title: Does Level of Response to SI Joint Block Predict Response to SI Joint Fusion?
abstract: BACKGROUND
  The degree of pain relief required to diagnose sacroiliac joint (SIJ) dysfunction following a diagnostic SIJ block (SIJB) is not known. No gold standard exists. Response to definitive (i.e., accepted as effective) treatment might be a reference standard.
  
  
  METHODS
  Subgroup analysis of 320 subjects enrolled in two prospective multicenter trials evaluating SIJ fusion (SIJF) in patients with SIJ dysfunction diagnosed by history, physical exam and standardized diagnostic SIJB. A 50% reduction in pain at 30 or 60 minutes following SIJB was considered confirmatory. The absolute and percentage improvements in Visual Analog Scale (VAS) SIJ pain and Oswestry Disability Index (ODI) scores at 6 and 12 months after SIJF were correlated with the average acute improvement in SIJ pain with SIJB.
  
  
  RESULTS
  The average pain reduction during the first hour after SIJB was 79.3%. Six months after SIJF, the overall mean VAS SIJ pain reduction was 50.9 points (0-100 scale) and the mean ODI reduction was 24.6 points. Reductions at 12 months after SIJF were similar. Examined in multiple ways, improvements in SIJ pain and ODI at 6 and 12 months did not correlate with SIJB findings.
  
  
  CONCLUSIONS
  The degree of pain improvement during SIJB did not predict improvements in pain or ODI scores after SIJF. A 50% SIJB threshold resulted in excellent post-SIJF responses. Using overly stringent selection criteria (i.e. 75%) to qualify patients for SIJF has no basis in evidence and would withhold a beneficial procedure from a substantial number of patients with SIJ dysfunction.
  
  
  METHODS
  Level 1.
  
  
  CONCLUSIONS
  The degree of pain improvement during an SIJ block does not predict the degree of pain improvement after SIJ fusion.
authors.affiliation: Departments of Orthopedic Surgery and Neurosurgery, University of Minnesota, Minneapolis, MN.
authors.forename: David
authors.initials: D
authors.lastname: Polly
authors.affiliation: SI-BONE, Inc., San Jose, CA.
authors.forename: Daniel
authors.initials: D
authors.lastname: Cher
authors.affiliation: Department of Orthopaedics and Rehabilitation, Yale University School of Medicine, New Haven CT.
authors.forename: Peter G
authors.initials: PG
authors.lastname: Whang
authors.affiliation: Integrated Spine Care, Wauwatosa, WI.
authors.forename: Clay
authors.initials: C
authors.lastname: Frank
authors.affiliation: Department of Orthopaedic Surgery, University of Minnesota, Minneapolis, MN.
authors.forename: Jonathan
authors.initials: J
authors.lastname: Sembrano
keywords: diagnostic sacroiliac joint block; risk factors; sacroiliac joint dysfunction; sacroiliac joint fusion