Patellar luxation Flashcards
Anatomy of the patella
Sesamoid bone within the tendinous insertion of the quadriceps
Femoral trochlear sulcus is the articular surface
Lateral and medial trochlear ridges aid patellar stability
Function of the patella
Acts as a pulley to enable efficient passage of the muscle tendon over the cranial aspect of the distal femur
Maintains even tension
Increases the mechanical advantage of the quadriceps
Patellar luxation
Displacement of the muscle tendon
Most are congenital
Result of malignment of the direction of force of contraction
Signalment of patellar luxation
Small breeds most commonly affected
Usually when skeletally immature
No sex predisposition
Presenting history for patellar luxation
Intermittent non-weight bearing, skipping lameness often seen
More chronic lameness may be seen secondary to articular cartilage damage
If acute onset lameness with stifle pain in a middle aged dog, they may have an additional injury like cranial cruciate ligament disease
Gait analysis in patellar luxation
Intermittent non-weight bearing, skipping lameness often seen
Sometimes collapse of the stifle on weight-bearing
Conformation of patellar luxation
Obvious conformational abnormalities may be present
If medial luxation may have genu vara
If lateral luxation may have genu valga
Stifle may be hyperflexed
Physical exam of patellar luxation
Palpation of the limbs to asses conformation, alignment and position of patella
Flex and extend stifle - may feel patella slip in and out, if not rotate tibia and apply medial or lateral pressure on the patella
May have crepitus due to chondromalacia
Classification of patella luxation
I: can be luxated but will return to sulcus once released
II: can be luxated and will stay luxated when pressure released
III: luxated when stifle palpated, can be physically returned to sulcus
IV: permanently luxated and cannot be returned
Radiography of patella luxation
Stifle radiographs may appear normal - palpation is the most reliable diagnostic test - dynamic condition
Femoral and tibial deformities may be present
May be seen luxated on radiograph
Can identify joint effusion or secondary osteoarthritis
Conservative treatment for patella luxation
For mild, asymptomatic cases (grade I) or in older animals
Weight management
Exercise restriction
NSAIDs and analgesics as needed
Joint supplements
Physiotherapy and hydrotherapy
Surgical options for patella luxation
Bony constructions are indicated in most cases
Recession sulcoplasty
Tibial tuberosity transposition (TTT)
Medial release
Lateral imbrication
Anti-rotational sutures
Patellar groove replacement
Artificial trochlear ridge enhancement
Recession sulcoplasty for patella luxation
Deepens the sulcus
4 types:
- abrasion sulcoplasty
- wedge recession sulcoplasty
- block recession sulcoplasty
- trochlear chondroplasty
TTT
Tibial tuberosity trransposition for patella luxation
Corrects the alignment of the pull of the quadrceps by moving the tibial tuberosity to line up with the sulcus
Involves performing an osteotomy of the tubercle
Medial release
For patella luxation
Medial joint capsule and retinacular soft tissues usually limit lateral repositioning of the patella are cut to allow patella to sit in groove without being pulled medially
These tissues are left unsutured
