Sx Diseases of the Stifle Objectives Flashcards
There are ___ cruciate ligaments in the stifle (knee)
2! Cranial and caudal
The cranial cruciate ligament arises from the ______ aspect of the
_______ femoral condyle,
and inserts on the _______ aspect of the region between the condyles.
The cranial cruciate ligament arises from the medial aspect of the
lateral femoral condyle,
and inserts on the cranial aspect of the region between the condyles.
The caudal cruciate arises from the _____ aspect of the _____ condyle,
and inserts on the _____ aspect of the intercondylar region.
The caudal cruciate arises from the lateral aspect of the medial condyle, and inserts on the caudal aspect of the intercondylar region.
Which ligament is indicated by the GREEN block?
Cranial cruciate ligament
Which ligament is indicated by the PINK block?
Caudal cruciate ligament
On this arthroscopic view, which ligament is
Cranial? Which is caudal?
Cranial = purple
Caudal = green
How are the cruciates named?
The cranial and caudal cruciate ligaments are designated as such based upon their distal component
I.E.: cranial cruciate ligament is so named because the distal portion (the insertion) sits cranially on the tibia relative to its proximal portion (the origin).
What is the relationship of the cruciate ligaments to the
synovial lining of the joint?
Ligaments are INSIDE the joint capsule, but OUTSIDE the synovial lining
“Intra-articular but extrasynovial”
Due to being intra-articular but extra-synovial, a damaged
cruciate disrupts the synovial barrier and is thus a
potent stimulus for ongoing _______ and there-by DJD
inflammation
What is the function of the cranial cruciate ligament?
prevents internal rotation, hyperextension, and tibial thrust.
the term usually used to refer to a force that causes the tibia to slide cranially relative to the femur
Cranial tibial thrust
What is the purpose of cranial tibial thrust?
Cranial tibial thrust is generated any time there is compression between the femur and the tibia (when weight applied to limb)
If the cranial cruciate ligament is intact, it opposes that cranial force
How does cranial tibial thrust relate to cruciate ligament rupture?
If the force of tibial thrust is greater than the breaking strength of the cruciate ligament = rupture
Most cruciate ruptures are a result of ____ tibial thrust forces applied to a cruciate ligament that is _____weak.
Most cruciate ruptures are a result of normal tibial thrust forces applied to a cruciate ligament that is abnormally weak.
What is the etiology of acute cranial cruciate ligament rupture?
Usually traumatic
In humans: They result from excessive torsion (rotation of the limb at the stifle) or extension on a normal, healthy CCL
In animals: almost always an acute aggravation of a chronic process
What is the etiology of chronic cranial cruciate ligament disease?
a chronically weakened cruciate ligament (due to a disease process) that cannot withstand the normal forces associated with weightbearing
In animals, which is more common:
Acute or Chronic cranial cruciate rupture/disease?
CHRONIC cranial cruciate dz is more common
What factors play a role in the pathogenesis of chronic cruciate ligament disease?
older age, weight (>15kg)
obesity, poor fitness,
conformation, excessive plateau angle
What is the risk of contralateral disease with chronic cruciate ligament disease?
Roughly 50% of dogs that blow one CCL as a result of chronic CCL disease will blow the other within 1‐2 years
Describe the signalment of the typical dog with cruciate ligament disease
Adult, large to giant breed,
FEMALE (slightly overrepresented), neutered dogs
Describe the history typical of chronic ligament disease
hindlimb lameness that is aggravated by activity OR after rest.
signs may be mild and episodic, with the lameness seeming to resolve between bouts (frayed rope analogy)
POOR response to NSAIDs and other arthritis drugs
(if DO respond to NSAIDs,
it is DJD responding and patient has advanced dz)
Describe the physical exam findings with cruciate ligament disease
Effusion behind patellar tendon
(if minimal effusion, patellar tendon divot is not palpable. if large effusion, stifle more rounded, normal “V” shape of the stifle obscured)
Distension→fibrotic change→disuse atrophy
Medial buttress
Crepitus
Tibial thrust (drawer test)
the accumulation of fibrosis along the medial collateral; a very firm, almost bone‐consistency lump on the medial aspect of the joint right where the medial collateral is.
Medial Buttress
The mainstay of a diagnosis of cruciate ligament rupture is the presence of _______ in the joint.
instability
(shown by tibial thrust on drawer test)
The _____and the _______ are two ways to test for cranial cruciate ligament rupture.
The cranial drawer test and the tibial compression test are two ways to test for cranial cruciate ligament rupture.
What is the difference between the two tests for cranial cruciate
ligament rupture?
The difference between the two tests is that the
cranial drawer test is testing the cranial cruciate ligament passively, i.e., without any effort from the patient.
The tibial compression test is testing the cranial cruciate actively, i.e., by simulating weightbearing.
