Sacral Insufficiency Fracture
Honda Sign

• General considerations
  
  
• Normal sacrum almost never sustains an isolated fracture
• They usually occur associated with other pelvic fracture and imply a force frequently sufficient to injure pelvic organs
• Insufficiency and fatigue fractures are subgroups of stress fractures
• Insufficiency fractures are fractures in abnormal bone (e.g. osteoporosis) which undergoes normal stress
• Fatigue fractures are fractures in normal bone which undergoes abnormal stress (e.g. March fractures)
• In the sacrum, such fractures occur in
• Postmenopausal women with osteoporosis (more common after age 60)
• Long-term corticosteroid use
• Such as those with rheumatoid arthritis or collagen-vascular disease
• Those who have undergone radiation therapy to the pelvis
  
  
• Clinical findings
  
  
• Sudden onset of pain in lower back, hip or groin with no trauma
• Pain may be significant and disabling
  
  
• Imaging findings
  
  
• Conventional radiographs are usually normal
• Some may show vertical or horizontal sclerotic lines in sacrum sclerotic, or
• A break in one or more of the three normal arcuate lines that form the roves of the sacral foramina
• Difficult to see with overlying bowel gas and because the underlying bone is osteoporotic
• The fractures are usually better visualized using bone scintigraphy scans following the injection of  Technetium 99m HDP which demonstrate increased radiotracer uptake (hotter, whiter areas) in a pattern that has been called the “Honda sign” after the carmaker’s insignia or the “butterfly sign”
• The characteristic appearance is that of fracture lines running vertically through both the left and right sacral ala, medial to the SI joints, and a transverse fracture just below the level of the SI joints
• The fractures appear as a hot, geographic lesions confined to the sacrum and often have a characteristic "butterfly" or "Honda sign" appearance
• Sacral fractures may also be demonstrated by MRI or CT scan
• CT may have trouble in demonstrating fractures in the plane of the image (transverse fracture)
• Sacral insufficiency fractures may be associated with insufficiency fractures elsewhere, such as
• Pubic rami (strong association)
• Symphysis pubis
• Supra-acetabular region
• Femoral neck
• Tibia
• Calcaneus
• Sternum
• Ribs
  
  
• Treatment
  
  
• Conservative management
• Bed rest
• Pain medication
• Reduced weight-bearing
• Prognosis is good but complete healing may take many months (4-9 months)
• Protect patient from possible sacral decubiti