Knee BM Flashcards
Joints in the knee
Tibiofemoral & patellofemoral
Tibiofemoral joint osteology: femur
Two condyles (M & L)
Radius of curvature
Femoral sulcus
(Look @ pic)
Osteology of tibia
Large proximal end with two large plateaus
Post incline
Intercondylar eidge
Tibial tuberosity
(Look at pic)
Genu Varum
Media compartment is susceptible to loading
Legs bow out. Like a cowboy
Genu Valgrum
Lateral compartment loads
“Knees together”
Normal Alignment during motion
Line of weight earring shifts medial to knee joint
Increases medial compartment compressive F
Dynamic valgus
Collapse inward at knee
Menisci
Semicircular shape on each tibial plateau
Thicker laterally
Circumferential fibers help dissipate loads
Menisci functions
Load absorption/dissipation
Guide osteokinematics and arthrokinematics at knee
Limit translations
Key bursas around the knee
Suprapatellar
Prepatellar
Infrapatellar
Crucially ligaments
Anterior: ACL
Posterior: PCL
ACL restricts
Anterior translation of tibia on femur
Posterior translation of femur on tibia
Also (hyperextension, rotations, and varus/valgus)
PCL restricts
Prevents posterior translation of tibia on femur
And anterior translation of femur on tibia
Also (hyperextension, rotations, and varus/valgus)
Why do ACL and PCL often get injured?
The protect a lot of loads
In ACL is absent, what muscle groups can substitute for its role in preventing anterior translation on the tibia?
Hamstrings
Contractions of what muscle groups may cause tibial anterior translation of ACL is absent?
Quads
In PCL is absent, what muscle groups can substitute for its role in preventing anterior translation on the tibia?
Quads
Contractions of what muscle groups may cause tibial anterior translation of ACL is absent?
Hamstrings
ACL injury mechanism
Non contact: cutting, planting, deceleration
Combination of femur IR & ER of tibia & valgus **
Stiff knee
Medial knee ligament
Medial collateral Ligament MCL
Posterior oblique ligament POL
*limits excessive valgus
Lateral knee ligament
Lateral collateral ligament LCL
Posterior knee ligaments
Don’t memorize all the names. Group of strong ligaments that prevent hyperextension
Iliotibial Band
Fasciae extension on lateral thigh
Passive restraint to anterior tibial translation with knee flexed
IT band in knee extension
Lies anterior to flex/ext axis of rotation
It band in knee flexion
Lies posterior to flex/ext
Flexion/ext kinematics at Tibiofemoral J
Axis of rotation shifts through ROM
Femur on tibia flexion
Post roll for first 25°
Post roll and anterior glide for remander
Femur on tibia extension
Ant roll initially
Ant roll & post glide through end of motion
Menisci during knee flexion
Compressed posteriorly
Menisci during extension
Compressed anteriorly
Internal/ext rotation of knee
Only when knee is flexed to 90°
Abd/add of knee
Occurs during function activities
Coupled with flex/ext
Flex-add
Ext-abd
Screw home mechanism: open chain
Look at knee slide 35-38
Screw home mechanism: closed chain
Knee slide 39
Primary flexor muscles at knee joint
Hamstring group
Secondary flexor muscles at the knee
Sartorius, Gracilis, popliteus, and gastrocnemius
Main extensors at knee
Quadriceps
*in weight bearing… glut max and soles can extend knee
Patellofemoral joint
Articulates between post patella and femoral condyles/sulcus
Function of the patellofemoral j
Functions as a pulley… increases internal moment arm for quads
Improves angle of insertion for quads
Normal, patella Baja, patella Alta
Look at pic
Q angle
Line of pull of the quads on the patella
What lower extremity alignment alterations would increase Q-angle?
Static - valgus
Dynamic - int rot
PFJ kinematics
Flexion/ext
Patellar flexion
Open chain: inf glide of patella in femoral groove
Patellar ext
Open chain: sup glide
Bowstring effect
Increased compression w/ greater knee flexion angle
Quads activation magnifies this effect
Quad F changes based on ext torque demands
Open chain: most F at terminal ext
Closed chain: most F at terminal flex
Patellofemoral ligaments
Medial and lateral retinacula
Medial and lateral patellofemoral lig
Med and latpatellotibial lig
Factors that may increase PFJ lateral F
Genu valgum Femoral med rot VM to VL imbalance IT band tightness Lat patellofemoral lig tightness
Regional interdependence on knee
Hip and ankle
