Exam 1 Flashcards
Anatomy of the Cranial Cruciate Ligament
Originates from the medial aspect of the lateral condyle, courses cranially and medially and attaches on the craniomedial aspect of the cranial plateau
Made up of two pieces
-Craniomedial band - taut in both flexion and extension
-Caudolateral part - taut only in extension
Functions of the Cranial Cruciate Ligament
Functions to Prevent:
- Cranial drawer
- Internal rotation
- Hyper-extension
Cranial Cruciate Ligament Basic Presentations
Insidious onset, mild but chronic lameness
Insidious onset, progressively worsening lameness
Acute onset, improved then worsening lameness
Acute onset, progressive with an acute worsening of lameness
Acute onset, non-weight bearing
Unable to use back end
Cranial Cruciate Ligament Presentation - Insidious Onset, Mild but Chronic Lameness
Presented by discriminating owner Younger dogs Active or performance Worse after exercise Early partial tears NO cranial drawer Exhibit pain while checking for drawer Radiographs WNL or mild effusion Definitive diagnosis requires MRI or arthrotomy
Cranial Cruciate Ligament Presentation - Insidious Onset, Progressively Worsening Lameness
Middle age, overweight, often female
No specific incidence of injury
Worse after exercise
Will sit sideways, affected leg extended - very characteristic of cruciate damage
Muscle atrophy
Thickening on inside of stifle - medial buttress
Will have drawer, especially in flexion
-Drawer in flexion means that only the craniomedial part is ruptured because in extension the caudolateral part is taut
Radiographic Signs of Cranial Cruciate Injury
Joint effusion
Osteoarthritis - osteophytes
Cranial Cruciate Ligament Presentation - Acute Onset, Improved then Worsening Lameness
Most common history Initial incident Better in days, then worse in 3-4 weeks Usually see 3-4 months after Worse after exercise, stiff after rest Hesitate to sit down, sits over to one site Medial thickening Moderate muscle atrophy Cranial drawer
Cranial Cruciate Ligament Presentation - Progressive with an Acute Worsening of Lameness
An initial episode with partial to complete resolution of signs
3-5 months thereafter, a second injury occurs
Often non-weight bearing
Muscle atrophy
Medial thickening
Cranial drawer
Crepitation (meniscal click)
Cranial Cruciate Ligament Presentation - Acute Onset, Non-Weight Bearing
Athletic dog History of injury during strenuous activity Usually non-weight bearing Swollen knee Effusion Dramatic cranial drawer No medial thickening
Cranial Cruciate Ligament Presentation - Unable to Use Back End
Most difficult situation Condition often confused with neurologic condition or hip dysplasia Trouble getting up Can ambulate if assisted Unsteady gait Can stumble Patellar reflexes are exaggerated Cranial drawer PRESENT May or may not have medial thickening Varying degree of osteoarthritis Very difficult cases Watch for endocrinopathies
What are the two tests that you do in the exam room to diagnose a cranial cruciate ligament rupture?
Cranial drawer test
Tibial thrust test
Cranial Drawer Test
Index finger on patella, thumb on fabella
Index finger on tibial tuberosity, thumb on fibula
Push caudal, then cranial
Perform through a variety of degrees of flexion
Look for pain response
Any drawer is abnormal
Tibial Thrust Test
Grasp stifle and place index finger from patella to tibial tuberosity across straight patellar tendon
Grasp tarsus and flex
Look for cranial motion of tibial tuberosity
Lateral Prosthesis Cranial Cruciate Ligament Repair
One of the most common procedures done
Extracapsular
A piece of nylon is run from the femoral fabellar ligament through the holes in the tibial tuberosity on the outside of the joint and tightened down using crimp clamp techniques
It is at the same angle on the outside of the joint as the cruciate is on the inside so it takes up the function of the cruciate
Tibial Plateau Leveling Osteotomy for Cranial Cruciate Ligament Repair
Compressive forces on the tibia are generated during normal locomotion
Because the tibial plateau is sloped caudally, shear creates a “cranial tibial thrust”
Cranial tibial thrust is opposed by the CCL in the normal knee
When the CCL tears, unrestrained tibial thrust results in an unstable knee during locomotion
The central principle of TPLO is an attempt to neutralize cranial tibial thrust in the CCL deficient knee
Neutralization of cranial tibial thrust is accomplished by flattening the tibial plateau
Preoperative planning
-Straight and lateral AP views
-Include distal femur and tarsus
-Check for limb alignment
-Measure preoperative slope of the tibial plateau
Medial approach to the stifle is recommended, although lateral is acceptable
Joint is explored, CCL remnants excised, and menisci examined
The tibial plateau is leveled
A patented oscillating saw and biradial saw blade is used to created the osteotomy in the proximal tibia
A patented jig is used to aid limb alignment during osteotomy and stabilize the proposed fracture in one plane during rotation
The tibial plateau is rotated a predetermined amount based on the preoperative tibial plateau slope
An IM pin is used as a handle for rotation, and the osteotomy is held in place temporarily with one or two K wires
The osteotomy is repaired with a patented plate and screws
Tibial torsion is corrected if present
Bending the distal jig pin will axially rotate the tibia distal to the osteotomy to eliminate internal torsion
Medial Meniscus in Cranial Cruciate Ligament Injury
Meniscal release or excision of a tear is performed in every surgical case
If the caudal horn of the medial meniscus is torn it comes out
If the meniscus is normal you do a meniscal release
Grade I Medially Luxating Patella
Patella can be manually luxated but spontaneously reduces
No clinical signs
Grade II Medially Luxating Patella
Patella is most often reduced (in normal position), can be manually luxated and will stay luxated
Intermittent non-weight bearing lameness followed by periods of normalcy
Grade III Medially Luxating Patella
Patella is luxated, but can be manually reduced
Chronic lameness
Grade IV Medially Luxating Patella
Patella is luxated and cannot be manually reduced
Chronic severe lameness with deformity of caudal limbs
Medially Luxating Patella Goals of Surgical Correction
Re-establish pull of the quadriceps so that the patella overlies a trochlear groove of sufficient depth
Simply reducing the patella and suturing into place results in a high rate of failure
Grade I Medially Luxating Patella Surgical Correction
None
Grade II Medially Luxating Patella Surgical Correction
Wedge recession
Tibial tuberosity transposition
Lateral imbrication
Grade III Medially Luxating Patella Surgical Correction
Wedge recession
Tibial tuberosity transposition
Medial release of sartorius muslce
Lateral imbrication
Grade IV Medially Luxating Patella Surgical Correction
Usually requires corrective osteotomies of distal femur
Anatomy of the Physis
From Epiphysis to Metaphysis Zone of Resting Cartilage Zone of Proliferation Zone of Maturation Zone of Hypertrophy Zone of Calcification