SA Ortho - Patellar Lux Flashcards
Congenital patellar luxation
Occurs in
Placement
Small toy breeds
Medial lux is most common
Traumatic patellar lux
Common group
Placement
Large breeds
Lateral lux is most common
Anatomy of medial pat lux
Patella is a sesamoid bone in quad tendon & patellar lig
Pathogenesis of medial pat lig
Unknown
May result from abnormal hip conformation
Another mechanism malfunction that could lead to med pat lux
Displacement of quadriceps mechanism could lead to pat lux
Angle of inclination to will most likely lead to medial pat lux
Coxa Vera - problem of angulation in hip expressed in stifle joint.
Secondary changes in limb of med pat lux
Med displacement of quads
Lateral bowing of femur
Torsion of distal femur
Shallow trochlear groove
Stifle instability
Medial displacement of tibial tuberosity
Clinical signs
(Can increase w grades)
Hoping lameness
Crouched - bow legged
Lameness could increase w development of DJD
Diagnosing pat lux
Using clinical signs/presentation
Physical exam findings
Radiographs
Grading pat lux
Grade 1
Patella can be manually luxation, but reduces spontaneously
Rarely lame, occasional skip
Minimal medial tibial rotation
Grading pat lux
Grade 2
Patella luxates spontaneously, reduced spontaneously with rotation of the tibia
Lameness varies - occasionally skip /WB lameness
Medial tibial rotation - up to 30*
Grading pat lux
Grade 3
Patella is luxated but can reluctantly be reduced
Chronic lameness
Medial tibial rotation of 30-60*
Moderate angular or torsional deformity
Grading pat lux
Grade 4
Patella is luxated continually and cannot be manually reduced
Limb is carried /crouched stance
Medial tibial rotation of 60-90*
Marked angular and torsional deformities
Radiograph shots for diagnosis of MPL
Skyline with rotation/angulation
Radio graphic signs of MPL
Displacement of patella on craniocaudal view
Shallow trochlear groove
Secondary OA
Patellar lux - surgery
Realign extensors apparatus
Normalize forces acting on physis/cartilage
Stabilize the patella in trochlear groove
Components of Patlux repair
Soft tissue reconstruction
Bone reconstruction
Aspects of soft tissue reconstruction
Imbrication of lateral retinacular fascia
Patellar and tibial anti rotational sutures
Medial release (Desmotomy)
Aspects of bone reconstruction for pat lux
Tibial tuberosity transposition
- transpose laterally for medial
- transpose medially for lateral
Corrective osteotomies of femur/tibia
Trochleoplasty techniques
Sulcoplasty
Wedge recession
Block recession
Chondroplasty
Trochleoplasty
Deepening of trochlear groove to depth of 1/2 patella thickness
Trochleoplasty block recession
Preserves more cartilage
Better for articular contact
Improved depth proximally
Prognosis for Pat lux surgical repair
Improves limb function
DOES NOT prevent progression of OA
Reluxation is common
-48%
- however usually mild
