knee part 2 Flashcards
what is tibiofemoral rotation at 90º flexion?
lateral 40º medial 30º via PROM
why is there more lateral rotation when the knee is flexed to 90º than medially?
there is more movement laterally because the AOR is further from the lateral compartment
where is the axis of rotation in the transverse plane at the tibiofemoral joint?
longitudinal axis that runs medial to the medial tibial intercondylar tubercle
what do the cruciate ligaments collectively check rein?
internal rotation because they are crossed
when are the cruciate ligaments slacked?
during external rotation when their unwinded from each other
during external rotation what ligaments are taut and are check reins?
the collateral ligaments
what plane do the femoral condyles lie in?
lateral in the sagittal plane
medial oblique to the sagittal plane
describe the lateral femoral condyle
> A-P dimension:
anterior projection buttress for patella to prevent lateral dislocations of patella
describe the medial femoral condyle
longitudinal dimension:
greater articulation surface for the tibia medially
what is the screw home mechanism?
an automatic, conjunct, obligatory ER of tibia with terminal 20-30º of knee extension
in OKC there’s an anterior roll and anterior slide, in the last 20-30º we run out of lateral anterior slide and continue medial anterior slide what is the result?
ER of tibia (leg)
in CKC as we stand up there’s and anterior roll and posterior slide, in the last 20-30º knee extension motion is stopped laterally but continued medially which results in what?
IR of femur = ER of tibia
how do the femoral condyles contribute to the screw home mechanism etiology?
there is greater SA more medial so there is more work to do on that side
how do the cruciate ligaments contribute to the screw home mechanism etiology?
the ligaments are tensioned and unwinding wanting to release tension which is ER rotation
what is the frontal plane posture at the tibiofemoral joint?
anatomic or longitudinal axis of the tibiofemoral joint is 5-10º of physiologic valgus.
stems from the femoral longitudinal axis being oblique that originates proximally from the proximal femoral angle of inclination
obliquity originates from the medial femoral condyle projecting farther distally than the lateral