Anterior and Posterior Fusion for Large, Rigid Idiopathic Scoliosis: Does Implant Density Matter?

World Neurosurg. 2020 Feb;134:e37-e45. doi: 10.1016/j.wneu.2019.08.123. Epub 2019 Aug 28.


Background: Despite advancements in surgical techniques, controversy remains regarding the optimal implant density for the correction of idiopathic scoliosis. Recent evidence has suggested that equivalent radiographic and clinical outcomes can be achieved with lower implant densities for those with moderate curves and good flexibility. Among the experts, the consensus has continued that higher implant densities should be used for larger, stiffer curves. The purpose of the present study was to compare the radiographic results between high-implant density (HID) and low-implant density (LID) constructs in patients with large (>65°), rigid (<50% flexibility) curves who had undergone anterior release and posterior spinal fusion.

Methods: We reviewed the idiopathic scoliosis cases performed at a single institution from 2006 to 2014. Only those meeting the inclusion criteria were selected. The patients were divided into HID and LID groups. The postoperative radiographs were compared for coronal correction, thoracic kyphosis, pelvic tilt, lumbar lordosis, and sagittal vertical axis.

Results: A statistically significant improvement in coronal correction was detected in the HID group at all follow-up points (final follow-up: HID, 81.1% vs. LID, 70.4%; P = 0.01). When preoperative thoracic kyphosis was considered, no differences were found between the 2 groups. No differences were found in the other sagittal parameters.

Conclusion: In patients with large, rigid idiopathic scoliosis undergoing anterior release and posterior spinal fusion, a small, but statistically, significant improvement in the coronal Cobb angle was seen. It remains to be determined whether this small difference in radiographic correction will have any influence on the clinical outcome.

Keywords: Anchor density; Anterior release; Curves; Idiopathic scoliosis; Implant density; Rigid.

MeSH terms

  • Adolescent
  • Child
  • Female
  • Humans
  • Kyphosis / surgery*
  • Lumbar Vertebrae / surgery
  • Male
  • Prostheses and Implants* / adverse effects
  • Retrospective Studies
  • Scoliosis / surgery*
  • Spinal Fusion / methods
  • Thoracic Vertebrae / surgery*
  • Treatment Outcome