title: Does the optimal position of the acetabular fragment should be within the radiological normal range for all developmental dysplasia of the hip? A patient-specific finite element analysis.
abstract: BACKGROUND
  The success of Bernese periacetabular osteotomy depends significantly on how extent the acetabular fragment can be corrected to its optimal position. This study was undertaken to investigate whether correcting the acetabular fragment into the so-called radiological "normal" range is the best choice for all developmental dysplasia of the hip with different severities of dysplasia from the biomechanical view? If not, is there any correlation between the biomechanically optimal position of the acetabular fragment and the severity of dysplasia?
  
  
  METHODS
  Four finite element models with different severities of dysplasia were developed. The virtual periacetabular osteotomy was performed with the acetabular fragment rotated anterolaterally to incremental center-edge angles; then, the contact area and pressure and von Mises stress in the cartilage were calculated at different correction angles.
  
  
  RESULTS
  The optimal position of the acetabular fragment for patients 1, 2, and 3 was when the acetabular fragment rotated 17° laterally (with the lateral center-edge angle of 36° and anterior center-edge angle of 58°; both were slightly larger than the "normal" range), 25° laterally following further 5° anterior rotation (with the lateral center-edge angle of 31° and anterior center-edge angle of 51°; both were within the "normal" range), and 30° laterally following further 10° anterior rotation (with the lateral center-edge angle of 25° and anterior center-edge angle of 40°; both were less than the "normal" range), respectively.
  
  
  CONCLUSIONS
  The optimal corrective position of the acetabular fragment is severity dependent rather than within the radiological "normal" range for developmental dysplasia of the hip. We prudently proposed that the optimal correction center-edge angle of mild, moderate, and severe developmental dysplasia of the hip is slightly larger than the "normal" range, within the "normal" range, and less than the lower limit of the "normal" range, respectively.
authors.affiliation: Department of Orthopaedics, The First Affiliated Hospital of Bengbu Medical College, Bengbu, Anhui, China.|Department of Orthopaedics, Xinhua Hospital, Affiliated to Shanghai Jiaotong University School of Medicine, Shanghai, China.
authors.forename: Xuyi
authors.initials: X
authors.lastname: Wang
authors.affiliation: Department of Orthopaedics, Xinhua Hospital, Affiliated to Shanghai Jiaotong University School of Medicine, Shanghai, China.
authors.forename: Jianping
authors.initials: J
authors.lastname: Peng
authors.affiliation: Department of Orthopaedics, Xinhua Hospital, Affiliated to Shanghai Jiaotong University School of Medicine, Shanghai, China.
authors.forename: De
authors.lastname: Li
authors.affiliation: Department of Biomedical Engineering, Shanghai University of Technology, Shanghai, China.
authors.forename: Linlin
authors.initials: L
authors.lastname: Zhang
authors.affiliation: Department of Orthopaedics, Xinhua Hospital, Affiliated to Shanghai Jiaotong University School of Medicine, Shanghai, China.
authors.forename: Hui
authors.initials: H
authors.lastname: Wang
authors.affiliation: Department of Orthopaedics, Xinhua Hospital, Affiliated to Shanghai Jiaotong University School of Medicine, Shanghai, China. 505516681@qq.com.
authors.forename: Leisheng
authors.initials: L
authors.lastname: Jiang
authors.affiliation: Department of Orthopaedics, Xinhua Hospital, Affiliated to Shanghai Jiaotong University School of Medicine, Shanghai, China. chenxdmd@163.com.
authors.forename: Xiaodong
authors.initials: X
authors.lastname: Chen
mesh_terms: D000077:Acetabulum / Q000000981:diagnostic imaging* / Q000503:physiopathology; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D020342:Finite Element Analysis; D006618:Hip Dislocation, Congenital / Q000000981:diagnostic imaging* / Q000503:physiopathology; D006801:Humans; D021621:Imaging, Three-Dimensional / Q000379:methods; D008875:Middle Aged; D055815:Young Adult
keywords: Developmental dysplasia of the hip; Finite element analysis; Periacetabular osteotomy