Predicting the optimal entry point for femoral antegrade nailing using a new measurement approach.

Purpose: To establish a new reliable approach for measuring proximal femoral anatomical parameters and determining the optimal entry point of the antegrade intramedullary (IM) nailing.

Methods: A new method for measuring the proximal femoral anatomy and locating the optimal entry point for the antegrade nailing was developed using Mimics and 3-Matic softwares (Materialise, Haasrode, Belgium). After verifying the reliability of the measurement method using 15 pairs of the femoral models by the intraclass correlation coefficient, the anatomical parameters of 200 Chinese femurs were measured, and statistical analyses were performed to compare the proximal femoral anatomical parameters between different genders or lateralities and determine the most relevant factors of the optimal entry point.

Results: Reliability study showed that both intraobserver reliability and interobserver reliability of the current measurement approach were excellent. After independent samples [Formula: see text]-test, the proximal femoral anatomical parameters were shown significant difference between genders. Stepwise regression statistical analyses showed that the most relevant factors of the distances between the optimal entry point and the femoral head centre, the femoral neck axis and the tip of the greater trochanter were the 3D femoral neck-shaft angle (Pearson's [Formula: see text]; the model's [Formula: see text]), the femoral radius (Pearson's [Formula: see text]; the model's [Formula: see text]) and the femoral length (Pearson's r = 0.316; the model's [Formula: see text]), respectively.

Conclusions: The current study provided a new and reliable measurement approach to evaluating the anatomical morphology of the proximal femur and revealed the most influential factors on the locations of the simulated optimal entry point for the proximal femoral antegrade IM nailing. Furthermore, this study was useful for establishing methodological basis for future researches and developments of the custom-made IM nailing and affiliated surgical instruments.