2. KneeKnee
JointJoint• actually 2 joints withinactually 2 joints within
the articular capsulethe articular capsule
• tibio-femoraltibio-femoral
• patello-femoralpatello-femoral
• thethe superior fibulo-tibialsuperior fibulo-tibial
jointjoint is also nearis also near
• modified hinge jointmodified hinge joint
• flexionflexion andand extensionextension isis
primary motionprimary motion
• some rotation is possiblesome rotation is possible
when the knee is flexedwhen the knee is flexed
5. MenisciMenisci
• The menisci areThe menisci are discs of fibrocartilagediscs of fibrocartilage attached toattached to
tibial plateaus. They are thicker along the periphery.tibial plateaus. They are thicker along the periphery.
6. The lateralThe lateral
meniscusmeniscus is smalleris smaller
and more mobileand more mobile
than the medialthan the medial
meniscus. The innermeniscus. The inner
portion of theportion of the
menisci aremenisci are
avascular. The outeravascular. The outer
portion has someportion has some
blood supply,blood supply,
making healing ofmaking healing of
tears possible.
lateralatera
ll
mediamedia
ll
7. Menisci FunctionMenisci Function
• increases stabilityincreases stability byby
deepening tibial plateausdeepening tibial plateaus
• decreases frictiondecreases friction by 20%by 20%
• increases contact areaincreases contact area
by 70%by 70%
• absorbs shockabsorbs shock
• removal of menisci does NOTremoval of menisci does NOT
preclude normal motion, butpreclude normal motion, but
• increase wear on articulatingincrease wear on articulating
surfacessurfaces
• increase chance of developingincrease chance of developing
degenerative joint diseasedegenerative joint disease
13. FF
EE
MM
UU
RR
T
I
B
I
A
PATELLA
TheThe ACLACL prevents theprevents the
femur from slidingfemur from sliding
posteriorly on the tibiaposteriorly on the tibia
or the tibia from slidingor the tibia from sliding
anteriorly on the femur.anteriorly on the femur.
TheThe PCLPCL preventsprevents
the femur fromthe femur from
sliding anteriorly onsliding anteriorly on
the tibia or the tibiathe tibia or the tibia
from slidingfrom sliding
posteriorly on theposteriorly on the
femurfemur.
15. Patello-femoral JointPatello-femoral Joint
• articulation of thearticulation of the
patella and femurpatella and femur
• the patella is a truethe patella is a true
sesamoid bonesesamoid bone
• posterior surface of theposterior surface of the
patella is covered withpatella is covered with
thick hyaline cartilagethick hyaline cartilage
• the patella slides withinthe patella slides within
the trochlear groovethe trochlear groove
16. Functions of Patello-femoralFunctions of Patello-femoral
JointJoint
(1)(1) increases angle of pull ofincreases angle of pull of
quads on tibiaquads on tibia, improves, improves
the ratio ofthe ratio of
motive:resistive torque bymotive:resistive torque by
50%50%
(2) centralizes divergent(2) centralizes divergent
tension of quads into atension of quads into a
single line of actionsingle line of action
(3) some(3) some protectionprotection ofof
anterior aspect of kneeanterior aspect of knee
without patellawith patella
17. Q-AngleQ-Angle
The Q-angle is the angleThe Q-angle is the angle
formed by a line from theformed by a line from the
anterior superior spine ofanterior superior spine of
the ilium to the middle of thethe ilium to the middle of the
patella and a line from thepatella and a line from the
middle of the patella to themiddle of the patella to the
tibial tuberosity.tibial tuberosity. MalesMales
typically have Q-anglestypically have Q-angles
betweenbetween 10 to 1410 to 14oo
,, femalesfemales
betweenbetween 15-1715-17oo
..
19. Knee RotationKnee Rotation
(Locking Your Knee)(Locking Your Knee)
• Six to 30 degrees of internalSix to 30 degrees of internal
rotation of the tibia on therotation of the tibia on the
femur occurs through 90femur occurs through 90
degrees of knee flexion.degrees of knee flexion.
1 The femoral condyles do not have the same diameters, thisThe femoral condyles do not have the same diameters, this
helps cause internal rotation when the knee is flexed andhelps cause internal rotation when the knee is flexed and
external rotation when the knee is extended.external rotation when the knee is extended.
2 The lateral condyle slides more than medial condyle.The lateral condyle slides more than medial condyle.
3 The anterior cruciate ligament becomes taut just prior to theThe anterior cruciate ligament becomes taut just prior to the
rotation, this may help force a rotation of the femur on therotation, this may help force a rotation of the femur on the
tibia.tibia.
Flexion
External
Rotation
Internal
Rotation
Extension
20. KneeKnee
MusculatureMusculature
many are 2 joint muscles
primary movements
- flexion and extension
- hams & quads, respectively
medial and lateral rotation
possible
necessary for screw-home
mechanism
