The knee Flashcards
the knee joint is made up of how many:
- Bones
- Articulating surfaces
- Compartments
- Mensici
- Joint capsules
- 3 bones
- 3 articulating surfaces
- 2 menisci
- 1 joint capsule
the knee joint can withstand forces how many times your body weight
4-6 x body weight
why is the knee joint ones of the most commonly injured joints?
becuase it is positioned between 2 long bony levers
what condyle is larger on the femur
the medial condyle
the intercondylar groove of the femur has a larger _____ projection on the lateral condyle, this is to prevent?
- anterior
- prevent patellar dislocation
if the ______ projection of the intercondylar groove is inadequate it can cause patellar instability
anterolateral
the cruciate ligaments lie in what part of the femur?
intercondylar fossa
what condyle is larger on the tibia
the medial
where does the patellar tendon insert
on the tibial tuberosity
what part of the fibula is in the knee joint
head of the fibula
the patella is the largest _____ bone in the body
sesamoid
the patella has the thickest ?
articular cartilage
the base of the patella is where? and the apex?
base= superior apex= inferior
how many degrees of freedom does the knee joint have
2 DOF
what are the movements of the knee joint
flexion, extension, and a little axial rotation
what are the osteokinamatic movements of the knee joint
swing
spin
what is the largest joint in the body
knee
how many degrees does the knee flex? and extend?
- 130-150 flexion
- 0-15 hyperextension
what is the end feel of knee flexion and extension
soft
firm
the degrees someone can flex will varying depending on?
size of muscle mass
the axis of motion of the knee is located a few cm _____ the joint line, passing horizontally through the _____
above,
femoral condyles
the condylar surface of the femur is much bigger than that of the tibia, what does this mean in regard to arthrokinametics?
- Must roll and glide
- the conter of motion CHANGES as the knee flexes and extends
- –> axis moves about 2cm translation (tibia moves)
with the axis of the knee moving with flexion and extension, what is made hard?
it is hard to create mechanical hinge joint devices such as goniometer, isokinetic dynamometer, knee-ankle-foot orthosis, or below knee prosthesis
the arms of the mechanical devices for the knee cannot remain parallel to the thigh and leg, what does this result in?
- motion or pressure between the mechanical and anatomical parts
what plane and axis does rotation of the tibia and fibula occur in
- transverse plane around the vertical axis that is just medial to the tibial intercondylar ridge
the tibia and fibular rotate ____ to each other
relative (could also be said that the lateral condyle rotates around the medial condyle)
with the knee flexed to 90 degrees, the ligaments are ____ allowing for ____
slackened, allowing for transverse rotation
with the knee fully extended, the collateral and cruciate ligaments are ___ and contribute to _____
tense, joint stability
total range of transverse rotation of the tibia is how many degrees?
- external rot?
- internal rot?
- 40 degrees
- 25
- 15
what is the end feel of rotation in the knee
firm
rotation motion of the knee is limited by ?
capsular and ligamentous structures
- collateral, cruciate, anterior lateral, oblique popliteal ligaments, coronary ligaments, retinacula and IT band
during the last 20 degrees of knee extension what happens? how does this change if the fix the tibia)
the tibia externally rotates about 20 degrees on the femur (tibia= lateral)
- femur rotates medially on the tibia
the 20 degrees of rotation in the last 20 degrees of extension allows for?
- permits humans to stand erect without quadriceps muscle contraction and withstand anterior -posterior forces on the extended knee
what structures of the knee are female and male
- this means?
- tibia surfaces are female and femoral condyles are male (in both directions)
- -> the tibia moves in the SAME direction as the osteokinamatic motion (roll and glide in the same direction)
the tibia articular surfaces are divided by ?
the intercondylar eminance
what does the bigger medial condyle result in ?
lateral rotation with extension
cruciate ligaments are INSIDE the _______ but OUTSIDE the _______
- capsule
- synovial lining
the joint capsule forms a sleeve around the joints, above the ____ condyles and below the _____ condyles
above, below
the capsule is reinforced by ?
retinaculum and ligaments
there is a cut out for what in the capsule?
the patella, anteriorly and central fold posteriorly (caved in)
the tibiofemoral capsule is made up of a inner ? and outer?
- inner synovial lining
- outer fibrous layer
the synovial lining goes on the ____ of the cruciate ligaments
outside
do the layers of the tibiofemoral joint adhere throughout capsule
no
2 characteristics of the tibiofemoral capsule
- suprapatellar pouch
- multiple bursa and fat pad to assist with reducing friction about the knee
what bursa communicates with the knee joint
suprapatellar bursa
the patellofemoral joint is the articulating surface between the ?
posterior surface of the patella and intercondylar surface of the femur (1 of 3 joint compartments)
the tibiofemoral joint makes up ? of 3 joint compartments of the knee
2
what are the functions of the patella?
- increase leverage or torque of the quadriceps muscles by increasing its distance from the axis of motion
- prevent damaging frictional or compression forces on the quadriceps tendon with full range resisted knee flexion / extension activities
by what percent does the patella increase the effectiveness of the quads
30-50%, (13% at 90-120 and 31% at 0-5) , but with considerable retropatellar compression force
where is the thickest hyaline cartilage we have in our bodies?
-back of the patella (need it because it gets pulled into the femur)
what can be a major issue if you dont have a patella
- all your quads insert on the tibial tuberosity, without the patella the quadriceps tendon will rub over bone and get worn out
Quadriceps mechanisms stabilizes the patella and guides its motion via?
lateral and medial retinaculum
what anchors the patella to the tibial tuberosity
the strong patellar tendon
how much should the patella move in full extension
half its width (with joint play)
at what facet is the patella in contact with at 0-10 degrees
no contact
at what facet is the patella in contact with at 10-20 degrees
inferior facet
at what facet is the patella in contact with at 45 degrees
middel facet
at what facet is the patella in contact with at 90 degrees
superior facet
at what facet is the patella in contact with at 120 degrees
ODD facet - medial
with the knee fully extended, what is the patellar apex in line with?
the tibiofemoral joint margins