title: Sacral insufficiency fractures following multilevel instrumented spinal fusion: case report.
abstract: METHODS
  Case series.
  
  
  OBJECTIVE
  To report a series of patients in whom sacral insufficiency fractures developed following multilevel spinal fusion with instrumentation.
  
  
  BACKGROUND
  Rigid spinal fusion with instrumentation results in abnormal distribution of forces in the spine. These forces have the potential to cause failure of adjacent segments, especially in older, osteopenic individuals. Sacral insufficiency fractures following lumbar-sacral fusion may be the result of these abnormal forces. However, this complication is not well described in the literature.
  
  
  METHODS
  Three patients who sustained sacral fractures after instrumented lumbar-sacral fusion performed for degenerative disease of the spine are discussed. History, physical examination findings, and radiographic features are presented, along with a brief review of the pertinent literature.
  
  
  RESULTS
  All 3 patients in our series started complaining of new-onset buttock pain a few weeks after their operative procedure. Radiographic examination revealed that they had transverse sacral fractures just below the fusion instrumentation. Nonoperative, conservative treatment was performed. At final follow-up, the fractures had healed completely and the patients' complaints had resolved.
  
  
  CONCLUSIONS
  Patients who complain of new-onset buttock pain following multilevel lumbar-sacral fusion with instrumentation should be evaluated for sacral insufficiency fractures, especially if they have been sitting for prolonged periods. Conservative treatment seems to be sufficient.
authors.affiliation: Department of Orthopedic Surgery, University of Pittsburgh Medical Center, Pittsburgh, PA, USA.
authors.forename: Mustafa H
authors.initials: MH
authors.lastname: Khan
authors.forename: Patrick N
authors.initials: PN
authors.lastname: Smith
authors.forename: James D
authors.initials: JD
authors.lastname: Kang
mesh_terms: D000368:Aged; D002081:Buttocks; D005260:Female; D017102:Fracture Healing; D006801:Humans; D016268:Internal Fixators / Q000009:adverse effects*; D008159:Lumbar Vertebrae / Q000601:surgery*; D008875:Middle Aged; D010146:Pain / Q000209:etiology; D011859:Radiography; D012447:Sacrum / Q000000981:diagnostic imaging / Q000293:injuries*; D013122:Spinal Diseases / Q000601:surgery*; D016103:Spinal Fractures / Q000150:complications / Q000209:etiology* / Q000503:physiopathology / Q000628:therapy; D013123:Spinal Fusion / Q000009:adverse effects*