The initial stability of uncemented acetabular components.
The osseo-integration of an uncemented acetabular component depends on its initial stability. This is usually provided by under-reaming of the acetabulum. We have assessed the fixation of 52 mm porous-coated hemispherical prostheses inserted into cadaveric acetabula under-reamed by 1, 2, 3 and 4 mm. We tested the torsional stability of fixation, after preloading with 686 N in compression, by measuring the torque required to produce 1 degree and 2 degrees of rotation. Under-reaming by 2 mm and 3 mm gave significantly better fixation than 1 mm (p less than 0.01, p less than 0.02). Insertion after under-reaming of 4 mm caused some fractures. To obtain maximum interference fit and optimal implant stability, we recommend the use of an implant 2 mm or 3 mm larger than the last reamer.
Curtis
M J
MJ
Johns Hopkins University, Baltimore, Maryland.
Jinnah
R H
RH
Wilson
V D
VD
Hungerford
D S
DS
D000077:Acetabulum / Q000502:physiology; D001696:Biomechanical Phenomena; D006622:Hip Prosthesis; D006801:Humans; D016348:Osseointegration; D013314:Stress, Mechanical