Three-dimensional-printed custom-made hemipelvic endoprosthesis for primary malignancies involving acetabulum: the design solution and surgical techniques

Abstract

BackgroundThis study is to describe the detailed design and surgical techniques of three-dimensional (3D)-printed custom-made endoprosthesis for hemipelvic tumorous bone defect.MethodsAccording to the pelvic tumor resection classification by Enneking and Dunham, the hemipelvis is divided into three zones including the ilium (P1), acetabulum (P2), and pubis and ischium (P3). Thirteen patients were included in this study. Of these, P1 and P2 were involved in three cases, while P1, P2, and P3 were involved in 10. Based on radiography data, 3D pelvic model was rebuilt, and virtual surgery was simulated. Different fixation methods were applied according to residual bone volume. Parameters of the first sacral (S1) vestibule, second sacral (S2) vestibule, the narrowest zone of superior pubic medullary cavity (NPSPMC), and the resected surface of superior pubic medullary cavity (RSSPMC) were selectively measured in various fixation methods. Model overlapping, feature simplifying, and size controlling were three basic steps during design procedure. Volume proportion of porous structure was determined according to estimated weight of resected specimen. Acetabular location, anteversion, and inclination were modulated. Screw diameter, direction, and combination were considered. The osteotomy guides and plastic models were used during surgery.ResultsOf 13 cases, after P1 resection, endoprostheses were fixed to sacra (8; 61.5%), ilia (3; 23.1%), and both (2; 15.4%). After P3 resection, endoprostheses were fixed to residual acetabulum (3; 23.1%), and residual pubis by stem (8; 61.5%) or “cap-like” structure (2; 15.4%). Mean area of the S1 vestibule, S2 vestibule, RSSPMC, and PSPMC were 327.9 (222.2 to 400), 131.7 (102.6 to 163.6), 200.5 (103.8 to 333.2), and 79.8 mm2 (40.4 to 126.2), respectively. Porous structure with 600 μm pore size and 70% porosity accounted for 68.8% (53.0 to 86.0) of the whole endoprosthesis on average. Mean acetabular anteversion and inclination were designed as 23.2° (20 to 25) and 42.4° (40 to 45). Median numbers of screws designed in the S1 vestibule was 5 (IQR, 4 to 6), in the S2 vestibule was 1 (IQR, 1 to 2), in the ilium was 5 (IQR, 2 to 6), and in the pubis was 1 (IQR, 1 to 1), while screws designed in the ischium was all 2. Median number of screws inserted in the S1 vestibule was 4 (IQR, 3 to 4), in the S2 vestibule was 1 (IQR, 1 to 1), in the ilium was 3 (IQR, 1 to 5), in the pubis was 1 (IQR, 0 to 1), and in the ischium was 1 (IQR, 1 to 1).ConclusionsThis study firstly presents detailed design and related surgical techniques of 3D-printed custom-made hemipelvic endoprosthesis reconstruction. Osseointegration is critical for long-term outcome and requires three design elements including interface connection, porous structure, and initial stability achieved by precise matching and proper fixation methods.

Reconstruction of Bony Defects after Tumor Resection with 3D‐Printed Anatomically Conforming Pelvic Prostheses through a Novel Treatment Strategy

“…We carried out simulation and guided osteotomy according to the imaging data collected before operation. Application of a 3D-printed osteotomy guide achieves limited exposure and high accuracy and facilitates the desired osteotomy procedure, [ 19 , 20 ] aiding in precise prosthesis implantation. By using an osteotomy guide, secondary damage to adjacent vessels and nerves can be avoided [ 21 , 22 ].…”

Pelvic Chondrosarcoma Treated by En Bloc Resection with Patient-Specific Osteotomy Guides and Reimplantation of the Extracorporeally Irradiated Bone as an Osseocartilaginous Structural Orthotopic Autograft: A Report of Two Cases with Description of the Surgical Technique

“…Whenever possible, limb salvage surgery has become the treatment of choice as new surgical techniques and reconstruction strategies have been developed [ 16 , 17 ]. Massive allograft, custom-made endoprosthetic constructs [ 6 , 8 , 9 ] and off-the-shelf tumoral prosthesis can be used, alone or combined, in order to reconstruct the resected pelvic segment. Specific complications include aseptic loosening and inadequate soft tissue coverage [ 5 ], instability [ 1 ], infection, graft resorption, and nonunion [ 18 ].…”

“…Allograft prosthetic composite or purely endoprosthetic reconstructive options exist, with complications ranging from inadequate soft tissue coverage of the voluminous implants and high rates of aseptic loosening to implant or allograft fractures [ 5 ]. With the onset and rapid evolution of 3D printing technology, custom-made implants have been added as valuable options to the reconstructive armamentarium of the surgeon [ 6 – 9 ].…”

Design and Application of 3D Printing Based Personalised Pelvic Prostheses

“…Enhanced magnetic resonance imaging (MRI) data were obtained using a 3.0T magnetic resonance scanner (MAGNETOM Verio 3.0T; Siemens, Engelberg, Germany), and the data were exported in the DICOM format. Thin-slice CT pelvic scanning sequences and enhanced MRI pelvic T1weighted image sequences were selected and imported into SenseCare software (SenseTime, Beijing, China) for image registration to obtain the 3D reconstruction models of the pelvis and tumour [17] , which were exported as STL format files.…”