Contribution to the method for determining femoral neck axis

Area of Science:

• Orthopedic surgery
• Radiology
• Biomechanical analysis

Background:

• Femoral neck axis plotting is crucial for assessing femoral head-neck junction sphericity in femoroacetabular impingement.
• Existing methods for determining the femoral neck axis carry risks of inaccurate parameter measurements.

Purpose of the Study:

• To propose a novel method for plotting the femoral neck axis using two parallel lines within the medial quarter of the femoral neck.
• To evaluate the efficacy of this new method on anatomical specimens and radiographs.

Main Methods:

• Utilized 31 proximal femur anatomical specimens and their radiographs.
• Plotted three femoral neck axes and determined the alpha angle.
• Applied parametric tests to assess measurement accuracy (error < 5%) and test strength (80%).

Main Results:

• Alpha angle values derived from the proposed method and literature methods showed no significant difference.
• The two plotted axes overlapped in over half of the specimens examined.

Conclusions:

• The proposed method's independence from femoral head rotation center position is advantageous for measuring sphericity angles in patients with femoral head translation.
• A limitation is the small sample size, which restricts definitive conclusions on clinical applicability.