A method for assessing joint line shift post knee arthroplasty considering the preoperative joint space

Area of Science:

• Orthopedic surgery
• Biomechanical analysis
• Medical imaging

Background:

• Accurate comparison of knee arthroplasty outcomes requires precise joint line analysis.
• Existing methods often neglect preoperative joint space, impacting outcome assessment.

Purpose of the Study:

• To introduce and validate a novel preoperative-based registration method for joint line analysis in knee arthroplasty.
• To assess the accuracy of this new method in measuring joint line alterations.

Main Methods:

• Overlaying 3D bone models with implants using preoperative CT scans.
• Utilizing preoperative and postoperative biplanar radiography.
• Testing the method on cadaveric specimens to measure medial and lateral joint line changes in extension and flexion.

Main Results:

• The new method measured joint line shifts ranging from -0.2 to 1.3 mm (average).
• Results showed significant differences (p≤0.01) compared to a postoperative-based method (mean 3.9-6.8 mm).
• The new method accounts for cartilage thickness, unlike the previous one.

Conclusions:

• Considering preoperative joint space is crucial for accurate joint line analysis post-arthroplasty.
• The newly introduced method provides a reliable tool for assessing joint line changes.
• This method aids in investigating surgical techniques and biomechanical effects in knee arthroplasty.