Joints of the Hip Complex Flashcards
What is the hip bone a part of?
Pelvis
What are the three parts of the hip bone?
Ilium
Ischium
Pubis
What structure do the three parts of the hip bone form?
Acetabulum
When does the epiphysis at the acetabulum close?
Mid to late teens
What proportion do each of the parts of the hip bone contribute to the acetabulum?
Ilium = 2/5 Ischium = 2/5 Pubis = 1/5
Why is the rim of the acetabulum smooth?
Articular surface
What is the articular surface of the acetabulum called?
Lunate surface
What covers the lunate surface?
Hyaline cartilage
Is the acetabular notch smooth?
No
Which part of the acetabulum is weight bearing?
Lunate surface
What happens to the cartilage with age?
Thins > osteoarthritic changes
What rims the articular surface of the acetabulum?
Labrum
What is the labrum made of?
Fibrocartilage
What fills the acetabular notch, and the acetabulum medioinferiorly?
Transverse acetabular ligament
What does the ligament coming straight out of the acetabulum and transverse acetabular ligament attach to?
Head of femur
What fills the non-articular area of the acetabulum?
Fat pad
What is the common name for fat pads associated with joints?
Aversium fat pad
What is the relevance of the aversium fat pad of the acetabulum having a nerve and blood supply?
Can become entrapped
Can cause pain
What is the relationship between the head and neck of the femur?
Large hemispherical ball at end of long neck
Where do the muscles attach to the femur?
Trochanter
- Greater
- Lesser
Why does the femoral neck have thick cortical bone?
Large amount of force applied here
What is the ligament of the head of the femur called>
Ligamentum terres
Where at the femur does ligamentum terres attach?
Depression = fovea capitis
When is the curvature of the neck of the femur disrupted?
Fracture of neck of femur
When is the perpendicular angle between the long axis of the femur and a line between the greater trochanter and fovea capitis disrupted?
Disruption of head of femur
What is the orientation of the head and neck of the femur?
Medially and upwards
In which direction does the head of the femur pass?
Slightly anterior
Which part of the head of the femur lies outside and in front of the socket?
Anterior part
What protects the part of the head of the femur outside the acetabulum?
Psoas bursa
Where is the psoas bursa located?
Underneath psoas muscle
What does a waisted neck of the femur allow?
Larger range of movement in all planes without making contact with edges of acetabulum
Why is the cartilage thickest where the head of the femur articulates with the roof of the acetabulum?
Main weight bearing at head of femur
What does the thick layer of cortical bone at the head of the femur do?
Resist shearing forces
What does the medial bundle of trabecular bone do?
Resist weight bearing
What does the arcuate bundle of trabecular bone do?
Resist shearing force
What does the trabecular bone at the greater trochanter resist?
Pull of muscles like gluteus medius and minimus
Where is there a site of weakness in the neck of the femur, where the trabecular bone is not as dense?
Inferior aspect
What are some of the epiphyses of the femur?
Greater trochanter Lesser trochanter Head of femur Ischial tuberosity Inferior iliac spine Superior iliac spine
What muscle attaches at the ischial tuberosity?
Hamstrings
What muscle attaches at the anterior superior iliac spine?
Rectus femoris
How can the epiphyses be pulled away from the bone in childhood?
Strong forces applied via attached muscles
What is it called when the epiphysis pulls away from the bone?
Avulsion fracture
What is the orientation of the acetabulum?
Faces a little anteriorly from coronal plane
What is the relationship between the anterior and posterior rims of the acetabulum in an A-P x-ray?
Posterior rim more inferior than anterior rim
What is the angle between the head and neck of the femur called?
Neck-shaft angle = angle of inclination
How does the neck-shaft angle change from childhood?
Reduces
What are the variations in the neck-shaft angle called?
Reduced angle = coxa vara
increased angle = coxa valga
What is the angle of torsion between the head of the femur and the coronal plane?
12-15 degrees
Can also vary
What can be a detrimental consequence of a coxa vara?
Increases stress on femoral neck
Extreme forces can cause capital epiphysis to become dislodged > slip inferiorly
What is it called when the capital epiphysis is dislodged and slips inferiorly?
Slipped capital femoral epiphysis
Why is there a natural tendency to tilt backwards at the hip joint?
Centre of gravity passes behind joint
What resists posterior rotation at the hip joint?
Reinforcing ligaments at front of capsule
What is the position of greatest stability for the hip joint?
Close packed position
- Extension
- Abduction
- Medial rotation
What is a loose packed position?
Flexion
Adduction
Lateral rotation
Where does the capsule attach to the femur?
