Kinesiology: Test 2 Lec. 1 The Knee

What two joints make up the knee joint?

- tibia femoral joint (TFJ) and patella femoral joint (PFJ)

What planes does the knee move on?

- sagittal and horizontal plane motion

What things help maintain the stability of the knee joint?

- Muscle

- Ligaments

- Menisci

- BW

T/F: Disease &/or injury is

common in knee joints

true

What is the normal alignment of the knee? Why?

- 5 - 10° Genu Valgum

- B/c of Femoral AOI (angle of inclination): Femur angles medially as it descends

Excessive coxa vera can lead to genu what?

Excessive coxa valgum can lead to genu what?

- genu valgum (valgus)

- genu varum (varus)

What angle of degrees is considered "knock knees"? "Bow Leg"?

- ≤ 165° = "Knock Knee"

- ≥ 180° = "Bow-Leg"

What are the anterior structures of the knee capsule?

- lateral patellar retinacular fibers

- medial patellar retinacular fibers

What are the lateral structures of the knee capsule?

- IT band

- Biceps Femoris

- Lateral collateral ligament

What are the posterior and posterior-lateral structures of the knee capsule?

- Gastrocnemius lateral head

- arcuate popliteal ligament

- oblique popliteal ligament

What are the medial structures of the knee capsule?

- semimembranosus

- Posterior and Anterior medial collateral ligament

- Pes anserinus tendons: sartorius, gracilis, semitendinosus

What do all of the structures in the capsule help do?

- create stability in all aspects (anterior, posterior, lateral, and medial)

What types of synovium and associated structures are in the knee capsule?

- extensive synovial membrane

- Plicae: Suprapatellar, mediopatellar, and infrapatellar

- 14 bursae

- fat pads

What are the 5 common bursae in the knee joint?

1. suprapatellar bursa

2. prepatellar bursa

3. infrapatellar pad of fat

4. deep infrapatellar bursa

5. superficial infrapatellar bursa

What is the bony fit of the tibiofemoral joint?

- convex femoral condyles

- flat tibial plateaus

What are the anatomic considerations of menisci?

- help increase stability btwn femur and tibia

- fibrocartilaginous

- attaches to some ligaments: coronary, transverse, posterior meniscofemoral ligament (PMFL)

What type of shape is the medial meniscus? Lateral meniscus?

- MM - 'C' shaped; MCL attachment

- LM - 'O' shaped

What type of blood supply do the meniscus have?

- outer most mensci has BS. and the inner most is avascular

What is a meniscectomy?

- when they remove the bad/frayed tissue from the menisci

Where does the inner layer of the meniscus get its nutrients from?

- synovial fluid

What are the 4 meniscal functions of the tibiofemoral joint?

1.) ↓ Compressive Forces

2.) ↑ Congruency → ↑ Stability

3.) ↑ Lubrication → ↓ Friction

4.) Guide Arthrokinematics

What is the number of degrees of freedom of the tibiofemoral joint? What are they?

- 2 DOF

- flexion/extension

- medial/lateral rotation

What degrees of open chain flexion and hyperextension do the tibiofemoral joint have? (tibial on femoral)

- flexion: 140 degrees

- hyperextension: 5-10 degrees

What degrees of closed chain flexion and hyperextension do the tibiofemoral joint have? (femoral on tibial)

- flexion: 140 degrees

- hyperextension: 5-10 degrees

What does flexion and extension do for the knee joint?

- alters internal moment arm

- external devices cause a fixed axis

What is the medial/ lateral rotation of the knee joint quantity dependent on?

What are the normal degrees of movement?

- Quantity dependent on sagittal plane motion

- 40 - 50°

What is the ration of lateral and medial movement of the tibiofemoral joint?

2:1

- lateral: medial

How can medial/lateral rotation of the tibiofemoral joint have functional implications and be an injury mechanism?

the opposite rotations between knee and hip can lead to injuries

Which type of joint will have the roll and slide going in the same direction and which will have them going in opposite directions?

- concave on convex: rolle and slide in same direction

- convex on concave: roll and slide in opposite directions

Femur moving on tibia would cause what type of roll and slide?

Tibia moving on femur would cause what type of roll and slide?

- opposite roll and slide

- same direction roll and slide

What is the "screw-home" mechanism?

- 10° Rotation that occurs in last 30° of extension

"Conjunct Rotation"

What causes the screw-home mechanism?

- Passive tension in ligaments (ACL)

- Lateral 'pull' of quadriceps

- Shape of Medial Femoral Condyle

What must occur during active knee flexion? What muscle helps with this?

