DPT 642: The Knee

position and stability

hip and ankle weakness can affect the knees...?

femur, tibia, patella and fibula

4 bones of the knee

tibiofemoral, patellofemoral, proximal tibiofibular

3 joints of the knee

femur, tibia

the knee consists of the convex _____ and concave _______

intercondylar notch

pathway for the cruciate ligaments

intercondylar groove

the patella glides on & articulates with this

sagittal

asymmetry of medial and lateral grooves affect motions in this plane

transfer weight across knee to ankle

what;s the primary function of the tibia?

tibial tuberosity

point where the patellar ligament attaches

medial

on the tibia, the ____ condyle is concave

lateral

on the tibia, the ____ condyle is convex

lateral meniscus

this structure helps the lateral tibial condyle to become concave

quadriceps tendon

the patella is embedded in this

apex

the patellar tendon comes off of which part of the patella?

apex

inferior portion of the patella

base

superior portion of the patella

flexion and extension

movement of the knee permitted in the sagittal plane

internal and external rotation

movement of the knee permitted in the frontal plane

130-150 degrees

normal ROM for knee flexion

5-10 degrees hyperextension

normal ROM for knee extension

tibial tuberosity

rotation is based off the position of this

90 degrees

maximal amount of rotation occurs when the knee is flexed to about...?

external rotation

tibial tuberosity travels laterally

internal rotation

tibial tuberosity travels medially

external rotation

in closed chain internal rotation, what does the femur do?

internal rotation

in closed chain external rotation, what does the femur do?

anteriorly

which way does the tibia roll/slide in open chain knee extension?

posteriorly

which way does the tibia roll/slide in open chain knee flexion?

screw home mechanism

tibia externally rotates during last 30 degrees of knee extension

shape of medial femoral condyle, passive tension of ACL, and slight lateral pull of the quads

what are the causes of the screw home mechanism

internal synovial layer

of the joint capsule, this Provides nourishment and lubrication & Allows freedom of motion

external fibrous layer

of the joint capsule, this Offers joint protection & Provides stability through a large ROM

menisci

web-shaped fibrocartilaginous discs that sit on the condyles of the tibia

Provides joint congruency and stability

Disperse weight bearing forces by providing cushioning

Provides nutrition and lubrication to the articular cartilage

Facilitates joint gliding

what are some of the functions of the menisci?

peripheral

which part of the menisci has a good blood supply?

menisectomy

this procedure is done when there a tear to the outside border of the meniscus

meniscus repair

this procedure is done when there a tear to the inside of the meniscus

lateral meniscus

more circular in shape

medial meniscus

more oval in shape

MCL and capsule

where does the medial meniscus attach to?

valgus motion

due to the attachment, the medial meniscus and MCL are commonly injured together when they encounter this

forceful, axial rotation of the femoral condyles over a partially flexed and weight bearing knee

what causes a medial meniscus tear?

cruciate ligaments

Prevent motion in all directions, best for prevent shear forces

proprioception

the cruciate ligaments contribute this of the knee, which is the knees understanding of where it is and what it is doing in space

Anterior Cruciate Ligament (ACL)

prevents anterior displacement of tibia

extension

the ACL is most taut in what position?

posterolateral and anteromedial

2 bundles of the ACL

posterolateral

this bundle of the ACL is taut in extension

anteromedial

this bundle of the ACL is taut in flexion

strong activation of the quadriceps muscle over a slightly flexed or fully extended knee, a marked valgus collapse of the knee, and excessive external rotation of the knee

What are the 3 common components of an ACL injuries

valgus

if a person injures their ACL via landing a jump, what position did their knee go in in order to cause the injury?

