title: Novel radiopaque ultrahigh molecular weight polyethylene sublaminar wires in a growth-guidance system for the treatment of early-onset scoliosis: feasibility in a large animal study.
abstract: METHODS
  In vivo analysis in an ovine model.
  
  
  OBJECTIVE
  To evaluate the feasibility of radiopaque ultrahigh molecular weight polyethylene (UHMWPE) sublaminar wires in a growth-guidance spinal system by assessing stability, biocompatibility, and growth potential.
  
  
  BACKGROUND
  Several growth-guidance systems have been developed for the treatment of early-onset scoliosis. The use of gliding pedicle screws and metal sublaminar wires during these procedures can cause metal-on-metal debris formation and neurological deficits. Novel radiopaque UHMWPE wires are introduced to safely facilitate longitudinal growth and provide stability in a growth-guidance system for early-onset scoliosis.
  
  
  METHODS
  Twelve immature sheep received posterior segmental spinal instrumentation; pedicle screws were inserted at L5 and radiopaque UHMWPE (bismuth trioxide) wires were passed sublaminarly at each level between L3 and T12 and fixed to dual cobalt-chromium rods. Four age-matched animals that were not operated were evaluated to serve as a control group. Radiographs were obtained to measure growth of the instrumented segment. After 24 weeks, the animals were killed and the spines were harvested for histological evaluation and high-resolution peripheral quantitative computed tomographic analysis.
  
  
  RESULTS
  No neurological deficits occurred and all instrumentation remained stable. One animal died from an unknown cause. Substantial growth occurred in the instrumented segments (L5-T11) in the intervention group (27 ± 2 mm), which was not significantly different to the control group, (30 ± 4 mm, P = 0.42). High-resolution peripheral quantitative computed tomographic analysis clearly showed safe routing and fixation of the UHMWPE wires and instrumentation. Despite the noted growth, ectopic bone formation with the formation of bony bridges was observed in all animals. Histology revealed no evidence of chronic inflammation or wear debris.
  
  
  CONCLUSIONS
  This study shows the first results of radiopaque UHMWPE sublaminar wires as part of a growth-guidance spinal system. UHMWPE sublaminar wires facilitated near-normal longitudinal spinal growth. All instrumentation remained stable throughout follow-up; no wire breakage or loosening occurred and no adverse local-tissue response to these wires was observed.
  
  
  METHODS
  N/A.
authors.affiliation: *Department of Orthopaedic Surgery, CAPHRI School for Public Health and Primary Care, Maastricht University Medical Centre, the Netherlands †Department of Orthopaedic Surgery, St. Anna Hospital, Geldrop, the Netherlands; and ‡Department of Internal Medicine, Research School NUTRIM, Maastricht University Medical Centre, the Netherlands.
authors.forename: Rob
authors.initials: R
authors.lastname: Bogie
authors.forename: A K
authors.initials: AK
authors.lastname: Roth
authors.forename: S
authors.initials: S
authors.lastname: de Faber
authors.forename: J J A
authors.initials: JJ
authors.lastname: de Jong
authors.forename: T J M
authors.initials: TJ
authors.lastname: Welting
authors.forename: P C
authors.initials: PC
authors.lastname: Willems
authors.forename: J J
authors.initials: JJ
authors.lastname: Arts
authors.forename: L W
authors.initials: LW
authors.lastname: van Rhijn
mesh_terms: D000818:Animals; D001864:Bone Wires; D003287:Contrast Media / Q000737:chemistry*; D004195:Disease Models, Animal; D005240:Feasibility Studies; D021621:Imaging, Three-Dimensional; D011095:Polyethylenes / Q000737:chemistry*; D012600:Scoliosis / Q000000981:diagnostic imaging* / Q000601:surgery*; D012756:Sheep; D014057:Tomography, X-Ray Computed
chemical_list: D003287:Contrast Media; D011095:Polyethylenes; C111601:ultra-high molecular weight polyethylene