The ability of various acetabular components to resist protrusio migration.
A foam model of a protrusio acetabulum with cylindrical voids of varying diameters was used to test acetabular components for their ability to resist migration within the defect. A bipolar component, a hemispherical cup, and a hemispherical cup with peripheral rim augmentation were tested in defects with diameters ranging from 1 to 3 mm less than the major diameter of the component. The cup with peripheral rim augmentation demonstrated 20% to 40% greater resistance to migration than the hemispherical cup, depending on the extent of under-reaming, with the bipolar component consistently demonstrating the lowest load to failure. The results of this study confirm the less-than-satisfactory clinical results seen with bipolar reconstruction of protrusio acetabuli, and support the use of "fixed" cups in these settings.
Benjamin
J
J
University of Arizona Health Sciences Center, Orthopedic Biomechanics Laboratory, Tucson 85724, USA.
Thomas
M
M
Szivek
J
J
D000077:Acetabulum / Q000033:anatomy & histology / Q000502:physiology*; D001696:Biomechanical Phenomena; D005548:Foreign-Body Migration / Q000517:prevention & control*; D006621:Hip Joint / Q000503:physiopathology / Q000601:surgery*; D006622:Hip Prosthesis; D006801:Humans; D004204:Joint Dislocations / Q000517:prevention & control*; D008953:Models, Anatomic; D011474:Prosthesis Design; D011475:Prosthesis Failure; D013314:Stress, Mechanical; D016474:Weight-Bearing / Q000502:physiology*