Knee Flashcards
2 Articulations
Tibiofemoral joint
-distal femur and prox tibia
-double condyloid
-flx/ext, IR/ER, ABd/ADD
Patellofemoral joint
-distal femur and patella
Tibiofemoral Joint
-medial tibial more anterior and longer
-separated by intercondylar notch
weightbearing through center of knee
Genu valgum: <175
Genu carum: >185
Meniscus
Medial: c shaped, restricted, more attachments
Lateral: circular, more mmt, popliteus, covers more surface
-Post deformation with flx
-ant deformation with ext
Nutrition:
-outer more vascularized
-inner gets nutrition from difussion
Joint Capsule
-close packed: full extension
-Posterior boarder: condyles, intercondylar notch
-Anterior boarder: quad tendon, patella, patellar lig, extensor mechanism
-Extensor Mechanism: medial and lateral retinaculum
-Synovial Layer
-Fibrous Layer
Synovial Layer
Extrasynovia but intracapsular: ACL and PCl, fat pads
-Bursae: invaginatons of synovium
Plica: folds of membrane, loose tissue
-not in everyone
-plica syndrome (inflammed)
-medial less common, source of pain
Fibrous Layer
-Medial patellofemoral lig: thickest band in med retinaculum, stabilized patella in femoral sulcus, blends with MCL
-Lateral patellofemoral lig: ITTB to lateral patella
MCL
-medial femoral condyle to medial tibia and med meniscus
-resist valgus and tibial ER
LCL
-lateral femoral epicondyle to fibular head with bicep fem tendon
-resistt varus and ER
ACL
-posteromedial aspect of lat femoral condyle to anterolateral aspect of medial intercondylar tibial notch
-taugh in CC flx
-anteromedial (taught in >15 flx) and posterolateral (taught in ext) bundles
-ACL retrains quads anterior shear on tibia
ACL Injury
-coconttraction ofo hamstrings and quads allow hammies to counter anterior translation from quads
-soleus can resist ant translation of tibia in closed chain
PCL
-anterolateral aspect of med femoral condyle to posterior aspect of intercondylar tibial notch
-taut in CC ext
-bigger than ACL
-posteromedial (taught in ext) and anterolateral (taught in 80 flx) bundles
-restains posterior translation of tibia (knee flexed too)
Posterior Capsule
-reinforced by politeus, semimembranosus and LCL
-Oblique popliteal lig: expansion of semimembranosus
-Posterior Oblique lig: taught in ext, reisist varus/valgus
-Arcuate lig: taught in ext, reisist varus/valgus
ITB
-extension of TFL and glute max to gerdy’s tub
-inc lat stability
-compresses or rolls during flx/ext
Joint Kinematics
CC Flx/ext: femur rolls post and glides ant (ext opp), convex on concave
OC Flx/Ext: Tibia rolls psot and glides post (ext opp), concave on convex
Normal Range:
5-0-140
Walking: 60-70 flx
Stairs: 80
Sit to stand: 90
IR in 90 flx: 15
ER in 90 flx: 20
ADD/ABD in Ext: 8 deg
ADD/ABD in flx: 13-20deg
Knee Extension
-can be limitted by DF
Knee Flexion
-can be limited by passive insufficiancy of hamstring
Coupled Motions
-Flexion with varus
-extension with valgus
-Terminal knee ext with ER (OC, screw home mechanism)
-Flex from full ext OC IR tibia
-FLex from full Ext CC ER of femur
Knee Flexors
Hamstrings:
-SM/ST IR
-BF ER
Sartorius: flx and IR
Gracilis: flx and IR
Popliteus: flx and IR
Gastroc and Soleus: Valgus/varus
Knee Extensors
Quads: VL and VM posterior compressive force
Quad tendon
Patellar tendon
Glute max: in WB
Soleus: in WB
Patella on Quad
-patella and femoral condyles lengthen MA of quads and increases torque (anatomical pulley)
-max MA at 45-60 flx
-MA decreases in full ext
Quads in Stance
-2x as strong as hamstrings
-Soleus and glute max assists with knee EXT
OC: quads generate more torque as knee aproches ext (concentric) (les ant tib shear)
CC: quads generated more force to control increasing torque (eccentric) (more ant tib shear)
Knee Stabilizers
Ant Tib translation:
-ACL, ITB, Hammies, soleus, glute max
Post tib translation: PCL, quads, popliteus, gastroc
Limit Valgus: MCL, ACL, PCL, arcuate, medial muscles
Limit Varus: LCL, ITB, ACL, PCL, arcuate, Lat muscles
IR TIbia: ACL, PCL, PM capsule
ER tibia: PL capsule, MCL, LCL, medial muscles
Patella Alta
-longer and higher on femur
-unstable
Patella Baja
-shorter and lower on femur