- Knee must 'unlock'

- Performed by popliteus

- the contraction of popliteus helps unlock the knee so it can flex

What are the med/lat rotation arthrokinematics of the tibiofemoral joint?

- Spin betwn menisci and articular surfaces

- Menisci deform 2° to compression of femoral condyles

What is the patellofemoral joint stabilized by?

- Quadriceps

- Articular Surfaces

- Retinacular Fibers (medial and lateral patellar retinacular fibers)

What occurs during tibia on femur (open chain)?

What occurs during femur on tibia (closed chain)?

- patella slides against femur

- femur slides against patella

Where is the patella located when the knee is flexed to:

- 135 degrees:

- 90 degrees:

- 20 degrees:

- 0 degrees:

- 135 degrees: Patella below intercondylar groove. Lateral & Odd facet articulate

- 90 degrees: Contact region migrates inferiorly

- 20 degrees: Contact located closer to apex

- 0 degrees: Patella rests superior to intercondylar groove

When is there the greatest amount of contact area with the patella and the femur?

- 90-60 degrees of knee flexion

What type of fashion does the patella move on the femur? What type of contact occurs?

- curvilinear progression

- Superior -> Inferior Contact of articular surfaces

- contact pressures being made with patella at diff ROM

T/F: the patella tendon does not increase the IMA of the quadricep tendons, which helps increase force

F: the patella tendon does increase the IMA of the quadricep tendons, which helps increase force

What is the difference between MCL and LCL?

- MCL Superficial & Deep fibers. Attachment to MM

- LCL Cord like structure

What are the goals/functions of the MCL and LCL

- resist frontal plance forces/motion of the knee (varus and valgus)

What are some considerations for cruciate ligaments?

- Intracapsular - Extrasynovial

- Named for insertion sites

- Resist Anterior and Posterior Shear forces

- injury to one or both ligaments greatly increases instability

- Reconstruction may be necessary

What is the origin and insertion fo the ACL?

- O: Medial side of LFC

- I: Anterior Intercondylar Fossa

What are the two spiraling fasicles/bundles of the ACL?

- Anterior-Medial

- Posterior-Lateral

Some of the fibers in the ACL are always tight, but where is the bulk of this ligament drawn taught?

- near full extension

What movements are related to ACL injuries?

- Cutting

- Pivoting

- Twisting

- Hyperextension

When are ACLs more likely to tear:

- contact or non contact

- males or females

- non contact

- females

How can ACL injuries be examinated and evaluated?

- Lachmann Test

- Anterior Drawer Test

- Instrumented

What is the origin and insertion of the PCL?

- O: Lateral side of MFC

- I: Posterior Intercondylar area

What are the two spiraling fasicles/bundles of the PCL?

- Posterior-medial

- Anterior-lateral

What are associated meniscofemoral ligaments of the PCL?

- Anterior (Humphrey)

- Posterior (Wrisberg)

What does the PCL limit?

When is tension of the PCL amplified?

- Limits Post translation of tibia on femur

- Limits Ant translation of femur on tibia

- Tension amplified by Hamstring Contraction

When do we see PCL injuries?

- injuries are uncommon

- Injury Mechanisms

-- Dashboard

-- Hyperflexion

-- Hyperextension

What occurs when there is a PCL injury?

- instability is uncommon

- don't require surgery

- chronic complaints: Pain (PFJ- patella femoral pain)

What is used to examine and evaluate a PCL injury?

Posterior Drawer Test

How many muscles are in the quadriceps?

Which structures produce what % of torque?

- Rectus Femoris, Vastus Lateralis, Vastus Medialis, Vastus Intermedialis

- Vasti= 80% torque

- Rectus= 20% torque

What are the quadriceps innervated by?

femoral nerve

What are the functions of the quadriceps with the knee?

- Stabilizes

- Shock absorption

- Accelerates femur

Which vastus has the largest line of pull?

- vastus lateralis

Which vastus extends farthest distally and what are its two parts and their angles of pull?

- Vastus medialis

- VMO (vastus medialis obliques) 50-55°∠

- VML (vastus medialis longus) 15-18 °∠

What pulls synovial membrane &

capsule proximally during

active knee extension?

- articularis genu

How does the patella increase IMA and Torque?

- ↑IMA → ↑Torque

- with the patella increases the distance from axis of rotation which increase IMA

- greater torque potential bc the patella is farther from the axis

With Tibia on femur movement, where do we see the greatest external torque?

