Subtrochanteric fracture: a rare but severe complication after screw fixation of femoral neck fractures in the elderly.

Cannulated screw fixation is a minimal invasive technique to treat undisplaced femoral neck fractures. It is the preferred method in elderly patients who often suffer co-morbidities. There is scarce literature on subtrochanteric femoral fracture as a complication of cannulated screw fixation of a femoral neck fracture. This complication occurred, without an adequate trauma, in two of 35 patients (5.7%) in this retrospective study of patients older than 65 years (mean age: 77 years) who were treated with cannulated screws for an undisplaced femoral neck fracture between 2004 and 2009. We reviewed the literature for the incidence of this complication and possible predisposing factors. The overall incidence reported in literature is 2.4-4.4% (mean: 2.97%). Despite a broad use of this type of osteosynthesis, the literature does not provide clear biomechanical or clinical indications for optimal screw placement to avoid this complication. Considering the literature and our personal results, surgeons should be aware of this severe complication; they may opt for a different implant in the very old, osteoporotic patient with an undisplaced femoral neck fracture.