Change in pelvic incidence between the supine and standing positions in patients with bilateral sacroiliac joint vacuum signs

Anthony L. Mikula, Jeremy L. Fogelson, Soliman Oushy, Zachariah W. Pinter, Pierce A. Peters, Kingsley Abode-Iyamah, Arjun S. Sebastian, Brett Freedman, Bradford L. Currier, David W. Polly, Benjamin D. Elder

Research output: Contribution to journalArticlepeer-review

Abstract

OBJECTIVE: Pelvic incidence (PI) is a commonly utilized spinopelvic parameter in the evaluation and treatment of patients with spinal deformity and is believed to be a fixed parameter. However, a fixed PI assumes that there is no motion across the sacroiliac (SI) joint, which has been disputed in recent literature. The objective of this study was to determine if patients with SI joint vacuum sign have a change in PI between the supine and standing positions.

METHODS: A retrospective chart review identified patients with a standing radiograph, supine radiograph, and CT scan encompassing the SI joints within a 6-month period. Patients were grouped according to their SI joints having either no vacuum sign, unilateral vacuum sign, or bilateral vacuum sign. PI was measured by two independent reviewers.

RESULTS: Seventy-three patients were identified with an average age of 66 years and a BMI of 30 kg/m2. Patients with bilateral SI joint vacuum sign (n = 27) had an average absolute change in PI of 7.2° (p < 0.0001) between the standing and supine positions compared to patients with unilateral SI joint vacuum sign (n = 20) who had a change of 5.2° (p = 0.0008), and patients without an SI joint vacuum sign (n = 26) who experienced a change of 4.1° (p = 0.74). ANOVA with post hoc Tukey test showed a statistically significant difference in the change in PI between patients with the bilateral SI joint vacuum sign and those without an SI joint vacuum sign (p = 0.023). The intraclass correlation coefficient between the two reviewers was 0.97 for standing PI and 0.96 for supine PI (p < 0.0001).

CONCLUSIONS: Patients with bilateral SI joint vacuum signs had a change in PI between the standing and supine positions, suggesting there may be increasing motion across the SI joint with significant joint degeneration.

Original languageEnglish (US)
Pages (from-to)617-622
Number of pages6
JournalJournal of Neurosurgery: Spine
Volume34
Issue number4
Early online dateJan 15 2021
DOIs
StatePublished - Apr 2021

Bibliographical note

Funding Information:
Dr. Fogelson reports being a consultant to Medtronic. Dr. Sebastian reports being a consultant to Johnson & Johnson. Dr. Currier reports receiving royalties from DePuy Synthes, Zimmer Biomet, and Wolters Kluwer, and receiving institutional support for a spine fellowship from AOSNA. Dr. Polly reports being a consultant to SI Bone and Globus; receiving royalties from Springer; and receiving support of non–study-related clinical or research effort from Medtronic and Mizuho. Dr. Elder reports receiving support of non–study-related clinical or research effort from SI Bone and being on the scientific advisory board of Injectsense.

Publisher Copyright:
© 2021 American Association of Neurological Surgeons. All rights reserved.

Keywords

  • Lumbar lordosis
  • Pelvic incidence
  • Sacral
  • Sacroiliac
  • Spinal deformity
  • Spinopelvic parameter
  • Vacuum sign

PubMed: MeSH publication types

  • Journal Article

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