n tips & techniques Tactile Surgical Navigation System for Complex Acetabular Fracture Surgery Takahiro Niikura, MD; Maki Sugimoto, MD; Sang Yang Lee, MD; Yoshitada Sakai, MD; Kotaro Nishida, MD; Ryosuke Kuroda, MD; Masahiro Kurosaka, MD understanding of fracture pat- CT scans can be converted into Abstract: The authors describe a tactile surgical navigation terns is difficult because of the 3D data, which can then be system using custom 3-dimensional (3D) models of the bony complex 3-dimensional (3D) used to manufacture life-size pelvis for complex acetabular fracture surgery. The bone anatomy of the pelvis and ac- 3D models of the bony pelvis area of interest was extracted from the Digital Imaging and etabulum, and assessment and using a 3D printer. Application Communications in Medicine (DICOM) data of computed classification of acetabular of such computer-aided design tomography scans. A standard triangulated language file was fractures can be difficult even and rapid prototyping to the used to create 3D models of the bony pelvis by layered manu- for experienced surgeons. field of orthopedics has been facturing using a 3D printer and non-cytotoxic, sterilizable, Improved understanding of reported in trauma, compli- acrylic-based photopolymers. No infections and no toxic or the anatomy and fracture pat- cated fractures, hand surgery, other adverse events were observed. The models were useful terns should improve surgical and osteotomies to correct de- for preoperative assessment, planning, and simulation; intra- outcomes. Tools that could formities.8-16 operative assessment; obtaining informed consent; and edu- assist in the assessment of Some previous reports cation. [Orthopedics. 2014; 37(4):237-242.] complicated fracture patterns have described using rapid would be useful. Traditional prototyping to manufacture radiological assessment of 3D models of the bony pelvis n acetabular fracture is are important for good func- acetabular fractures involves prior to surgery for acetabular Aan intra-articular frac- tional recovery.1-3,6 However, plain radiography (Figure 1) fractures.8,17-20 However, these ture of the hip joint, which is the anatomical complexity of and computed tomography models were for preoperative generally treated by open re- acetabular fractures makes (CT). However, these modali- use only. It is difficult for less duction and internal fixation them particularly challenging ties provide only 2-dimension- experienced surgeons, and if displaced.1-5 Anatomical and technically demanding al (2D) images of the complex even experienced surgeons, to reduction and stable fixation to treat surgically.7 Precise 3D anatomy. The 3D digital achieve precise intraoperative images reconstructed from CT understanding of acetabular data (Figure 2) can be rotated fracture patterns. Surgical The authors are from the Department of Orthopaedic Surgery (TN, SYL, and viewed from any angle, teams do not always consist YS, KN, RK, MK) and the Department of Gastroenterology (MS), Kobe Uni- versity Graduate School of Medicine, Kobe, Japan. but are still viewed as 2D im- of experienced surgeons, and The authors have no relevant financial relationships to disclose. ages on a flat screen. sharing information and com- Correspondence should be addressed to: Takahiro Niikura, MD, Depart- The design and manufac- municating effectively are ment of Orthopaedic Surgery, Kobe University Graduate School of Medicine, turing industries now use com- important to achieving good 7-5-1 Kusunoki-cho, Chuo-ku, Kobe 650-0017, Japan ([email protected] u.ac.jp). puter-aided design and rapid surgical results and educating Received: January 17, 2013; Accepted: September 5, 2013; Posted: April prototyping to manufacture 3D surgeons. 15, 2014. prototypes. Using this technol- The authors report the pre- doi: 10.3928/01477447-20140401-05 ogy and specialized software, operative and intraoperative APRIL 2014 | Volume 37 • Number 4 237 n tips & techniques Table Uses for the 3-Dimensional Models of the Bony Pelvis Preoperatively Assessment and understanding of the complex fracture pattern Figure 1: A plain radiograph provides Surgical planning and simulation only a 2-dimensional image of the Figure 2: A 3-dimensional digital im- Pre-bending of plates complex 3-dimensional anatomy. age reconstructed from computed Determining the appropriate screw trajectories and lengths tomography data is viewed on a flat Can be performed by the operating surgeon and assistant sur- screen. geons use of tactile 3D models of the Obtaining informed consent bony pelvis manufactured us- osirix-viewer.com), the bone Easily understood by patients and their families ing a 3D printer. They describe area of interest was extracted Intraoperatively the usefulness of these models from