Codes used in identifying fractures.

<div><p>Background</p><p>Postoperative periprosthetic femoral fracture (POPFF) after total hip replacement (THR) requires complex surgery and is associated with a high morbidity, mortality, and cost. Although the United Kingdom based National Joint Registry (NJR) captures over 95% of THRs treated with revision, before June 2023 it did not capture POPFF treated with fixation. We aimed to estimate the incidence and epidemiology of POPFF treated with either surgery in England.</p><p>Methods and findings</p><p>We performed a retrospective analysis of a mandatory, prospective database (NJR) linked to Hospital Episode Statistics (HES). All linkable primary THRs between 01/01/2004 and 31/12/2020 were included. Revision or fixation of POPFF were identified using a combination of procedural and diagnosis codes.</p><p>We identified 809,832 THRs representing 5,542,332 prosthesis years at risk. A total of 5,100 POPFF were identified that had been surgically treated by revision, fixation, or both, and 2,831 of these fractures were treated with fixation alone, meaning 56% were not represented with revision data alone. The incidence of POPFF needing surgery was 0.92 (95% CI 0.90, 0.95) per 1,000 prostheses years. This incidence was higher in patients over the age of 70 at the time of primary THR (1.31 [95% CI 1.26, 1.35] per 1,000 prostheses years) and for patients who underwent THR for hip fracture (2.19 [95% CI 1.97, 2.42] per 1,000 prostheses years). This incidence appears to be increasing year on year. The cumulative probability of sustaining a POPFF within 10 years of THR was 1% and over 15% of patients died within 1 year of surgery for a POPFF.</p><p>Conclusions</p><p>To date, the incidence of POPFF may have been underestimated with over 50% of cases missed if the case identification in this study is correct. After including these cases, we observed that POPFF is the largest reason for major reoperation following THR and patients sustaining these injuries have a high risk of death. The prevention and treatment of POPFF and requires further resource allocation and research.</p></div>