summary Sacral Agenesis is a congenital condition associated with caudal regression syndrome characterized by the partial or complete absence of sacrum and lower lumbar spine. Diagnosis is made clinically with prominence of the last vertebral segment and postural abnormalities. Treatment involves a multidisciplinary approach to address neurological, genitoturinary, and orthopedic manifestations Epidemiology Incidence 1 - 2.5 per 100,000 newborns Risk factors highly associated with maternal diabetes Etiology Pathophysiology neurologic involvement motor deficit corresponds to level protective sensation is usually intact login to view 2 more bullets Associated conditions caudal regression syndrome gastrointestinal disorders (imperforate anus) genitourinary disorders cardiovascular disorders lower extremity deformities progressive kyphosis Classification 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 Presentation Symptoms clinical presentation is based on the severity of disease Physical exam inspection prominence of the last vertebral segment login to view 1 more bullet postural abnormalities (e.g. sitting buddha) limb and joint contractures login to view 1 more bullet 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 Treatment Nonoperative physical therapy indications login to view 1 more bullet outcomes login to view 2 more bullets Operative spinal stabilization procedures indications login to view 1 more bullet outcomes login to view 2 more bullets limb amputation indication login to view 1 more bullet outcomes login to view 1 more bullet Complications