Abstract
Introduction and aim
Avascular necrosis (AVN) of femoral head remains a major post-operative complication of the surgical fixation of femoral neck fractures (#NOF). In order to reduce the incidence of AVN following this type of fracture, the National Institute for Clinical Excellence (NICE) has stated that fixation must occur within 6 hours. However, there is a paucity of information concerning whether time to fixation influences the development of AVN. The aim of the present study was to assess whether time to fixation affects the development of AVN in patients aged under 60 who had sustained a fracture (#)NOF.
Methods
We looked retrospectively at 101 patients (61 female, 40 male aged under 60 (mean age 47 years) who were admitted to a multi-tertiary centre having sustained an intracapsular #NOF. The underlying co morbidity of the patient sample was varied, as was the mechanism of trauma, though in the majority of cases the cause was a simple fall. The time delay (TD) between the time of injury and the time of operation for each patient was determined.
Results
72 patients sustained an intracapsular displaced fracture and 29 an intracapsular undisplaced fracture. Of these, 33 patients were treated with a dynamic hip screw (DHS), 10 received a DHS plus a cannulated screw, and 54 were treated with cannulated screws only. We looked at time to fixation(TD) as follows: Group A-less than 6 hours (7 patients), Group B-6 to 12 hours (16 patients), Group C-12 to 18 hours (15 patients), Group D-18 to 24 hours (18 patients), Group E −24 to 48 hours (26 patients) and Group F- more than 48 hours(15 patients). Out of 97 patients, 15 (15.46%) developed AVN. Of these, 13 were patients who had sustained an intracapsular displaced fracture, two had sustained an undisplaced fracture. Of the intracapsular displaced fractures patients, the time to fixation varied from 3 hours to 26 hours post-trauma. Of note, twelve of these patients received a cannulated screw and only one was treated with a DHS. The two patients with an undisplaced intracapsular fracture underwent fixation at 13 and 24 hours respectively. The method of fixation was a cannulated screw.
Conclusion
Current NICE guidelines state that intracapsular #NOF must be fixed within 6 hours in order to prevent AVN of femoral head. In our sample, 15.46% of patients developed AVN post-fixation. Crucially, 2 patients out of the 7 patients (28.57%) developed AVN despite undergoing fixation within 6 hours. Interestingly, we have observed that fracture fixation with a cannulated screw has a greater propensity to develop AVN despite time to fixation, since 15.46% of patients treated in this manner developed AVN. Taken together, method of fixation rather than time to fixation appears to be a key factor in the incidence of AVN in our patient group.
