A computed tomography assessment of femoral and acetabular bone changes after total hip arthroplasty.
Using computed tomography-assisted (CT) osteodensitometry, we studied the bone changes that occurred in 12 patients at 2 weeks and again at 1 year after total hip arthroplasty with insertion of a press-fit acetabular cup and an uncemented femoral tapered stem. There was a greater decrease in full bone density (BD) lateral to the femoral stem when compared to the medial side, at the proximal end of the femur this difference was significant (-22.1% versus -16.2%) ( P<0.001). At the tip of the stem cortical BD had decreased between 2.3% and 1.9% only. Proximal to the cup, the cortical BD increased by about 3.4% ( P< or =0.05), while the full BD decreased markedly by 8% ( P< or =0.001). These changes represent a response to a decrease in regional bone stress induced by the presence of the press-fit implant, and this might be considered as retro-acetabular stress shielding. No focal bone resorption was found.
Schmidt
R
R
Orthopaedische Klinik mit Poliklinik, University of Erlangen, Waldkrankenhaus St Marien, Rathsberger Str 57, D-91054 Erlangen, Germany. rainer.schmidt@ortho.med.uni-erlangen.de
Muller
L
L
Kress
A
A
Hirschfelder
H
H
Aplas
A
A
Pitto
R P
RP
D000077:Acetabulum / Q000000981:diagnostic imaging*; D000328:Adult; D000368:Aged; D019644:Arthroplasty, Replacement, Hip; D015519:Bone Density / Q000502:physiology*; D005260:Female; D005269:Femur / Q000000981:diagnostic imaging*; D006801:Humans; D008297:Male; D008875:Middle Aged; D014057:Tomography, X-Ray Computed