Background: We report the results of cementless
total hip arthroplasty with a tapered, rectangular titanium stem
that was introduced in 1979 and continues to be used today with
only minor changes. The aim of the design is to achieve primary
stability to resist rotational and axial forces through precision
rasping and press-fit implantation of a tapered, rectangular femoral
Methods: Between October 1986 and November 1987,
208 total hip arthroplasties with insertion of a tapered, rectangular
titanium stem and a threaded cup without cement were performed in 200
consecutive patients (average age, sixty-one years; range, twenty-two
to eighty-four years).
Results: At the time of the latest follow-up, fifty-one
patients (fifty-two hips) had died and sixteen patients had been
lost to follow-up, leaving 133 patients. Twelve hips had been revised, two
in patients who subsequently died, leaving 123 living patients without
revision. The median follow-up time was 120.7 months. Five cups
needed revision surgery because of aseptic loosening; two, because
of massive polyethylene wear; one, because of posttraumatic migration;
and one, because of breakage. Three femoral stems were revised:
one because of malpositioning (the reoperation was done five days after
implantation); one, because of infection; and the third, after multiple
failed acetabular revisions. The mean Harris hip score for the patients
who did not have revision was 85.4 points (range, 46 to 100 points)
at the time of the latest follow-up. Four patients (3%)
complained of thigh pain that was not associated with another disorder.
According to the criteria of Engh et al., all femoral implants were
graded as stable bone-ingrown. The probability of survival of both
the femoral and the acetabular component at ten years, with any
revision as the end point, was 0.92 (95% confidence interval,
0.88 to 0.97). The probability of survival of the cup was 0.93 (95% confidence
interval, 0.89 to 0.97), and that of the stem was 0.99 (95% confidence
interval, 0.97 to 1.00).
Conclusions: The results of arthroplasty with a
tapered, rectangular titanium stem combined with a conical threaded
cup inserted without cement were excellent at a minimum of ten years.
Our data suggest that femoral stem fixation continues to be secure, while
the threaded cup is prone to aseptic loosening.