Flashcards in M: The pelvis and hip joint Deck (32):
How many bones is the pelvic girdle made up of, what are they?
Left and right innominate bones, sacrum
How many joints are found in the pelvic girdle?
3: 2 sacroiliac joints and the pubic symphysis joint
What is the name of the area where the 3 bones making up the innominate bone fuse?
What part of the pelvic girdle articulates with the head of the femur?
What 3 bones make up the innominate bone?
Ilium, ischium and pubic bones
What kind of joint is the hip joint?
Ball and socket synovial joint between the head of the femur and the acetabulum of the innominate bone
What 3 things provide stability to the hip joint?
1) Acetabular anatomy
2) Fibrous capsule
Describe the acetabulum?
Smooth crescent shaped articular surface called the lunate surface, this is deficient inferiorly and is called the acetabular notch, the acetabular notch is bridged by the transverse acetabular ligament
What bridges the acetabular notch?
Transverse acetabular ligament
What is the acetabular labrum, what is its function?
A rim/lip of cartilage
Deepens the articular surface improving stability
Describe the properties of the articular capsule of the hip joint?
Strong and dense but still loose to allow the range of movement of the hip joint
What are the attachments of the articular capsule of the hip joint?
Proximal - encircles rim of the acetabulum
Distal - femoral neck - intertrochanteric line and greater trochanter
What 3 ligaments surround the hip joint and how do they improve stability?
Iliofemoral, pubofemoral, ischiofemoral
Spiral around the hip joint, taut when the hip is extended, pull the femoral head into the acetabulum, improves stability
Where does the iliofemoral ligament lie?
covers the hip joint superiorly and anteriorly, from the anterior inferior iliac spine to the femur
What role does the iliofemoral ligament play in improving stability?
Strongest ligament. prevents hyperextension of the hip during standing, 'screws in' the femoral head
Where does the pubofemoral ligament ligament lie?
Covers the hip joint inferiorly and anteriorly
From the iliopubic eminence to the femur
What role does the pubofemoral ligament play in improving stability?
Prevents excessive abduction
Where does the ischiofemoral ligament lie?
Covers hip joint posteriorly
Which is the weakest of the 3 ligaments surrounding the hip joint?
Give 2 possible pelvic ring fractures?
1) Pubic rami fracture
2) Open book pelvic fracture - the 2 pubic bones no longer attached, large gap inbetween, unlikely to be an isolated fracture
What is meant by #NOF?
Fractured neck of femur ('hip fracture')
What is particularly worrying about fractures to the pelvic ring?
The pelvis can hold lots of blood - cant see this internal bleeding
What are the 3 possible hip dislocations?
1) Posterior dislocation
2) Anterior dislocation
3) Medial dislocation/acetabular fracture
How does the limb appear in a posterior dislocation of the hip?
Shortened and internally rotated
Posterior dislocation occurs from impact when the lower limb is in what position?
Flexed, internally rotated, adducted
What are the possible associated problems in a posterior dislocation of the hip?
Damage to the sciatic nerve
May be associated with acetabular fracture
Anterior dislocation tends occur when?
When force is applied during extreme abduction with external rotation of the hip, the femoral head is levered out anteriorly
How does the limb appear in an anterior dislocation?
Externally rotated, abducted and flexed
How may dislocations of the hip affect the blood supply and what are the possible consequences?
Blood vessels may be torn or stretched
Some branches may remain kinked or compressed until the hip is reduced, lack of blood supply leads to avascular necrosis of femoral head
What is developmental displacement of the hip?
Congenital abnormality, of varying severity. Can have slight subluxation (femur not in contact with all of acetabulum), low dislocation (femoral head only just not in contact with acetabulum) or high dislocation (femoral head completely above acetabulum)
How is developmental displacement of the hip treated?
Child is placed in a cast which holds the lower limb abducted which levers the femoral head back into position in the acetabulum