patellofemoral joint Flashcards
week 10
patella anatomy
sesamoid bone
flat, triangluar, embedded in quad tendon
medial & lateral patellar retinaculum
fuctions as pulley and reduces friction
talk about patellar anatomy in full flexion, full extension and 45-60° of flexion
full flexion: femoral condyles help maintain MA of a lengthened quadriceps (passive insufficiency)
full extension: increases MA of a shortened quadriceps (active insufficiency)
45-60° of knee flexion: maximal MA and optimal length - tension relationship (highest torque)
patellar tendon length ? patella length
patellar tendon length = patella length (1:1)
patella baja (short tendon) =
more stable
patella alta (long tendon)
= less stable
patella site in central groove between femoral condyle facets:
- incongruent small patella and large femur
- lateral femoral facet is bigger
lateral femoral condyle sits slightly anterior and is more of a ___ _____ for the patella
bony block
patellar flexion:
during tibial-on-femoral flexion, patella:
- glides inferiorly
- enters intercondylar fossa
- rotates on the sagittal plane (apex of the patella moves posteriorly) “patellar flexion”
patellar facets
- articular cartilage (takes a lot of load and movement)
- slightly convex
- patellar ridge
How does the patella fit into the trochlea at different degrees of movement?
0° - no contact
20° - starts to move into grove
60°- majority in contact
90° - full contact with trochlea
what is incontact at the knee in full tibiofemoral extension
only the inferior pole is in contact with the femur
past 90 degrees of flexion what makes contact ?
at the patellafemoral joint
oddfacet makes contact
patellofemoral joint
what makes contact in full flexion?
only the lateral and odd facets are making contact with the femur
motion of patella occurs to keep?
keep the patella seated between the femoral condyles
patellar tilt occurs along what axis?
longitudinal
goes with frontal plane
what is the patellar tilt referenced by?
anterior surface of the patella
lateral patella tilt =
lateral edge of the patella approximates the surface of the lateral femoral range of motion
what are some symptoms of patella alta?
- congenital
- problems with patella ages 10-20
- patellofemoral pain
- high dislocations
what are some signs of patella alta?
- look at position of patella with knee in ex
- m/l glides
- j tracking sign
- patella tendon rupture
patellar shift
translations on the frontal plane
lateral patellar shift
= patella mvoing toward the lateral femoral condyle
the patella rotates about what axis?
rotations about an anteroposterior axis
what is patellar rotation referenced by?
apex of the patella
patella
medial rotation?
= patella spins around the anterioposterior axi with the apex pointing towrad the medial femoral