Knee Flashcards
Femur - femoral condyles are
Convex ant/post and med/lat
Medial condyle descends further inferiorly
Lateral has larger SA
Tibia - Medial tibial condyle is
Biconcave
Larger SA - more stable, less mobile
Tibia - Lateral tibial condyle is
Convex ant/post
Concave med/lat
Smaller surface area, less stable, more mobile
Proximal tibiofibular joint
Tibial facet is slightly convex
Fibular head is slightly concave
Tibiofemoral joint
Synovial hinge joint with 2 DF
Minimal stability - relies on capsule, ligaments, mm
Patellofemoral joint - what guides patellar tracking
Oblique groove running inferiorly and laterally is guiding mechanism on femur for patellar tracking
Patellofemoral joint - Patellar surface of femur
Patellar surface of femur is concave transversely
Convex sagitally
Gives is saddle (sellar) shape
Knee flexors
Biceps femoris Semimembranous Semitendinosus Gracilis Sartorius TFL at more than 45 Popliteus Gastroc Plantaris
Knee extensors
Vastus lateralis Vastus medialis Vastus intermedius Rectus femoris TFL less than 30 degrees
Knee IR
Semiten Semimem Sartorius Gracilis Popliteus
Knee ER
Biceps femoris
Tibiofemoral capsule is attached where
a fibrous sleeve attached to distal femur and proximal tibia
TIbiofemoral capsule - inner wall is covered by
synovium
Proximal tibiofibular joint has a fibrous capsule that is
Continuous with knee joint capsule 10% of time
Medial Collateral Ligament runs from
Medial aspect of medial femoral condyle to upper end of tibia
Post fibers blend with capsule
Medial Collateral Ligament - taut in ___ ;slack in ___
taut - extension
slack - flexion
Medial collateral ligament - provides
stability against valgus forces
Medial collateral ligament - runs in what direction
same as ACL
oblique - ant and inf
Lateral collateral ligament - runs from
lateral femoral condyle to head of fibula
No capsular attachment
Lateral collateral ligament - runs in what direction
oblique inf and post
Same as PCL
Lateral collateral ligament - taut ___ ; slack ___
Taut - extension
Slack - flexion
Lateral collateral ligament - prevents
ER and provides stability against varus forces
Anterior cruciate ligament - attaches to
anterior intercondylar fossa of tibia and to femur at medial aspect of lateral condyle
ACL - runs in what direction
oblique sup and lat
thickening of the capsule
ACL - check ___ and limits __
Checks forward gliding of tibia on femur
Limits IR of tibia during flexion as it twists around PCL
Posterior cruciate ligament - attaches to
Posterior intercondylar fossa of tibia and on lateral surface of femoral medial condyle
PCL - runs in what direction
Oblique med and ant/sup
PCL - checks ___
posterior displacement of tibia on femur
Meniscofemoral ligament - runs with
PCL
Meniscofemoral ligament - attaches
below posterior horn of lateral meniscus
Insertion into lateral aspect of medial condyle
Oblique popliteal ligament - inserts into
expansion from tendon of semimembranosus
Partially blends with capsule
Oblique popliteal ligament - function
forms floor of popliteal fossa
in contact with popliteal arterial artery
strengthens posteriomedial capsule
Arcuate popiteal ligament - commonly describes as
Y - has two bands - medial and lateral
Arcuate popliteal ligament - stem, med and lat attachments
Stem - fibular head
Med band - post border of intercondylar area pf tibia
Lat band - lateral epicondyle of femur
Arcuate popliteal ligament - strengthens
posterolateral capsule
Transverse ligament - connects
lateral and medial meniscus anteriorly
Meniscopatellar ligament -
runs from inferolateral edges of patella to lateral borders of each meniscus
Pulls menisci forward with ext
Alar fold - runs from
lateral borders of patella to medial and lateral aspects of femoral condyles
Keeps patella in contact with femur
Infrapatellar fold - formed by attachments of
patella fat pad and tendons via fibroadipose band lying in intercondylar notch
Acts as stop gap as is compressed by patellar tendon with full flexion
Proximal tibiofibular joint ligament - anterior is located ____ and reinforces ___
Located on anterior aspect of joint
Reinforces anterior capsule
Proximal tibiofemoral joint ligaments - posterior is located ___ and reinforces ____
Located on posterior aspect of joint
Reinforces posterior capsule
Menisci - Medial - attachments
Laterally is attached to MCL and capsule
Semimem attaches to it
Medial meniscopatellar lig attaches to it
Menisci - Lateral vs. Medial
Lateral is smaller and more circular
Menisci - Lateral - What attaches to it
Popliteus mm
Lateral meniscopatellar ligament
Meniscofemoral ligament
Lateral meniscus is separated from LCL and lateral capsule by what
Popliteus mm tendon
Function of the menisci (6)
1 Deepen fossa of tibia
2 Inc congruency of tibia and femur
3 Provide stability to tibiofemoral joint
4 Provide shock absorption and lubrication to knee
5 Reduce friction during mvmnt
6 Improve weight distribution
Movement of menisci with flex/ext
Follow movement of tibia
Movement of menisci with IR/ER
Follow femoral condyles
Movement of menisci - medial vs. lateral
Medial - 6mm
Lateral - 12mm
With isolated tibial rotation, the menisci move
opposite
So with tibial IR, medial moves ant and lat moves post
Medial meniscus is pulled post (flexion) by
Semimem mm and ACL
Medial meniscus is pulled ant (ext) by
medial meniscopatellar ligament
Lateral meniscus is pulled post (flex) by
popliteus mm
Lateral meniscus is pulled ant (ext) by
lateral meniscopatellar ligament and meniscofemoral ligament
Prepatellar bursa - located
btw skin and anterior distal patella
Superficial infrapatellar bursa - located
anterior to ligamentum patella
Deep infrapatellar bursa - located
btw post ligamentum patella and anterior tibial tub
Suprapatellar bursa - located
between patella and tibiofemoral joint
Popliteal bursa - lcoated
posterior knee - often connected to synovial cavity
Semimembranous bursa - located
between mm and femoral condyle
Gastrocnemius bursa - located
one for each head
medial usually communicates with semimembranous bursa
Pes anserine bursa - located
between pes anserine and MCL
Movement of femoral condyles with flex
femoral condyles roll post, ACL becomes taut, condyles glide anteriorly
Movement of femoral condyles with ext
femoral condyles roll ant, PCL becomes taut, condyles glide posteriorly
Conjunct rotation - during flexion there is a conjunct rotation of what
medial rotation of tibia
Conjunct rotation - during extension there is conjunct rotation of what
lateral rotation of tibia
Screw home mechanism describes what
5 degrees of ER that occurs at terminal extension
Causes for screw home mechanism
1 lateral femoral condyle glides more freely on tibia
2 medial femoral condyle has longer articular surface
3 medial meniscus attached to MCL (which tightens in ext) - medial men stops gliding but lateral continues and you get IR of femur - or ER of tibia
Biomechanics of proximal tibiofibular joint - DF of talocrural joint
Fibular head glides superiorly and posteriorly
Fibular shaft ER
Biomechanics of proximal tibiofibular joint - PF of talocrural joint
Fibular head glides inf and ant
Fibular shaft IR