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Uncemented grit-blasted straight tapered titanium stems in patients younger than fifty-five years of age. Fifteen to twenty-year results.

BACKGROUND
Total hip arthroplasty without cement is frequently performed in young active patients, but only limited outcomes data are available after durations of follow-up of more than fifteen years.


METHODS
We retrospectively evaluated the clinical and radiographic results of a consecutive series of 154 total hip arthroplasties (in 141 patients) performed with an uncemented grit-blasted straight tapered titanium femoral stem combined with a threaded socket in patients under the age of fifty-five years. The median duration of follow-up was seventeen years. Clinical results were evaluated with use of the Harris hip score. The canal fill index was used as the criterion to determine the adequacy of stem sizing. Kaplan-Meier survivorship analysis was performed to predict long-term outcomes.


RESULTS
The stem was undersized, with a canal fill index of < or =80%, in forty-one hips (27%). Late aseptic loosening of the stem occurred in four femora, and the femoral component was undersized in all four. These four stems were stable for ten years and then underwent progressive subsidence, which was associated with pain. Five stems were revised because of a late postoperative periprosthetic fracture following trauma. Localized proximal femoral osteolysis was seen in seven hips without signs of loosening. Survivorship of the stem with revision for any reason as the end point was estimated to be 90% (95% confidence interval, 87% to 97%) at twenty years. Survivorship with aseptic loosening as the end point was estimated to be 95% (95% confidence interval, 91% to 99%) at twenty years. Sixty-seven (44%) of the threaded uncemented acetabular components were revised during the follow-up period.


CONCLUSIONS
After a minimum duration of follow-up of fifteen years, the survival of this type of femoral component is excellent in individuals younger than fifty-five years. The main mode of stem failure was a periprosthetic fracture due to trauma, or late aseptic loosening in a small percentage of the hips in which the femoral implant was undersized. The high rate of failure of the acetabular components was attributable to a poor design that is no longer in use.