Lecture 24: Hip Joint Flashcards
at what joint do hip bones articulate with the sacrum?
sacroiliac joint
what is the name of the cartilage covering most of the articular surface of the acetabulum?
lunate surface
covers 2/3 of acetabulum
increases SA for articulation
(worn out in Osteosrthiritis)
what is located in the acetabular fossa?
-fat
-no cartilage
ligament that connects the acetabular fossa to the fovea of femoral head…
ligamentum teres
( has an artery that runs through it)
what artery does the artery of ligament of head branch off from?
obturator artery
what does the artery of ligament of head supply
head of femur
* Important in infant: supplying head of femur
* Reduced in size greatly in early teens
* In adult it provides very little - zero blood to
femoral head
can be damaged in fractures
function of ligamentum teres
sturdy structure that prevents hip dislocation( debated on )
transverse acetabular ligament : locatin, function
- Transverse Acetabular Ligament
(TAL) covers the acetabular notch
inferiorly where there is no cartilage - Helps suspend femoral head in
acetabulum - Important clinically to orient hip
replacements
* important in surgical placements clinically!
acetabular foramen: function
allows blood vessel of
ligamentum teres to come through
why is the axis of femoral neck is 125 degrees to long axis instead of just being straight 90?
allows a greater range of movement superiorly/abduction + maintains strength of the bone
-a lot of stress is put on the lower half of the femoral neck-> bone is thicker in the inferior part of the neck.
joint capsule of the hip: function, structure
- The hip has a very strong thick
joint capsule - Unlike the shoulder the hip is
designed to bear weight - Needs to be held together tightly
or will dislocate - The capsule is attached proximally
to the acetabulum and transverse
acetabular ligament and distally into
the intertrochateric line of the
femu
Some fibers run diagonally- increases strength of capsule + limits the amount of flexion & extension( allow more flexion than extension)
flexion of hip joint:
muscles( & myotomes)?
psoas major
iliacus
rectus femoris
sartorius
pectineus
TFL
myotomes: L2, L3
extension of hip joint:
muscles( & myotomes)
G.Maximus
Semitendinosis
Semimembranosis
Biceps femoris
Myotomes: L4, L5
Adduction of hip joint:
muscles( & myotomes)
Adductor longus
Adductor brevis
Adductor magnus
Pectineus
Gracilis
Myotomes: L4-S2
Abduction of the hip joint:
muscles( & myotomes)
G.Medius
G.Minimus
TFL
Myotomes: L4-S1
Describe the arterial supply to the hip
- The arteries supplying the hip joint
are the Medial and Lateral
Circumflex Arteries, which are
branches off the Profunda Femoris
Artery - The medial circumflex femoral
artery runs posteriorly; the lateral
circumflex femoral artery runs
anteriorly around the femoral neck
to form a lateral anastomosis - Also anastomose with gluteal
vessel anastomoses. Can supply the hip if inadequate supply from femoral artery.
arterial supply to the femoral head and neck
- Off the circumflex arteries come
the retinacular arteries, pierce the
capsule and run in the retinacular
folds of the synovial membrane and
run up into the femoral head - These retinacular vessels are crucial
for vascular supply to the femoral
head and neck
if these are damaged-> ischemia in the head
Hiltons law
a joint tends to be innervated by a branch of a motor nerve which also supplies a muscle extending and acting across the joint.
application of Hilton’s Law to hip joint
For hip joint:
the Femoral Nerve (iliacus ), the Obturator Nerve (medial compartment adductors)
and the Superior Gluteal Nerve (gluteus medius) and Nerve to Quadratus Femoris
(posteriorly)
Many nerves supply the hip joint:
Clinical application: problem with femoral nerve block that other nerves also supply the hip joint so not completely blocked. But femoral nerve block DOES block most of the pain.
what happens if femur fractures are not repaired?
- Bone is more sensitive to ischemia
than cartilage - Ischemic bone develops avascular
necrosis
the fractured side appers more translucent- osteoporotic. Probably due to the patient putting less weight on that leg due to pain.
Neck of femur fracture: mechanism of injury
- High energy in young patients
- low energy falls in older patients
- Esp. women with osteoporosis
- High Mortality (40 % by one year, 50-
60% at 2 years) Indicates high level of
frailty.
types of fracture(femoral head and neck)
group 1: risk of vessels being interrupted-> avascular necrosis
group 2: fracture line is distal to the blood supply-> lower risk of vessels being interrupted
type of fracture? How can it be repaired?
intertrochanteric fracture
less worried about blood supply being interrupted
type of fracture? How can it be repaired?
transcervical -risk of arteries being damaged
need to replace the head of femur( hemi or full arthroplasty.)
what can lead to neck of femur fractures?
Trauma, osteoporosis and tumour can all lead to fractures of the femoral neck
clinical importance: neck of femur fractures
- Trauma, osteoporosis and tumour can all lead to fractures of the
femoral neck - Depending on the location of the fracture the blood supply to the
head of the femur may be disrupted - A subcapital (under the head) fracture is most likely to disrupt the
blood supply to the head, while a more distal intertrochanteric
fracture usually leaves the vascular supply intact. - The choice of treatment depends on the head viability
what is the most common mechanism of hip dislocation?
The hip joint can dislocated anteriorly or posteriorly (90% posterior)
* The usual position for this to occur is with the hip flexed, adducted and
internally rotated (as when seated in a car)
* The femoral head then moves superiorly, resulting in a short, internally rotated leg.
posterior dislocation : causes, consequences
Causes:
- Car crashes
- Falls from height
- Sports injuries
Serious Injury!
- Soft tissue damage( disrupt the capsule)
- risk of avascular necrosis from
arterial damage
Somewhat common result
of hip replacement surgeries
Anterior Hip Joint Dislocation: causes, consequences
Causes:
- Forceful abduction with external
rotation of the thigh
- Car crashes
- Falls from height
- Sports injuries
Serious Injury!
- Soft tissue
damage
- risk of avascular necrosis from
arterial damage
