[Stress analysis on the acetabular side of bipolar hemiarthroplasty by the two-dimensional finite element method incorporating the boundary friction layer].
We compared the biomechanical characteristics of bipolar and unipolar hemiarthroplasty on the proximal migration of the outer head by determining the von Mises stress distribution and acetabular (outer head) displacement with clinical assessment of hemiarthroplasty in 75 patients. This analysis used the two-dimensional finite element method, which incorporated boundary friction layers on both the inner and outer bearings of the prosthesis. Acetabular reaming increased stress within the pelvic bone and migration of the outer head. A combination of the acetabular reaming and bone transplantation increased the stress within the pelvic bone and grafted bone, and caused outer head migration. These findings were supported by clinical results. Although the bipolar endoprosthesis was biomechanically superior to the unipolar endoprosthesis, migration of the outer head still occurred. The bipolar endoprosthesis appeared to be indicated in cases of a femoral neck fracture or of avascular necrosis in the femoral head, but its use in cases of osteoarthritis in the hip required caution.
Department of Orthopaedic Surgery, Fukui Medical School, Japan.
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K
Ichihashi
S
S
Imura
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H
Oomori
H
H
Gesso
D000077:Acetabulum / Q000503:physiopathology* / Q000601:surgery; D000368:Aged; D001696:Biomechanical Phenomena; D001703:Biophysics / Q000379:methods*; D005265:Femoral Neck Fractures / Q000601:surgery; D005271:Femur Head Necrosis / Q000601:surgery; D006622:Hip Prosthesis / Q000379:methods*; D006801:Humans; D008875:Middle Aged; D010003:Osteoarthritis / Q000601:surgery