title: Skeletal and soft tissue response to automated, continuous, curvilinear distraction osteogenesis.
abstract: OBJECTIVE
  To document the bone formation and soft tissue changes in response to automated, continuous, curvilinear distraction osteogenesis (DO) at rates greater than 1 mm/day in a minipig model.
  
  
  METHODS
  Two groups of Yucatan minipigs underwent automated, continuous, curvilinear DO of the right mandible: group A, 1.5 mm/day (n = 5); and group B, 3.0 mm/day (n = 5). Each minipig underwent 12 mm of distraction followed by 24 days of fixation. The distracted and contralateral mandibles were harvested at the end of fixation. The percentage of surface area (PSA) of the regenerate occupied by bone, fibrous tissue, cartilage, and hematoma was determined using computerized histomorphometric analysis. The control groups consisted of DO wounds distracted discontinuously at 1 mm/day and the nonoperated contralateral mandible. The ipsilateral and contralateral digastric muscles were harvested and stained for proliferating cell nuclear antigen (PCNA), myogenic differentiation-1 (MyoD), and paired Box 7 protein (PAX7).
  
  
  RESULTS
  All 10 minipigs completed the distraction and fixation period. The PSA occupied by bone was similar for groups A (PSA 64.36% ± 5.87%) and B (PSA 63.83% ± 3.37%) and the control group (1 mm/day; PSA 64.89% ± 0.56%) but was less than that on the nonoperated side (PSA 84.67% ± 0.86%). The PSA occupied by cartilage and hematoma in all groups was minimal (<1.1%). The digastric muscles had no abnormal tissue or inflammation, and PAX7, MyoD, and PCNA expression had returned to the baseline levels.
  
  
  CONCLUSIONS
  The results of the present study indicate that bone formation in response to automated, continuous, and curvilinear DO at a rate of 1.5 and 3.0 mm/day is nearly identical to that with discontinuous DO at 1 mm/day. In addition, no deleterious effects were found on the digastric muscles.
authors.affiliation: Assistant Professor, Department of Oral and Maxillofacial Surgery, Massachusetts General Hospital, Boston, MA. Electronic address: zpeacock@partners.org.
authors.forename: Zachary S
authors.initials: ZS
authors.lastname: Peacock
authors.affiliation: Masters Student, University of Massachusetts Boston; Research Fellow, Massachusetts General Hospital, Boston, MA.
authors.forename: Brad J
authors.initials: BJ
authors.lastname: Tricomi
authors.affiliation: Current Resident, Former Synthes/Craniomaxillofacial Student Research Fellow, Department of Oral and Maxillofacial Surgery, Massachusetts General Hospital, Boston, MA.
authors.forename: Matthew E
authors.initials: ME
authors.lastname: Lawler
authors.affiliation: Associate Professor, Department of Pathology, Massachusetts General Hospital, Boston, MA.
authors.forename: William C
authors.initials: WC
authors.lastname: Faquin
authors.affiliation: Principal Research Scientist, Physical Sciences, Inc, Andover, MA.
authors.forename: John C
authors.initials: JC
authors.lastname: Magill
authors.affiliation: Principal Scientist, Physical Sciences, Inc, Andover, MA.
authors.forename: Brian A
authors.initials: BA
authors.lastname: Murphy
authors.affiliation: Walter C. Guralnick Professor and Chairman, Department of Oral and Maxillofacial Surgery, Massachusetts General Hospital, Boston, MA.
authors.forename: Leonard B
authors.initials: LB
authors.lastname: Kaban
authors.affiliation: Associate Professor, Department of Oral and Maxillofacial Surgery, Massachusetts General Hospital, Boston, MA.
authors.forename: Maria J
authors.initials: MJ
authors.lastname: Troulis
mesh_terms: D000818:Animals; D015519:Bone Density / Q000502:physiology; D001861:Bone Regeneration / Q000502:physiology; D002356:Cartilage / Q000473:pathology; D003238:Connective Tissue / Q000473:pathology; D005260:Female; D006406:Hematoma / Q000473:pathology; D007091:Image Processing, Computer-Assisted / Q000379:methods; D008334:Mandible / Q000473:pathology / Q000601:surgery*; D023421:Models, Animal; D017570:MyoD Protein / Q000032:analysis; D009334:Neck Muscles / Q000473:pathology*; D010012:Osteogenesis / Q000502:physiology; D019857:Osteogenesis, Distraction / Q000379:methods*; D051763:PAX7 Transcription Factor / Q000032:analysis; D018809:Proliferating Cell Nuclear Antigen / Q000032:analysis; D013552:Swine; D013556:Swine, Miniature; D013997:Time Factors
chemical_list: D017570:MyoD Protein; C057363:MyoD1 myogenic differentiation protein; D051763:PAX7 Transcription Factor; D018809:Proliferating Cell Nuclear Antigen