- EMA- increases as knee approaches 0°

- at full knee extension

With femur on tibia movement, where do we see the greatest external torque?

- At 90 degree flexion (squat)

- EMA- decreases as knee approaches 0°

What are rehab suggestions with quadricep exercises:

- OKC (tibia moving on femur)

- CKC (femur moving on tibia)

- OKC: 90-45 degrees

- CKC: 45-0 degrees

Maximal knee extension internal torque is at what degrees of the knee?

- 45-70 degrees

Maximal knee extension torque remains at 90% between what angles? When do we see a rapid decline?

- 80-30 degrees

- Rapid Decline with Terminal Extension

Where do we produce the greatest amount of internal torque with the knee?

- around 45 degree of knee flexion

Internal torque is a balance between what two things?

- lever arm (IMA) and muscle length

- more force at resting muscle length (greatest csa and cross bridges)

When do you have large compression forces of the PFJ?

- greater the angle (more flexion with CKC) the more compression forces you have

- 3.3x BW - Climbing Stairs

- 7.8x BW - Deep Knee Bends

Compression forces of the PFJ function by what factors?

- Knee ∠

- Quadriceps Muscle Force

- Contact Area - Knee ∠

How can we withstand a lot of load in a squat position?

- the patella has most amount of contact from 60-90

- we can withstand a lot of load in the squat position bc there is the greatest amount of surface area between the patella and the femur

- greatest amount of compression forces and greatest amount of SA at this area (so we can dissipate the forces)

- increase the angle of knee flexion you are going to take the patella and jam it into the intercondylar groove

What is the cause of PFJ pain?

- Medial - Lateral Forces Must Balance

- causes of pat fem pain is an imbalance in these forces

What are the benefits of the lateral and medial directed forces of the patella?

- bow string force helps direct the patella laterally

- if you didn't have the medial forces, the knee cap will slide laterally

- if the Q angle is high you have more of the ability to laterally pull the patella

- lateral forces also help stabilize the patella

Glute med weakness is responsible for trendelemburg gait. This weakness will cause what things during a single leg squat?

- Contralateral Drop

- Lateral Trunk Flexion

- Medial Knee Deviation

- Balance strategy

What are the Q angles of males vs females?

- Females > Males

- 15.8° vs. 11.2°

An increased Q angle causes an increase in what?

increased sublux/dislocation

What are the knee flexor and rotator muscles?

- hamstrings: flex the knee and IR/ER the knee. and extend the hip

- Pes group: flexes the knee and internally rotates

What knee flexors/rotator muscles are used during tibia on femur (open chain kinematics)?

- Hamstrings

Gait: Knee Flex/Ext

Conc/Ecc

What knee flexors/rotator muscles are used during femoral on tibia kinematics?

- Biceps - SH;

- Pes Group

- closed chain needs more muscular demand vs open chain actions

- this is closed kin chain fem on pelvic and fem on tibia. these muscles need to control at the hip and knee

Where do the hamstrings produce the greatest amount of force?

- Greatest near extension

- Substantial influence from hip position (length tension)

Where does the greatest amount of IR and ER of the knee occur?

- greatest near 90 degrees

How do we determine the knee flexor (hamstrings)/extensor(quads) ratios? What are they?

- Determined isokinetically

- 2:3 at 60°/sec

- Closer to 1:1 at faster speeds

Why are the knee flexor/extensor ratios like this?

- quads are more dominant at producing torque

- at slower speeds quads are dominant

- as we get into faster speeds theres a 1:1 relationship with hamstring and quad force production

- ppl who are working at faster speeds will need work on both flexors and extensors

What are two synergistic actions?

- Hip & knee extension

- Hip & knee flexion

What are atypical movement combinations?

- Hip Flexion & Knee Extension

- Hip Extension & Knee Flexion

What can occur because of abnormal frontal plane alignment?

- medial compartment arthritis

- the resultant ground rxn force is coming from ground upward (if you step hard, it will be hard back)

- the ground rxn forces are going through the knee

- ppl who are overweight will have a very high ground rxn force every time they take a step. this causes a wearing down of the medial compartment

What other things can cause abnormal frontal plane alignment and medial compartment arthritis?

- Excessive Genu Valgum

- Influenced by:

-- Hip - Coxa Vara

-- Foot - Pronated

What is abnormal sagittal plane aligment?

- Genu Recurvatum (>10° hyperextension)

-- Ideal posture encourages knee extension

- weak quads create genu recurvatum to help stabilize