Frontal alignment in total knee arthroplasty. Comparative study between radiographic measurement and surgical...

Area of Science:

• Orthopedic Surgery
• Medical Imaging
• Biomechanical Engineering

Background:

• Accurate alignment of the femoro-tibial mechanical axis is crucial for successful total knee arthroplasty (TKA).
• Traditional radiographic methods and modern surgical navigation systems are used to assess this alignment.
• Understanding the concordance between these methods is essential for optimizing surgical planning and execution.

Purpose of the Study:

• To evaluate the agreement between radiographic and surgical navigation measurements of the femoro-tibial mechanical axis.
• To compare these measurements in the pre- and postoperative periods following TKA.
• To determine if radiographic assessment is redundant when surgical navigation is employed.

Main Methods:

• Analysis of pre- and postoperative measurements in 88 TKAs using a consistent surgical navigation system.
• Measurement of the mechanical frontal angle (MFA) and femoro-tibial anatomic angle via digital teleradiography and surgical navigation.
• Calculation of the average MFA from navigation data including measurements at rest, forced varus, and forced valgus.

Main Results:

• Mean preoperative MFA on radiographs was 4.55°, reducing to 1.72° postoperatively (p=0.05).
• Mean MFA measured by navigation was 3.12° preoperatively and 0.53° postoperatively (P=.013).
• Strong concordance coefficients were observed: 0.869 preoperatively (P<.001) and 0.709 postoperatively (P=.017) between radiographic and navigation MFA.

Conclusions:

• A significant concordance exists between radiographic and surgical navigation measurements of the mechanical frontal angle in TKA.
• Surgical navigation provides reliable assessment of femoro-tibial alignment.
• Radiographic assessment may not be necessary when utilizing surgical navigation in TKA, potentially streamlining the procedure.