Conversion to Arthroplasty After Internal Fixation of Nondisplaced Femoral Neck Fractures: Results from a Swedish Register Cohort of 5,428 Individuals 60 Years of Age or Older

Nondisplaced or minimally displaced femoral neck fractures are commonly treated with internal fixation, because of its less invasive and less time-consuming nature, as well its retention of the biological properties of the hip. Internal fixation with screws or pins is the current clinical routine in Sweden. However, the authors of some recent studies in elderly patients have suggested that the use of hip arthroplasty, rather than internal fixation, as the primary treatment for nondisplaced femoral neck fractures has benefits of lower reoperation and mortality rates as well as improved mobility1–5. Some countries have implemented primary arthroplasty as the treatment for nondisplaced femoral neck fractures in patients ≥60 years of age. The 2021 annual report of the Australian & New Zealand Hip Fracture Registry showed that approximately 50% of nondisplaced femoral neck fractures were treated with arthroplasty during 20206. In Sweden, internal fixation has been reported to be used in 87% of patients ≥60 years7 and arthroplasty is used only in selected cases8. There is an increasing interest in the degree of posterior tilt9. In an informal questionnaire in 2021, a majority of hospitals in Sweden reported that they were also guided by the lateral radiograph when choosing the surgical method (unpublished data). Some hospitals use only parallel screws, some use only parallel hook pins, and some use both. The principles of fixation are the same for both. Biplanar fluoroscopy is used in most but not all hospitals. These variations illustrate the lack of solid scientific evidence regarding the optimal treatment of this common fracture and also the lack of national guidelines in Sweden. As hip fracture surgery is performed in every emergency hospital by a variety of orthopaedic surgeons, we sought to explore the results after internal fixation for nondisplaced femoral neck fractures in contemporary everyday practice.

The objective of this observational study was to describe the conversion rate to arthroplasty within 5 years after internal fixation of nondisplaced femoral neck fractures in patients ≥60 years of age, using a competing-risk analysis with death as a competing event. In addition, we explored the conversion rate in various age groups, as well as risk factors for conversion surgery and mortality.