T/F:
sedation is required to definitively test either cranial drawer or tibial compression
TRUE!
MUST sedate to be sure!
What is the significance of “puppy drawer” ?
Puppy drawer has an abrupt stop, where “standard” drawer has a softer, less well‐ defined stop.
can be a normal finding in a young patient (<6m).
If concerned with +test in young animal, look to see if effusion or pain
Describe the functional divisions of the Cranial CL
two subdivisions, the craniomedial band and the caudolateral band
craniomedial band is taut throughout the entire range of motion, caudolateral band is taut only in extension. (and lax in flexion)
This is a FUNCTIONAL division (NOT anatomical!)
How does disruption of one band (functional division)
affect the palpation findings
in partial vs. complete tears of the cruciate ligament?
With a partial tear, it is the craniomedial band that ruptures.
In this situation there will be a positive cranial drawer or tibial thrust, but ONLY when the joint is in partial flexion. When the stifle is in extension, it will appear stable.
T/F:
You should ALWAYS test for instability in the stifle joint
in BOTH flexion and extension
TRUE!
(could be a partial tear and could miss it if not)
How does treatment of a partial tear differ
from treatment of a complete tear?
IT DOESN’T
What is the function of the menisci?
Primarily, the menisci are shock absorbers.
As fibrocartilage, they are compressible and thus act as padding between the femur and tibia.
reduce the stress on the cartilage.
dissipates the force of weightbearing
The secondary function of the menisci is to improve stability of the joint.
What is responsible for preventing subluxation of the joint
when the cranial cruciate is damaged?
Menisci!
______% of dogs with cruciate rupture
will have some amount of meniscal disease.
60 - 70%
What else is likely to be injured if the cranial cruciate is injured?
Menisci!
Which meniscus is most commonly damaged?
Why?
MEDIAL meniscus
medial meniscus is attached to the tibia (so when CCL ruptures, tibia displaces cranially and meniscus moves with it)
What is the effect of meniscal injury in the stifle?
Meniscal injury will increase the pain level (i.e., lameness) over uncomplicated CCL disease.
A history of a sudden increase in lameness = meniscus damage
“meniscal click” (a distinct popping sensation as the stifle goes from full flexion to full extension) - only in 25% of cases
Meniscal disease significantly accelerates cartilage wear.
Arthritis will appear sooner and be more severe over time in a stifle with damage to the meniscus.
What are the typical radiographic findings with cruciate ligament disease
Effusion
Osteophytosis, subchondral sclerosis, medial soft tissue thickening
( Increased diameter of the joint silhouette (light grey) into the area normally occupied by the fat pad (darker grey area between the joint and the patellar ligament) indicates effusion)
What is occurring in this radiograph?
Tibial thrust!
What is the relative value of medical vs. surgical treatment in
cruciate ligament disease?
Some think medical mgmt can help in animals <10kg, but NOT recommended because even small animals improve quicked with sx.
Given a choice between surgical and medical management, even in a small patient surgery would be preferable
What are the goals of surgical management of cruciate ligament disease?
Stabilize the joint
Explore the joint
What is the most common type of meniscal injury associated with cruciate ligament disease?
“buckethandle” tear
(e damaged portion of meniscus remains attached to the meniscal body at its periphery)
Describe surgical management of a meniscal injury
the damaged portion of meniscus is simply removed
What is meniscal release and why might it be done?
cutting the caudal pole of the medial meniscus
done to reduce the likelihood developing a meniscal injury after surgery.
Why is meniscal release NOT benign?
Release of the meniscus alters the function of the meniscus (shock‐ absorbing, weight‐distributing functions)
Changes the way weight is focused on portions of the cartilage and tends to increase the development of arthritis.
The effect of meniscal release is similar to completely removing the caudal pole of the meniscus.
What is the general difference between extracapsular and osteotomy stabilization techniques of CCL repair
Extracapsular techniques rely on an implant to stabilize the joint
Osteotomy techniques rely on a change in the forces on the joint to neutralize tibial thrust.
What are the most common extrascapular stabilization techniques for CCL tears? How about most common osteotomy techniques?
Extracapsular= Lateral suture (most common) and Tightrope
Osteotomy= TPLO and TTA (Tibial tuberosity advancement)
What is the most common stabilization techniques employed for cruciate ligament disease?
TPLO
Describe the lateral suture technique in general terms
placing a heavy gauge suture around the lateral fabella and through a bone tunnel in the tibia (in an orientation similar to the originial CCL)
List the complications of the lateral suture technique
Low complication rate of:
infection
implant failure
incomplete stabilization
peroneal nerve deficits/entrapment
Why is the possibility of peroneal nerve damage
unique to the lateral suture technique for CCL tears?
due to proximity of the nerve to the fabella.
Generally the suture is passed around the fabella with a large, curved needle.
