A mechanical pivot-shift device for continuously applying defined loads to cadaveric knees.

Area of Science:

• Orthopaedic biomechanics
• Knee joint mechanics
• Anterior cruciate ligament (ACL) research

Background:

• Current pivot-shift biomechanical studies use static or poorly defined loading conditions.
• The pivot-shift test is crucial for evaluating knee instability, particularly after ACL injury.

Purpose of the Study:

• To characterize and validate a novel mechanical device for applying well-defined, continuous loads during the pivot-shift test.
• To compare the biomechanical data generated by the mechanical device with the traditional manual pivot-shift test.

Main Methods:

• Six cadaveric knees were tested using the mechanical device and manual pivot-shift before and after ACL transection.
• Three-dimensional kinematics and kinetics were recorded using an optical navigation system and a 6-axis load cell.
• Statistical analyses (ANOVA, Bland-Altman) assessed repeatability, reproducibility, and agreement between methods and examiners.

Main Results:

• The mechanical device applied continuous, repeatable, and reproducible forces and moments within 4-10% of maximum values.
• Pivot-shift kinematics generated by the device were qualitatively and quantitatively similar to manual testing.
• The mechanical device demonstrated superior repeatability and reproducibility compared to the manual method.

Conclusions:

• The novel mechanical device reliably induces pivot-shift kinematics through repeatable 3D loading of cadaver knees.
• The device is mechanically simple, utilizes readily available components, and offers enhanced reliability.
• This tool facilitates accurate quantification of ACL injury and reconstruction effects on pivot-shift biomechanics.