knee Flashcards
Tibial Articular Surface- media and lateral condyles
Medial condyle is concave both direction (larger than the lateral)
Lateral is convex sagittal and convex
what effect do the different condyle shapes have
affect the mechanic of the knee
3 joints on the knee
Tibiofemoral
Medial and lateral
Patellofemoral
Proximal tibiofibular
Function of Patellofemoral Joint
Increases the mechanical advantage of the quadriceps muscle
Protects the anterior knee
how does the Patellofemoral Joint Increases the mechanical advantage of the quadriceps muscle
By having patella, the quads get a better line of pulls to extend the knee, uses less force then if there was no patella
Patellofemoral Joint- what type of joint
Modified plane joint
what type of bone is the patella
sesamoid bone - lies within the quadriceps tendon
where does the patella sit
sits in trochlear groove of femur
Open packed position for the Patellofemoral Joint
full extension of the knee
in full extension of the knee is the patella touching the femur
patella not touching the femur – superior to the trochlear groove
what position do we normally assess a joint
in the open packed position
Closed packed position for Patellofemoral Joint
full flexion
Patella fully engaged in the trochlear groove
(test- try to move patella in the knee completely flexed)
for the closed packed position of the Patellofemoral Joint is this an are of max congruity
yes - unlike the hip
this is the standard
Patellofemoral Motion
In flexion the patella is engaging with the femur – glides down the femur with flexion
side to side movement of the patella
There is some side-to-side motion guided by the patella femoral ligaments and the ret
Patellofemoral Tracking
how the patella slides in the trochlear groove during motion
the motion of the patella relative to the femur or femoral groove on knee flexion and extension
Knee flexion is what degreee of motion in the knee
0
in complete knee flexion is the patella touching the femur
no - not at all
what happens to the patella as we start to flex the knee
the patella starts to interacting with the trochlear groove of the femur
at full flexion what part of the patella is tough the femur
odd facet - smashed in the femur
what is the order of patella parts touching the femur during flexion
inferior to superior
distal to proximal
size of the contact area no the patella as the knee flexes
Contact area becomes larger as knee is flexed
The bigger area to distributing forces the better the bone is handling those forces
what happens to the patella when the quads are contracted
mashes the patella into femur
Quadriceps force creates patellofemoral compression force
Magnitude of Quadriceps force on the patella depends on
Magnitude of force changes with knee flexion angle
Q- angle
line through ASIS - center of the patella and another line from the tibial tubercle - the center of the patella
- Valgus
angle lateral to medially and then down (see above)
- Normally have little bit of this – 14 -17 degrees
- Bigger in women
- Knock knees: the knees are going inward
- Varus
bow legged, knees look further apart
- The natural valgus creates what
natural lateral pull on the patella
q angle and injuries
might be the cause of some injuries
Tibiofemoral Joint type of joint
Bicondylarsynovial joint
Tibiofemoral Joint allows what kind of movement
Allows flex/ext, ER/IR
Open-packed position Tibiofemoral Joint
30° flexion
Normally accessed at this angle
Closed-packed position Tibiofemoral Joint
full extension
Most ligamentous lax
This is where we have the least amount of rotation- less tib femoral ration that we would in flex position
what is a Capsular pattern
a joint-specific pattern of restriction
decrease in joint mobility occurs in a pattern
when do we look at capsular patterns
to find out If something is capsule is patho
the pt should look at lose ROM in predictable pattern
If it not a capsule problem we will look at something that is not in the capsule like ligaments or tendons
Capsular pattern of tin-femoral joint
flexion > extension restrictions
Lose more flex degrees the extension degrees
Open Kinetic Chain of Tibiofemoral jt
Tibia moving on femur
Concave on convex roll and glide SAME direction
Extension: Anterior roll, anterior glide
Flexion: Posterior roll, posterior glide
Tibiofemoral jt Closed Kinetic Chain
Femur moving on tibia
Convex on concave roll and glide OPPOSITE directions
Extension: Anterior roll, posterior glide
Flexion: Posterior roll, anterior glide
“Screw Home” Mechanism part of what joint
Tibiofemoral
“Screw Home” Mechanism-
There is an observable rotation of the knee during flexion and extension
what causes screw home mech
Happens because the medial condyle of the femur is longer(extends more distally) then the lat
The lateral finished rolling and gliding and med is not done so it keeps rolling and gliding producing the rotation
The medial tibial plateau is larger so the med can keep going when the lat side is done
WB screw home
10-15 degrees of lateral tibial rotation at end range extension
WB screw home
10-15 degrees of femoral medial rotation at end range extension
joint type Proximal Tibiofibular Joint
Plane synovial joint – flat on flat
Allows gliding and sliding
how much weight can the tibialfemoral and proximities tibia joint bear
tibfib - 1/6 body weight
tibfemoral – 5/6 of body
pain seen with proximities tbfib joint
knee and ankle pain
Fibular Motion Anterior glide
ankle eversion
Fibular Motion Posterior glide
Posterior glide accompanies ankle inversion
what happens when fibular motion become hypomobile
Can become hypomobile and cause lateral knee pain after ankle sprains
Stiff - not moving at well
