Time to internal fixation of femoral neck fractures in patients under sixty years-does this matter in the development of osteonecrosis of femoral head?

Osteonecrosis of femoral head remains a major complication of femoral neck fractures. It has been postulated that early internal fixation drastically reduces the incidence of osteonecrosis of the femoral head. However, there is a paucity of literature looking at the effect of time delay to internal fixation on the development of this late complication. In this study, we aim to assess the effect of time delay and method of internal fixation on the development of osteonecrosis in those less than 60 years of age. We retrospectively analysed 92 patients less than 60 years of age who presented with intracapsular neck of femur fractures that underwent internal fixation between 1999 and 2009. Of the 92 intracapsular fractures, 50 underwent fixation using cannulated screws, 32 using a dynamic hip screw, and ten using a dynamic hip screw with a derotation screw. In total, 13 patients (14.1 %) developed osteonecrosis of the femoral head, the highest incidence being in the cannulated screw fixation group with an osteonecrosis rate of 24 %. We did not find the time delay to internal fixation to be a significant predictor of the development of osteonecrosis. Our study demonstrated that the method of internal fixation rather than delay in internal fixation was more predictive of osteonecrosis of the femoral head. We did not find support to the current belief that early surgical fixation of neck of femur fractures reduces the risk of osteonecrosis in patients less than 60 years.