Stifle Flashcards
What are the surgical disorders of the stifle?
Cranial cruciate ligament rupture
Meniscus injury
Collateral ligament injury
Patellar luxation
What is the anatomy of the cranial cruciate ligament?
Craniomedial band
—taut during all phases of flexion and extensions
Caudolateral band
—taut in extension but lax in flexion
T/F: you you only have a partial rupture of the cranial cruciate ligament, it is usually the craniomedial band that is ruptured
True
What is the function of the cranial cruciate ligament ?
Prevent internal rotation of the tibia
Prevent hyperextension of the joint
Prevent cranial tibial thrust (cranial translocation of the tibia on weight bearing
What is cranial tibial thrust?
Natural force created by stifle because of the 145degree angle
Cranial force on the tibia when the hock is flexed and the gastrocnemius muscle contracts
Cranial tibial thrust exceeds breaking strength of the cruciate ligament = tear
What are conditions that can predispose to cranial crutiate rupture?
Aging process — degeneration of the joint
Obesity, poor conditioning
Confirmation — straight stifle joint
Increased tibial plateau angle (TPA)
Immune mediated arthroapthies
What is the etiology of cranial cruciate rupture
Trauma
Hyperextension and internal rotation
Jumping and landing
High TPA (tibial plateau angle) increases strain on CCL
What is the the cause of a high tibial plateau angle?
Retared growth of the caudal portion of proximal tibial physis
Signalment for CCL rupture?
Mature dogs
Mostly active large breeds
Obese
Can happen in any gender/breed
History associated with acute CCL rutpure?
Following some activity
Sudden onset of non/partial -weight bearing lameness that decreases in 3-6wks
History associated with a chronic CCL rutpure?
Prolonged weight bearing lameness
History of acute non-weight bearing lameness with gradual improvement
Difficulty rising, sits with affected limb out
Worse after exercise
What physical exam findings are consistent with an acute CCL rupture?
Protective of joint
Need to get dog to relax quadriceps — may need sedation
Joint effusion adjacent to patellar tendon
Positive cranial drawer test or tibial compression test
What physical exam findings are consistent with a chronic CCL rupture?
Muscle atrophy
From medial swelling :buttress
Crepitation on flexion and extension
Palpable periarticular osteophyte formation
Firm fiberous generalized swelling of joint
Limited/ “constrained” drawer sign
Palapable and audible meniscal “click”
What clinical exam findings are consistent with a partial tear of the CCL ?
Cranial drawer in FLEXION only
Pain on extension of joint
Presence of degenerative changes lead to diagnosis
In time, show same sings as a chronic tear without joint instability
How do you do a cranial drawer test?
Flex and extend limb to relax quads
Forefinger and thumb on bony points of each side of joint (patella and lateral fabella, tibial tuberosity and head of fibula
Hold femur in place, push tibia cranially using thumb on fibular head, while preventing internal rotation and flexion or extension of joint
How do you do the cranial tibial thrust test AKA tibal compression test?
Place hand on cranial surface of joint, stifle slightly flexed with hock extended
Dorsiflex hock
Positive result = cranial subluxation of tibia
How much drawer ins normal??
None!!
Puppies may have4-5mm but have abrupt stop at cranial extend
What would you see on radiographs of a dog with acute CCL rupture? How does it appear in a chronic case?
Acute : Joint effusion
— squished fat pad
—increased radioopacity in joint
R/O other injuries
Chronic : joint effusion + osteophyte formation on patella and trochlear ridge +increased medial periarticular soft tissue
What imaging method can you use to confirm partial CCL tears and assess degree of osteoarthritis?
Arthroscopy
Also therapeutic — removal of CCL remnants — assist in reconstruction of CCL —treat meniscal injury — treat OCD lesions
DDX for CCL rupture?
Sprain/strains Patellar luxation Caudal cruciate ligament injury Primary meniscal injury Immune-mediated arthritis
When is medial management indicated for CCL rupture?
Small dogs <10kgs
How can CCL rupture be managed medically?
Confinement, rest
Weight reduction
Pain management
Physical therapy: swimming to improve muscular strength
What are the goals of surgical management of CCL rupture ?
Establish joint stability
Lessen secondary DJD
Address any concurrent meniscal injury
What are the surgical options for CCL rutpure?
Intracapsular reconstruction Extracapuslar reconstruciton Tibial osteotomy EVS — tibial plateau leveling osteotomy (TPLO) —tibial tuberosity advancement (TTA)
What is done for intracapsular reconstructions of CCL ?
Replacement of CCL wit fascial graft or section of patellar tendon
Placed either though bone tunnels or over the top of the femoral condyle
(Inferior to other techniques)
How is extracapsular reconstruction done for CCL ?
Lateral fabellar tibial suture technique
—> Heavy suture is passed around the lateral fabella and through a hole drilled in tibial tuberosity … or …
—>Secured to bone with a “bone anchor”
Suture is tied or crimped
Monofilament nylon fishing line
TightRope CCL
—>toggle fixation mechanism, fiber tape and guide wires to allow consistent placement
T/F: Tibial plateau leveling osteotomy (TPLO) neutralizes cranial tibial thrust and drawer sign, and eliminates hamstring function by changing angle of tibial plateau
False
Tibial plateau leveling osteotomy (TPLO) neutralizes cranial tibial thrust and eliminates hamstring function by changing angle of tibial plateau (active/dynamic constraint)
DOES NOT eliminate drawer
A tibial plateau slope of ________ degrees allows control of tibial thrust by caudal cruciate ligament and quadriceps muscles
5-7
What is a TTA?
