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What are the 2 jts of the knee?
modified hinge jt
In the tibiofemoral jt, what are the concave/convex bony partners?
With an open kinematic chain, what is the direction of the glide during flexion?
With an open kinematic chain, what is the direction of the glide during extension?
With a closed kinematic chain, what is the direction of the glide during flexion?
With a closed kinematic chain, what is the direction of the glide during extension?
What is the loose packed postion of the knee?
25 degrees flexion
What is the closed pack position of the knee?
What is the capsular pattern of the knee?
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
What is another name for locking and unlocking of the knee?
screw home mechanism
Which of the femoral condyles are longer from front to back?
Which way does the tibia rotate during knee ext (lock) in an open chain?
Which way does the tibia rotate during knee flex (unlock) in an open chain?
Which way does the femur rotate during ext (lock) in a closed chain?
Which way does the femur rotate during flexion (unlock) in a closed chain?
What lig limits ant. motion of the knee?
What lig limits post. motion of the knee?
What ligs provide medial/lateral stability?
How does the gastroc and soleus work during open and closed chains?
- closed- helps with knee ext
- open- helps with knee flex
What is the pes anserinus?
- sartorious, gracilis, semitendinosus
- provide medial stability and affect rotation of tibia in closed chain
What is the mechanical axis?
line from head of femur thru the center of the head of the talus (straight line)
What is the anatomical axis?
runs along the shaft of the femur and tibia (almost a straight line)
When the anatomical axes meet, what does it form?
normal 170-175 degrees
What occurs when the tibiofemoral angle is less than 165 degrees?
What occurs when the tibiofemoral angle is greater than 180 degrees?
What is genu recurvatum?
- hyperextension of th eknee in full weight bearing
- more common in women
How much flexion is needed to perform ADLs?
What is the normal range for flex/ext?
How much hyperextension is considered normal?
What are the articulating surfaces of the patellofemoral jt?
When the knee is extending, which way does the patella slide?
When the knee is flexing which way does the patella slide?
What function does the patella help with?
increases lever arm which increases torque
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
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
What could be seen with an increased Q angle?
- genu valgum
- femoral anteversion
- tibial torsion
- patella alta (high riding patella)
- pronated feet
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
How much kne flexion do you need for gait?
- 0 at initial contact
- up to 60 at the end of terminal swing
Which way does the femur rotate as the knee extends at the end of swing to prepare for intial contact?
Which way does the femur rotate just before heel off?
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
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
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)
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)
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
Which way is the patella normally dislocated, and what are some causes?
- patella alta
- imbalance betwen medial and lateral vastus muscles
- genu valgum (increased Q angle)
What is osteochondritis of the TT in young athletes?
- strong pull of quads causes patellar lig. to partially pull away from TT
- must allow to reossify
What nerve is superficial and winds around the fibula just below the fibular head?
- common site for injury
- symptoms:sensory loss, muscular weakness distal to that site
What nerve innervates the skin along the medial side of the knee and leg?
- injured with trauma or surgery
- sensation nerve, not functional
- be careful with modalities if injured
What are varus/valgus stress tests?
- push on pts knee medially and laterally
- (+) if theres too much motion
- -tear in medial/lateral collateral lig
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
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)
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
What are some gait deviations you may see with weak quads?
- ant trunk bending(initial contact)
- hyperextension (midstance)
What are some gait deviations that are seen with weak hamstrings?
- hip hiking
What are some gait deviations seen with weak PF's?
insufficient push-off (midstance/end of swing)