title: Plaster of Paris as an osteoconductive material for interbody vertebral fusion in mature sheep.
abstract: METHODS
  In adult female sheep, histologic and biomechanical criteria were used to determine whether the osteoconductive performance of plaster of paris would promote the incorporation of the tubular titanium mesh implants used for interbody vertebral fusions.
  
  
  OBJECTIVE
  To compare the osteogenicity of plaster of paris with that of autogenous iliac crest bone and bone marrow 6 months after they were loaded into tubular titanium mesh cages and implanted as L3-L5 bridges after L4 corpectomies.
  
  
  BACKGROUND
  One of the aims of surgery for vertebral pathology is to stabilize the spine by interbody fusions. The morbidity associated with the use of iliac crest autograft bone for fusion grafts prompted trials using plaster of paris as an osteoconductive substrate.
  
  
  METHODS
  The total volume of bone that invested the L3-L5 mesh cages after 6 months was quantitated by computed tomography scans. All specimens subsequently were cut into fusion mass segments for biomechanical testing in flexion, extension, compression, and torsion, and then embedded in plastic for sectioning and histomorphometry to determine the trabecular bone volume within the titanium mesh.
  
  
  RESULTS
  In each experimental model, implants of plaster of paris were the osteoconductive equal of autogenous iliac crest bone/marrow preparations. The volumes of bone formed around and within the titanium mesh were identical, and the tissues were biomechanically indistinguishable. A partial mechanism was determined by modifying the system for midshaft femoral defects.
  
  
  CONCLUSIONS
  In the sheep, a tubular titanium mesh packed with plaster of paris forms an osteoconductive conduit to achieve a biomechanically stable interbody lumbar vertebral fusion.
authors.affiliation: Department of Orthopaedic Surgery and Traumatology, University of Kriti Medical School, Greece.
authors.forename: A G
authors.initials: AG
authors.lastname: Hadjipavlou
authors.forename: J W
authors.initials: JW
authors.lastname: Simmons
authors.forename: J
authors.initials: J
authors.lastname: Yang
authors.forename: C L
authors.initials: CL
authors.lastname: Nicodemus
authors.forename: O
authors.initials: O
authors.lastname: Esch
authors.forename: D J
authors.initials: DJ
authors.lastname: Simmons
mesh_terms: D000818:Animals; D001696:Biomechanical Phenomena; D016025:Bone Transplantation; D002133:Calcium Sulfate; D005260:Female; D005269:Femur / Q000601:surgery; D016268:Internal Fixators; D008159:Lumbar Vertebrae / Q000601:surgery; D016348:Osseointegration / Q000502:physiology*; D010027:Osteotomy; D012756:Sheep; D013123:Spinal Fusion / Q000295:instrumentation* / Q000379:methods*; D018709:Statistics, Nonparametric; D014025:Titanium
chemical_list: D014025:Titanium; D002133:Calcium Sulfate