Failure rates for screw fixation in femoral neck fracture in young patients are often high, with risk of aseptic femoral head osteonecrosis and non-consolidation. The present study sought to identify factors for success or failure of internal fixation according to: 1) initial treatment; 2) initial reduction quality; and 3) population characteristics.

The study hypothesis was that population, fracture type, initial treatment and reduction quality can predict survival.

A retrospective study included all cases of femoral neck fracture in under 65-years-old treated by screwing in our center: i.e., 112 patients. Patient characteristics, time to surgery were collated; surviving patients were followed up at a minimum 24 months. Reduction quality was assessed on X-rays in 3 dimensions and cervico-diaphyseal angle.

Mean follow-up was 5.3±3.0 years [range, 2.0–13.6 years]. At 2 years, 23 of the 112 patients (20.5%) had developed complications: 10 osteonecroses (8.9%) and 13 non-unions (11.6%). Known hip osteonecrosis risk factors showed no significant association with survival. Failure rates were significantly higher in unstable (Garden≥3) than stable (Garden≤2) fracture: HR=2.77 [95%CI: 1.09–7.02]; p=0.025. There was no significant association with time to treatment (≤6 hours): HR=1.08 [95%CI: 0.46–2.54]; p=0.86. On 2-year radiographs, mean shortening on the z-axis was 12.3±4.8mm [−0.7 to 26.2], 8.5±5.0mm [−6.8 to 23.9] on the x-axis, and 6.4±6.1mm [−6.3 to 25.3] on the y-axis. There was a significant negative correlation between z shortening and HOOS pain component (r=−0.38; p=0.005), a non-significant negative correlation with quality of life (r=−0.20; p=0.16), and a significant negative correlation with sports activity (r=−0.28; p=0.039).

The present series showed lower rates of complications and of arthroplasty than in the literature. Internal fixation seemed to be indicated even at an interval of 6 hours or more.

IV, retrospective study.