knee joint Flashcards
2 parts of knee joint function (3)
1. tibiofemoral and patellofemoral functions 1. shortens leg during swing 2. lengthens led during stance 3. transmits weight btwn hip and ankle
anatomy of knee joint (2)
- femoral condyles sit on shallow menisci = exposed shallow joint
- long exposed bone levers (femur and tibia) = most injured joint in body
normal ROM of knee and needed ROM for…
walking
stairs
normal = 0-140 degrees walking = 65 degrees stairs = 110
tibiofemoral joint - type and movements available
- modified hinge joint
2. biaxial - flex/ extend and rotation
volitional movement of tibiofemoral joint
- volitional rotation using med and lateral hamstrings
mechanical movement of tibiofemoral joint
- medial condyle is larger than lateral
2. in open chain- going into terminal extension - lat side runs out of room to keep moving => ext rotation of tibia
open vs. close kinematic rotation
rotary and translatory movement
rotation of tibia and femur when going into and out of terminal ext
open
1. tibia on femur = concave on convex (rotary same as translatory)
2. terminal ext -> slight flexion = slight tibial int rotation
closed
1. femur on tibia = convex on concave so rotary opposite of translatory
2. slight flex -> terminal ext = femoral int rotation
*see sticky note on computer
nemonic for closed chain kinematics
FE - Flex -> ext
MuR = medial rotation
patellofemoral joint
type of joint and movements available
- diarthrodial
2. planar joint
patella
action on quads
translatory movements (when you flex and extend your knee)
- lengthens quads b/c of angle of insertion => increases mechanical advantage
translatory:
- going into extension- patella glids sup and lateral
- going into flexion - patella glides inf and medial
movements of patella in transverse plane
- z- axis
- flexion- med tilting
- extension- lat tilting
inferior pole is point of reference
tibial tubercles
location
where they are in extension
- located on top of tibial plateau
2. in extension lodged in intertrochanteric fossa and contribute to locking mechanism
menisci
size
shape
function
- medial is larger than lateral
- lateral- is circular
- medial- crescent and bound down stronger
- function is shock absorption
two types of menisci tears
and where it will heal faster
- transverse/ radial - goes horizontal
- longitudinal - bucket handle
- outside is more likely to heal because more blood supply
2 cardinal signs of meniscal issue
- compliant knee locking
2. excessive clicking
2 meniscal ligaments
- meniscal-tibial ligaments (coronary)
2. transverse ligament- binds menisci to each other
knee stability
anatomy
- long levers w/ shallow articulation- contractile and non-contractile tissues give support
knee stability- ant support (2)
- quad tendons
2. infrapatellar tendon
knee stability posterior support (6)
- joint capsule - snaps knee back
- popliteus- in closed chain does ER rotation of femur => unlocking; open chain does IR rotation
- gastroc heads - cross knee joint
- arcuate popliteal ligament
- posterior oblique popliteal ligament
- hamstring tendons
knee stability - cruciate ligaments
where they attach and purpose
give ant and posterior stabilization
PCL
1. posterior on tib -> med femoral condyle.
2. prevents posterior slippage of tib on femor (or visa versa)
ACL
1. ant on tib -> lat femoral condyle
2. prevents anterior slippage of tib on femur
drawer sign
- hooklying position, grab behind gastroc head and try to translate the fib forward. excessive translation = tear or strain in ACL
ligament of wristberg
posterior part of lateral meniscus and goes to medial femoral condyle
medial/ lateral support of knee
ligaments (4)
unhappy triad of knee injury (what usually causes it)
muscle attachments (2 med)
- medial and lateral collateral ligaments
- patellofemoral ligament
- IT band
- unhappy triad = Med collateral, ACL, and medial meniscus
from lateral side impact
muscles:
pes anserine- gives medial stabilization
medial hamstrings
joint slide (2)
- more knee flexion- femoral condyles slide anterior
2. flex -> extend - joint surfaces slide posterior
instantaneous axis of rotation
- axis is constantly changing because of sliding movements around joint, usually around femoral condyle
knee bursae (5)
- pre-patella bursa- btwn skin and patella
- infrapatella bursa- 2-
superficial- btwn skin and tendon
deep - underneath infrapatellar tendon - suprapatella bursa- btwn quadriceps tendon and bone
- gastroc bursa- gastroc head and medial femoral condyle
- pes anserine bursa
muscles that do knee extension
5 quads
articularis genu
quads: 1. vastus lateralis- strongest 2. vastus intermedius 3. vastus medialis longus 4. vastus medialis oblique 5. rec fem articularis genu inserts into joint capsule -> suprapatellar bursa does the last 15 degrees of extension, helps terminal extension, pulls joint capsule up and out of the way
quad hamstring ratio
- hamstrings have 50-60% strenghth of quads
when can quads generate most amount of torque
- sitting position 30-60 degrees (45)
2. in this range pt can generate most force and lift more weight
Q- angle (quadricep angle)- how you measure
normal angles
what happens in genu valgum and genu varum
2 lines
1. ASIS drop down to midpoint of patella
2. line thru tibial crest, tibial tuberosity -> thru patella , straight up
angle is above knee cap
3. regular is 10-15 degrees (women are closer to 15)
4. genu valgum- q-angle is larger b/c excessive lateral tracking of patella
5. genu varum- q-angle is smaller because b/c excessive medial tracking of patella
posterior knee muscles (flexors)
4 muscles
3 muscles:
- hamstrings - do knee flexion w/ rotation of tibia (medial do IR)
- plantaris (lat fem condyle -> achilles tendon)
- gastroc
- popliteus - oblique med- > lat, does unlocking (ER femur, IR tibia)
gastroc
when can they generate most torque?
shunt vs. spurt
- can generate most amt of torque when knee is flexed at 90
- shunt at knee (stability) -close to origin
- spurt at ankle (movement)- far from origin
movement of patella in frontal plane
which axis
what happens in flexion and extension
- y axis
- flexion = lateral rotation (spin) 3. extension =med rotation
- inferior pole is point of reference
movement of patella in saggital plane
which axis
what happens in flexion
- x- axis
- in flexion - sup pole => forward, inf pole -> back
- inferior pole is point of reference
