Ohzono et al classified nontraumatic avascular necrosis of the femoral head based on changes seen on anteroposterior X-rays of the hip. The radiographic findings correlate with prognosis. The authors are from the Osaka University Medical School and the Japanese Investigation Committee for Avascular Necrosis of the Femoral Head.
The x-ray is taken while the patient is standing.
Parameters:
(1) presence of a line of demarcation
(2) flattening of the weight-bearing surface
(3) cystic lesion in the femoral head
|
X-ray Change |
Major Type |
|
line of demarcation present (bandlike sclerosis) |
Type 1 |
|
flattening of the weight-bearing surface with a line of demarcation or cystic change |
Type 2 |
|
cystic change in the femoral head |
Type 3 |
Type 1 is subdivided based on the location of the cephalad terminus of the line of demarcation, relative to the weight bearing surface of the acetabulum. The weight bearing surface of the acetabulum is an arc on the X-ray and is divided into thirds. The cephalad point for the line of demarcation in the femoral head is lined up with the arc.
|
Subtypes for Type 1 |
Cephalad Terminus for the Line of Demarcation |
|
Type 1A |
medial third of the weight bearing surface of acetabulum |
|
Type 1B |
middle third of the weight bearing surface of acetabulum |
|
Type 1C |
lateral third of the weight bearing surface of acetabulum |
Type 3 is divided based on the location of the cystic lesion.
|
Subtypes for Type 3 |
Location of Cystic Lesion |
|
Type 3A |
far from the weight-bearing surface (medial or anterior) |
|
Type 3B |
under the lateral weight bearing surface |
The radiographic type correlates with the risk of collapse.
|
Radiographic Type |
Percent Collapse |
|
Type 1A |
0% |
|
Type 1B |
19% |
|
Type 1C |
94% |
|
Type 2 |
100% |
|
Type 3A |
12% |
|
Type 3B |
100% |
Specialty: Surgery, orthopedic
ICD-10: ,
