Session 8 - The too Hip to handle Joint

Question 1

What type of joint is the hip joint?

Answer 1

Synovial ball and socket joint

Question 2

What are the articulations of the hip joint?

Answer 2

Head of the femur and the acetabulum of the pelvis

Question 3

What is the hip joint designed to be? What is sacrificed to achieve this?

Answer 3

A stable, weight bearing joint A large range of movement in exchange for stability is sacrificed to achieve this

Question 4

What is the acetabulum?

Answer 4

A cup like depression on the lateral side of the pelvis

Question 5

What are the head of the femur and acetabulum covered in? Where is it thicker?

Answer 5

Both covered in articular cartilage, which is thicker at points of weight bearing

Question 6

What are the four ligaments that connect thefemur to the pelvis and increase stability?

Answer 6

Ligament of head of femur Pubogemoral ligament Iliofemoral ligament Ischiofemoral ligament

Question 7

What is the ligament of the head of femur attached to?

Answer 7

The acetabular fossa

Question 8

What does the ligament of the head of femur enclose?

Answer 8

A branch of the oburator artery which contributes a small proportion of the blood supply to the hip joint

Question 9

What is A?

Answer 9

The iliofemoral ligament

Question 10

Where does the iliofemoral ligament attach and what is its function?

Answer 10

The intertrochanteric line Prevents hyperextension of the hip joint

Question 11

What is B?

Answer 11

pubofemoral ligament

Question 12

What does the pubofemoral ligament prevent?

Answer 12

Excessive abduction and medial rotation

Question 13

What is C

Answer 13

Ischiofemoral ligament

Question 14

What does the ischiofemoral ligament prevent?

Answer 14

Excessive medial rotation of the femur at the hip joint

Question 15

What factors stabilise the hip joint? (4)

Answer 15

The structure of the acetabulum The fibrocartaliginous collar around the acetabulum The iliofemoral, ischiofemoral and pubofemoral ligaments, along with thickened joint capsule Reciprocal support of muscles and ligaments

Question 16

How does the structure of the acetabulum contribute to stability?

Answer 16

It is deep, and encompasses nearly all of the head of the femur. This decreases the probablity of the head slipping out of the acetabulum, and causing a dislocation.

Question 17

How does the fibrocartaliginous collar around the acetabulum increase stability?

Answer 17

Increases the depth and articular surface of the acetabulum, and the stability of the joint

Question 18

How do the iliofemoral, ischiofemoral and pubofemoral ligaments and the thickened joint capsule increase stability?

Answer 18

These ligaments have a unique spiral orientation; this causes them to become tighter when the joint is extended, which adds stability to the joint. Also means less energy is needed to maintain a standing position.

Question 19

How do muscles and ligaments work in a reciprocal fashion at the hip joint?

Answer 19

Anteriorly, where the ligaments are strongest, the medial flexors (located anteriorly) are fewer and weaker. Posteriorly, where the ligaments are weakest, the medial rotators are greater in number and stronger - the effectively pull the head of the femur into the acetabulum

Question 20

What movements can occur at hip joint?

Answer 20

flexion, extension, abduction, adduction and medial/lateral rotation

Question 21

What does the degree to which the hip can flex depend on?

Answer 21

whether the knee is flexed, which relaxes the hamstrings, and increases the range of flexion

Question 22

What is extension at the hip joint limited by?

Answer 22

The joint capsule, in particular the iliofemoral ligament. The structures become taut during extension to limit further movement

Question 23

What are the muscles responsible for flexion at the hip?

Answer 23

Iliosoas, rectus femoris, sartorius

Question 24

What are the muscles responsible for extension at the hip?

Answer 24

Gluteus maximus, semimembranous,semitendinosus and biceps femoris

Question 25

What are the muscles responsible for abduction at the hip?

Answer 25

Gluteus medius, gluteus minimus and the deep gluteals (piriformis, gemelli etc)

Question 26

What are the muscles responsible for adduction at the hip?

Answer 26

Adductors longus, brevis and magnus,pectineus and gracillis

Question 27

What are the muscles responsible for lateral rotation at the hip?

Answer 27

Biceps femoris, gluteus maximus, and the deep gluteals (piriformis, gemelli etc)

Question 28

What are the muscles responsible for medial rotation at the hip?

