Unit 3: Biomechanics of the Lower Limb

Question 1

What are the 2 functions of the joints of the lower limb?

Answer 1

Movement

Weight bearing

Question 2

What type of joint is the hip joint?

Answer 2

Ball-and-socket shaped synovial joint

Question 3

What are the movements of the hip joint?

Answer 3

Flexion/extension
Abduction/adduction
Internal/external rottion
Circumduction

Question 4

Describe the structure of a synovial joint

Answer 4

Covered in articular cartilage
Enclosed in a sleeve of tough fibrous tissue (joint capsule) which forms the synovial cavity.
Synovial cavity is filled with synovial fluid.
Synovial fluid is produced by the synovial membrane which lines the inner surface of the capsule

Question 5

Why is the hip joint intrinsically stable?

Answer 5

Surrounded by a very strong articular joint capsule and several ligament. These are the surrounded by several large, strong muscles. This along with the ball-and-socket shape make the joint very stable

Question 6

In which plane is the range of motion greatest in the ip?

Answer 6

Sagittal plane (flexion & extension)

Question 7

What is the range of flexion of the hip?

Answer 7

140 degrees

Question 8

What is the range of extension of the hip?

Answer 8

20 degrees

Question 9

What is the range of abduction of the hip?

Answer 9

30 degrees

Question 10

What is the range of adduction of the hip?

Answer 10

25 degrees

Question 11

In which plane to internal & external rotation occur?

Answer 11

Transverse plane

Question 12

What is the range of external rotation of the hip when it is flexed at 90 degrees?

Answer 12

90 degrees

Question 13

What is the range of internal rotation of the hip when it is flexed at 90 degrees?

Answer 13

70 degrees

Question 14

Why is there less internal and external rotation possible when the hip is extended?

Answer 14

Restrictions of soft tissues

Question 15

What degree of movement is required of the hip for normal daily activities?

Answer 15

120 - flexion/extension
20 - abduction/adduction
20 - rotation

Question 16

What is the motion in the sagittal plane of the hip when walking?

Answer 16

30 flex to 15 extension

Question 17

Which muscles are active at the hip joint during bilateral stance?

Answer 17

Normally no muscles active

Question 18

What percentage of body weight does the upper body (head, arms & trunk) make up?

Answer 18

70%

Question 19

Which muscle group is used to stabilise the body in unilateral stance?

Answer 19

Abductor muscles

Question 20

What are the 4 forces involved in calculating the hip joint force during unilateral stance?

Answer 20

Weight of lower limb
Abductor muscle force
Joint force at hip
Ground reaction force

Question 21

Where is the insertion point of the abductor muscles?

Answer 21

Greater trochanter of the femur

Question 22

What are the 2 articulations of the knee joint?

Answer 22

Tibiofemoral

Patellofemoral

Question 23

What are the menisci of the knee?

Answer 23

2 crescent shaped pieces of fibrocartillage that are attached to the tibia by short tough ligaments

Question 24

What is the purpose of menisci in the knee?

Answer 24

Make the flat top of the tibia slightly concave which aids stability. Also act as load distributors and shock absorbers

Question 25

What is the trochlea?

Answer 25

Smooth anterior depression between the femoral condyles

Question 26

What is the intercondylar notch?

Answer 26

Deep posterior depression between the femoral condyles that the cruciate ligaments are lodged in

Question 27

What is the largest sesamoid bone in the body?

Answer 27

Patella

Question 28

Where is the patella located?

Answer 28

In the tendon of the quadriceps femoris muscle

Question 29

Does the fibula form part of the knee joint?

Answer 29

No (but does act as anchor for biceps femoris muscle and lateral collateral ligament )

Question 30

How do the cruciate ligaments aid stability in the knee?

Answer 30

Limit forward and backward sliding of the femur on the tibia & limit hyperextension

Question 31

How do the collateral ligaments aid knee joint stability?

Answer 31

Prevent abduction & adduction

Question 32

How does the tibia rotate as the knee moves?

Answer 32

Knee flexes - tibia rotates internally | Knee extends - tibia rotates externally

Question 33

Which condyle is normally bigger?

Answer 33

Medial

Question 34

How does the knee joint's centre of rotation change in the sagittal plane as it flexes and extends?

Answer 34

Follows a semi circular pattern

Question 35

In which plane is the greatest range of movement in the knee?

Answer 35

Sagittal plane

Question 36

What is the range of motion in the sagittal plane of the knee?

Answer 36

few degrees of extension to about 140 degrees of flexion

Question 37

What is the range of motion in the knee in the frontal plane dependent on?

Answer 37

How much the knee is flexed

Question 38

At what degree of flexion is their maximum abduction & adduction in the knee & how many degrees?

Answer 38

Max at about 30 degrees flexion but is still only a few degrees

Question 39

What restricts rotation when the knee is in full extension?

Answer 39

Interlocking femoral & tibial condyles

Question 40

At what angle is the maximum internal and external rotation of the knee?

