Migration pattern of a femoral short-stem prosthesis: a 2-year EBRA-FCA-study

Short-stem prostheses enable bone stock preserving total hip arthroplasty. However, little is known about the durability of this group of implants. The most common cause for implant failure is aseptic loosening. Early implant migration is supposed to be the best indicator for mechanical failure of femoral stems. The purpose of this study was to evaluate the migration pattern of a short stem implant and the influence of BMI, gender and femoral offset on implant migration. After a minimum follow-up of 2 years, 72 hips were included in this EBRA-FCA-study. The mean age at surgery of the 34 female and 32 male patients was 54 years (range 22-75 years). The mean BMI was 29 kg/m(2) (range 21-51 kg/m(2)). Mean axial subsidence was 1 mm (+/- 1.4 mm) after 24 months. BMI, gender and implant offset did not influence implant migration on a statistical significant level. Nevertheless, a tendency towards more migration in obese and female patients was observed. The evaluated short stem prosthesis showed a migration pattern similar to clinical proven standard straight stem implants. The indication of short-stem prostheses should be critically evaluated in obese and female patients.