Virtual Planning and Allograft Preparation Guided by Navigation for Reconstructive Oncologic Surgery: A Technical Report

JBJS Essent Surg Tech. 2017 Oct 11;7(4):e30. doi: 10.2106/JBJS.ST.17.00001. eCollection 2017 Dec 28.

Abstract

Introduction: Advanced virtual simulators can be used to accurately detect the best allograft according to size and shape.

Step 1 acquisition of medical images: Obtain a multislice CT scan and a magnetic resonance imaging (MRI) scan preoperatively for each patient; however, if the time between the scans and the surgery is >1 month, consider repeating the MRI because the size of the tumor may have changed during that time.

Step 2 select an allograft using virtual imaging to optimize size matching: Load DICOM images into a virtual simulation station (Windows 7 Service Pack 1, 64 bit, Intel Core i5/i7 or equivalent) and use mediCAS planning software (medicas3d.com) or equivalent (Materialise Mimics or Amira software [FEI]) for image segmentation and virtual simulation with STL (stereolithography) files.

Step 3 plan and outline the tumor margins on the preoperative imaging: Determine and outline the tumor margin on manually fused CT and MRI studies using the registration tool of the mediCAS planning software or equivalent (Materialise Mimics software.).

Step 4 plan and outline the same osteotomies on the allograft: Determine and outline the osteotomies between host and donor using the registration tool of the mediCAS planning software or equivalent (Materialise Mimics software.).

Step 5 assess the patient and allograft in a virtual scenario: Be sure to consider the disintegration of bone tissue that occurs during the osteotomy and corresponds to the thickness of the blade (approximately 1.5 mm).

Step 6 navigation settings: A tool of the mediCAS planning software allows the virtual preoperative planning (STL files) to be transferred to the surgical navigation format, DICOM files.

Step 7 patient and allograft intraoperative navigation: The tumor and allograft are resected using the navigated guidelines, which were previously planned with the virtual platform.

Results: The 3D virtual preoperative planning and surgical navigation software are tools designed to increase the accuracy of bone tumor resection and allograft reconstruction3.