Week 3: Hip Joint & Femur

Question 1

What are the 3 main functions of the hip joint?

Answer 1

1. Links lower limb to pelvic girdle
2. Allows movement of the hip and lower limb during weight-bearing
3. Stability, but also allows motion

Question 2

What is the shape of the articular surface of the head of the femur? And what is the functional relevance of this shape?

Answer 2

• 2/3 of a sphere
• Formation for a ball and socket joint – with the acetabulum

Question 3

What are the osteokinemtic movements of the hip in the 3 different planes?

Answer 3

1. Sagittal: Coronal axis - flexion & extension
2. Coronal: Sagittal axis - abduction & adduction
3. Transverse: Longitudinal axis - internal & external rotation

Question 4

What arthrokinematic movements are present at the hip joint?

Answer 4

Glide, spin, roll

Question 5

Why is the acetabular notch present?

Answer 5

To allow vessels and nerves to enter the acetabulum

Question 6

Describe the form of the acetabular labrum:

Answer 6

Fibrocartilaginous lip that is attached to the bony rim of the acetabulum

Question 7

What is the function of the acetabular labrum?

Answer 7

• Increases the extent (surface area) of the acetabular socket
• The femoral head is maintained in the acetabulum even after the capsule and muscle have been severed - largely due to the labrum

Question 8

What are the 2 intracapsular ligament of the hip joint?

Answer 8

1. Transverse acetabular ligament
2. Ligamentum teres (ligament of the head)

Question 9

What is the function of ligamentum teres?

Answer 9

• Connects the femoral head and acetabulum
• The artery to the head of the femur runs along or within the ligament

Question 10

Describe the morphology of the hip joint capsule:

Answer 10

• Thick fibrous capsule of the hip joint
• Lined with synovial membrane and encloses a joint cavity containing the head and neck of femur

Question 11

What is the proximal attachment of the hip joint capsule?

Answer 11

Bony rim of the acetabulum

Question 12

Describe the femoral attachment of the hip joint capsule:

Answer 12

Anteriorly: intertrochanteric line
Posteriorly: base of the neck of the femur

Question 13

On a radiograph of a normal hip joint what fills the apparent joint space?

Answer 13

Articular cartilage, the ligamentum teres and a pad of fat

Question 14

What are the 3 capsular ligaments of the hip joint capsule and their attachment sites?

Answer 14

1. Iliofemoral ligament: AIIS to intertrochanteric line
2. Ischiofemoral ligament: Ischial portion of acetabulum to greater trochanter
3. Pubofemoral ligament: Pubic part of acetabular rim to neck of femur

Question 15

Why is the iliofemoral ligament the chief structure that counterbalances gravitational force during relaxed standing?

Answer 15

Line of gravity falls behind transverse axis of the hip, the force tends to tilt the pelvis backwards on the femoral heads
- This is resisted by the iliofemoral ligament

Question 16

In which positions of the hip joint does the iliofemoral ligament become maximally taut?

Answer 16

Extension, external rotation, adduction (superior band)

Question 17

In which positions of the hip joint does the ischiofemoral ligament become maximally taut?

Answer 17

Extension, internal rotation, abduction

Question 18

In which positions of the hip joint does the pubofemoral ligament become maximally taut?

Answer 18

Extension, external rotation, abduction

Question 19

In what position are all 3 capsular ligaments of the hip joint capsule relaxed?

Answer 19

Hip joint flexion

Question 20

What are the key factors in maintaining stability at the hip joint?

Answer 20

• Deep articular surfaces, extended by the labrum
• Strong ligaments and surrounding muscles
• The joint is constructed so that the body weight can be supported on the femoral heads with minimal or no expenditure of muscle energy

Question 21

Is it easy to dislocate your hip joint?

Answer 21

• No - traumatic dislocation is not common
• May occur in a car-accident (posterior dislocation) or in conjunction with a fracture to the neck of femur as is often seen in elderly people following a fall

Question 22

Describe the pattern of innervation of the hip joint:

Answer 22

Femoral nerve, obturator nerve, superior gluteal nerve, nerve to quadratus femoris

Question 23

Describe the arterial supply to the hip joint:

Answer 23

• Medial and lateral circumflex femoral arteries - from deep femoral artery
• Retinacular arteries - branches of the MCFA & LCFA
• Artery to head of femur - branch of obturator artery

Question 24

What are the clinical implications of a fracture to the neck of the femur?

Answer 24

• Most arteries to the neck and head of femur go through the capsule of the joint at its attachment to the femur and then run proximally along the neck
• Fractures of the neck will often tear the vessels and so hinder healing of the fracture

Question 25

What is the function of the relationship between the femur and acetabulum?

Answer 25

Important for stability and mobility of the hip joint

Question 26

What are 2 features of the femoral neck and shaft that are important for function?

Answer 26

1. The neck-to-shaft angle (frontal plane) 2. The angle of anteversion (transverse plane)

Question 27

Describe the inclination of the shaft of the femur:

Answer 27

* Inclines downward and inward * The shaft makes an angle of about 10° with the vertical line dropped from the head of the femur

Question 28

Why does the femur have this inclination?

Answer 28

* Greater width of body at the hips than at the knees (larger in women due to wider pelvis) * Femur is angled so the condyles are aligned at the knee joint (as the medial condyle projects further distally than lateral)

Question 29

Where is the neck-to-shaft angle?

Answer 29

Between the axis of the shaft of the femur and the axis of the head and neck

Question 30

What is the average neck-to-shaft angle in adults?

Answer 30

~135°, but this varies a little between individuals and males/females.

Question 31

What happens when the angle of inclination decreases (<125 degrees)?

Answer 31

Results in a condition known as coxa vara

Question 32

What happens when the angle of inclination increases (>125 degrees)?

Answer 32

Results in a condition known as coxa valga

Question 33

What is the angle of anteversion?

Answer 33

* Refers to the rotation of the neck and head of the femur in relation to the shaft * Measured in the transverse plane between the axis of the femoral neck and the axis of the femoral condyles * The angle is approximately 10-15°, but varies between individuals

Question 34

What happens if the angle of anteversion is greater than 10-15°?

Answer 34

Leads to internal rotation of the lower limb when walking - pigeon-toed

Question 35

What happens if the angle of anteversion is less than 10-15°?

Answer 35

Retroversion - tendency towards external rotation with gait

Question 36

On the anterior aspect of the femur, what bony structure runs between, or links the greater and lesser trochanters?

Answer 36

Intertrochanteric line (intertrochanteric crest is on posterior surface of femur)

Question 37

Where does ossification of the femur occur?

Answer 37

1. Shaft 2. Head 3. Greater trochanter 4. Less trochanter 5. Distal end