Answer 28

Gluteus medius and minimus, semitendinosus and semimembranosus

Question 29

What does the blood supply to the hip joint come from?

Answer 29

Medial and lateral circumflex femoral arteries Artery to the head of the femur

Question 30

The disruption of which artery causes avascular necrosis of femoral head and neck and why?

Answer 30

Medial circumflex femoral artery, as it supplies the largest proportion of blood

Question 31

Why does the lateral circumflex femoral artery supply less blood than the medial?

Answer 31

Has to penetrate through the thick iliofemoral ligament reach hip joint

Question 32

What is hilton’s law?

Answer 32

the nerves supplying the muscles extending directly across and acting at a given joint also innervate the joint

Question 33

What nerves innervate the hip joint?

Answer 33

Femoral nerve Obturator nerve Nerve to quadratus femoris Superior gluteal nerve

Question 34

What does the femoral nerve innervate?

Answer 34

: The femoral nerve innervates the flexors of the hip joint, which pass anterior to the hip joint.

Question 35

What does the obturator nerve innervate?

Answer 35

lateral rotators that pass inferiorly

Question 36

What does nerve to quadratus femoris innervate

Answer 36

nnervates lateral rotators that pass posteriorly

Question 37

What does superior gluteal nerve innervate?

Answer 37

Innervates adductor muscles that pass superiorly

Question 38

Why is the term a “broken hip” often misleading

Answer 38

Because it often refers to a fractured femoral neck

Question 39

In people below 40 years old, how do femoral neck fractures often occur?

Answer 39

as a result of high energy collisions, with the lower limb extended

Question 40

In people older than 40, how do femoral neck fractures occur?

Answer 40

falls

Question 41

Why are women more at risk of femoral neck fractures?

Answer 41

More at risk of osteoporosis in neck of femur

Question 42

What happens upon a fracture neck of femur?

Answer 42

The affected limb is often laterally rotated. The arteries arising from the medial circumflex femoral artery are usually torn, disrupting the blood supply. This can cause asvascular necrosis of the femoral head and neck.

Question 43

Outline a surgical hip replacement

Answer 43

a plastic socket is cemented to the hip bone to replace the acetabulum, while a stainless steel femoral stem and head replaces the femur.

Question 44

Why are hip replacements peformed?

Answer 44

after traumatic injury, or degenerative disease of the joint

Question 45

What are two types of hip dislocation?

Answer 45

Acquired and congenital

Question 46

How does a congenital hip dislocation arise?

Answer 46

During development the femoral head is not placed within the acetabulum, resulting in a dislocated joint

Question 47

What are three common sympotms of a congenital hip dislocation?

Answer 47

inability to abduct at the hip joint - affected limb is shorter - positive Trendelenburg sign

Question 48

What is trendelenburg sign?

Answer 48

A gait in which during step, instead pelvis being raised on the side of the lifted foot, it drops and pelvis appears to be tilting towards lifted foot. Required flexion at knee on affected side in order for foot to stay clear off the ground

Question 49

What does congenital hip displacement predispose the patient to?

Answer 49

Arthritis of the hip in later life

Question 50

Why are aqcuired hip dislocations quite uncommon?

Answer 50

Due to strength and stability of the joint

Question 51

What are two types of acquired hip dislocation?

Answer 51

Anterior and posterior

Question 52

Which is the more common type of acquired hip dislocation?

Answer 52

Posterior

Question 53

What occurs in an acquired posterior hip dislocation?

Answer 53

The femoral head is forced posteriorly (backwards), and tears through the inferior and posterior part of the joint capsule, where it is at its weakest. The affected limb becomes shortened and medially rotated.

Question 54

What nerve is at risk in a posterior hip dislocation?

Answer 54

The sciatic nerve

Question 55

What occurs if sciatic nerve damaged?

Answer 55

paralysis of the hamstrings, and the muscles distal to the knee

Question 56

What are anterior hip dislocation a consequence of?

Answer 56

extension, abduction and lateral rotation

Question 57

What occurs in an anterior hip dislocation?

Answer 57

The femoral head ends up inferior to the acetabulum, and often pulls the acetabular labrum with it.