Answer 40

90 degrees flexion

Question 41

What is the range of internal & external rotation of the knee with it flexed at 90 degrees?

Answer 41

External - 45 degrees | Internal - 30 degrees

Question 42

What degree of movement is need in the knee for daily activities?

Answer 42

Full extension to about 115 degrees of flexion | 10 degrees of rotation

Question 43

What is the most important function of the patella?

Answer 43

Increase the lever arm of the quadriceps femoris muscle (assists knee extension by displacing quadriceps tendon)

Question 44

At which point does the patella have the largest contribution to the lever arm?

Answer 44

At full extension (at flexion patella is in intercondylar notch and contributes little)

Question 45

If the patella is removed how must the knee compensate?

Answer 45

Quadriceps muscle force must increase

Question 46

Why when mensci are damaged to they have no capacity to heal?

Answer 46

As there is only a blood supply to their outer edges

Question 47

What are the 3 articulations that comprise the ankle joint?

Answer 47

Tibiotalar Fibulotalar Distal tibiofibular

Question 48

What are the 2 distinctive prominences on the sides of the ankle joint?

Answer 48

Medial (tibia) & lateral (fibula) malleolus

Question 49

What are the 3 most important ligaments in the ankle?

Answer 49

Anterior inferior talofibular ligament Medial ligament Lateral ligament

Question 50

What is the range of motion of the ankle joint?

Answer 50

10-20 dorsiflexion | 25-35 plantarflexion

Question 51

What motion is needed in the ankle joint during walking?

Answer 51

10 degrees dorsiflexion | 15 degrees plantarflexion

Question 52

What is a sprained ankle?

Answer 52

Partial tear of the anterior inferior talofibular ligament resulting from sudden adduction of the foot whilst the ankle is plantarflexed

Question 53

How many bones are in the foot?

Answer 53

26

Question 54

What makes up the hindfoot?

Answer 54

Talus & calcaneus (os calcis)

Question 55

What makes up the midfoot?

Answer 55

Cuboid Medial, intermediate & lateral cuneiforms Navicular

Question 56

What makes up the forefoot?

Answer 56

Metatarsals & phalanges

Question 57

What articulates at the subtalar joint?

Answer 57

Talus & calcaneus

Question 58

What movements does the subtalar joint allow?

Answer 58

Inversion & eversion of the foot

Question 59

What is the range of inversion & eversion at the subtalar joint?

Answer 59

Inversion - 20 degrees | Eversion - 5 degrees

Question 60

What is the walking range of motion at the subtalar joint?

Answer 60

6 degrees

Question 61

What arches make up the foot?

Answer 61

5 longitudinal arches | 1 transverse arch

Question 62

What structure supports the longitudinal arch?

Answer 62

Plantar fascia

Question 63

What is the plantar fascia?

Answer 63

Heavy ligamentous structure that extends from the calcaneus to attach to the plantar aspect of the proximal phalanges

Question 64

Describe the mechanisms when bending toes

Answer 64

Plantar fascia tenses and longitudinal arches are raised thus holding the bones of the foot together

Question 65

What type of gait might someone who has broken their femur use?

Answer 65

Swing-through gait

Question 66

Why might a patient need gait analysis?

Answer 66

Improvement in CP Determine outcome of an operation Determine if surgery is required Ensure alignment of protheses

Question 67

What are the phases of a gait cycle?

Answer 67

``` Stance phase (R & L) Swing phase (R & L) Single support (R & L) Double support ```

Question 68

When is the stance phase?

Answer 68

From heel contact to toe off

Question 69

When is the swing phase?

Answer 69

From toe off to next heel contact

Question 70

What phenomenon would be seen in a patient with weak dorsiflexor muscles?

Answer 70

Foot drop

Question 71

What is the range of motion at the hip during reciprocal gait?

Answer 71

15 ext - 30 flex

Question 72

When does peak hip extension occur in the gait cycle?

Answer 72

Just before toe off

Question 73

When is the peak amount of hip flexion in the gait cycle?

Answer 73

Mid step

Question 74

What is the range of motion in the knee joint in reciprocal gait?

Answer 74

Few degrees of extension to 70 degrees flexion

Question 75

When is the peak amount of knee flexion in reciprocal gait?

Answer 75

During swing phase

Question 76

What is the range of motion at the ankle joint in reciprocal gait?

Answer 76

15 degrees plantarflexion - 10 degrees dorsiflexion

Question 77

What are ground reaction forces?

Answer 77

When foot is in contact with the ground it exerts an equal and opposite force

Question 78

What is the characterstic appearance of a graph of the vertical force measured using force platforms?

Answer 78

Double hump

Question 79

Why do hip extensors contract just after heel contact?

Answer 79

To prevent upper body falling forward

Question 80

Why do the hamstrings contract just after heel contact?

Answer 80

To prevent hyperextension of the knee

Question 81

Why do quadriceps contract during gait?

Answer 81

To prevent knee from bucking

Question 82

Why does the triceps surae contract just before toe off?

Answer 82

To push the foot up and off the ground