Kinesiology and Biomechanics 2.2 Knee

What is normal for the knee alignment varus or valgus?

Valgus

How much Valgus is normal for knee alignment?

5 to 10 degrees

What influencing factors does genu varum have on the knee?

Genetic disposition

Foot alignment

Tibial alignment

What influencing factors does genu valgum have on the knee?

Genetic disposition

Foot and/or hip alignment

Muscle imbalance

Higher BMI

Ligamentous laxity

What is genu recurvatum?

Hyperextension of the knee

What measurement defines genu recurvatum?

5 to 10 degrees beyond neutral

What resists genu recurvatum?

Posterior capsule

Knee flexor (hamstrings)

Collateral and Cruciate ligaments

Menisci

What are the possible causes of genu recurvatum?

Poor postural control

Neuromuscular imbalance

Fixed plantarflexed foot

Combination of these factors

Does pronation or supination lengthen the limb in closed chain?

Supination

Does pronation or supination shorten the limb in closed chain?

Pronation

What are the mechanisms of the body that are caused by pronation during closed chain?

Tibial internal rotation

Knee flexion

Femoral internal rotation

Hip flexion

What are the mechanisms of the body that are caused by supination during closed chain?

Tibial external rotation

Knee extension

Femoral external rotation

Hip extension

When does the screw holm mechanism take place during knee extension?

Last 30 degrees

What does the screw holm mechanism in the knee do?

Locks in full extension

The scree holm mechanism is coupled with BLANK degrees of tibial BLANK rotation.

10 to 15; external

What does the screw holm mechanism do for the joint?

Stability

What muscle unlocks the knee for flexion?

Popliteus

During open chain the is BLANK rotation of the BLANK on the BLANK during the screw holm mechanism.

Internal; tibia; femur

During closed chain the is BLANK rotation of the BLANK on the BLANK during the screw holm mechanism.

External; femur; tibia

What are the three screw holm mechanism factors?

Shape of medial femoral condyle

Passive tension in ACL

Lateral pull of quadriceps

What is the loose packed position for the tibiofemoral joint?

30 degrees of flexion

What is the closed packed position for the tibiofemoral joint?

Full extension

What is the loose packed position for the patellofemoral joint?

Full extension to 5 degrees of flexion

What is the closed packed position for the patellofemoral joint?

Full knee flexion

What is the loose packed position for the proximal tibiofibular joint?

Not applicable

What is the closed packed position for the proximal tibiofibular joint?

Not applicable

Are the tibial plateau and menisci concave or convex?

Concave

Are the femoral condyles concave or convex?

Convex

If you want to assess knee extension, you could perform a BLANK tibial glide relative to the femur.

Anterior glide

If you want to assess knee flexion, you could perform a BLANK tibial glide relative to the femur.

Posterior glide

Is the medial or lateral collateral ligament a part of the knee joint capsule?

Medial

What does the MCL resist?

Valgus

Extension

Extreme rotation

What are the two mechanisms of injury of the MCL?

Excessive valgus with foot planted

Severe hypertension

What is a clip injury?

Lateral sided hit with foot planted causing MCL tear and contusion of lateral femoral condyle

Which is less broad the MCL or LCL?

LCL

How many layers does the MCL have?

2

How many layers does the LCL have?

1

What does the LCL resist?

Varus

Extension forces

Extreme rotation

What are the 2 mechanisms of injury of the LCL?

Excessive varus force with foot planted

Severe hypertension

What part of the tibia is the ACL on?

Lateral part of medial tibia

What part of the femur is the ACL on?

Medial part of the lateral femur

What does the ACL consist of?

Anterior medial band

Posterior lateral band

What is the function of the ACL?

Stability (primarily extension)

Arthrokinematics

Proprioception

What does the ACL prevent in the open chain?

Excessive anterior translation of the tibia on the femur

What does the ACL prevent in the closed chain?

Excessive posterior translation of femur on the tibia

What percent of ACL injuries are non-contact injuries?

70%

Are ACL injuries more common in males or females?

Females

What are the mechanisms of injury of the ACL?

Valgus force

Knee rotation (either rotation)

Severe hyperextension

Decelerating

Where is the PCL on the tibia?

Posterior condylar area

Where is the PCL on the femur?

Lateral side of the medial femoral condyle

Which is thicker, the ACL or the PCL?

PCL

What is the function of the PCL?

Arthrokinematics

Resist flexion

Resist extreme valgus, varus, & rotational forces

What does the PCL prevent in open chain?

Excessive posterior translation of the tibia on the femur

What does the PCL prevent in closed chain?

Excessive anterior translation of the femur on the tibia

What is the most common mechanism of injury of the PCL?

Dashboard injury

What is a dashboard injury?

Posterior translation of tibia OR anterior translation of femur with knee bent

What are the mechanisms of injury for the PCL aside from dashboard injury?