Base of neck
What are the three ligaments attaching to the capsule?
Ileofemoral = in front Pubofemoral = behind Ischiofemoral = behind
To where do the ligaments of the capsule extend?
Intertrochanteric line
From where does the ileofemoral ligament come?
Ilium
From where does the pubofemoral ligament come?
Pubis
From where does the ischiofemoral ligament come?
Ischium
How much force at the hip joint does the ileofemoral ligament provide?
60%
What does thee ileofemoral ligament do?
Prevents joint from rotating backwards
Where do the pubofemoral and ischiofemoral ligaments attach to the femur?
Blend with capsule only to greater trochanter
Why aren’t the pubofemoral and ischiofemoral ligaments as extensive as the ileofemoral ligament?
Allow more movement at joint
Why is the hip joint most stable in extension?
Primarily because of ileofemoral ligament > spiral and tightens with hip extension
What lines the inside of the ligamentous supports of the hip joint?
Zona obicularis = ring of fibres
What does the labrum of the hip joint do?
Bridges acetabular notch
Deepens socket > enhances stability
Increases surface area
What does the labrum of the hip joint become continuous with?
Transverse ligament
Where is the blood supply of the labrum of the hip joint?
Towards periphery > can potentially be repaired
When is the labrum of the hip joint commonly damaged?
Dislocation of hip
What is the function of the ligament of the head of the femur?
No supporting role
Large number of Golgi tendon organs > proprioception
Directs branch of obdurator artery into joint before epiphysis closes
When does the branch of the obdurator artery that travels with the ligament of the head of the femur regress?
When epiphysis closes = after puberty
What are the movements at the hip joint?
Flexion much greater than extension
Abduction greater than adduction
Medial rotation with extension > joint locked
Lateral rotation with flexion
What types of rotation occur at the hip joint during locomotion?
Medial rotation in early stance phase
Lateral rotation in swing phase
How is the hip joint linked with the knee joint?
Long powerful muscles including
- Sartorius
- Rectus femoris
- Hamstrings
What is the role of the muscles that link the hip and the knee?
Synchronisation of hip with knee
Injury to these muscles > loss of synchronicity
What are the gluteal muscles?
Gluteus maximus
Gluteus medius
Gluteus minimus
What does the gluteus maximus muscle do?
Terminal extension - important in sprinting
What do gluteus medius and minimus do?
Abduct hip
When one foot extends in gait, gluteus medius and minimus contract on supported side > strop trunk falling towards unsupported side
What happens when gluteus medius and minimus are injured?
Trendellenberg gait = classic gait where pelvis falls to unsupported side
Where are the outward rotators of the hip?
Run along line of femoral neck
Deep to gluteus maximus
From hip bone to region around greater trochanter
What do the outward rotators of the hip do?
Stabilise head of femur in acetabulum
Act like rotator cuff muscles of arm
What is the nerve supply to the hip joint?
Articular branches of
- Femoral nerve
- Obdurator nerve
- Gluteal nerve
Where is pain from the hip referred to?
Medial aspect of thigh via obdurator nerve
Where is pain to the hip referred from?
Lumbar spine, particularly upper lumbar segments
What is the blood supply of the hip joint?
Medial and lateral femoral circumflex arteries
Anastomose around neck of femur
What is the articular circle formed by the anastomosis around the neck of the femur called?
Vascular arteriosus
What are the medial and lateral femoral circumflex arteries branches of?
Profunda femoris
Variation - might get one/both coming from common femoral artery
How does the blood supply extend into the capsule of the hip joint?
Retinacular vessels from anastomosis around neck of femur travel longitudinally up head of femur into capsule
When are the retinacular vessels susceptible to damage?
Fractures of neck of femur
What do you do surgically if there is serious injury to the blood vessels of the hip joint?
Only option may be to remove head of femur/put in pins to hold head to femoral neck > commonly causes problems distal to attachment of pins though
Where is the location of the femoral artery in relation to the hip joint?
Between anterior superior iliac crest and pubic tubercle
Bisects inguinal ligamnt
Passes over psoas
Where is the sciatic nerve in relation to the hip joint?
Behind, just inferior to head of femur
When may the sciatic nerve be endangered by the hip joint?
Head of femur dislocates posteriorly
Why must the head of the femur be re-articulated within hours in a posterior dislocation?
Risk of avascular necrosis
In whom is congenital dislocation of the hip more common: males or females?
Females
How can congenital dislocation of the hip occur?
Little movement in utero > fixation of joint > flattening of actabulum > developmental dysplasia
