7 Ischemic Changes
Avascular Necrosis of the Humeral Head
Definition
Demarcated area of necrotic bone marrow, spongiosa, and cortex in the humeral head
Pathology
Damaged vascularization (blood supply and drainage, vascular structures) impairs the oxygen supply and induces necrosis of the cellular structures
Staging
Stage 0:
– Histologically small marrow necroses, plasmostasis
Stage I:
– Reversible early stage
– Repair process
– Proliferation of fibrovascular tissue
Stage II:
– Irreversible early stage
– Insufficient repair mechanism with marginal sclerosis
Stage III:
– Subchondral fracture due to mechanical failure
– Collapse of subchondral bone
– Flattening of the humeral head
Stage IV:
– Secondary osteoarthritis
– Destructive changes
Causes:
Underlying diseases
– Gaucher disease
– Caisson disease
– Hemoglobinopathies (sickle cell anemia)
– Ionizing radiation
– Systemic lupus erythematosus
– Hypercorticoidism (corticosteroid therapy)
Risk factors
– Alcoholism
– Dyslipidosis
– Hyperuricemia
– Pancreatitis
– Pregnancy
Clinical Findings
Nonspecific pain
Diagnostic Evaluation
Recommended views
Anteroposterior (AP)
Axial
Possibly in internal and external rotation
Possibly “outlet view”
Findings
Stage 0/I: Normal findings
Stage II: Sclerotic rim, densities
Stage III: Flattening of the humeral head, crescent sign
Stage IV: Collapse
(→ Supplementary method)
Findings
Exclusion of associated changes:
– Effusion
– Tendon lesion
(→ Supplementary method)
Recommended protocol
Unenhanced axial sections
Bone window display
Findings
Stage 0/I: Normal findings
Stage II: Sclerotic demarcation of the lesion, irregular trabecular structure
Stage III: Fracture of the subchondral bone
Stage IV: Deformed humeral head
Indications
Staging
Quantification
Localization
Prognostic statements
Recommended sections
Coronal
Axial
Possibly sagittal
Recommended sequences
T1-weighted spin-echo (SE)
Turbo inversion recovery magnitude (TIRM) (or fast spin [echo] T2-weighted imaging [FS TT2 w])
Possibly application of contrast medium
Findings
Signal intensity of the necrosis:
– Type A: Isointense with fat (T1 weighting: hyperintense; T2 weighting: intermediate signal intensity; fast spin [echo] T2-weighted [FS T2]/short time inversion recovery [STIR]: low signal intensity)
– Type B: T1 weighting and T2 weighting: hyperintense, hemorrhage
– Type C: fluid-intense signal pattern, cystic components; T1 weighting hypointense, T2 weighting hyperintense
– Type D: Extensive fibrosis, sclerosis; T1 weighting and T2 weighting hypointense
Goals of Imaging
Determination of the extent of the necrosis
Presence of a subchondral or osteochondral fracture
Detection of an associated edema or effusion
Determination of secondary degenerative changes
Fig. 7.1 a, b 
Osteonecrosis, stage II
a Sagittal T1-weighted SE sequence. Along the convex surface, a lesion separated from the remaining humeral head by a small signal-void rim (intact osteochondral interface).
b Coronal T2-weighted turbo spin-echo (TSE) sequence. The lesion is demarcated by a thin hypointense rim (sclerotic rim). Hyperintense signal changes are apparent along the lesion (granulation tissue, thin arrow), as well as along the adjoining bone marrow (discrete edema, curved arrow).
Fig. 7.2 a–c 
Osteonecrosis, stage III
a Conventional radiograph: The humeral head shows a small lesion, which is partially demarcated by a discrete radiolucent rim (subchondral fracture, arrow).
b
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