Good stability but high periprosthetic bone mineral loss and late-occurring periprosthetic fractures with use of uncemented tapered femoral stems in patients with a femoral neck fracture: A 5-year follow-up of 31 patients using RSA and DXA

Background and purpose

We previously evaluated a new uncemented femoral stem designed for elderly patients with a femoral neck fracture and found stable implant fixation and good clinical results up to 2 years postoperatively, despite substantial periprosthetic bone mineral loss. We now present the medium-term follow-up results from this study.

Patients and methods

In this observational prospective cohort study, we included 50 patients (mean age 81 (70–92) years) with a femoral neck fracture. All patients underwent surgery with a cemented cup and an uncemented stem specifically designed for fracture treatment. Outcome variables were migration of the stem measured with radiostereometry (RSA) and periprosthetic change in bone mineral density (BMD), measured with dual-energy X-ray absorptiometry (DXA). Hip function and health-related quality of life were assessed using the Harris hip score (HHS) and the EuroQol-5D (EQ-5D). DXA and RSA data were collected at regular intervals up to 4 years, and data concerning reoperations and hip-related complications were collected during a mean follow-up time of 5 (0.2–7.5) years.

Results

At 5 years, 19 patients had either passed away or were unavailable for further participation and 31 could be followed up. Of the original 50 patients, 6 patients had suffered a periprosthetic fracture, all of them sustained after the 2-year follow-up. In 19 patients, we obtained complete RSA and DXA data and no component had migrated after the 2-year follow-up. We also found a continuous total periprosthetic bone loss amounting to a median of –19% (–39 to 2). No changes in HHS or EQ-5D were observed during the follow-up period.

Interpretation

In this medium-term follow-up, the stem remained firmly fixed in bone despite considerable periprosthetic bone mineral loss. However, this bone loss might explain the high number of late-occurring periprosthetic fractures. Based on these results, we would not recommend uncemented femoral stems for the treatment of femoral neck fractures in the elderly.In Sweden, cemented stems have been used primarily for patients with a femoral neck fracture (FNF), but with the introduction of modern hydroxyapatite- (HA-) coated implants, uncemented fixation has increased in popularity (Garellick et al. 2011). Excellent long-term results have been reported for patients with primary osteoarthritis (OA) of the hip (Boden et al. 2006a). The concept of inserting an uncemented femoral component is attractive to many surgeons, as the cementing procedure can induce cardiac arrhythmia and/or cardiorespiratory collapse (Parvizi et al. 1999). However, a recent report from the Swedish Hip Arthroplasty Register indicated that uncemented implants used for patients with an FNF are associated with a 20-fold higher risk of reoperation due to periprosthetic fracture than cemented matte stems (Leonardsson et al. 2012).We have already published an evaluation of a new uncemented femoral stem designed for elderly patients with an FNF; this showed good clinical results and stable implant fixation up to 2 years after surgery despite substantial periprosthetic bone loss (Sköldenberg et al. 2011). We now present the medium-term follow-up from this study.