MR (magnetic resonance) is the only means to diagnose ultra-early (pre-symptomatic – stage 0 and I) and early (pre-collapse – stage II) stages and to make a correct diagnosis based on the size and location of the necrotic area. However, for the intermediate stage (differentiation between stage II and III), the most important subchondral fracture or crescentic sign needs to be diagnosed in combination with X-rays, CT and MR. The correct diagnosis and staging of ischemic necrosis of the femoral head is the key to choosing an individualized and effective treatment plan. The specific content of the staging is now told to the patients, if you have questions, you can communicate through my.
I. ARCO international staging of osteonecrosis (1992)
Stage 0: bone biopsy results are consistent with ischemic necrosis, but all other tests are normal.
Stage Ⅰ: positive bone scan or positive MR or both, depending on the site of femoral head involvement, the lesion is subdivided into medial, central and lateral.
ⅠA: femoral head involvement <15%;
ⅠB: femoral head involvement 15-30%;
ⅠC: femoral head involvement >30%
Stage II: abnormal radiographs (femoral head speckled manifestation, osteosclerosis, cyst formation and osteoporosis), no femur on radiographs and CT films
IIA: femoral head involvement <15%;
ⅡB: femoral head involvement 15-30%;
ⅡC: femoral head involvement >30%
Stage III: crescentic sign, depending on the location of femoral head involvement, the lesion can be subdivided into medial, central and lateral.
IIIA: crescentic sign <15%; or femoral head collapse >2mm;
IIIB: crescentic sign 15-30% or femoral head collapse 2-4mm;
ⅢC: crescentic sign >30% or femoral head collapse >4mm.
Stage IV: X-rays show flattening of the femoral head joint surface, narrowing of the joint space, sclerosis of the acetabulum, cystic changes and marginal bone redundancy.
Second, Ficat and Arlet stage (type)
Ficat and Arlet (1980) proposed the following staging according to the signs of bone and articular cartilage lesions on X-ray during ischemic necrosis and combined with functional examination, which can achieve early diagnosis for some people with symptoms and no X-ray signs.
Stage I: stiffness of hip pain, restricted movement, no special signs on X-ray, or mild unevenness of trabeculae, or speckled sparse areas, no change in epiphysis or joint space, this stage can also be called: stage 0 to l. This stage is suitable for comprehensive examination such as hemodynamics, radionuclide bone scan or marrow core biopsy.
Stage II: The entire femoral head shape and joint space are normal, which is further divided into three types according to the bone quality changes.
Type IIA (lax type): diffuse osteoporosis in the weight-bearing area;
Type IIB (sclerotic type): there is cystic change in the round ligament area of the femoral head with clear periphery, while the head shows uniform sclerotic changes, sometimes with more or less variable patchy sclerosis. This type may be the repair phase of osteonecrosis, and the prognosis is better than type II A and C.
Type II C (mixed type): the translucent and sclerotic areas are mixed, and the sclerotic area is often located at the cephalocervical junction;
Stage III: The continuity of the femoral head is broken, and on lateral or tomographic films, collapse or flattening of the head tip may be seen, which is evident at the contact edge with the acetabulum. The dead bone is confined to the corresponding area of compression, and the dead bone may be fractured and embedded. The crescentic sign appears, with cone-shaped subsidence of the dead bone.
Stage IV: further head necrosis, narrowing of the joint space and typical osteoarthritic changes, deformation of the roof of the socket to correspond to the flattened head, and change of the round joint to an oval shape. The joint is dysfunctional and only extension is retained, while abduction and rotation are completely lost.