[Influence of femoral neck area on larger anteversion angle of lag screw guide pin initial placement in proximal femoral intramedullary nail fixation].

OBJECTIVE

To invstigate the influence of femoral neck area on larger anteversion angle of lag screw guide pin initial placement in proximal femoral intertrochanteric fracture treated with intramedullary nail.

METHODS

From June 2014 to June 2016, 60 patients with femoral intertrochanteric fractures were treated with intramedullary nail, including 27 males and 33 females with an average age of 75 years old ranging from 49 to 88 years old. The lateral images of femoral neck were divided into areas during operation. The anteversion angle of lag screw guide pin of proximal femoral nail was observed at the time of initial insertion. The incidence of normal and larger was counted and the angle index of influencing factors was recorded.

RESULTS

Among 60 patients, the screw guide pins of 23 cases were in the central region of the femoral neck and the anteversion angle was normal;screw guide pins of 37 cases were in the front area of the femoral neck, leading to larger anteversion angle. The single factor analysis showed that the independent variables influence factors of larger anteversion were internal collection of the affected limb, internal rotation of the affected limb, hip elevation and screw guide pin level(<0.05). The multi-factor regression analysis showed that the anteversion angle larger was significantly related to the internal rotation of the affected limb and screw guide pin level, and the screw guide pin level was the most relevant(=0.030).

CONCLUSIONS

The internal rotation of the affected limb and screw guide pin level may affect the anteversion angle of femoral neck when lag screw guide pin initial insertion, cause it to be too large and the screw guide pin level is the main influencing factor.