Improved Calculation Method of TAD for Intertrochanteric Fractures

Area of Science:

• Orthopedic surgery
• Radiographic imaging analysis
• Biomechanical engineering

Background:

• Intertrochanteric fractures require precise surgical fixation using intramedullary systems.
• Accurate measurement of tip-to-apex distance (TAD) is critical for successful outcomes.
• Current measurement methods may be susceptible to projection angle variations.

Purpose of the Study:

• To investigate the relative position of femur fixed screws in intramedullary systems for intertrochanteric fractures.
• To refine the measurement technique for tip-to-apex distance (TAD).
• To provide a theoretical basis for improved clinical treatment strategies.

Main Methods:

• Defined anatomical axes (X, Y, Z) on anteroposterior (AP) and lateral hip radiographs.
• Established projection points of the nail tip (A_AP, B, A_LAT, C) and femoral head radius (D).
• Formulated equations for TAD (X_AP, X_LAT) based on these measurements.

Main Results:

• When lateral projection angle was standardized, A_AP equaled A_LAT.
• Standardized angles yielded consistent TAD calculations: X_AP^2 = B^2 + (D - A_AP)^2 and X_LAT^2 = C^2 + (D - A_LAT)^2.
• Non-standardized lateral angles altered (D - A_LAT) values, impacting TAD accuracy.

Conclusions:

• Non-standardized lateral projection angles lead to inaccurate TAD measurements.
• This inaccuracy can cause misinterpretation in clinical practice.
• An amended formula, X_LAT^2 = C^2 + (D - A_AP)^2, is proposed for improved lateral TAD accuracy.