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What are the 2 jts of the knee?
- tibiofemoral
- patellofemoral
modified hinge jt
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In the tibiofemoral jt, what are the concave/convex bony partners?
- tibia=concave
- femur=convex
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With an open kinematic chain, what is the direction of the glide during flexion?
posterior
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With an open kinematic chain, what is the direction of the glide during extension?
anterior
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With a closed kinematic chain, what is the direction of the glide during flexion?
anterior
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With a closed kinematic chain, what is the direction of the glide during extension?
posterior
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What is the loose packed postion of the knee?
25 degrees flexion
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What is the closed pack position of the knee?
full extension
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What is the capsular pattern of the knee?
flex>ext
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What are the characteristics of the menisci?
- shock absorbers
- flattens the area
- makes cup like area to hold femoral condyles (deepens jt surface)
- thicker laterally
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What is another name for locking and unlocking of the knee?
screw home mechanism
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Which of the femoral condyles are longer from front to back?
medial
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Which way does the tibia rotate during knee ext (lock) in an open chain?
laterally
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Which way does the tibia rotate during knee flex (unlock) in an open chain?
medially
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Which way does the femur rotate during ext (lock) in a closed chain?
medially
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Which way does the femur rotate during flexion (unlock) in a closed chain?
laterally
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What lig limits ant. motion of the knee?
ACL
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What lig limits post. motion of the knee?
PCL
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What ligs provide medial/lateral stability?
MCL/LCL
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How does the gastroc and soleus work during open and closed chains?
- closed- helps with knee ext
- open- helps with knee flex
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What is the pes anserinus?
- sartorious, gracilis, semitendinosus
- provide medial stability and affect rotation of tibia in closed chain
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What is the mechanical axis?
line from head of femur thru the center of the head of the talus (straight line)
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What is the anatomical axis?
runs along the shaft of the femur and tibia (almost a straight line)
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When the anatomical axes meet, what does it form?
tibiofemoral angle
normal 170-175 degrees
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What occurs when the tibiofemoral angle is less than 165 degrees?
genu valgum
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What occurs when the tibiofemoral angle is greater than 180 degrees?
genu varum
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What is genu recurvatum?
- hyperextension of th eknee in full weight bearing
- more common in women
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How much flexion is needed to perform ADLs?
90 degrees
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What is the normal range for flex/ext?
0-130
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How much hyperextension is considered normal?
15degrees
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What are the articulating surfaces of the patellofemoral jt?
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When the knee is extending, which way does the patella slide?
superior
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When the knee is flexing which way does the patella slide?
inferior
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What function does the patella help with?
increases lever arm which increases torque
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What is muscle opposition?
- if theres an imbalance in VM and VL, the patella will lie on the stronger side
- VMO is never stronger
- VL is longer and stronger
- typically the patella shifts laterally bc of this
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What is the Q-angle, and what are the normal ranges?
- deviation in the line of quads (ASIS) and the patellar ligament (TT)
- describes lateral tracking (bowstringing) effect that quads and patellar tendon have on the patella
- male 10-15 degrees
- female 10-19 degrees
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What could be seen with an increased Q angle?
- genu valgum
- femoral anteversion
- tibial torsion
- patella alta (high riding patella)
- pronated feet
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What could be seen with a decreased Q angle?
- chondromalacia (softening of the back of the patella)
- femoral retroversion
- genu varum
- patella baja (low riding patella)
- supinated feet
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How much kne flexion do you need for gait?
60 degrees
- 0 at initial contact
- up to 60 at the end of terminal swing
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Which way does the femur rotate as the knee extends at the end of swing to prepare for intial contact?
medially
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Which way does the femur rotate just before heel off?
laterally
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What effects do the quads have on gait?
- controls amt of knee flexion during initial contact
- extends knee in preparation for midstance
- controls the amt of flexion during preswing (heel-off to toe-off) and prevents excessive heel rise during initial swing
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What effects do the HS's have on gait?
- control the fwd swing of the LE during terminal swing (deceleration)
- provide posterior support to the knee capsule when the knee is extended during stance
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What effects do the ankle PF's have on gait?
primary action: soleus m. controls the amt of knee flexion during preswing (with help from quads) by controlling fwd mvmt of tibia (prevents knee buckling)
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What is CMP?
- chondromalacia patella/ patello-femoral dysfunction
- common degenerative condition which causes softening of the patellar articular surface
causes are: mal-aligned patella, weak VMO, faulty biomechanics (genu valgum)
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What occurs with muscle injury?
- tears and displacement of menisci and ligaments
- medial involved 10X more than lateral
mechanism, sudden IR of femur or fixed tibia when knee is flexed
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Which way is the patella normally dislocated, and what are some causes?
laterally
- patella alta
- imbalance betwen medial and lateral vastus muscles
- genu valgum (increased Q angle)
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What is osteochondritis of the TT in young athletes?
- osgood-schlatters
- strong pull of quads causes patellar lig. to partially pull away from TT
- must allow to reossify
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What nerve is superficial and winds around the fibula just below the fibular head?
common peroneal
- common site for injury
- symptoms:sensory loss, muscular weakness distal to that site
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What nerve innervates the skin along the medial side of the knee and leg?
- saphenous
- injured with trauma or surgery
- sensation nerve, not functional
- be careful with modalities if injured
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What are varus/valgus stress tests?
- push on pts knee medially and laterally
- (+) if theres too much motion
- -tear in medial/lateral collateral lig
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What is the anterior/posterior drawer test?
- pt lays back, flexes knee, pull tibia anterior, or push tibia posterior
- (+) if theres too much motion
- -torn ACL/PCL
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What is the apley compression/distraction test?
- pt prone, knee bent to 90, push down and shift med/lat for compression., pull up and twist med/lat for distraction
- (+) pain for compression (med/lat meniscus)
- (+) pain for distraction (med/lat collateral lig)
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What is the patella femoral grinding test?
- cause compression of patella in groove (put hand on patella and pt does a quad set)
- (+) if theres pain
- -chondromalacia patellae
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What are some gait deviations you may see with weak quads?
- ant trunk bending(initial contact)
- hyperextension (midstance)
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What are some gait deviations that are seen with weak hamstrings?
- hip hiking
- circumduction
- vaulting
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What are some gait deviations seen with weak PF's?
insufficient push-off (midstance/end of swing)
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