A Multicenter Radiographic Evaluation of the Rates of Preoperative and Postoperative Malalignment in Degenerative Spinal Fusions

Spine (Phila Pa 1976). 2018 Jul 1;43(13):E782-E789. doi: 10.1097/BRS.0000000000002500.


Study design: Multicenter, retrospective, institutional-review-board -approved study at 18 institutions in the United States with 24 treating investigators.

Objective: This study was designed to retrospectively assess the prevalence of spinopelvic malalignment in patients who underwent one- or two-level lumbar fusions for degenerative (nondeformity) indications and to assess the incidence of malalignment after fusion surgery as well as the rate of alignment preservation and/or correction in this population.

Summary of background data: Spinopelvic malalignment after lumbar fusion has been associated with lower postoperative health-related quality of life and elevated risk of adjacent segment failure. The prevalence of spinopelvic malalignment in short-segment degenerative lumbar fusion procedures from a large sample of patients is heretofore unreported and may lead to an under-appreciation of these factors in surgical planning and ultimate preservation or correction of alignment.

Methods: Lateral preoperative and postoperative lumbar radiographs were retrospectively acquired from 578 one- or two-level lumbar fusion patients and newly measured for lumbar lordosis (LL), pelvic incidence (PI), and pelvic tilt. Patients were categorized at preop and postop time points as aligned if PI-LL < 10° or malaligned if PI-LL≥10°. Patients were grouped into categories based on their alignment progression from pre- to postoperative, with preserved (aligned to aligned), restored (malaligned to aligned), not corrected (malaligned to malaligned), and worsened (aligned to malaligned) designations.

Results: Preoperatively, 173 (30%) patients exhibited malalignment. Postoperatively, 161 (28%) of patients were malaligned. Alignment was preserved in 63%, restored in 9%, not corrected in 21%, and worsened in 7% of patients.

Conclusion: This is the first multicenter study to evaluate the preoperative prevalence and postoperative incidence of spinopelvic malalignment in a large series of short-segment degenerative lumbar fusions, finding over 25% of patients out of alignment at both time points, suggesting that alignment preservation/restoration considerations should be incorporated into the decision-making of even degenerative lumbar spinal fusions.

Level of evidence: 3.

Publication types

  • Multicenter Study

MeSH terms

  • Female
  • Humans
  • Lumbar Vertebrae / diagnostic imaging
  • Lumbar Vertebrae / surgery
  • Male
  • Neurodegenerative Diseases / diagnostic imaging*
  • Neurodegenerative Diseases / epidemiology
  • Neurodegenerative Diseases / surgery*
  • Postoperative Complications / diagnostic imaging*
  • Postoperative Complications / epidemiology
  • Preoperative Care / methods
  • Preoperative Care / trends*
  • Retrospective Studies
  • Sacrum / diagnostic imaging
  • Sacrum / surgery
  • Spinal Fusion / adverse effects
  • Spinal Fusion / trends*