Rod Fracture After Apparently Solid Radiographic Fusion in Adult Spinal Deformity Patients

World Neurosurg. 2018 Sep:117:e530-e537. doi: 10.1016/j.wneu.2018.06.071. Epub 2018 Jun 19.


Background: Rod fracture occurs with delayed fusion or pseudarthrosis after adult spinal deformity (ASD) surgery. Rod fracture after apparent radiographic fusion has not been previously investigated.

Methods: Patients with ASD in a multicenter database were assessed for radiographic fusion by a committee of 3 spinal deformity surgeons. Fusions were rated as bilaterally fused (A), unilaterally fused (B), partially fused (C), or not fused (D). Patients with grade A or B fusion and 2-year follow-up were included. Patients with radiographic fusion were evaluated for subsequent rod fracture. Adjusted analyses were conducted with multiple logistic regression, using backwards-variable selection to a threshold of P < 0.2, to assess for associated factors.

Results: Of 402 patients with radiographically apparent solid fusion, 9.5% (38) subsequently suffered a broken rod. On multivariate analysis, greater rates of rod fracture were seen among patients of age group 60-69 years (vs. 18-49), body mass index 30-34 and 35+ (vs. <25), stainless-steel rods (vs. titanium), patients with rods ≤5.5 mm (vs. 6.35 mm), and patients with Charlson score 0 (vs. 3+). Of the 38 patients with rod fractures, 18 (47.4%) presented with worsened pain, and 8 (21.1%) required revision at minimum 2-year follow-up.

Conclusions: Rod fracture occurred in 9.5% of patients with apparently solid radiographic fusion after ASD surgery. Advanced age, obesity, small diameter rods (5.5 mm), osteotomy, and lower comorbidity burden were significantly associated with rod fracture. Nearly one-half of these patients noted worsening pain, and 21.1% required revision surgery. Instrumentation failure may occur and may be symptomatic even in the setting of apparent fusion on plain radiographs.

Keywords: ASD; Adult spinal deformity; Fusion; Pseudarthrosis; Rod Fracture.

Publication types

  • Multicenter Study

MeSH terms

  • Adolescent
  • Adult
  • Aged
  • Female
  • Follow-Up Studies
  • Humans
  • Internal Fixators*
  • Male
  • Middle Aged
  • Multivariate Analysis
  • Prosthesis Failure*
  • Reoperation
  • Scoliosis / diagnostic imaging
  • Scoliosis / surgery*
  • Spinal Fusion* / instrumentation
  • Spine / diagnostic imaging
  • Spine / surgery*
  • Young Adult