Retrospective paired cohort study comparing internal fixation for undisplaced versus hemiarthroplasty for displaced femoral neck fracture in the elderly

Introduction: The debate continues regarding the best treatment for elderly patients with non-displaced femoral neck fractures (FNFs): internal fixation (IF) vs hemiarthroplasty (HA). The Aim of the present study is to compare surgical insult, mortality, complications, and walking recovery after one year in patients older than 65 treated with cannulated screws or HA for FNFs. Patients and methods: Match-paired comparison of retrospective cohorts: 220 non-displaced FNFs treated with cannulated screws vs 220 displaced FNFs treated with bipolar HA from 2013 to 2021. No differences were observed in age (82.1 +/- 7.5 IF vs 83 +/- 6.8 HA) (p = 0.172), sex (74.6 % IF females vs 74.6 % HA females) (p = 0.912), year of intervention (p = 0.638) and ASA scale (III in 55.5 % IF vs 55.9 % HA) (IV in 21.8 % IF vs 18.2 % HA) (p = 0.726). Medical complications analyzed included respiratory and urinary infections, heart failure, myocardial infarction, stroke, pulmonary embolism, deep vein thrombosis, acute digestive bleeding. Results: Lower surgical aggression in IF: surgical time (p < 0.001), hemoglobin and hematocrit decrease (p < 0.001), need for transfusion (p < 0.001), hospital stay (p < 0.001). Mortality: higher in-hospital for hemiarthroplasties: 12 deaths (5.5 %) vs 1 (0.5 %) (p = 0.004) (RR=12, 1.5-91.5). No differences after 1 month (13 (6 %) in HA vs 9 (4.1 %) in cannulated screws) and 1 year (33 (15 %) in HA vs 35 (16 %) in IF). Medical complications showed no significant differences (p = 0.055). Surgical complications: No differences in surgical infections (5 HA (2.3 %) vs 2 IF (0.9 %);p = 0,253) or neurovascular injuries (3 HA (1,4 %) vs 2 IF (0.9 %); p = 1). HA: 10 dislocations (4.5 %), 11 periprosthetic fractures (5 %). Cannulated screws: 10 fixation failures (4.6 %), 9 non-unions (4.1 %), 16 ischemic necrosis of femoral head (7.3 %). Reoperation rate: 15/220 IF (6.8 %) and 8/220 HA (3.6 %) (p = 0.134). Functional results: No differences were detected (p = 0.285): 111 osteosynthesis patients (50.45 %) and 99 HA (45 %) returned to their pre-fracture walking ability (p = 0.322). There were also no differences between groups in those patients with worsening of walking status: 108 (49 %) osteosynthesis and 118 (53,6 %) prosthesis (p = 0.412). Conclusions: Cannulated screws in patients over 65 with non-displaced femoral neck fractures results in less surgical insult, lower in-hospital mortality, comparable medical and surgical complications, a similar re-operation rate, and functional outcomes equivalent to hemiarthroplasty.