title: Effects of low-intensity pulsed ultrasound on spinal pseudarthrosis created by nicotine administration: a model of lumbar posterolateral pseudarthrosis in rabbits.
abstract: OBJECTIVE
  Low-intensity pulsed ultrasound (US) can enhance spinal fusion and fracture healing; however, its effect on spinal pseudarthrosis has not been reported in the literature. We hypothesized that low-intensity pulsed US could overcome spinal pseudarthrosis created by nicotine administration.
  
  
  METHODS
  Thirty-two rabbits underwent posterolateral fusion with an iliac bone graft and nicotine administration. At 5 weeks, the spines were examined by computed tomography (CT) to determine the presence of pseudarthrosis. All rabbits with pseudarthrosis were randomly divided into groups A, B, C, and D according to treatment: no second graft, iliac autograft only, low-intensity pulsed US only, and iliac autograft and low-intensity pulsed US, respectively. At 10 weeks, the rabbits were euthanized, and the specimens were assessed with radiography, CT, manual palpation, and histologic analysis.
  
  
  RESULTS
  One rabbit was lost because of severe infection. Twenty-seven (87%) had pseudarthrosis on CT at 5 weeks. On manual palpation at 10 weeks, the fusion rates were 0%, 29%, 0%, and 57% in groups A, B, C, and D, respectively. Group D had highest radiographic scores (mean ± SD, 2.87 ± 0.92), and the difference was statistically significant compared to the other groups (P < .001). Computed tomography confirmed that group D had the most fused segments at 10 weeks. Histologic specimens from group D also showed the most mature bone formation inside the fusion mass.
  
  
  CONCLUSIONS
  Low-intensity pulsed US can enhance spinal fusion but cannot overcome spinal pseudarthrosis created by nicotine administration. Stopping nicotine consumption or administering a more powerful bone substitute might be an alternative method for overcoming spinal pseudarthrosis.
authors.affiliation: Department of Orthopedics, Musculoskeletal Research Center, Chang Gung Memorial Hospital, College of Medicine, Chang Gung University, Taoyuan, Taiwan. jcl1265@adm.cgmh.org.tw.
authors.forename: Jen-Chung
authors.initials: JC
authors.lastname: Liao
authors.affiliation: Department of Orthopedics, Musculoskeletal Research Center, Chang Gung Memorial Hospital, College of Medicine, Chang Gung University, Taoyuan, Taiwan.
authors.forename: Wen-Jer
authors.initials: WJ
authors.lastname: Chen
authors.affiliation: Department of Orthopedics, Musculoskeletal Research Center, Chang Gung Memorial Hospital, College of Medicine, Chang Gung University, Taoyuan, Taiwan.
authors.forename: Chi-Chien
authors.initials: CC
authors.lastname: Niu
authors.affiliation: Department of Orthopedics, Musculoskeletal Research Center, Chang Gung Memorial Hospital, College of Medicine, Chang Gung University, Taoyuan, Taiwan.
authors.forename: Lih-Hui
authors.initials: LH
authors.lastname: Chen
mesh_terms: D000818:Animals; D004195:Disease Models, Animal; D008159:Lumbar Vertebrae / Q000000981:diagnostic imaging* / Q000293:injuries*; D009538:Nicotine / Q000008:administration & dosage; D011542:Pseudarthrosis / Q000000981:diagnostic imaging*; D011817:Rabbits; D016103:Spinal Fractures / Q000000981:diagnostic imaging*; D000069453:Ultrasonic Waves; D014463:Ultrasonography
chemical_list: D009538:Nicotine
keywords: low-intensity pulsed ultrasound; musculoskeletal ultrasound; nicotine; pseudarthrosis; rabbits