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Describe the movements of the stifle joint.
- internal- external rotation
- varus-valgus angulation
Describe the functions of the craniomedial and caudolateral bands of the CCL and a clinical correlate of this.
- Craniomedial band is taut in flexion and tension
- Caudolateral band is taut only in extension
- If you're testing drawer on a dog, and there is only drawer in flexion, you know the craniomedial band is torn
The stifle joint has little ___________; therefore, stability relies on __________, such as... (5)
bony congruence; soft tissue stabilizers; cranial and caudal cruciate ligaments, menisci, joint capsule, and collateral ligaments
Describe the anatomy and functions (3) of the menisci.
- C-shaped fibrocartilagenous discs
- firmly attached to the tibia by the cranial and caudal menisco-tibial ligaments, the joint capsule, and the medial collateral ligament
- function in shock absorption, reduces friction, increases stifle congruity
With CCL rupture, the ___________ becomes the primary stabilizer of the stifle joint because...
medial meniscus; it is firmly attached to the tibia by the cranial and caudal menisco-tibial ligaments, the joint capsule, and the medial collateral ligament [in contrast, the lateral meniscus is loosely attached to the tibia and cannot stabilize the joint well]
Describe the anatomy and function of the lateral menicus.
loosely attached to the tibia by the cranial and caudal menisco-tibial ligaments and the menisco-femoral ligament
What are the functions of the CrCL? (3)
primary restraint against cranial tibial translation, internal tibial rotation, and stifle hyperextension
Describe the proposed pathogenesis of CrCL rupture.
- degeneration of the CCL, adaption and remodeling with ligament ischemia, mechanical stress, and microinjury
- Risk factors include: breed, age, body weight, MPL, and inflammatory arthropathy
What are PE findings with CCL rupture? (6)
- stifle effusion
- medial buttress (thickening on the medial aspect of the joint)
- muscle atrophy
- positive cranial drawer/ tibial thrust
- pain on hyperextension
- palpable click?
When can you do medical management for CCL rupture?
- small dogs and cats can respond well
- but all dogs, large and small, and cats respond BETTER to surgical management
What are the best/ most common ways to surgically manage CCL rupture?
lateral suture and TPLO
How does extracapsular stabilization (lateral suture) help with management of CCL rupture?
eliminate tibial thrust (which leads to subluxation during daily activity and lameness)--> stable during daily activity--> resolution of lameness
Where does the lateral suture run?
- fabello-tibial lateral suture: behind the fabella (sesamoids), anchoring around the fabello-femoral ligament, to the tibial tuberosity
- trying to mimic the effects of the cranial crucial ligament without actually being in the joint
- fibrosis and scar tissue form around the joint, so by the time the suture breaks, the joint has stabilized
Pros and cons of the lateral suture.
- Pros- quick, relatively easy, minimal instrumentation, cheap
- Cons- suture loosening and breakage, infection, peroneal nerve damage, patellar luxation
How do tibial osteotomies work to manage CCL rupture?
- goal is to neutralize cranial tibial thrust
- TPLO, TTA, cranial tibial wedge osteotomy
Describe TPLO surgery and how it works.
- [tibial plateau leveling osteotomy]
- radial metphyseal cut
- rotate proximal tibial segment
- stabilized with plate and screws
- eliminates cranial tibial thrust by reducing the slope of tibial plateau
What are the pros and cons of TPLO?
- Pros- good to excellent outcomes, can correct angular and torsional tibial deformities, modified to correct patellar luxations
- Cons- tibial tuberosity fractures, implant failure, "rock back", gait abnormalities, patella tendinosis, infection, hard to do in very small dogs, cost, equipment
How do we treat meniscal tears?
- MAYBE repair if in periphery of meniscus
- USUALLY remove by caudal hemi-meniscectomy or partial meniscectomy
Regardless of technique, stifle ligaments tears eventually progress to __________.