Breitaupt 1885
Normal bone - abnormal pressure (insufficiency fracture: abnormal bone, normal pressure)
Radiograph:
Sensitivity in early stage is as low as 15%, in late stages 50%
Cortical bone:
Common in shaft, usually oriented perpendicular to cortex
Early: Gray cortex sign = subtle ill definition of cortex, faint intracortical lucent striations, delicate linear periosteal reaction
Late: Periosteal new bone formation, endosteal thickening, true fracture line
Common bone - posterior shaft of tibia
Cancellous bone:
Very difficult to detect
Early: Subtle blurring of trabecular margins, faint sclerotic areas
Late: Sclerotic band
Common bones - calcaneus, proximal and distal tibia and fibula, femoral neck, pelvis
Radionuclide imaging:
Abnormal uptake is seen within 6-72 hours of injury
Sensitivity approaches 100%
Focal intense fusiform cortical uptake, if less intense (prefracture), termed as stress reaction
CT:
HRCT is useful
Cortical resorption cavity, localised geographic osteopenia
MR:
Normal radiograph with abnormal MR almost excludes bone tumor. The diagnosis is likely to be marrow edema syndromes or a stress fracture
More sensitive than scintigraphy
Low on T1 an high on T2, marrow edema, periosteal edema, multiple parallel straitions in the cortex, detached periosteum, thickened periosteum
MR grading:
1. Periosteal edema only
2. Marrow edema on STIR only
3. Marrow edema on STIR and T1
4. Visible fracture
Kiuru et al grading:
1. Endosteal edema
2. Periosteal and endosteal edema
3. Muscle, periosteal and endosteal edema
4. Fracture line
5. Callus formation
Radiological grading and treatment:
Gr 1: Normal plain film; Poorly defined increased uptake; positive STIR - 3 weeks rest
Gr 2: Normal plain film; Intense poorly defined increased uptake; positive STIR and T2WI - 3-6 weeks rest
Gr 3: Line or periosteal reaction on plain film; well defined increased uptake; positive T1 and T2WI without obvious fracture line - 12-16 weeks rest
Gr 4: Fracture or periosteal reaction on plain film; intense intracortical increased uptake; fracture line on MR - more than 16 weeks rest
References:
1. Anderson MW, Greenspan A. Stress fractures. Radiology 1996; 199:1-12
2. Datir AP et al. Stress-related bone injuries with emphasis on MRI.Clinical Radiology Volume 62 Pages 828-836
