title: A novel combined hemipelvic endoprosthesis for peri-acetabular tumours involving sacroiliac joint: a finite element study.
abstract: OBJECTIVE
  Our aim was to introduce a novel combined hemipelvic endoprosthesis for pelvic reconstruction after Enneking type I/II/IV resection and to evaluate the biomechanical properties of the endoprosthesis using finite element analysis.
  
  
  METHODS
  A three-dimensional finite element model of the postoperative pelvis was developed based on computed tomography (CT) images of the patient with the best post-operative limb function. A force of 400 N was applied along the longitudinal axis of the normal and post-operative pelvis for two positions: standing on two feet and sitting. Stress-distribution analysis was performed in both positions, and results were compared. Prosthesis improvements were simulated by intervertebral fusion and extra screw fixation.
  
  
  RESULTS
  In the normal pelvis, stress distributions were mostly concentrated on the superior area of the acetabulum, arcuate line, sacroiliac joint and sacral midline in both static conditions, and peak stresses of 1.52 MPa and 4.53 MPa were observed at the superior area of the greater sciatic notch and ischial tuberosity, respectively. For the reconstructed hemipelvis, stress distributions were concentrated on the connecting rods of the acetabular component and the proximal segment of the pedicle rods, and peak stresses of 252 MPa and 213 MPa were observed on the proximal pedicle rods of the fourth lumbar vertebra for standing and sitting, respectively. Interbody fusion of the fourth and fifth lumbar vertebrae and extra screw fixation to the sacrum decreased the peak stresses by 33.0 % and 18.3 % while standing and by 10.8 % and 6.6 % while sitting.
  
  
  CONCLUSIONS
  Reconstruction with combined hemipelvic endoprosthesis after types I/II/IV resection of the pelvis fulfilled physiological and biomechanical demands of the hemipelvis and yielded good biomechanical characteristics.
authors.affiliation: Department of Musculoskeletal Oncology, The First Affiliated Hospital of Sun Yat-Sen University, 58#,Zhongshan Road II, Guangzhou, Guangdong, China, 510080.
authors.forename: Bo
authors.initials: B
authors.lastname: Wang
authors.affiliation: Guangdong Provincial Medical Biomechanical Key Laboratory, Department of Anatomy, Southern Medical University, Tonghe, Guangzhou, Guangdong, China, 510515.
authors.forename: Peidong
authors.initials: P
authors.lastname: Sun
authors.affiliation: Department of Musculoskeletal Oncology, The First Affiliated Hospital of Sun Yat-Sen University, 58#,Zhongshan Road II, Guangzhou, Guangdong, China, 510080.
authors.forename: Xianbiao
authors.initials: X
authors.lastname: Xie
authors.affiliation: Guangdong Provincial Medical Biomechanical Key Laboratory, Department of Anatomy, Southern Medical University, Tonghe, Guangzhou, Guangdong, China, 510515.
authors.forename: Weidong
authors.initials: W
authors.lastname: Wu
authors.affiliation: Department of Musculoskeletal Oncology, The First Affiliated Hospital of Sun Yat-Sen University, 58#,Zhongshan Road II, Guangzhou, Guangdong, China, 510080.
authors.forename: Jian
authors.initials: J
authors.lastname: Tu
authors.affiliation: Guangdong Provincial Medical Biomechanical Key Laboratory, Department of Anatomy, Southern Medical University, Tonghe, Guangzhou, Guangdong, China, 510515. jouyang@126.com.
authors.forename: Jun
authors.initials: J
authors.lastname: Ouyang
authors.affiliation: Department of Musculoskeletal Oncology, The First Affiliated Hospital of Sun Yat-Sen University, 58#,Zhongshan Road II, Guangzhou, Guangdong, China, 510080. shenjingnan@126.com.
authors.forename: Jingnan
authors.initials: J
authors.lastname: Shen
mesh_terms: D000077:Acetabulum / Q000503:physiopathology / Q000601:surgery*; D000293:Adolescent; D000328:Adult; D001696:Biomechanical Phenomena; D001859:Bone Neoplasms / Q000503:physiopathology / Q000601:surgery*; D001863:Bone Screws; D003198:Computer Simulation; D005260:Female; D020342:Finite Element Analysis; D006801:Humans; D021621:Imaging, Three-Dimensional; D008297:Male; D008875:Middle Aged; D010384:Pelvic Bones / Q000503:physiopathology / Q000601:surgery*; D010386:Pelvic Neoplasms / Q000601:surgery; D010388:Pelvis / Q000601:surgery; D011474:Prosthesis Design; D019919:Prosthesis Implantation; D019651:Plastic Surgery Procedures; D012446:Sacroiliac Joint / Q000503:physiopathology / Q000601:surgery*; D012447:Sacrum / Q000503:physiopathology / Q000601:surgery; D013314:Stress, Mechanical; D014057:Tomography, X-Ray Computed; D055815:Young Adult
keywords: Biomechanics; Finite element analysis; Limb salvage; Pelvic tumour; Prosthetic reconstruction