Accuracy of a computer-assisted navigation system for total knee replacement.

Area of Science:

• Orthopedic Surgery
• Biomedical Engineering
• Surgical Navigation Technology

Background:

• Accurate assessment of mechanical leg axis is crucial for successful total knee replacement (TKR).
• Image-free navigation systems offer potential advantages in TKR procedures by reducing radiation exposure and operative time.
• Validation of these systems, especially in cases with non-ideal leg anatomy, is essential.

Purpose of the Study:

• To develop and validate a method for assessing the accuracy of an image-free navigation system for total knee replacement.
• To evaluate the system's performance in both normal and abnormal mechanical leg axis conditions.
• To establish the in vitro accuracy of a clinically-validated, image-free navigation system.

Main Methods:

• Construction of a phantom leg model with simulated hip, knee, and ankle joints.
• Incorporation of adjustable joints allowing for simulated flexion/extension, varus/valgus, and rotational deformities.
• Utilizing a digital caliper for precise coordinate measurement and a developed software for leg alignment determination.
• Comparative analysis between digital caliper measurements and the image-free navigation system's output.

Main Results:

• The image-free navigation system demonstrated a mean error within 0.5 degrees in normal leg alignment.
• In cases of abnormal femoral and tibial plane alignment, the system's mean error remained within 1 degree.
• This study provides the first in vitro accuracy assessment of this specific clinically-validated navigation system.

Conclusions:

• The image-free total knee replacement navigation system exhibits high accuracy in assessing leg alignment.
• The system performs reliably across both normal and abnormal mechanical leg axis configurations.
• These findings support the potential clinical utility of image-free navigation in total knee arthroplasty.