1. 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
Knee

2. Anterior
Posterior
Transverse
condyles
epicondyles
intercondylar notch
patella
tibial tuberosity
tibial plateaus

3. Ligamentous Support Menisci Cruciate Ligaments Other Collateral

4. Menisci
The menisci are discs of fibrocartilage attached to tibial plateaus. They are thicker along the periphery.

5. 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.
lateral
medial

6. Menisci Function increases stability by deepening tibial plateaus
decreases friction by 20%
increases contact area by 70%
absorbs shock
removal of menisci does NOT preclude normal motion, but
increase wear on articulating surfaces
increase chance of developing degenerative joint disease

7. Collateral Ligaments
lateral (fibular)
medial (tibial)

8. Collateral Ligaments prevents abduction and adduction movement
of the knee
Collateral Ligaments

9. Additional Ligamentous Support
iliotibial band
thick, strong band of tissue connecting tensor fascia latae to femur and tibia

10. Cruciate Ligaments cruciate -- ‘cross’ ligaments form an ‘X’
or cross within the joint
named for their TIBIAL
attachments
Anterior Cruciate (ACL)

11. Posterior Crucuate (PCL)
shorter and stronger than
ACL

12. The ACL prevents the femur from sliding posteriorly on the tibia or the tibia from sliding anteriorly on the femur.
FEMUR
The PCL prevents the femur from sliding anteriorly on the tibia or the tibia from sliding posteriorly on the femur.
PATELLA
TIBIA

13. The PCL prevents the tibia from sliding posteriorly on the femur.
Anterior
Posterior

14. Cruciates During Flexion/Extension
Note: the cruciate ligaments also limit rotation

15. Patello-femoral Joint
articulation of the patella and femur
the patella is a true sesamoid bone
posterior surface of the patella is covered with thick hyaline cartilage
the patella slides within the trochlear groove

16. Functions of Patello-femoral Joint
with patella
without patella
(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

17. Q-Angle
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.

18. Atypical Q-angles
bowleggedness
knock-knees

19. Knee Rotation (Locking Your Knee)
Flexion
External
Rotation
Internal
Extension
Knee Rotation (Locking Your Knee)
Six to 30 degrees of internal rotation of the tibia on the femur occurs through 90 degrees of knee flexion.
The femoral condyles do not have the same diameters, this helps cause internal rotation when the knee is flexed and external rotation when the knee is extended.
The lateral condyle slides more than medial condyle.
The anterior cruciate ligament becomes taut just prior to the rotation, this may help force a rotation of the femur on the tibia.

20. Knee Musculature many 2 joint muscles primary movements
- flexion and extension
- hams & quads,
respectively
medial and lateral
rotation possible
necessary for screw-
home mechanism

21. Knee Flexion Hamstrings cross hip and knee biceps femoris
semitendinosus
semimembranosus
gastrocnemius
cross knee and ankle
popliteus

22. Knee Extension - Quadriceps
rectus femoris
vastus lateralis
vastus medialis
vastus intermedius
quadriceps tendon
patellar ligament

23. Lateral Rotation
biceps femoris
attaches to lateral aspect of knee

24. Medial Rotation semitendinosus semimembranosus popliteus
attach to medial aspect of knee

25. Common Knee Injuries one of the most commonly injured joints
lack of bony and muscular support
positioned between the 2 longest bones
weight bearing and locomotion functions
often tear or stretching of soft tissue

26. Ligament Injuries ACL PCL more prevalent than PCL injuries
forces directed from posterior side of leg
PCL
forces directed from anterior side of leg
forced flexion of knee w/external rotation
wrestling and football

27. Ruptured ACL Knee
Intact Knee with ACL
& PCL

28. Mechanisms of ACL injury
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
Example
backward falling skier - boot and skis accelerate forward creating an anterior drawer mechanism

29. Gender issues related to ACL injuries
females more likely to sustain an ACL injury than males
soccer - 2.6X
basketball X
wider pelvis
greater flexibility
less-developed musculature
hypoplastic vastus medialis obliquus
narrow femoral notch
genu valgum
external tibial torsion

30. PCL Injuries
When the knee is forcefully twisted or hyperextended BUT other ligaments are usually injured or torn, before the posterior cruciate ligament (PCL) is torn
Most common mechanism for PCL alone to be injured is from a direct blow to the front of the knee while the knee is bent. 
Automobile accident
Automobile strikes another and stops suddenly
Front passenger or driver slides forward. 
Bent knee hits the dashboard just below the knee cap forcing tibia backwards on the femur tearing PCL.
The same force can occur during a fall on the bent knee, where the force of the fall on the tibia pushes it back against the femur and tears the posterior cruciate ligament (PCL).

31. Common mechanism of
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.

32. Ligament Injuries injuries to MCL more prevalent than LCL MCL
foot planted and force applied to the lateral side of knee
football

33. Meniscus Injuries most common injury in the knee
tearing is most common
medial side injured more often
medial meniscus more secured
foot planted with excessive rotation

34. Iliotibial Band Syndrome
IT-band
thick strong band of ligamentous tissue
connects tensor fascia latae to the lateral condyle of the femur and the lateral tuberosity of the tibia
IT-band rubs against the lateral femoral condyle when there is excessive tension

35. excessive pronation increases internal rotation of the tibia, which accentuates the friction of the IT band and femoral condyle
tibial alignment and size of femoral condyle may also contribute to the development of this condition