Three-dimensional-printed customized prosthesis for pubic defect: prosthesis design and surgical techniques

Yuqi Zhang,Li Min,Jie Wang,Yi Luo,Chongqi Tu,Hong Duan,Yong Zhou,Yitian Wang,Minxun Lu

doi:10.1186/s13018-020-01766-8

Abstract

BackgroundThis study is to describe the detailed design and surgical techniques of three-dimensional (3D)-printed customized prosthesis for pubic bone defect.Patients and methodsFive patients under type III resections were included in this study. Based on radiography data, 3D pelvic model was established and virtual surgery was simulated. Detailed anatomy data were measured including the size and arc of normal pubis, the size of residual bone in acetabular side. Different fixation ways were considered according to shape of defect. After features modification and porous structure design, prostheses were fabricated. The osteotomy guides and plastic models were used during surgery.ResultOf 5 cases, the prostheses consist of the type with stem (3, 60%) and the type without stem (2, 40%). Mean follow-up period was 13.6 months (range, 8-24 months). For partial pubis removed cases, the mean length and width of narrowest part of normal superior pubis were 13.19 mm (range, 12.51-14.12 mm) and 7.80 mm (range, 7.18-8.26 mm) respectively. Mean arc of normal pubis was 2.71 rad (range, 2.66-2.73 rad). For the entire pubis resection cases, the mean diameter of narrowest parts and length of normal superior pubis were 11.52 mm (range, 11.13-11.91 mm) and 64.78 mm (range, 63.46-66.09 mm), while the diameter of narrowest part and length of normal inferior pubis were 7.37 mm (range, 7.20-7.54 mm) and 86.43 mm (range, 84.28-88.57 mm). Mean length and arc of intramedullary stem was 20 mm (range, 18-21 mm) and 2.7 rad. Mean screw holes number was 6.3 (range, 6-7) while ultimate screws number in surgeries was 4.3 (range, 4-5). Porous structure with 600-μm-pore size and 70% porosity was applied in parts of contact with residual bone.Conclusion3D-printed customized prostheses could be a feasible option to reconstruct bone defect after type III resection. The design of 3D-printed customized prostheses is a multi-step process which is based on strict anatomic measurement.

Highlights

This study is to describe the detailed design and surgical techniques of three-dimensional (3D)printed customized prosthesis for pubic bone defect
The design of Three dimensional (3D)-printed customized prostheses is a multi-step process which is based on strict anatomic measurement
According to Tile [10], the anterior pelvic ring structure accounts for 40% of the stability of the entire pelvic ring, and the posterior ring structure accounts for 60%

Summary

Introduction

This study is to describe the detailed design and surgical techniques of three-dimensional (3D)printed customized prosthesis for pubic bone defect. Pelvectomy and defect reconstruction after resection are common ways to treat pelvic tumors. Both resection and construction are challenging for surgeons due to the complexity and irregularity of pelvis. According to Enneking’s classification of pelvectomy [1], the type III resection refers to the partial removal of the pubis or the pubis from the pubic symphysis to the lateral obturator. Partial defects involving region III were reconstructed, most pure type III resections were usually not reconstructed because the weight-bearing axis, which goes through the proximal femur, acetabulum, sciatic buttress, and spine, is preserved [4,5,6]. The integrity of the anterior pelvic ring should not be ignored, the continuity of the weight-bearing axis was preserved. Reconstruction after type III resection is accepted by more and more people

Results

Discussion

Conclusion