Quantification of the pivot-shift test using a navigation system with non-invasive surface markers.

Area of Science:

• Orthopedic surgery
• Biomechanical analysis
• Medical device validation

Background:

• The pivot-shift test is crucial for diagnosing anterior cruciate ligament (ACL) injuries.
• Accurate quantification of the pivot-shift phenomenon is essential for surgical planning and outcomes.
• Current methods for measuring knee kinematics during the pivot-shift test often rely on invasive pin-fixed markers.

Purpose of the Study:

• To validate a navigation system utilizing non-invasive surface markers for quantifying the pivot-shift phenomenon.
• To compare measurements obtained with surface markers against those from traditional pin-fixed markers.
• To assess the correlation between surface marker measurements and clinical grading of the pivot-shift test.

Main Methods:

• Seventy patients with ACL injuries underwent assessment under general anesthesia.
• Knee kinematics during the pivot-shift test were recorded using an image-free navigation system with either surface markers or pin-fixed markers.
• Posterior tibial reduction (PTR) was calculated and compared between the two marker types and with clinical grades.

Main Results:

• The pivot-shift phenomenon was identifiable in all patients via the navigation system.
• Posterior tibial reduction (PTR) measured with surface markers showed moderate correlation with pin-fixed markers (ρ=0.524, p<0.001).
• Moderate correlations were observed between clinical grades and PTRs obtained using both surface markers (ρ=0.522, p<0.001) and pin-fixed markers (ρ=0.645, p<0.001).

Conclusions:

• Posterior tibial reduction (PTR) during the pivot-shift test can be quantified in ACL-injured knees using a navigation system with surface markers.
• Measurements from surface markers moderately correlate with both pin-fixed marker measurements and clinical pivot-shift grades.
• This non-invasive method using surface markers offers a viable approach for assessing knee kinematics in ACL-injured and reconstructed knees.