Background: We previously reported our two and five-year results of arthrop
lasty with the Porous Coated Anatomic total hip prosthesis. We now report o
n the performance of this prosthesis at ten to fourteen years.
Methods: The results of 311 total hip replacements in which a Porous Coated
Anatomic prosthesis was inserted without cement in 279 patients were analy
zed prospectively. The average age of the patients at the time of the repla
cement was sixty-one years (range, twenty to eighty-one years). Sixty-four
patients (seventy-six hips) died postoperatively. Forty-five patients (fort
y-seven hips) were lost to follow-up, and four were excluded because of the
ir medical condition. One hundred and sixty-eight patients (187 hips) were
followed for ten to fourteen years (average, twelve years). Seventeen of th
ose patients (seventeen hips) had a revision.
Results: The overall survival rate (with any revision as the end point) was
90.0% +/- 5.4% at fourteen years, with an average Harris hip score of 85 /- 14 points. The prevalence of thigh pain was 36% (fifty-six of 157) in th
e late period (more than ten years postoperatively). Radiographs showed sta
ble fixation, with bone ingrowth, of 83% (130) of the 156 acetabular compon
ents and 88% (137) of the 156 femoral components at the latest follow-up ev
aluation. Men had a significantly higher rate of femoral osteolysis. than d
id women (p < 0.001). The rates of acetabular and femoral osteolysis associ
ated with 32-mm femoral heads (49% [twenty-three] of forty-seven and 70% [t
hirty-three] of forty-seven, respectively) were significantly higher (p < 0
.01) than those associated with 26-mm heads (26% [twenty-eight] of 109 and
30% [thirty-three] of 109, respectively). Despite this, revision (removal o
r exchange of components) was not directly related to head size; instead, i
t was related to polyethylene thickness.
Conclusions: There have been persistent problems with the Porous Coated Ana
tomic hip system, including thigh pain and an increasing prevalence of oste
olysis with time. Revision because of aseptic loosening was related more to
the thickness of the polyethylene liner than to the size of the femoral he
ad. Femoral heads with a 32-mm diameter did not increase the risk for revis
ion provided that an adequate thickness of polyethylene had been used.