Analysis of skeletal movements in mandibular distraction osteogenesis.
OBJECTIVE
The purpose of this study was to use geometric parameters of movement, calculated from 3-dimensional computed tomography (CT) data, to determine the curvilinear distractor dimensions required to correct mandibular deformities in a series of patients.


METHODS
Preoperative CT scans from 15 patients with symmetric (n = 5) and asymmetric (n = 10) deformities were imported into a CT-based software program (Osteoplan; an open-source visualization application developed by Gering et al at the Surgical Planning Laboratory [SPL, Brigham and Womens Hospital, Boston, MA]). The software was used to reconstruct virtual 3-dimensional models from these scans. Two experienced surgeons, working with a computer scientist, then used Osteoplan to create an ideal treatment plan for each patient. In each case, the 3-dimensional curvilinear movement was quantified using 4 "parameters of movement" (POMs). These parameters were then used to prescribe a distraction device capable of executing the planned skeletal correction. Curvilinear distractor dimensions calculated by Osteoplan included the radius of curvature of the prescribed device, and the distractor elongation, pitch, and handedness.


RESULTS
Treatment plans including POMs were developed for each patient. The radii of curvature for the prescribed distractors ranged from 2.3 to 14.1 cm, the distractor elongation dimensions ranged from 0.7 to 3.2 cm, and the pitch (horizontal plane) dimensions ranged from 0.005 to 0.8 cm. Handedness was either a left (n = 12) or right (n = 8) turning helix.


CONCLUSIONS
The results of this study indicate that, using geometric parameters of movement calculated from 3-dimensional CT scans, curvilinear devices could be prescribed for correction of the range of skeletal deformities in this group of patients.
Yeshwant
Krishna
K
Department of Oral and Maxillofacial Surgery, Massachusetts General Hospital, Boston 02114, USA.
Seldin
Edward B
EB
Gateno
Jaime
J
Everett
Peter
P
White
Carl L
CL
Kikinis
Ron
R
Kaban
Leonard B
LB
Troulis
Maria J
MJ
D003198:Computer Simulation; D004867:Equipment Design; D005146:Facial Asymmetry / Q000601:surgery; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods; D021621:Imaging, Three-Dimensional / Q000379:methods*; D008334:Mandible / Q000601:surgery*; D008338:Mandibular Injuries / Q000601:surgery; D008342:Mandibulofacial Dysostosis / Q000601:surgery; D008433:Mathematics; D008953:Models, Anatomic; D009068:Movement; D019857:Osteogenesis, Distraction / Q000295:instrumentation / Q000379:methods*; D010027:Osteotomy; D010347:Patient Care Planning; D012399:Rotation; D012984:Software; D013813:Therapy, Computer-Assisted; D014057:Tomography, X-Ray Computed / Q000379:methods*; D014584:User-Computer Interface