Revision rate following unipolar versus bipolar hemiarthroplasty.

INTRODUCTION: There has been much debate on use of bipolar or unipolar femoral heads in hemiarthroplasty for the treatment of femoral neck fractures. The outcome of these implants should be studied in the America Joint Replacement Registry (AJRR).

METHODS: All primary femoral neck fractures treated with hemiarthroplasty between January 2012 and June 2020 were searched in the AJRR. All cause-revision of unipolar and bipolar hemiarthroplasty and reasons for revision were assessed for these patients until June of 2023.

RESULTS: There were no differences in number and reason for all cause revisions between unipolar and bipolar hemiarthroplasty ( p   =  0.41). Bipolar hemiarthroplasty had more revisons at 6 months postoperatively ( p   =  0.0281), but unipolar hemiarthroplasty had more revisions between 2 and 3 years ( p   =  0.0003), and after 3-years ( p   =  0.0085), as analysed with a Cox model. Patients with older age (HR = 0.999; 95% CI, 0.998-0.999; p   =  0.0006) and higher Charlson Comorbidity Index (HR = 0.996; 95% CI, 0.992- 0.999; p   =  0.0192) had a significant increase in revision risk.

CONCLUSIONS: We suggest that surgeons should consider using bipolar prosthesis when performing hemiarthroplasty for femoral neck fracture in patients expected to live >2 years post injury.