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Describe the movements of the stifle joint.
- flexion-extension
- internal- external rotation
- varus-valgus angulation
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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
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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
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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
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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]
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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
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What are the functions of the CrCL? (3)
primary restraint against cranial tibial translation, internal tibial rotation, and stifle hyperextension
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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
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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?
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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
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What are the best/ most common ways to surgically manage CCL rupture?
lateral suture and TPLO
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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
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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
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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
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How do tibial osteotomies work to manage CCL rupture?
- goal is to neutralize cranial tibial thrust
- TPLO, TTA, cranial tibial wedge osteotomy
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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
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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
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How do we treat meniscal tears?
- MAYBE repair if in periphery of meniscus
- USUALLY remove by caudal hemi-meniscectomy or partial meniscectomy
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Regardless of technique, stifle ligaments tears eventually progress to __________.
osteoarthritis
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