The aim of this study is to outline the steps and techniques required to create a patient specific 3D printed guide for the accurate placement of the origin of the femoral tunnel for single bundle ACL reconstruction. Placements of the femoral tunnels for ACL reconstruction have changed over the years 1,2. Most recently there has been a trend towards placing the tunnels in a more anatomic position. There has been subsequent debate as to where this anatomic position should be 3. The problem with any attempt at consensus over the placement of an anatomic landmark is that each patient has some variation in their positioning and therefore a fixed point for all has compromise for all, as it is an average 4. Our aim was to attempt to make a cost effective and quick custom guide that could allow placement of the center of the patients’ newly created femoral tunnel in the mid position of their contralateral native ACL femoral footprint.Aim
Introduction
Many orthopaedic procedures require implants to be trialled before definitive implantation. Where this is required, the trials are provided in a set with the instrumentation. The most common scenario this is seen in during elective joint replacements. In Scotland (2007) the Scottish Executive ( Several implants which are commonly used within Glasgow Royal Infirmary and do not have trials were identified. These implants were then CT scanned within their sealed and sterile packaging without contamination. Digital 3D surface renders of the models were created using free open source software (OsiriX, MeshLab, NetFabb). These models were then processed in to a suitable format for 3D printing using laser sintering via a cloud 3D printing bureau ( The implants produced were accurate facsimiles of the original implant with dimensions within 0.7mm. The implants were cost effective, an example being a rim mesh was reproduced in polyamide PA220 plastic for £3.50 and in 316L stainless steel for £15. The models were produced within 10 days of scanning. The stainless steel trials were durable and suitable for reprocessing and resterilisation. The production of durable, low cost and functional implant trials all completed in department was successful. The cost of production of each implant is so low that it would be offset if just one incorrect implant was opened during a single procedure. With some of the implants tested, the trials would have paid for themselves 100 times. This is a simple and cost saving technique that would help reduce department funding and aid patient care.
3D printing an additive manufacturing technique, allowing for rapid prototyping in many industries. To date, medical applications have generally been within a research or industry environment, as the costs (expertise, software and equipment) have been prohibitive. We have established a means by which 3D printing of bones can be achieved quickly, cost-effectively and accurately from standard computer tomography (CT) digital imaging and communications in medicine (DICOM) data. CT DICOM data of a malunited forearm fracture were manipulated using open-source software (no cost) and a 3D model was produced by selective-laser-sintering. The entire process took 7 days (total cost £77). This process and the resultant model were then assessed for overall accuracy. This sequential methodology provides ready and economical access to a technology that is valuable for preoperative templating/rehearsal in complex 3D reconstructive cases.
Rapid prototyping (RP), especially useful in surgical specialities involving critical three-dimensional relationships, has recently become cheaper to access both in terms of file processing and commercially available printing resources. One potential problem has been the accuracy of models generated. We performed computed tomography on a cadaveric human patella followed by data conversion using open source software through to selective-laser-sintering of a polyamide model, to allow comparative morphometric measurements (bone No significant differences in the dimensional measurements could be demonstrated. These data provide us with optimism as to the accuracy of the technology, and the feasibility of using RP cheaply to generate appropriate models for operative rehearsal of intricate orthopaedic procedures.
