INFLUENCE OF NON-CEMENTED FEMORAL STEMS INSERTED IN VARUS ON FUNCTIONAL OUTCOME IN PRIMARY TOTAL HIP ARTHROPLASTY

Abstract

Historically, cemented THA femoral stems inserted in varus have yielded poor clinical results. Very few studies to date have addressed the question of the effects of varus alignment on uncemented stems. We have conducted a retrospective review of one hundred and twenty-five uncemented THA femoral stems implanted by a single surgeon from 1994 to 1999. Within this single surgeon group we were able to identify sixteen stems implanted in varus and thus proceeded to analyze the effect of varus alignment on functional outcome.

To assess functional and radiographic outcome of uncemented primary THA femoral stems implanted in varus.

After four-years of follow-up, there have been no radiographic or clinical problems associated with implanting uncemented femoral stems in varus.

Although it is not recommended to implant stems in varus, radiographic and clinical problems associated with implanting uncemented femoral stems in varus appear to be non-consequential.

Of the study sample, one hundred and sixteen hips were in neutral alignment as compared to sixteen varus hips. We could not show any significant difference in Harris Hip scores between the varus and non-varus hips (p> 0.5). No cases showed evidence of radiographic loosening, or subsidence (p=0.3) at four-year follow-up.

Retrospective radiographic review of one hundred and twenty-five uncemented primary THA femoral stems implanted by a single surgeon (now retired) from 1994 to 1999, using the Watson-Jones approach, identified sixteen femoral stems implanted in varus. These sixteen stems were matched 1:1 for demographics and preoperative diagnosis to a cohort of sixteen non-varus uncemented stems implanted by the same surgeon over the same study period. Functional outcome included Harris Hip score and range of motion at four-years postoperative. Radiographic signs of loosening and subsidence, defined as > 2mm, were measured. Varus alignment was defined as ≥ 5°. Paired t-tests were conducted on all outcome variables, p< 0.05 was considered statistically significant.

Study results suggest there to be no consequence of varus femoral alignment in uncemented stems. Patients will need to be followed for a longer duration to further examine the effects of varus implantation of unce-mented femoral stems.