valgus knee or genu valgum

varus knee or genu varum

flexion

the PCL is most taut in what position

Posterior Cruciate Ligament (PCL)

prevents posterior displacement of tibia

posteromedial and anterolateral

2 bundles of the PCL

posteromedial

PCL bundle taut in flexion

anterolateral

PCL bundle taut in increasing extension

dashboard injury

injury to PCL because proximal anterior tibia of flexed knee hits the dashboard forcing excessive posterior translation of tibia on femur

fall on fully flexed knee with ankle in full plantar flexion

describe how a PCL may be torn during contact sports?

skip

study checkpoint- i hope someone studying this understands this meme.

anyways, you're doing great, keep up the focus & the great work! 💙

answer is 'skip'

frontal plane stability

collateral ligaments play the biggest role in this

Medial Collateral Ligament (MCL)

limits valgus force and some anterior translation

Lateral Collateral Ligament (LCL)

limits varus force & excessive lateral rotation

biceps femoris

the LCL blends with this tendon

valgus force with foot planted or severe hyperextenstion of knee

Common MOI to MCL?

varus force with foot planted or severe hyperextenstion of knee

Common MOI to LCL?

hyperextension or combined hyperextension with external rotation of the knee

Common MOI to posterior capsule?

patellar tendon and patellar retinacular fibers

connective tissue that reinforces the anterior capsule

lateral collateral ligament/lcl, lateral patellar retinacular fibers, IT band

connective tissue that reinforces the lateral capsule

oblique popliteal ligament and arcuate popliteal ligament

connective tissue that reinforces the posterior capsule

arcuate popliteal ligament and lateral collateral ligament/lcl

connective tissue that reinforces the posterior-lateral capsule

medial patellar retinacular fibers, medial collateral ligament and thickened fibers posterior-medially

connective tissue that reinforces the medial capsule

quadriceps

muscular-tendinous reinforcement of the anterior capsule

biceps femoris, tendon of the popliteus and lateral head of gastrocnemius

muscular-tendinous reinforcement of the lateral capsule

popliteus, gastrocnemius, hamstrings (especially semimembranosus tendon)

muscular-tendinous reinforcement of the posterior capsule

tendon of the popliteus

muscular-tendinous reinforcement of the posterior-lateral capsule

expansions from the tendon the semimembranosus and tendons of sartorius, gracilis and semitendinosus

muscular-tendinous reinforcement of the medial capsule

20-30° of flexion

Patella moves inferiorly and sits in the shallow part of the trochlear groove

60-90° of flexion

Patella continues to move inferiorly and is in max contact with the trochlear groove

135° of flexion

Patella continues to move inferiorly and sits below the trochlear groove

the patella loses much of its mechanical engagement with intercondylar groove

why is 20-30° of flexion a common position of instability of the patellofemoral joint?

fixed patella

During femoral on tibial movement, the intercondylar groove moves relative to the...?

Medial and lateral patellar retinacular fibers or medial and lateral patellofemoral fibers

aid in patellar tracking in trochlear groove

medial patellofemoral ligament

becomes taut in extension due to its connection to oblique fibers of vastus medialis

Q-angle

angle represented by force vector of quads and long axis of patellar tendon

10-15 degrees

average Q-angle in men

15-20 degrees

average Q-angle in women

lateral pull force

Q-angles above 20 degrees increase...?

compressive forces

Force within quadriceps and knee flexion angle affect this greatly

contact force

compressive forces create a bigger __________ thanks to compressive forces

90

Flexion angles greater than _____ degrees increase contact from quad tendon & it helps to offset forces

quadriceps femoris

muscle(s) responsible for knee extension

hamstrings, sartorius, gracilis, popliteus, and gastrocnemius

muscle(s) responsible for knee flexion/rotation

quadriceps

Consists of rectus femoris, vastus lateralis/medialis/intermedius

Most internal torque is created between 45-70 degrees of flexion

bowstring force

the quads oull the patella superior and lateral, causing this force

vastus lateralis

largest component of bowstring force

internal rotation

if the muscle is more medially located, what kind of rotation will it do?

external rotation

if the muscle is more laterally located, what kind of rotation will it do?

biceps femoris

does External rotation of knee (flexed knee)