To analyze the causes of internal fixation failure in elderly intertrochanteric femoral fractures.

We retrospectively analyzed 93 intertrochanteric femoral fractures that were treated by internal fixation. The follow-up period was at least 24 months. The mean age was 73 years. We analyzed the classification of the fracture, screw position, reduction state of the fracture, and neck-shaft angle.

Internal fixation failure occurred in 12 cases (12.9%). The causes of internal fixation failure were one case (1.0%) of head perforation, 7 cases (7.5%) of excessive slippage of a screw, and 4 cases (4.3%) of varus deformity. Significant factors infixation failure were displacement of the posterolateral fragment more than 8 mm in anteroposterior radiograph, anterior displacement of a fragment, or more than 20-degree angulation in lateral radiography. Thirty-three cases had a screw in the middle position and 4 of these cases (12.1%) had fixation failure. Notably, 14 cases had a screw in the posteromedial position and 6 of these cases had fixation failure (42.8%).

Accurate reduction of the posteromedial fragment is essential in unstable intertrochanteric fracture and anterior displacement or angulation should be avoided to prevent fixation failure. The tip apex distance of the screw and central location of the screw in the femoral head is also an important factor.