Knee Flashcards
Explain the knee (tibiofemoral) jt
Modified hinge between the femur, patella, and tibia
Tibiofemoral alignment: the femoral shaft is _____________ lateral from the tibial shaft. Resulting in..
170/175*
Slight physiological valgus
Describe Knock-knees
Excessive genu valgus ( less than 165*)
Describe bow legs
Genu valgus
Greater than 180*
The ________ compartment of the knee accepts greater compressive force during genu varum. Which could result in..
Medial
OA in that area
Increased Lateral compression force in the knee could be a result of ____________
Genu valgum
Increased stress on MCL, increased stress in lateral compartment, Excessive lateral tracking of the patella, and Increased stress on ACL can be a result from
Genu valgum
Increased medial compartment loading, Greater loss of medial joint space, and Increased strain on LCL could be a result of
Genu varum
Genu recurvatum can occur secondary to
Laxity of posterior knee structure (posterior capsule and knee flexors)
Or
Overpowering knee extension torque
Meniscus functions in the knee
Distribute wt bearing forces
Increase jt congruence
Shock absorption
Which meniscus of the knee is less mobile
Medial meniscus, due to greater ligament restraint
The medial meniscus has connections to the
MCL, ACL, PCL, and semimembranosus
The lateral meniscus has connections to the
ACL, PCL, and popliteus
Menisci of the knee are vascularized ______ and diffuse synovium ________
Peripherally
Centrally
The menisci increase _____________ and reduce _________
Contact area
Reduce jt stress
Which crucible lig. Resists anterior translation of the tibia, hyperextnsion, varus and valgus stretches, and tibial rotation?
Anterior cruciate lig
Functions of the PCL
restrains posterior translation of the tibia, varus and valgus stretch and tibial rotation medially
What is the primary restrains to valgus force and lateral tibial rotation
Medial collateral lig
What is the primary restraint to varus stretch, and also restrains lateral tibial rotation?
Lateral collateral lig
Function of the iliotibial tract
Assists ACL in resisting anterior translation of tibia on femur
3 factors associated with non-contact injuries
Strong activation of quad over moderately flexed or nearly extended knee
Marked valgus collapse of the knee
Excessive ER of the knee
Common MOI for ACL tear
Excessive hyperextension with foot firmly planted
MOI of PCL tear
Falling on to fully flexed knee with ankle plantar flexed (proximal tibia his ground first)
“Dashboard” injury
Usually high energy trauma
Posterior sag sign
Tibia sags posterior in hook lying.
Shows PCL is not in tact
Tibiofemoral Osteokinematics
Flex/ext
IR/ER
ABD/ADD accessory mvmts
Arthrokinematics of flexion in the tibiofemoral jt
OKC and CKC
OKC: posterior roll and glide
CKC: posterior roll anterior glide
Arthrokinematics of extension at the tibiofemoral jt
OKC & CKC
OKC: anterior roll and glide
CKC: anterior roll and posterior glide
Screw home mechanism
ER with terminal extension
Knee needs 10 deg of er to fully ext, usually in the last 5 deg of ext
To unlock the knee from full ext, the ______________ bust _________________ the knee to perform flexion
Popliteus
Medially rotate
Closed packed position of the tibiofemoral jt
Full ext
Open packed position of tibiofemoral jt
25 deg of flexion
Capsular pattern of the tibiofemoral jt
Flexion» ext
The patella functions as a ________ for the quad
Pulley
Ability of the patella to function appropriately is dependent on
Patellar mobility
During full extension, the patella lies on the _____________________ . The minimal congruency in this position results in …
Femoral sulcus
Greater chance for instability near full extension
Patellofemoral pain syndrome
Less than optimal congruency or subtle structural anomalies of the PF joint likely results in abnormal “tracking” of the patella causing pain
Patellofemoral Passive Structures
Lateral patellofemoral ligament Medial patellofemoral ligament Medial patellotibial ligament Lateral patellotibial ligament Quadriceps
Function of the patella
Increases the internal moment arm> increasing mechanical advantage > increases extension torque
Knee extensor moment arm is greatest btw
20-60 deg of knee flex
Sup/inf glide at the patellofemoral jt is present in what motions
Flex/ext
Medial and lateral shift of the patellofenoral jt is described as
Frontal plane translation
During medial/lateral tilt, the patella….
Rotates around the vertical axis
During Medial and lateral rotation at the patellofemoral jt, the patella…
Rotates around the a/p axis
Q-angle
Angle formed between:
Line connecting ASIS to middle of patella
Line connecting tibial tuberosity to middle of patella
Estimation of the line of pull of quadriceps
Increased Q angle increases…
Lat force on the patella
Normal Q angle
13-15 deg
Structures that oppose lateral pull of the patella
Raised lateral facet of trochlear groove
Quadriceps – particularly the VMO
Medial patellar retinacular fibers
Medial passive structures
The PF jt is exposed to high loads of compressive force during what activities
- 3x body weight with walking on level surfaces
- 6x body weight with SLR
- 3x body weight climbing stairs
- 8x body weight with deep squats
The quads product the greatest torque in a seated leg ext between…
45- 0 deg of ext
The quads produce the greatest torque during a squat between…
45- 90 deg of knee flex
Qualities of a stiff landing
Unsafe landing pattern
Larger knee EMA
Smaller hip EMA
Note high activation of quad
Qualities of a safe landing
Smaller knee EMA
Larger hip EMA
Increased hamstring-to-quad contraction pattern
