Development of a Virtual Surgical Planning (VSP) Algorithm for Delayed Osseous Maxillomandibular Reconstruction
John T. Stranix, MD1, Carrie S. Stern, MD2, Michael Rensberger, MS3, Ian Ganly, MD, PhD4, Jay O. Boyle, MD4, Robert J. Allen Jr., MD5, Joseph J. Disa, MD5, Peter G. Cordeiro, MD5, Evan S. Garfein, MD2, Evan Matros, MD5.
1Hansjorg Wyss Department of Plastic Surgery, New York University Langone Medical Center, New York, NY, USA, 2Department of Surgery, Division of Plastic and Reconstructive Surgery, Montefiore Medical Center, Albert Einstein College of Medicine, New York, NY, USA, 3Medical Modeling Inc., Golden, CO, USA, 4Division of Head and Neck Surgery, Memorial Sloan-Kettering Cancer Center, New York, NY, USA, 5Division of Plastic and Reconstructive Surgery, Memorial Sloan-Kettering Cancer Center, New York, NY, USA.
Purpose: Delayed maxillomandibular reconstructions are challenging because the position of remaining anatomy is distorted or no surgical specimen is available for measurement. To optimize outcomes following reconstruction of these complex defects an algorithm using novel VSP techniques was developed.
Methods: Delayed maxillomandibular reconstructions using VSP between 2009-2016 were identified at two medical centers. Demographics, modeling techniques, and surgical characteristics were analyzed.
Results: Sixteen reconstructions met inclusion criteria with a mean follow-up of 21 months. Mandibular defects were most common (81.2%), followed by maxilla (12.5%), and one combined defect(6.3%). Indications for reconstruction were osteoradionecrosis with displaced fracture(50.0%), tumor (37.5%) or trauma(12.5%). Three VSP techniques(Figure 1) were developed and used to facilitate delayed reconstruction: 1) patient-specific modeling using radiographs obtained prior to the defect(43.8%); 2) mirror imaging of the remaining contralateral normal anatomy(37.5%); 3) normative samples scaled to patient size(18.8%). Normative and mirrored reconstructions were always designed to restore normal anatomy; however, patient-specific data identified constraints necessitating non-anatomic reconstructions in 71% of cases. Complications: partial loss requiring a second fibula flap(1), complete flap failure(1), hardware exposure(3), infection(2), wound dehiscence(2), and sinus tract(2).
Conclusions: The current series of complex craniofacial defects was reliably reconstructed using a novel algorithm employing three different VSP techniques. The ability to preoperatively design reconstructions and precisely execute them in absence of normal anatomic landmarks demonstrates an added value of VSP beyond traditional techniques.
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