The natural history of traumatic femur head necrosis after femoral neck fracture in children and adolescent: a retrospective case series of 64 patients

Abstract

Background: The natural history of traumatic femur head necrosis (TFHN) after femoral neck fracture (FNF) in children and adolescent is relatively unknown and has never been specifically characterized. As we speculated, the natural history in such population would be poor and characterized as the high risk of femoral head collapse, hip deformity and degeneration in a short term. Methods: This retrospective case series enrolled 64 children and adolescent with TFHN who treated with observational treatment from 2000.1 to 2018.1. The primary outcomes, such as the progression of femoral head collapse, hip deformity (Stulberg classification) and hip degeneration (Tönnis grade), and their prognostic factors were analysed. Results: 42 males and 22 females with a mean age of 13 years (6-16 years), were included. A total of 28 hips (44%) showed unsatisfactory outcome and Twenty-five (39%) hips collapsed progressively during a mean follow-up of 48 months (24-203 months). Finally, 38 hips (59%) experienced hip deformity, 20 of them were class IV/V. 34 hips (53%) generally progressed to osteoarthritis, 14 of them were classified as grades II/III. The location of the lesion and the presence of lateral subluxation were found to be independently related to progression of femoral head collapse; however, the presence of lateral subluxation was the only independent risk factor of severe hip deformity and degeneration. Conclusion: TFHN in children and adolescent is a rapidly progressing disease with a poor natural history characterized by a high risk of femoral head collapse progression. If the lateral subluxation emerged, collapsed cases showed increasingly tendency towards severe hip deformity and degeneration.