Hip Flashcards
acetabulum composed of?
ilium, pubis, ischium; fused with triradiate cartilage
insertion site at greater/lesser trochanter apophyses
greater: gluteus medius, minimus, obturator internus/externus and piriformus
lesser: iliopsoas
classification system for acetabular fracture
Judet Letournel
intracapsular femoral fractures? extracapsular?
intracapasular: femoral head and neck fractures
extracapsular: intertrochanteric and subtrochanteric
complication of intracapsular fracture? blood supply
osteonecrosis due to injury to medial circumflex femoral arteries at femoral head; little blood supply from ligamentum teres
classification for femoral head fractures
Pipkin
association with femoral head fractures
posterior hip dislocations , AVN, post traumatic arthritis
categories of femoral neck fractures
subcapital, transcervical, basicervical
subcapital femoral neck fracture classification system
Garden classification
Garden classification
I: incomplete/impacted fracture; valgus
II: complete, nondisplaced; varus ~160
III: complete, partially displaced; varus < 160
IV: complete, displaced; head/neck/acetabulum aligned
intertrochanteric extracapsular fracture classification?
Boyd-Griffin and Evans classification for intertrochanteric fractures by orthopedics
subtrochanteric extracapsular fracture classification?
Fielding or Seinsheimer classifications by orthopedics; inferior/lesser trochanter
optimizing hip MRI with hardware
- low field strength, fast spin echo sequences (not GRE)
- increased receiver bandwidth (increase number of aquisitions/NEX, since noise increases)
- direct artifacts in superior/inferior plane so region medial/lateral to implant will not be obscured
- decrease voxel size (decrease slice thickness, increase matrix)
hip fracture on MRI
T1/2 hypointense; hyperintense edema on T2
Stress fracture types
fatigue: abnormal stress, normal bone
insufficiency: normal stress, demineralized/abnormal bone
Stress fracture imaging appearance (XR, MRI)
XR:band of sclerosis
MR: hypointense fracture line with hyperintense T2 bone marrow edema
common location for stress fracture in hip? atypical locations?
inferomedial femoral neck
superior femoral head fractures may also occur, indistinguishable from AVN
atypical: lateral/transverse femoral diaphyseal fracture (secondary to bisphosphonate use)
primary blood supply of the femur
medial femoral circumflex artery
traumatic AVN cause:
nontraumatic AVN cause:
traumatic: fracture in elderly, transient subluxation in athletes
nontraumatic: sickle cell disease, abnormal marrow packing (Gaucher disease), steroids, alcohol, immunosuppression; more likely to be bilateral
how can spleen help you narrow down cause of AVN?
splenomegaly: Gaucher
small calcified spleen: sickle cell
most common sites of AVN
proximal femur, second is the proximal humor
XR staging system for AVN hip
Ficat system, radiographic system
Stage 1: Normal radiograph, with signs of AVN visible on MRI (discussed below) or bone scan (reduced tracer uptake in the femoral head). Treatment is core femoral head drilling.
Stage 2: Cystic and sclerotic changes. Treatment is same as stage I.
Stage 3: There is loss of the normal spherical shape of the femoral had due to collapse of subchondral bone. A subchondral lucent line representing the crescent sign may be visible on radiographs. Treatment is variable.
Stage 4: Flattening of the femoral head and secondary osteoarthritis. Treatment is joint replacement.
MR classification for AVN hip
Mitchell system or modified Ficat system?
MR findings for AVN
geographic subchondral lesion with serpentine low signal rim (T1)
- anterior/superior portions
- 10 o’clock
- 2 o’clock
double line sign on T2WI with peripheral low intensity rim and inner high intensity band (pathognomonic)
include presence of collapse, size of T1 signal abnormality (percentage of femoral head), secondary involvement of acetebulum