the DICOM data using Assessment of the fracture based on their experience and the surface rendering function Can be performed by the operating surgeon and assistant sur- previous reports. and converted to standard tri- geons angulated language or stereo- MATERIALS AND METHODS lithography (STL) data. The Postoperatively A preoperative 0.5-mm- STL data were imported into Educational tool for surgeons, other physicians, and medical students slice CT scan of the pelvis computer-aided design soft- Can be used as a library of various fracture types was obtained using a 64-row ware and processed using a multidetector-row CT scanner modeling operation to prevent (Aquilion; Toshiba Medical separation at the fracture site. Systems Corp, Otawara, Ja- The processed STL data were This inkjet printer uses acryl- not cytotoxic and can tolerate pan). After 3D reconstruction used to manufacture 3D mod- ic-based photopolymers (Full- gas sterilization. Polymers of the images (OsiriX; open- els of the bony pelvis using the Cure720 and VeroWhitePlus were layered in 16-µm-thick source Digital Imaging and layered manufacturing process FullCure835; Objet Japan) and slices using sliced data created Communications in Medicine on a 3D printer (Connex500; stiffens them via ultraviolet ir- from the imported STL data. A [DICOM] application, http:// Objet Japan, Chiba, Japan). radiation. These materials are mirror image of the contralat- Figure 3: Photographs of the model showing that the fracture can be viewed from multiple directions, and that the intra- articular surface can be visualized (same patient as in Figures 1 and 2). 238 ORTHOPEDICS | Healio.com/Orthopedics n tips & techniques A Figure 5: The life-size model of the mirror image of the contralateral un- injured pelvis is useful for determin- ing the appropriate lengths (A) and bending (B) of the plates. B Figure 4: The 3-dimensional model of the bony pelvis provides both visual and tactile information. Figure 7: Touching and viewing the model helps to assess the fracture intra- operatively. Figure 6: Discussion among surgeons using the 3-dimensional model, help- etabular fractures. Four of consent for inclusion in the ing to ensure that each surgeon has a similar understanding of the anatomy these patients had both anteri- study. of the fracture. or and posterior column frac- tures, and 1 had an anterior SURGICAL TECHNIQUES eral uninjured hemipelvis was This process was under- column fracture only. All pa- The custom-made models also prepared. taken for 5 patients with ac- tients gave written informed were used in the operative field APRIL 2014 | Volume 37 • Number 4 239 n tips & techniques 1-cm width could be built in 1 hour and a full-size pelvic model in 1 day. Postoperative CT assess- ments showed no screw pen- etration into the hip joints. Bone union was achieved in all cases with no loss of reduc- Figure 8: Both the bones and the implants can be modeled. The bones and Figure 9: Life-size hemi-pelvis and tion. All patients regained the metal are manufactured in different colors. reduced in size full-pelvis models. Using smaller models reduces costs. ability to walk. DISCUSSION to assess the fractures. An- The 3D models of the bony terior column fractures were pelvis were useful for gaining exposed via an ilioinguinal ap- a better understanding of many proach, and posterior column aspects of the complex acetab- fractures were exposed via the ular fractures (Table) preop- Kocher-Langenbeck approach. eratively, intraoperatively, and The fractures were surgically postoperatively. reduced and fixed using stan- The authors’ models were dard screws and reconstruc- useful for preoperative as- tion plates. sessment and understanding of complex fracture patterns, RESULTS surgical planning, and simu- Solid, durable models were lation. The models assisted successfully manufactured in surgeons in understanding the all cases. The models were gas anatomy of complex fractures, sterilized, and no infections which could be viewed from were observed after using multiple directions. Although them in the operative field. No the intraoperative view of the toxic or other adverse events intra-articular fracture surface were observed. was obscured by the femoral The 3D model has 3 axes: head, the intra-articular sur- x, y, and z. The accuracy of face was easily assessed us- the authors’ manufacturing ing the model (Figure 3). The process along the z axis was models provided both visual 16 µm, which was the thick- and tactile information for ness of each layer. The accura- the surgeons (Figure 4). The cy along the x axis and along life-size model of the mirror the y axis depended on the image of the contralateral un- accuracy of the printer head; injured pelvis was useful for they were approximately