Internal fixation or hip replacement for undisplaced femoral neck fractures? Pre-fracture health differences reflect survival and functional outcome

Background and purpose - Internal fixation (IF) has been the standard procedure for undisplaced femoral neck fractures (FNFs). However, there is a changing trend towards hip replacement (HR). Yet there is a knowledge gap regarding the benefits of this surgical method. We investigated functional outcomes in patients >= 70 years following HR compared to IF for undisplaced FNFs. Patients and methods - Patients >= 70 years with undisplaced FNF registered in the Swedish National Hip Fracture Registry (SHR) who underwent either IF or HR (hemiarthroplasty [HA)] or total hip arthroplasty [THA]) were investigated in terms of 1-year survival and proportion of reoperation. In a subsample with 4-month follow-up data (n = 3,623), pain, changes in living status, and physical function were additionally analyzed. Results - 7,758 patients were included with a mean age of 85 years. 93% of the patients were operated on with IF, 5% with HA, and 2% with THA. Patients with THA more often lived independently and were able to walk outdoors, both before and after the hip fracture. The IF and HA groups were similar in baseline characteristics, and in functional and survival outcomes. The THA group had a 54% lower adjusted risk of 1-year mortality. The proportion of reoperations within 1 year was 9.5% for IF, 5.3% for HA, and 7% for THA. Interpretation - The pre-fracture difference in health and function between patients operated on with IF, HA, and THA maked it difficult to compare outcomes of the 2 methods. Decision on surgical method must be taken on an individual level, considering patients' well-being and allocation of resources.