Knee Flashcards
3 landmarks of distal femur
- Lateral condyle
- Medial condyle
- Intercondylar notch/groove
Which tibial condyle is larger?
Medial
Fibula has ____________ function @ knee
No direct
3 parts of tibial articulation surface
- Lateral plateau
- Medial plateau
- Intercondylar region
Anterior surface of patella is ________ in all directions
Convex
Posterior surface of patella is covered with ___________
Cartilage
Where does the patellar tendon attach on the patella?
Apex
3 facets of post patella
Medial, lateral, odd
Primary function of patella
Increase angle of application - (MA of quads)
Secondary function of patella
Protect quad tendon from excessive friction
If no patella, quads are __________
On slack; active insufficienc
Term for “knock kneed”
Genu valgum
Angle ________ is excessive for genu valgum
Of femur in relation to tibia (<170 degrees)
Angle ________ is excessive for genu varum
Of femur in relation to tib (>180 degrees)
“Bow leg”
Genu varum
Normal alignment of femur
Shaft of femur slightly medial
The joint capsule is ______, ____________ and ________ with several recesses
Large, complexly attached, lax
How is joint capsule reinforced posteriorly?
Muscles and popliteal ligs
How is capsule reinforced M/L?
Collateral ligs
How is capsule reinforced anteriorly?
Vastus medialis, lateralus, MPFL, retinacula
Unique thing about synovial lining of knee
Most extensive and involved in the body
Where is the bursa located
Suprapatellar
Purpose of fat pads
Reduce friction
Shape of menisci
Crescent
Composition of menisci
Fibrocartilaginous discs
Shape of medial meniscus
Semicircular
Shape of lateral meniscus
Circular
Where are menisci thick and thin?
Thick peripherally, thin centrally
Blood supply of menisci is greatest in the ____________
Periphery
What anchors the menisci?
A/P horns
3 secondary attachments of menisci
- Quads (bilaterally)
- Semimembranosus (bilaterally)
- Popliteus to lateral only
2 primary functions of menisci
- Reduce compressive stress
2. Stabilize joint during motion (restrict translation)
3 secondary functions of menisci
- Lubricate art cartilage
- Proprioception
- Guide arthrokinematics
Why is rotation not possible in extension?
Bony congruency
Flexion/extension AOR
M/L, migrating
Axis of flex/ext is ________
Oblique
In full flexion, the tibia is slightly ________ to the femur
Medial
Axial rotation _________ with knee flexion
Increases
At 90 deg knee flexion: _______ total axial rot
40-45 degrees
When tibial tuberosity is lateral to anterior distal femur
External rotation
What does tibia need to do to “unlock” to go into flexion?
IR via popliteus
Describe the arthrokinematics at the knee during ext
T-on-F: tib rolls and glides anteriorly
F-on-T: fem roll anteriorly and glide posteriorly
Describe action of popliteus during flexion both ways
T-on-F: popliteus initiates tib IR
F-on-T: popliteus initiates fem ER
____________________ dictates arthrokinematics during final 30 degrees of KE
Joint arthrology
Lock:
Unlock:
ER
IR
Is an extension loss or a flexion loss more meaningful for a pt?
Extension
Collateral ligs provide ________ plane stability against _____________ forces
Frontal; varus/valgus
Cruciate ligs provice _____________ stability
Multiplanar
MCL resists _______ stress
Valgus
Secondary role of MCL
Preventing anterior translation
______ may place increased stress on ACL if injured
MCL
MCL has the capacity to __________
Heal; vascularized
MCL works ________ in flexion
Harder
Resists varus stresses
LCL
LCL accounts for more restraining force in more ___________
Flexion
Named for their attachment to the tibia
cruciate ligs
These ligs work mostly in the saggital plane
Cruciate
Cruciate ligs guide _________
Arthrokinematics
Cruciate ligs contribute to ________________
Proprioception
Where ACL originates and inserts
O: anterior tib plateau
I: lateral femoral condyle
When is ACL most taut?
With knee close to extension
ACL is most commonly injured when…
Knee is slightly flexed and tib is rotated in either direction
How to strain ACL
Forceful contraction of quads, especially near full extension (pulls tib anteriorly)
Origin and insertion of PCL
O: posterior intercondylar area of tib
I: medial femoral condyle
Primary function of PCL
Restraint to post displacement of tibia on femoral condyles (or ant displacement of femur in closed chain)
When are fibers of PCL taut?
Greater flexion
Contraction of the ________ can slide tib/fib posteriorly
Hamstring
Most injuries of PCL
Traumatic
Interface between the patella and intercondylar groove of femur
Patellofemoral joint
Max contact of PFJ ______ of total surface area
30%
Describe where patella is during extension and flexion
Extension: inferior pole of patella with most contact
Flexion: superior pole of patella with most contact
Talk about the motions of the patella relative to the ___________________
Inferior pole
3 movements of the patella
- Shift
- Tilt
- Rotation
What comprises the q angle?
ASIS –> mid patella
Tib tub –> mid patella (vertical)
Approx q angles in women and men
15 degrees in women
11 degrees in men
Abnormal q angle
> 15 degrees
Knees over toes in squat increases
Resultant forces of quads
Quad efficiency is affected by _____
Patella
Quads produce a force __________ than hamstrings
2/3 greater
When do quads produce max torque?
40-70 deg flexion
2 functions of quads
- Dampens impact of loading
2. Accelerates tib or femur for tasks requiring knee extension
In open chain, when is external moment arm greatest in quads?
Seated knee extension
In a squat, when is external moment arm the greatest?
Deep squat (90 degrees of flexion)
When are hamstrings most active?
Walking/running
Role of hamstrings on tibia and femur
Tib: accelerate or decelerate during T-on-F movements
Femur: stabilizer
When can hamstrings produce max torque?
Near full knee extension (seated)
Provides medial stability and functions to IR tibia
Pes anserine
Muscles responsible for IR tibia
Sartorius and gracilis
2 actions of popliteus
IR and knee flexion
3 major LATERAL forces on patella
- IT band
- Bowstringing force on patella (caused by quads/pat tendon)
- Lateral patellar retinacular fibers
Major MEDIAL forces on patella
- VMO
- Raised lateral facet of IC groove
- Medial patellar retinacular fibers
What motions increase bowstringing force on patella?
Excessive knee external rotation and valgus
How does a deep squat affect the bowstringing of the patella?
Increased forces of quads/patellar tendon increase bowstringing resultant force