The effect of femoral stem size on failure rates in total hip replacement cemented with Boneloc.

We report the clinical and radiological outcome of 111 primary Taperloc hip arthroplasties implanted with Boneloc bone cement and the effect of stem size on survival. The mean follow-up was 5.3 years (range 3.2-6.6 years). The average age of the patients at operation was 73.4 years. Twenty-seven were male and 84 female. We defined clinical failures as those who had revision for aseptic loosening, or those symptomatic with pain and subsequent confirmation of radiographic loosening. The overall failure rate noted for this type of stem was 20.7%. Failure occurred on average at 3.3 years (0.3-6.3 years). However, when the data is broken down to different sizes of stem, the patients who had smaller Taperloc stems (7.5 mm or 10 mm) had a 27% failure rate whereas stems equal to, or greater than, 12.5 mm had a 12% failure rate over the same period (p < 0.05). As compared to other types of femoral stems used with Boneloc cement, the Taperloc stems survive better. Furthermore, larger stems survive even better. We suggest that these larger stems behave more like uncemented femoral stems. The finish on the stem is not a major contributor as has been suggested in the past.