Relative pelvic version displays persistent compensatory measures with normalised sagittal vertical axis after deformity correction.


Cawley D. T. , Boissiere L., Yilgor C. , Larrieu D., Fujishiro T., Kieser D., ...More

Spine deformity, vol.9, pp.1449-1456, 2021 (Journal Indexed in ESCI) identifier identifier identifier

  • Publication Type: Article / Article
  • Volume: 9
  • Publication Date: 2021
  • Doi Number: 10.1007/s43390-021-00345-z
  • Title of Journal : Spine deformity
  • Page Numbers: pp.1449-1456
  • Keywords: Adult spinal deformity, Relative pelvic version, Sacral slope, Pelvic tilt, Spino-pelvic, Fusion, Sagittal vertical axis, Alignment, Kyphosis, Lumbar lordosis, PROXIMAL JUNCTIONAL KYPHOSIS, RADIOGRAPHIC PARAMETERS, ADULT, CLASSIFICATION, ALIGNMENT, SPINE, TILT

Abstract

Purpose A normal sagittal vertical axis (SVA) after spinal deformity correction can yield mechanical complications of up to 30%. Post-operative compensatory pelvic orientation can produce a normal SVA. We assess relative pelvic version (RPV), an individualised measure, for persistent post-operative compensatory measures. Methods Adult spinal deformity (ASD) patients who were treated operatively, with a normal SVA (< +/- 50 mm) at 6-week follow-up were included, who were then followed-up after 2 years. These only included patients with fusion of > 4 vertebrae extending to L5 or below. Six-week subgroups were made regarding pelvis orientation, relative pelvic version (RPV: anteversion, aligned, moderate or severe retroversion) with analysis of patient-related outcome measures (PROMs), complications and spino-pelvic sagittal parameters. Results At 6 weeks, 140 patients met the inclusion criteria, 5 (3.6%) patients had anteversion, 59 (42.1%) were aligned, 60 (42.9%) had moderate retroversion and 16 (11.4%) patients had severe retroversion. Follow-up after 2 years demonstrated increased RPV in all groups except the severe RPV group who were more likely to develop SVA > 50 mm. Complications occurred in all groups. Significant 2-year differences were observed between moderate and severe RPV for back pain and PROMs but not between other RPV groups. Conclusion Adult spinal deformity patients with a normal SVA after spino-pelvic instrumentation carry a significant risk of retroversion progression post-operatively, followed by increased positive sagittal balance. Relative pelvic version (RPV) measurements when categorised into anteversion, aligned, moderate retroversion and severe retroversion at 6 weeks were predictive of PROMs at 2 years.