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Knee Joint
Functional Anatomy
Term | Definition |
---|---|
genu valgum | foot lat to knee; slight med angulation of the femur; normal; lat compartment compression; knock-knee; < or = 165 degrees |
genu varum | foot med to knee; more common; med compartment compression; bow-leg; > or = 180 degrees |
3 compartments of knee | 1. Medial compartment 2. lateral compartment 3. patellofemoral compartment |
joint stability of the knee | not due to bony approx b/c of mismatch btwn surfs of femur to tibia; stability provided by menisci, ligs, capsule & body weight |
menisci | fibrocartilagenous; anchored at the intercondylar area; coronary ligaments= meniscotibial ligs; move with the tibia |
medial meniscus | c-shaped; less mobile; attachments to deep layer of jt capsule & MCL through coronary ligs; attached to ACL & Semimembranosus |
lateral meniscus | o-shaped; more mobile; not as many attachments; not attached to LCL; PCL, popliteus attachments; attached ant to med meniscus via transverse ligament |
Intraarticular ligs of the knee | ACL & PCL |
extraarticular ligs of the knee | MCL & LCL |
anterior capsule | medial & lateral patellar retinacular fibers |
post capsule | oblique popliteal lig, arcuate popliteal lig, & popliteus musc |
lat capsule | ITB |
med capsule | runs from patellar tendon to post capsule |
Baker's Cyst | Popliteal cyst; will limit full flexion |
semiflexed (15-20 degrees) position | position of comfort |
cruciate ligaments | named for their tibial attachments |
ACL | runs in a post, sup & lat direction to attach to lat femoral condyle; tight in extension |
Mechs of injury of ACL | sudden hyperext'n of knee; 60-70% are non-contact injuries; K in slight flexion w/ sudden varus or valgus stress on the knee |
O'Donoghues/Unhappy triad | Medial meniscus, MCL, & ACL tears |
PCL | thicker than ACL' attaches to med femoral condyle; tension peaks btwn 90-120 degrees of k flex |
mechs of PCL injury | dashboard injury & contact sports; much larger impact; doesn't simultaneously injure other structures as often |
Collateral ligaments | both tight in ext'n; taught in ER of tibia |
MCL (tibial collateral lig) | flat & broad; like tissue paper; more posterior; limits valgus/abd force (gapping of the med structures) |
Gurdy's tubercle | just lat to tibial tubercle; attachment of hams & ITB |