Tibial tuberosity advancement
T/F: Tibial tuberosity advancement (TTA) eliminates tibial thrust by positioning the patellar tendon perpendicular to the slope of the tibial plateau
True
How are patients managed postop from cranial cruciate surgery?
Compression bandage may be used for 24-36hours to control swelling
Physical therapy within 48-72hours
Limited exercise for 4-6weeks, until radiographic healing with TPLO or TTA
Gradual return to exercise over an additional 1-2 months
Complications of surgical CCL rupture repair?
Infection Lack of stabilization Meniscal injury Implant complications Progressive osteoarthritis
What is the prognosis for CCL rupture surgeries?
Long term fxn good with all surgical methods
One year post op function is better with TTA and TPLO (also a more rapid return to full function)
DJD is progressive but slowed
Medical injures are caused by excessive crushing or shearing forces associated with stifle injury. Which meniscus is most affected?
Caudal body of medial meniscus
Usually associated with CCL rupture which displaces the medial femoral condyle caudally in flexion —> wedging/crushing of meniscus on weight bearing and extension
What is the function of the meniscus?
Make joint surfaces congruent
Distribute load transmission
Shock absorption
Lubrication
What is usually the presenting complaint with meniscal injuries?
Owner reports loud “pop or click” when dog walks or when joint is manipulated
Sudden worsening of lameness or more lame than expected
T/F: all meniscal ruptures have pain
False
Chronic - can lack pain
How are meniscal injuries diagnosed?
Arthroscopy
What is the most common type of meniscal tear?>
Caudal bucket handle tear in medial meniscus
What is the most common surgical management for meniscal tears?
Partial meniscetomy
Function of the collateral ligaments?
Provide joint stability medial and lateral
Prevents varus-valgus motion
Collateral ligament injury isusualy due to?
Severe direct trauma to stifle joint
Eg motor vehicle
Leg caught in tree
Landings
How can you diagnose a collateral ligament injur?
Varus and valgus stress test with rads to see joint laxity
Joint but be extended in both tests
What is the DDX for collateral ligament injuries?
Avulsion or salter Harris fracture
Condyle fracture
Concurrent ligament damage (CCL)
Treatment for collateral ligament injury?
Primary reconstruction of ligaments, PO support with external fixator
Prosthetic collateral support using suture or wire placed around bone anchors or bone screws
What is a common triad of ligament injuries of the stifle?
Cranial and caudal cruciate Medial restraints (collateral and meniscus)
Signalment for medial patellar luxation?
Smal and toy breeds
Most common congenital deformity
What predisposes dogs to medial patellar luxation?
Medial malalignment of quadriceps —> forces alter growth of distal femoral physis and proximal tibia
- lateral bowing of distal femur
- lateral torsion of distal femur
- medial displacement of tibial tuberosity
- medial bowing of proximal tibia
- abnormal development of tracheal groove
- hypoplasia of medial condylar ridge
History that would be consisted with a medial patellar luxation?
Intermittent weight bearing lameness
Holds leg in flexed position for a few steps “skipping gait”
Grade IV have severe mechanical lameness and gait abnormalities
Grade this patellar luxation ..
Patella can be manually luxated but sponteneously returns to normal position
Spontaneous luxation is rare
Flexion and extension of joint are normal
Grade 1
Grade this patellar luxation..
Patella luxated with lateral pressure or on flexion of stifle, remains luxated until reduced manually or when animal extends
Spontaneous luxation and reduction occurs, with intermittent lameness
Grade 2
Grade this patellar luxation..
Patella is luxated most of time but can be manually reduced
Reluxates spontaneously
Deformities of femur and tibia
Grade 3
Grade this patellar luxation..
Stifle cannot be fully extended
Patella is hypoplastic, 80-90degree of medial rotation of proximal tibial pleateau
Medial displacement of quadricpts
Tracheal groove is shallow
Patella is luxated and cannot be manually reduced
Grade IV
DDX for patellar luxation ?
Legg-Perthes disease Hip luxation CCL rupture Tibial tuberosity fracture Rupture of patellar ligament
When is conservative management of patellar luxations indicated?
Asymptomatic older patients
Grade I-II with no clinical signs
— must monitor
When is surgical management of patellar luxation indicated ?
Symptomatic immature or young patients
Patients with lameness and active open growth plates
Why do we want to do arthrotomy to assess the joint in patellar luxation ?
Arthrotomy to assess joint
— chronic patellar luxation leads to increased stress on CCL
—CCL rupture and MPL common findings
Surgical prodecures for patellar luxation?
Soft tissue reconstruction
- medial fascial release
- lateral imbrication
Bone reconstruction
- trocheoplasties (wedge/block recession OR resection)
- tibial tuberosity transposition
- wedge or corrective osteotomy of distal femur in severe skeletal deformity
How is a tibial tuberosity transposition done?
Tibial tuberosity is cut from proximal to distal, leaving periosteum attached distally
Cranialis tibialis muscle is elevated and periosteum is removed from area lateral to tuberosity
Tibial tuberosity it reattached to shaft of tibial with K wires
What is a lateral imbrication ?
When closing a lateral arthrotomy, imbricate (tighten) lateral joint capsule and retinaculum
Medial release incision in joint capsule and retinaculum
What is the primary reason for recurrence of medial patellar luxation?
Only doing soft tissue reconstruction
Incorporating bone reconstruction is MOST important for good prognosis
Lateral patellar luxation is usually seen in what breeds?
Large breed
Appear Knock kneed
Much less common than medial luxation
