity transposition
3. corrective femoral and tibial osteotomy (not recommended)

stabilizing procedures: attempt to maintain patella in normal position

1. retinacular/capsular imbrinication - tightens the tissues on the lateral aspect of the joint with suture to PULL the patella over
2. capsulectomy - release the medial aspect by separating the muscles and fascia

Question 23

define osteochondrosis

Answer 23

failure of endochondral ossification that leads to cartilage retention

Question 24

define osteochondrosis dessicans

Answer 24

manifestation of osteochondrosis in which a flap of cartilage is lifted from the cartilage surface

Question 25

what are the most common sites for OCD?

Answer 25

most common in forelimb but in hindlimb its most common at:

stifle - lateral aspect of femoral condyle
hock - medial trochlear limb

Question 26

Ortolani test

Answer 26

tests for hip dysplasia

1. anesthesia required
2. in lateral recumbency
3. apply axial pressure, monitor with thumb over joint
4. continue axial pressure, ABDUCT the limb, feel and listen for a click or thunk. the thunk is REDUCTION - going back into the joint!