Knee joint Flashcards
the [….] condyles of the knee and fibula are both longer in the A-P direction than the [….] condyles. Thus they also bear 75% of the weight on the joint.
medial condyles
longer than the
lateral condyles
name these features of the tibial plateau
which two joints share the knee capsule?
tibiofemoral
and
patellofemoral
since articular surfaces provide little support in knee joint, the capsule is reinforced by powerful muscles/tendinous insertions.
What are these reinforcements on the anterior, lateral, medial, and posterior planes?
anterior - patellar tendon (superiorly) and retinacular fibres (inferiorly)
medial- pes anserinus tendons
lateral - popliteus, biceps femoris, and iliotibial tract aka tensor fascialata
posterior - oblique popliteal ligament - from semimembranosus
which muscular insertions comprise pes anserinus (on the medial aspect of capsule)
Say Grace Before Tea.
Some goddamn tendons.
Semimbranosus, Gracilis, Bursa, semiTendinosus
ACL function? how many fibres? ROM? vulnerability?
made up of two fibres (anteromedial and posterolateral). primary stabilizer in A-P direction. Limits forward diplacement of tibia on femur.
ROM:
Taut in both extension and full flexion. Loose-packed position in semi flexion.
Permits medial rotation on a fixed, weight bearing tibia. Limits backward movement of lateral condyle.
“passive screw home mechanism” where femur rotates medially and joint gets to full extension and locks in, key in stabilization of knee in full extension.
Injury: when rotation occurs in lateral direction, involving extension on a weight bearing leg.
—>anterior drawer sign detects ACL injury
PCL function? how many fibres? ROM? vulnerability?
limits posterior displacement of tibia in knee flexion.
2x the thickness of ACL, reinforced by meniscofemoral ligaments.
prone to injury when you fall on a flexed knee, or when a car bumper hits your femur displacing it posteriorly.
“posterior drawer sign” indicates injury
which muscle is being described here?
what is its purpose?
popliteus muscle rotates the femur laterally on a fixed tibia.
the MCL is taut in [….] and slack in [….]. It functions to resist [….] forces and [….] rotation of the tibia. It also limits anterior displacement of the tibia when the ACL is damaged. It is often injured together with the [….and…].
extension
flexion
vagus (abduction)
lateral rotation
ACL and medial meniscus
the LCL is seperated from the lateral meniscus by the [….] tendon. It functions to resist [….] forces.
It is injured much less frequently than the MCL.
popliteal tendon
varus (adduction)
between the medial meniscus and lateral meniscus which is most commonly injured? why?
what are the outcomes with injury?
medial meniscus:
- longer
- horns further apart
- its less mobile (due to MCL attachment)
NB: contributes to ‘locked knee’
areas that are better vascularized have better outcomes. tears to the outer third has a rich capillary blood supply.
which bursa lies deep to the insertion of hamstring muscle and communicates with the bursa underneath popliteus?
which pathology is associated?
semimbranosus bursa can become thickened/enlarged—>“Baker’s cyst”—>causes reduced flexion of the knee
which 3 structures maintain the alignment of the patellofemoral joint?
- strong vastus medialis muscle (active stabilizer) (medial aspect of quadriceps)
- medial patellar retinaculum (semi-passive, fibres mostly blend with patella on medial aspect)
- raised lip on lateral femoral condyle (prevents patella from being displaced in lateral direction)
what is the the Q Angle? how is it generated? What’s the relevance in females?
quadriceps angle, between patella and quads. Patella is pulled laterally by the strong quadriceps muscle.
b/c of width of pelvis, in females the patella comes from a more lateral position, thus greater propensity for it to be dragged laterally by strength/force of the quadriceps.
