Background: Subcapital hip fractures in younger patients are generally treated with internal fixation rather than with primary hemiarthroplasty, which is generally reserved for older, low-demand patients. Avascular necrosis can occur following this injury because of disruption of the femoral head blood supply. Some believe that emergent fracture reduction is necessary to minimize the risk of avascular necrosis. The purposes of this study were (1) to investigate the functional outcomes of subcapital hip fractures in patients sixty years old or younger and (2) to compare the rates of avascular necrosis after early and delayed fracture fixation.
Methods: This retrospective study included adults in whom a subcapital hip fracture had been treated with reduction and internal fixation when they were sixty years of age or less and who had been followed clinically for a minimum of two years. The patients were divided into two groups: those treated with early fixation (within twelve hours after the injury) and those treated with delayed fixation (more than twelve hours after the injury). Functional outcomes were assessed with use of the Short Form-36 and the Western Ontario and McMaster University (WOMAC) Osteoarthritis Index. The rates of avascular necrosis were compared between the two groups.
Results: Thirty-eight patients (average age, 46.4 years) participated in the study. Twenty-nine patients had a displaced subcapital hip fracture. Fifteen patients underwent early fracture fixation, and the remainder underwent delayed fixation. No differences in the Short Form-36 (p = 0.68) or WOMAC (p = 0.69) scores were seen between the early and delayed fixation groups. Radiographic evidence of avascular necrosis developed in six patients treated with delayed fixation, one of whom had had an undisplaced fracture preoperatively, and in no patient treated with early fixation. The difference in the rates of avascular necrosis was significant (p = 0.03).
Conclusions: Although delayed surgical treatment of subcapital hip fractures was associated with a higher rate of avascular necrosis, this complication did not significantly affect functional outcome. Longer follow-up is required to assess the effect of avascular necrosis on the development of arthritis and on long-term patient function. Although the results could be biased because patients were not randomly assigned to delayed or early fixation, the data suggest that urgent reduction and fracture fixation within twelve hours after a displaced subcapital hip fracture in high-demand patients may be associated with a reduced rate of radiographic signs of avascular necrosis.