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Application of additive manufacturing technology in orthopedic medical implant-Spinal surgery as an example
traditionally relied on imaging modalities including X-rays, et al. reported the previous use of the technology in
[2]
fluoroscopy, CT and MRI. Unfortunately, two-dimensional craniomaxillofacial surgery and undertook a preliminary
projections of radiographic images or three-dimensional prospective study of five complex cases to determine its
(3D) scan data will always be limited in their ability to usefulness in spine deformity surgery. Members of this
accurately display the complete image of 3D anatomic group continue to be at the forefront in this area, having
deformities, detracting from their value during the pre- published a number of other key papers in the field [3-5] .
operative planning process. As presented in the other papers These papers include a total of 51 cases where spine
in this article, the use of 3D modeling and rapid prototyping biomodels have been utilized, with the remaining four
(RP) or additive manufacturing has been increasingly papers in this field are from Japan and China, which
used in complex surgical pre-operative planning, as these describe 53 additional cases [6-9] . All the authors from
techniques can accurately reproduce the anatomic details these published articles agreed that a 3D reconstructed
of highly complex deformities that could be missed or model is required to obtain comprehensive information
misinterpreted with standard imaging modalities. about the complex spinal deformities that would have
The purpose of this article is to explore the existing been unavailable if conventional imaging modalities
uses of additive manufacturing in complex spinal surgery were exclusively used. They found that although CT
and to discuss the future potentials of this technology. 3D reconstruction could be displayed and viewed from
The common techniques and requirements for additive any direction and angle on the computer, these method
manufacturing are addressed elsewhere . Literature lack of tactile view which frequently view the biomodel
[1]
search was conducted using PubMed for articles separately and results in some alteration being made to
containing the terms “additive manufacturing”, “RP”, the surgical case, be it an implant, approach, or fixation
“biomodelling”, or “biomodeling”, and in combination related [6-9] .
with “spine/spinal” and “surgery/surgical planning”.
General reviews or discussions of this technology where 4. Complex Spinal Deformity Surgical
spinal usage is only briefly mentioned were not included. Planning

2. Method Literature findings concluded that the use of additively
manufactured biomodels offered numerous benefits
From the 16 articles that were found, one was excluded resulting in better surgical outcomes for the patients for
from further review as it is not available in English. example, Mizutani et al. fifteen cases were evaluated
[7]
Publication years ranged between 1999 and 2015, with and reported that 3D modeling was beneficial as a pre-
nearly half of the papers published in the past 5 years, operative planning tool in rheumatoid cervical spine
consistent with the rapidly increasing interest in this surgery. This was attributed to a better assessment of the
technology. Three key areas of focus are evident: trajectory and entry points of cervical pedicle screws,
Complex spinal deformity cases in which models have as well as allowing for the ability to determine the
been printed for surgical planning purposes; the design of entire plate-rod contours for occipitocervical junctions,
patient-specific drill guides; and the very recent advent of avoiding post-operative dysphagia. Although having
printing custom titanium implants. a 3D biomodel have advantages such as a detailed
Interestingly, there is a clear change in focus of the representation of anatomy and as a tool for planning
publications from 2009 to 2011 when simple printing for surgical procedures, the authors concluded that coupling
surgical planning was replaced by the printing of surgical the 3D model with computer-assisted navigation systems
tools and finally the implants themselves. Although likely provided better surgical results. Izatt et al. aim
[5]
publications on the use of additive manufacturing for to quantify the surgeon’s perception on the usefulness of
surgical planning have declined in numbers recently, biomodels compared with standard imaging modalities
the current usage rates remain unclear. Has the spinal as a pre-operative planning tool and as an intraoperative
surgical community adopted this as a routine technology, anatomic reference in 26 spinal tumor and deformity
or abandoned it in the past 10 years altogether? To better cases. This study entailed a survey completed by the
understand this shift, we conducted a survey of spinal surgeons after each surgical case and found that anatomic
surgeons attending the 2015 Annual Scientific Meeting details were better or exclusively visible on the biomodel
of the Spine Society of Australia and presented the results (65% and 11%, respectively) compared with the CT or
here. MRI 3D reconstructions. Therefore, different decisions

3. Historical Usage and Current Trends were made as a direct result of the biomodel regarding
the materials used (52%) and implantation sites (74%),
The use of additively manufactured models in complex thereby reducing the likelihood of surgical revision being
spine deformity surgical planning was first reported in required. Importantly, this paper also recorded an estimated
1999 by a group of researchers from Australia. D’Urso 17% decrease in operating time for all 26 patients, with

4 International Journal of Bioprinting (2019)–Volume 5, Issue 2