Three-dimensional printed surgical templates for fresh cadaveric osteochondral allograft surgery with dimension verification by multivariate computed tomography analysis.

Abstract

BACKGROUND\nThe fit of the allograft is a particular concern in fresh cadaveric osteochondral allograft (FOCA) surgery. Digital design and fabrication were utilized in conjunction with traditional surgery to enable efficient discovery and reproduction of appropriately dimensioned allograft.\n\n\nMETHODS\nA patient with large osteochondral defects in the lateral femoral condyle was to undergo FOCA surgery. A digital virtual operation was performed, based on computed tomography (CT) images of the patient. Polyamide saw templates were manufactured using a selective laser sintering process, and gypsum powder was used to manufacture preoperative and intraoperative medical models with binder jetting process. The design dimensions were verified numerically by determining the intactness of the section surface and allograft volume based on four independent measurements of the initial design, and an automated design optimization strategy was postulated. For the surgery, a lateral longitudinal approach was employed.\n\n\nRESULTS\nThe virtual operation allowed an efficient design of the saw templates. Their shape and dimensions were verified with a numerical CT analysis method. The allograft dimensions (medial-lateral/superior-inferior/anterior-posterior) were approximately 40/28.5/24\u202fmm, respectively, with the anterosuperior corner diagonally removed, yielding a section volume of approximately 16.5\u202fcm3. These manually chosen dimensions were reminiscent of the corresponding computationally optimized values.\n\n\nCONCLUSIONS\nUse of computer-aided design in virtual operation planning and three-dimensional printing in the fabrication of designed templates allowed for an efficient FOCA procedure and accurate allograft fitting. The numerical optimization method allowed for a semiautomated design process, which could in turn be realized also with surgical navigation or robotic surgery methods.