If the fabella is not visualized properly, can stretch or entrap the peroneal nerve.
what patient factors increase complication rates for the lateral suture?
Larger dogs and younger dogs
What is the principal difference between the technique for placement of the TightRope and the technique for placement of a lateral suture?
Tightrope: intended to be placed noninvasively.
intention is that recovery is more rapid with less invasive techniques.
How does altering the angle between the force of weightbearing and the tibial plateau neutralize tibial thrust?
making the force of weightbearing perpendicular to the plateau,
eliminates shear and thereby eliminates tibial thrust.
THIS IS HOW osteotomy procedures neutralize tibial thrust without affecting cranial drawer
T/F:
if you have a patient that has had a TPLO or TTA, cranial drawer will test positive and a tibial compression test will test negative
TRUE
List potential complications of the osteotomy procedures
infection
implant failure
pins move
loss of stabilization
There are possible complications unique to the TPLO and TTA, related to the nature of the specific osteotomies that are created. Describe them.
The cuts that are made have to be carefully measured and oriented properly, perpendicular or parallel to various planes or axes. If they aren’t perfect, there can be problems.
What is the importance of postoperative activity restriction following osteotomy procedures?
osteotomy is essentially creating a fracture
Just as prolonged activity restriction is important following fracture repair,
it important following osteotomy.
Most osteotomies are healed in 8‐12 weeks, just like fractures
What is the prognosis for cruciate ligament disease following surgery?
GOOD!
DJD will still progress, but slower
What is the liklihood of return to normal function following surgery
in tx of cruciate tears?
UNLIKELY (tell owner)
T/F:
Lateral suture has a more rapid return to function that TPLO and TTA
FALSE!!!
TPLO and TTA are faster!
T/F:
TPLO outcomes are better than for lateral suture,
particularly for larger dogs.
TRUE
T/F:
Tightrope is difficult to compare to the other procedures,
but the outcome is closer to TPLO and TTA than to lateral suture
TRUE
T/F:
TPLO and TTA can be considered largely equivalent in outcome
True!
What is the difference between medial and lateral patellar luxation
MEDIAL most common, LATERAL most common in LARGE breeds
-
Medial:
- lateral bowing of distal femur (femoral varus)
- medial displacement of tibial tuberosity (tibial valgus)
- abnormally shallow trochlear groove
- hypoplasia of medial condylar ridge
-
Lateral:
- Femoral valgus
- Tibial varus
- Knock-kneed
Medial patellar luxation is ____% of all cases
98%
How is patellar luxation named?
Named for the displacement of the patella
Which type of patellar luxation is more severe?
LATERAL PL
What is the typical history of patellar luxation and how does that relate to pathology?
intermittent WB lameness
skipping gait (holds leg flexed for few steps)
Describe the grading system for patellar luxation
(In-Out= patella location without manipulation vs. where patella stays)
-
Grade 1 (In-In)
- Patella manually luxated but spontaneously returns to normal
- Flex and extend are normal
-
Grade 2 (In-Out)
- Patella manually luxated and remains luxated until animal extends
-
Grade 3 (Out-In)
- Patella luxated most of the time
- Manually reduced, but spontaneously reluxates
- May see deformed femur or tibia
-
Grade 4 (Out-Out)
- Patella fixed in luxation and manual reduction not possible
T/F:
Grade of patellar luxation is frequently different from one side to another
TRUE
Why are radiographs are used with patellar luxation when
they are insensitive for diagnosing PL?
To r/o other probs and provide a pre-sx baseline
What are the indications for conservative management in tx of
patellar luxation?
Grade 1 - 2 MPL with minimal clinical signs
What are the tx options for patellar luxation (surgical options)?
- Soft tissue reconstruction
- Lateral imbrication
- Medial release
- Bone reconstruction and alignment
- Trochleoplasties
- Tibial tuberosity transposition (T3)
- Distal femoral osteotomy (DFO)
NEED ONE OF BOTH!
why is monitoring required for patellar luxation if conservative management is chosen?
Condition tends to progress over time, so must monitor for changes
What are the indications for surgical management?
Significant lameness regardless of grade
Episodes 2-3 weeks or more
3 or more episodes in a month or less
Grade 3 or 4 with RCCL
Larger dogs
What are the indications for Distal Femoral Osteotomy (DFO)
in patellar luxation treatment?
LARGE breeds or Grade 4 luxation!
Describe postoperative care for patellar luxation
Controlled activity (6w)
PT
Rads to assess healing (6w later)
What is the risk of recurrence for patellar luxations?
50% reluxation (in 1987 study), but only 8% in a 2007 study
What are the factors that increase risk of complications (e.g., recurrence)
of patella luxations?
Dogs > 20 kg
Grade 4 PL
What is the prognosis for patellar luxation?
Grades 1 - 3: EXCELLENT for return to function
Grade 4: Guarded to poor :(
