Knee Joint. actually 2 joints within the articular capsule tibio-femoral patello-femoral the superior fibulo-tibial joint is also near modified hinge joint flexion and extension is primary motion some rotation is possible when the knee is flexed. epicondyles. condyles. patella.
The lateral meniscus is smaller and more mobile than the medial meniscus. The inner portion of the menisci are avascular. The outer portion has some blood supply, making healing of tears possible.
of the knee
cruciate -- ‘cross’
ligaments form an ‘X’
or cross within the joint
named for their TIBIAL
Anterior Cruciate (ACL)
shorter and stronger than
The ACL prevents the femur from sliding posteriorly on the tibia or the tibia from sliding anteriorly on the femur.
The PCL prevents the femur from sliding anteriorly on the tibia or the tibia from sliding posteriorly on the femur.
Note: the cruciate ligaments also limit rotation
(1) increases angle of pull of quads on tibia, improves the ratio of motive:resistive torque by 50%
(2) centralizes divergent tension of quads into a single line of action
(3) some protection of anterior aspect of knee
The Q-angle is the angle formed by a line from the anterior superior spine of the ilium to the middle of the patella and a line from the middle of the patella to the tibial tuberosity. Males typically have Q-angles between 10 to 14o, females between 15-17o.
RotationKnee Rotation(Locking Your Knee)
many 2 joint muscles
- flexion and extension
- hams & quads,
medial and lateral
necessary for screw-
cross hip and knee
cross knee and ankle
attaches to lateral aspect of knee
attach to medial aspect of knee
Intact Knee with ACL
1) attempting a rapid cutting maneuver with foot in contact with the ground and knee flexed (problem exacerbated if an external force applied to knee during this movement)
2) knee hyperextension with internal tibial rotation
backward falling skier - boot and skis accelerate forward creating an anterior drawer mechanism
females more likely to sustain an ACL injury than males
soccer - 2.6X
basketball - 5.75X
hypoplastic vastus medialis obliquus
narrow femoral notch
external tibial torsion
PCL injury in football is being tackled while the knee is fully extended.
When the tibia is displaced too much in the posterior direction the PCL may rupture.