Mechanized pivot shift test achieves greater accuracy than manual pivot shift test.

Area of Science:

• Orthopedic biomechanics
• Knee joint kinematics
• Surgical assessment techniques

Background:

• The pivot shift test is crucial for assessing anterior cruciate ligament (ACL) integrity.
• Manual pivot shift testing can be subjective and variable.
• Objective quantification of knee laxity is needed for improved diagnostic accuracy.

Purpose of the Study:

• To design and evaluate a navigated, mechanized pivot shift test setup.
• To compare the repeatability of mechanized versus manual pivot shift testing in ACL-deficient knees.
• To hypothesize that mechanized testing yields more repeatable measurements of tibial translation and rotation.

Main Methods:

• Twelve cadaveric lower extremities were used, tested intact and ACL-deficient.
• A novel mechanized pivot shift system using a modified continuous passive motion (CPM) machine was developed.
• Tibial translation and rotation were simultaneously recorded using a navigation system during both manual and mechanized tests.

Main Results:

• Mechanized pivot shift testing demonstrated significantly lower translation (7.4 mm vs. 11.7 mm) and rotation (11.0° vs. 18.6°) compared to manual testing in ACL-deficient knees.
• Intra-class correlation coefficients (ICC) for translation were higher for mechanized (0.92) versus manual (0.76) testing.
• ICC for rotation was 0.82 for mechanized and 0.89 for manual testing, indicating high repeatability for both, but superior for mechanized translation.

Conclusions:

• The developed navigated mechanized pivot shift test setup provides a more repeatable measurement of anterior tibial translation than manual testing.
• This system has the potential to enhance the consistency and objectivity of clinical pivot shift test grading.
• Further clinical validation is warranted to confirm its utility in surgical decision-making.