Knee Kinesiology Lecture - Dr. Glenn, includes charts from Neumann Flashcards
PCL: Functions (2)
- Most fibers resist knee flexion (either excessive posterior translation of the tibia or anterior translation of the femur, or a combination thereof)
- Resists extremes of varus, valgus, and axial rotation
Does the axis of rotation in the knee also waver mediolaterally?
yes, and this causes knee braces to be less effective than we would think
MCL (and posterior-medial capsule): common MOI:
Common MOI:
- Valgus producing force with foot planted (eg “clip” in football)
- Severe hyperextension of the knee
Posterior capsule, knee: Common MOI (2)
- Hyperextension or
- combined hyperextension with ER of the knee
how does PCL usually get ruptured?
extreme hyperextension.
(even though PCL also usually resists flexion)
Which meniscus has most things attached to it and has the least freedom of motion?
the medial meniscus
(Lateral meniscus has very few things attached to it, so it is freer to move. Many people theorize that this makes it harder to injure than medial meniscus)
Importance of co-contraction of eccentric and concentric muscles in the lower extremity
Co-contractions in the LE is much more important than UE. To keep the joint working correctly, all the muscles must work together. Big problems can happen if some of them are not working well (like hamstrings in a squat, even if it is a small squat)
Hamstrings keep femur from going too far forward in squats
Posterior Capsule: Functions (3)
- Resists knee extension
- Oblique popliteal ligament resists knee ER
- Posterior-lateral capsule resists varus
Q- angle: what is it and what is normal?
Quadriceps Angle: Formed between (1) a line representing the resultant line of force of the quadriceps, made by conecting ta point near the ASIS to the midpoint of the patella, and (2) a line representing the long axis of the patellar tendon, made by connecting a point on the tiial tuberosity with the midpoint of the patella.
Normal is about 13-15 degrees (+ or 1 4.5 degrees).
Measuring it has been the most popular and simple clinical index for assessing the relative lteral pull of the quads on the patella.
is the ACL or PCL bigger?
PCL is bigger than the ACL
LCL: Common MOI (2)
- Varus-producing force with foot planted
- Severe hyperextension of the knee
Can the quadriceps rupture the ACL?
Quadriceps cause extension, so they are a muscle that can be responsible for overstressing the ACL. (Quadriceps is definitely one of the things that can rupture ACL). Pretty rare for Quad to rupture normal ACL. A reconstructed ACL is a different story, especially open chain extension during rehab!!! Very prohibited.
Varus Force, Knee: Secondary Restraint(s) (7 general)
- Arcuate complex (includes LCL, posterior-lateral capsule, popliteaus tendon, and acruate popliteal ligament)
- ITB
- Biceps femoris tendon
- Joint contact medially
- Compression of the medial meniscus
- ACL and PCL
- Gastrocnemius (lateral head)
Anterior Region of capsule: passive and active restraints
Connective Tissue Reinforcement (passive)
- patellar tendon
- patellar retniacular fibers
Muscular-Tendinous Reinforcement (active)
- Quadriceps
Screw home mechanism: as the knee is flexing from full extension, no matter whether it is OKC or CKC, what is the direction of rotation for the femur and tibia RELATIVE to EACH OTHER?
Femur externally rotates
Tibia internally rotates
(in CKC the femur moves more while the tibia is more fixed.
In OKC the tibia moves more while the femur is more fixed)
These movements add up to 10 degrees total relative rotation at the knee joint.
Is the medial or lateral retinaculum bigger?
Medial retinaculum is much bigger than lateral retinaculum.
Also: Medial knee is very powerful. Partly because we live in a little bit of genu valgum. Our activity encourages developing more genu valgum. Some of the largest ligaments in the body are here, except maybe some of the large spinal ligaments.
Fabella
An accessory sesamoid bone in the knee in the lateral head of the gastrocnemius (neumann) or in distal biceps femoris in some people.
You can see it in an x-ray
Posterior-Lateral Region of knee capsule: passive and active restraints
Connective Tissue Reinforcement:
- Arcuate poplitial ligament
- LCL
Muscular-Tendon Reinforcement:
- Tendon of the popliteus
What are the purposes of the menisci?
- Shock absorption
- Neumann book says they triple the contact surface
Normal walking increases contact force about 3x body weight.
How many facets does the patella have?
Five
We mostly talked about the medial, lateral and odd facet (next to the medial facet - most medial)
Base of patella is also known as _______
Apex of patella is also known as ______
superior pole
inferior pole
what is the “antagonist” muscle group for the PCL?
hamstrings
Why does the meniscus slide anterior during knee extension?
Menisci are pulled anteriorly because the tibia is moving anterior!!! (not the quads. Quads don’t substantially connect and do not dictate the movement of the meniscus. No magic with the quads)
Structures included in the Acruate complex: (4)
- LCL
- Posterior-lateral capsule
- Popliteus tendon
- Acruate popliteal ligament