Effect of periacetabular osteotomy for acetabular dysplasia clarified by three-dimensional finite element analysis.
BACKGROUND
Finite element analysis (FEA) has been applied for the biomechanical analysis of acetabular dysplasia, but not for biomechanical studies of periacetabular osteotomy (PAO) or those performing analysis taking into consideration the severity of acetabular dysplasia. This study aimed to perform biomechanical evaluation of changes in stress distribution following PAO and to determine the effect of the severity of developmental dysplasia of the hip (DDH) using three-dimensional FEA.


METHODS
A normal model was designed with a 25° center-edge (CE) angle and a 25° vertical-center-anterior margin (VCA) angle. DDH models were designed with CE and VCA angles each of 10, 0, or -10°. Post-PAO models were created by separating each DDH model and rotating the acetabular bone fragment in the anterolateral direction so that the femoral head was covered by the acetabular bone fragment, with CE and VCA angles each at 25°.


RESULTS
Compared to the normal hip joint model, the DDH models showed stress concentration in the acetabular edge and contacting femoral head, and higher stress values; stress increased with decreasing CE and VCA angles. Compared to the DDH models, the post-PAO models showed near-normal patterns of stress distribution in the acetabulum and femoral head, with stress concentration areas shifted from the lateral to medial sides. Stress dispersion was especially apparent in the severe acetabular dysplasia models. PAO provided greater decreases in the maximum values of von Mises stress in the load-bearing area of the acetabulum and femoral head when applied to the DDH models of higher degrees of severity, although the values increased with increasing severity of DDH.


CONCLUSIONS
PAO is expected to provide biomechanical improvement of the hip joint and to be particularly effective in patients with severe preoperative DDH, although the results also suggested a limitation in the applicability of PAO for these patients.
Zhao
Xin
X
Department of Medicine of Sensory and Motor Organs, Division of Orthopedic Surgery, Faculty of Medicine, University of Miyazaki, 5200 Kihara, Kiyotake, Miyazaki 889-1692, Japan.
Chosa
Etsuo
E
Totoribe
Koji
K
Deng
Gang
G
D000077:Acetabulum / Q000473:pathology / Q000502:physiology* / Q000601:surgery*; D001696:Biomechanical Phenomena; D003198:Computer Simulation; D005270:Femur Head / Q000473:pathology; D020342:Finite Element Analysis; D006618:Hip Dislocation, Congenital / Q000150:complications / Q000503:physiopathology* / Q000601:surgery; D006621:Hip Joint / Q000503:physiopathology*; D006801:Humans; D008297:Male; D015207:Osteoarthritis, Hip / Q000209:etiology / Q000503:physiopathology; D010027:Osteotomy; D013314:Stress, Mechanical; D055815:Young Adult