Excessive varus/valgus with foot planted

Excessive rotation with foot planted

Severe hyperextension

Falling on flexed knee with ankle plantarflexed

Are the menisci thicker or thinner towards the outside edges?

Thicker

What are the menisci attached by?

Anterior and posterior horns

Do the menisci shift during knee movement?

Yes

Which menisci is more C-shaped?

Medial

Which menisci is attached to the MCL/capsule?

Medial

Which menisci is more O-shaped?

Lateral

What are the functions of the menisci?

Shock absorption and distribution

Stabilization

Guide arthrokinematics

Lubricate articular cartilage

Which menisci moves more?

Lateral

Does the menisci move the same or opposite from the tibia during flexion and extension?

Same

Does the menisci move the same or opposite from the tibia during internal and external rotation?

Opposite

During external rotation the lateral meniscus moves BLANK and the medial meniscus moves BLANK.

Anteriorly; posteriorly

During internal rotation the lateral meniscus moves BLANK and the medial meniscus moves BLANK.

Posteriorly; anteriorly

What is the mechanism of injury for menisci?

Forceful compression

Axial rotation

Knee flexion

What is the mechanism of injury for the medial menisci?

Flexion

Axial rotation

Valgus

How many ACL tears also have meniscal injuries?

50%

What is the function of the patellofemoral joint?

Protects tibiofemoral joint

Improves mechanical advantage for quadriceps to lower leg

Decreases friction

What is used to describe the patella movement?

Inferior pole

What are the two intersecting lines from when measuring Q-angle?

ASIS to midpoint of patella

Tibial tuberosity to midpoint of patella

What is a normal Q-angle?

10 to 15 degrees

Is the Q-angle often greater in males or females?

Females

What is the average Q-angle for females?

18 degrees

What all can increase a Q-angle?

Tibial torsion: external

Femoral rotation: internal

Width of the pelvis: greater

Genu valgum: greater

Hip adduction: greater

What are abnormally high Q-angles thought to be associated with?

Increased lateral forces on patella

What is the patellar motion during knee extension?

Superior and lateral glide

What is the patellar motion during knee flexion?

Inferior and medial glide

At what degree of knee flexion is the patella inferior pole contacting the femur?

20 degrees

At what degree of knee flexion is the middle patella contacting the femur?

45 degrees

At what degree of knee flexion is the superior portion of the patella contacting the femur?

90 degrees

At what degree of knee flexion is the odd facet and superolateral portion of the patella contacting the femur?

135 degrees

What are the accessory dynamic motions of the patella?

Tilt

Spin (rotation)

Shift

What influences the compression of the patellofemoral joint?

Force of the quadriceps muscle

Knee flexion angle

What is patellofemoral dysfunction?

Abnormal tracking of the patella

What does a mild case of patellofemoral dysfunction present with?

Anterior knee pain

What does a severe case of patellofemoral dysfunction present with?

Patellar subluxation/dislocation

During weight-bearing (closed-chain) activities, what does the ACL primarily prevent?

A) Excessive tibial external rotation

B) Anterior translation of tibia on femur

C) Posterior translation of femur on tibia

D) Varus collapse of the knee

Posterior translation of femur on tibia

During weight-bearing (closed-chain) activities, what does the PCL primarily prevent?

A) Excessive tibial external rotation

B) Anterior translation of femur on tibia

C) Posterior translation of femur on tibia

D) Varus collapse of the knee

Anterior translation of femur on tibia

During open-chain activities, what does the ACL primarily prevent?

A) Excessive tibial external rotation

B) Anterior translation of tibia on femur

C) Posterior translation of femur on tibia

D) Varus collapse of the knee

Anterior translation of tibia on femur

During open-chain activities, what does the PCL primarily prevent?

A) Excessive tibial external rotation

B) Anterior translation of tibia on femur

C) Posterior translation of tibia on femur

D) Varus collapse of the knee

Posterior translation of tibia on femur

Which of the following is primarily responsible for the screw-home mechanism?

A) Shape of lateral femoral condyle

B) Action of the hamstrings

C) Shape of medial femoral condyle

D) Passive tension in PCL

Shape of medial femoral condyle

During closed-chain, entire lower extremity pronation, what happens with the tibia?

A) External rotation

B) Extension

C) Internal rotation

D) Abduction

Internal rotation

During closed-chain, entire lower extremity supination, what happens with the tibia?

A) External rotation

B) Extension

C) Internal rotation

D) Abduction

External rotation

During closed-chain, entire lower extremity supination, what happens with the tibiofemoral joint?

A) External rotation

B) Extension

C) Internal rotation

D) Abduction

Extension

During closed-chain, entire lower extremity pronation, what happens with the tibiofemoral joint?

A) External rotation

B) Extension

C) Internal rotation

D) Flexion

Flexion