Patella luxation Flashcards
Cause of patella luxation?
Usually secondary to pelvic limb deformity
presentation?
6-12 months, or older due to OA or CCL
What type of disease is patella lux?
developmental, as is not present at birth
What is the extensor mechanism of the stifle?
- quadriceps muscle
- patella
- trochlea
- patellar ligament
- tibial tuberosity
Misalignement of this mechanism gives patella lux, lack of pressure on groove -> hypoplastic
Bilateral in?
60%
Breed predisposition?
Spaniels
Yorkshire Terrier
Poodles
Staffordshire Bullterrier
Labrador
Flatcoat retriever
Patella stability is evaluated?
When extended and flexed, best when not sedated
What can indicate cartilage erosion on clinical exam?
Pain on retropatellar pressure
Grading of patella lux?
Grade 1 - the patella can be luxated manually when the stifle is extended, but returns to normal position when released
Grade 2 - the patella luxates and reduces spontaneously during motion
Grade 3 - The patella is permanently luxated but can be manually reduced
Grade 4 - Permanent, irreducible luxation of the patella
Indications for conservative treatment?
Small dogs (or cats) with no or mild clinical signs
Grade 1-2 without clinical signs
sedentary dogs -> can manage with conservative treatment
Indications for surgery?
Puppies grade 3-4 -> 2 step surgery (as TTA cannot be done in growing animals)
All grade 3+4, and grade 2 with symptoms
What is the reluxation rate and complication rate?
48% reluxation
18% complication
What are the options for surgical alignement?
- tibial tuberosity transposition
- distal femoral corrective osteotomy (closed wedge, open wedge or de-rotational osteotomy)
- proximal tibial corrective osteotomy
What are the adjunct procedures of patella lux?
- Trochleoplasty (block, wedge, trochlear chondroplasty, abrasion)
- Soft tissue release
- Imbrication
- rectus femoris muscle release
- antirotational suture
What is the salvage procedure?
Patellectomy
What is the difference between the block and wedge sucoplasty?
Block ensures a deeper groove especially proximally, increasing cartilage contact and decreasing proximal patella luxaiton
What are the anatomical landmarks for block sulcoplasty?
From intercondylar notch to ostechondral junction
What size tension band should you choose for TTT in animals below and above 20kg?
Tension band wire
<20kg = 0,8mm
>20kg = 1 mm
Complications of TTT?
- implant failure
- loss of reduction of TT
- non-union, mal-union, delayed union
- implant associated infection
- fracture (of tibial tuberosity or tibia)
Complications of sulcoplasty?
- recurrent luxation
- recurrent pain
- loss of reduction of autograf
- septic arthritis
- fracture of trochlear ridges
- reurrent patella luxation
- OA
What is the reluxation rate?
6-28%
Patella luxation in the cat?
Uncommon, usually medially
Often associated with HD
Surgery recommended if symptomatic
As dogs
Other treatment options for patella luxation?
- antirotational suture (historic)
- corrective femoral osteotomy (if distal femoral varus)
- patellar groove replacement (salvage)
- medial trochlear ridge elevation (can give erosion)
- partial patellectomy (discoid patella, cats)
What is the key for patella luxation with concomitant cranial cruciate ligament disease?
Signalement! Was the patella lux a problem prior to CCL -> if yes, you must adress it! If not -> focus on CCL
