title: 3D Volumetric Modeling and Microvascular Reconstruction of Irradiated Lumbosacral Defects after Oncologic Resection.
abstract: BACKGROUND
  Locoregional flaps are sufficient in most sacral reconstructions. However, large sacral defects due to malignancy necessitate a different reconstructive approach, with local flaps compromised by radiation and regional flaps inadequate for broad surface areas or substantial volume obliteration. In this report, we present our experience using free muscle transfer for volumetric reconstruction, in such cases, and demonstrate three-dimensional (3D) haptic models of the sacral defect to aid preoperative planning.
  
  
  METHODS
  Five consecutive patients with irradiated sacral defects secondary to oncologic resections were included, surface area ranging from 143-600 cm2. Latissimus dorsi (LD)-based free flap sacral reconstruction was performed in each case, between 2005 and 2011. Where the superior gluteal artery was compromised, the subcostal artery (SA) was used as a recipient vessel. Microvascular technique, complications, and outcomes are reported. The use of volumetric analysis and 3D printing is also demonstrated, with imaging data converted to 3D images suitable for 3D printing with Osirix software (Pixmeo, Geneva, Switzerland). An office-based, desktop 3D printer was used to print 3D models of sacral defects, used to demonstrate surface area and contour and produce a volumetric print of the dead space needed for flap obliteration.
  
  
  RESULTS
  The clinical series of LD free flap reconstructions is presented, with successful transfer in all cases, and adequate soft-tissue cover and volume obliteration achieved. The original use of the SA as a recipient vessel was successfully achieved. All wounds healed uneventfully. 3D printing is also demonstrated as a useful tool for 3D evaluation of volume and dead space.
  
  
  CONCLUSIONS
  Free flaps offer unique benefits in sacral reconstruction where local tissue is compromised by irradiation and tumor recurrence, and dead space requires accurate volumetric reconstruction. We describe for the first time the use of the SA as a recipient in free flap sacral reconstruction. 3D printing of haptic bio-models is a rapidly evolving field with a substantial role in preoperative planning.
authors.affiliation: Department of Plastic and Reconstructive Surgery, Hospital de Guadalajara, Guadalajara, Spain; MD Anderson Cancer Center, Madrid, Spain.
authors.forename: Emilio
authors.initials: E
authors.lastname: Garcia-Tutor
authors.affiliation: Department of Plastic and Reconstructive Surgery, Hospital de Guadalajara , Guadalajara , Spain.
authors.forename: Marco
authors.initials: M
authors.lastname: Romeo
authors.affiliation: Department of Surgery, School of Clinical Science at Monash Health, Faculty of Medicine, Monash University, Monash Medical Centre, Clayton, VIC, Australia; Monash University Plastic and Reconstructive Surgery Unit (Peninsula Clinical School), Peninsula Health, Frankston, VIC, Australia.
authors.forename: Michael P
authors.initials: MP
authors.lastname: Chae
authors.affiliation: Department of Surgery, School of Clinical Science at Monash Health, Faculty of Medicine, Monash University, Monash Medical Centre, Clayton, VIC, Australia; Monash University Plastic and Reconstructive Surgery Unit (Peninsula Clinical School), Peninsula Health, Frankston, VIC, Australia.
authors.forename: David J
authors.initials: DJ
authors.lastname: Hunter-Smith
authors.affiliation: Department of Surgery, School of Clinical Science at Monash Health, Faculty of Medicine, Monash University, Monash Medical Centre, Clayton, VIC, Australia; Monash University Plastic and Reconstructive Surgery Unit (Peninsula Clinical School), Peninsula Health, Frankston, VIC, Australia.
authors.forename: Warren Matthew
authors.initials: WM
authors.lastname: Rozen
keywords: free flap; model; planning; preoperative imaging; volumetric analysis