Diagnostic criteria
I. Main criteria
1, clinical symptoms, signs and medical history: arthralgia mainly in the groin and hip and thigh areas, limited internal rotation of the hip joint, history of hip trauma, history of corticosteroid application, history of alcoholism.
2.X-ray changes: femoral head collapse without joint space narrowing; sclerotic zone with demarcation within the femoral head; subchondral bone with transverse X-ray zone (crescent sign, subchondral fracture).
3.Nuclear scan shows a cold zone in the hot zone within the femoral head.
4, T1-weighted phase of MRI of the femoral head shows banded low signal (banding type) or T2-weighted phase with double line sign.
5. Bone biopsy shows more than 50% osteocyte vacuolation sockets in the trabeculae, and involves multiple adjacent trabeculae with bone marrow necrosis.
Femoral head necrosis
Second, secondary criteria
1.X-ray shows collapse of the femoral head with narrowing of the joint space, cystic change or speckle sclerosis in the femoral head, and flattening of the external upper part of the femoral head.
2.Nucleotide bone scan shows cold or hot areas.
3, MRI shows a band type with homogeneous or heterogeneous low signal intensity without T1 phase.
The diagnosis can be confirmed if two or more major criteria are met. Meeting one major criterion, or the number of positive secondary criteria ≥ 4 (including at least one positive radiographic change), is likely to be diagnosed.
Key points of each diagnostic method
The diagnosis of femoral head necrosis can be made by asking medical history, clinical examination, X-ray radiography, magnetic resonance imaging (MRI), nuclear scan, computerized tomography (CT) and other methods.
1, clinical diagnosis should be carefully inquired into the medical history, including the history of hip trauma, application of corticosteroids, alcohol consumption or anemia, etc. The clinical symptoms should clarify the pain location, nature and relationship with weight-bearing, etc. The physical examination should include the rotational activity of the hip joint. Early clinical symptoms of femoral head necrosis are not typical, and internal rotation of the hip joint leading to pain is the most common symptom. After the femoral head collapses, the range of hip joint activities may be limited. Signs:Local deep pressure pain, pressure pain at the stop of the adductor muscle, and axial percussion pain may be positive in some patients. In the early stage, the hip joint pain, Thomas sign and 4-character test may be positive; in the late stage, the femoral head collapse, hip joint dislocation, Allis sign and single-leg independent test may be positive. Other signs include limited abduction, external rotation or internal rotation, shortening of the affected limb, muscle atrophy, and even signs of subluxation. If the hip joint is dislocated, the Nelaton line may be upwardly displaced, the base of Bryant’s triangle is less than 5 cm, and the Shenton line is discontinuous.
2.X-ray film is difficult to diagnose ONFH in early stage (stage 0 and I), but it can show positive changes in lesions above stage II, such as sclerotic zone, cystic changes on X-ray, and cystic changes on X-ray.
The X-ray can show positive changes for stage II lesions and above, such as sclerotic zone, cystic change, speckled sclerosis, subchondral fracture and femoral head collapse. It is recommended to take X-rays in the posterior-anterior position of both hips (orthogonal) and in the lateral frog position, the latter can show the changes of the necrotic area of the femoral head more clearly.
3.Nuclide scanNuclide scan has high sensitivity but low specificity in diagnosing early ONFH. The diagnosis can be confirmed by using 99Tc diphosphate scan if there is a cold area in the hot area. However, the simple nuclide concentration (hot zone) should be differentiated from other hip diseases. This test can be used to screen for lesions and to look for multi-site necrotic foci. Single photon emission tomography (SPECT) can enhance the sensitivity, but the specificity is still not high.
4, CT for stage II and III lesions, CT examination can clearly show the boundary, area, sclerotic zone, self-repair and subchondral bone of the necrotic foci, etc. CT shows the clarity and positive rate of subchondral fracture better than MRI and X-ray, and the addition of two-dimensional reconstruction can show the overall situation of the coronal position of the femoral head. CT scan helps to determine the lesion and select the treatment method.