Sacral Agenesis

Topic updated on 10/26/14 8:38am
  • Condition characterized by partial or complete absence of sacrum and lower lumbar spine
  • Epidemiology
    • incidence
      • 1 - 2.5 per 100,000 newborns
    • risk factors
      • highly associated with maternal diabetes
  • Pathophysiology
    • neurologic involvement
      • motor deficit corresponds to level
      • protective sensation is usually intact
        • important in that there is a lesser rate of decubiti ulcers
        • this differentiate from myelodysplasia
  • Associated conditions
    • caudal regression syndrome
      • gastrointestinal disorders (imperforate anus)
      • genitourinary disorders
      • cardiovascular disorders
      • lower extremity deformities
      • progressive kyphosis
Renshaw Classification
Type I Partial or total unilateral sacral agenesis
Type II Partial sacral agenesis with a bilaterally symmetrical defect
Type III Ilium articulating with the sides of the lowest vertebra present
Type IV Caudal endplate of vertebra resting above fused ilia or an iliac amphiarthrosis   
  • Symptoms
    • clinical presentation is based on the severity of disease
  • Physical exam
    • inspection
      • prominence of the last vertebral segment
        • classic sign of buttock dimping 
      • postural abnormalities (e.g. sitting buddha )
      • limb and joint contractures
        • extended knees, flexed hips, and equinovarus feet.
    • motion
      • flexion and extension may occur at the junction of the spine rather than hips
    • neurovascular examination
      • motor and sensory deficits are common in severe disease
  • Nonoperative
    • physical therapy
      • indications
        • Renshaw type 1/2
      • outcomes
        • most become community ambulators
        • foot and knee deformities to be addressed
  • Operative
    • spinal stabilization procedures
      • indications
        • Renshaw type 3/4 with progressive kyphosis or scoliosis
      • outcomes
        • progressive kyphosis and/or scoliosis may develop between the spine and pelvis
        • child must use his or her hands to support the trunk, and therefore is unable to use his or her hands for other activities
    • limb amputation
      • indication
        • non-fuctional lower limb deformities
      • outcomes
        • better mobility 


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