We performed an in vivo study in a canine model to compare the results
of the use of a porous-coated collared femoral component with those of the
use of a porous-coated collarless femoral component in total hip
arthroplasties without cement. Our study focused on the comparative
proximal strain pattern, bone ingrowth, and cortical porosity of the two
types of prostheses. We used a trochanteric wire marker to measure
subsidence. The use of the limb was assessed with gait analysis. Twelve
weeks after the operation, the collarless components had significantly
greater bone ingrowth proximally (p = 0.003) and were associated with
significantly lower cortical porosity (p = 0.006). There were no
differences between the groups with regard to either axial or hoop strain.
While the group that had a collarless prosthesis had significantly less
proximal-medial radiolucency (p = 0.03), there were no differences between
the groups with regard to subsidence.