Background and purpose: In patients around retirement age controversy exists as to whether to treat displaced femoral neck fracture (dFNF) with internal fixation (IF) or arthroplasty. An arthroplasty in this age group may need revision due to a long expected remaining lifetime. IF carries a higher risk of early failure but a maintained native hip if healing occurs. We aimed to determine the cumulative 5-year rate of conversion to arthroplasty after IF and implant revision after primary total hip arthroplasty (THA), respectively.
Patients and methods: In this longitudinal cohort study, patients aged 60-69 years registered with a dFNF in the Swedish Fracture Register (SFR) 2012-2018 were cross-referenced with available data from the Swedish Arthroplasty Register (SAR) until December 31, 2019. Conversion to arthroplasty or revision were analyzed utilizing competing risk, with death as competing event.
Results: At 5 years, the cumulative rate of conversion to arthroplasty after IF was 31% (95% confidence interval [CI] 26-37). For primary THA, the 5-year rate of revision was 4.0% (CI 2.8-5.8). The 5-year mortality did not differ, being 20% (CI 16-27) and 23% (CI 20-28) after IF and THA, respectively. Regression analyses did not identify any risk factors for conversion arthroplasty based on the variables in the register.
Conclusion: A follow-up of 5 years catches most reoperations after IF, resulting in a 31% conversion rate. The 4% revision rate at 5 years after primary THA should be seen as an intermediate result, as late complications may occur.