Mechanical pivot shift measurement to evaluate joints

摘要

An unmet need of orthopedic practitioners is a clinically-relevant measurement device and technique to objectively quantify joint (e.g., knee) stability, including rotational stability. An apparatus and method is disclosed for performing a mechanical joint movement test, such as a knee pivot shift test, through the application of standardized dynamic loads (e.g., using a constant-tension spring or other mechanism). When used for knee evaluation, this test reliably induces the characteristic “pivot” tibial subluxation/reduction event in an ACL-deficient knee, allowing for more sensitive detection of deficiencies in rotational knee stability, quantification of the relative importance of knee stabilizers, and comparison of the performance of contemporary ACL reconstruction techniques. The test allows for better understanding joint biomechanics and for defining unique kinematic and kinetic signatures for common joint injuries, such as knee injuries, that will be valuable for diagnostic purposes.

主权项

1. An apparatus for performing a mechanical pivot shift test on a knee of a leg, the apparatus comprising:
a first rigid frame positioned against a first portion of the leg for holding the apparatus against the leg; a second rigid frame positioned against a second portion of the leg for holding the apparatus against the leg; at least one stabilizer attached to the first rigid frame for stabilizing a portion of the apparatus against a portion of the leg; at least one fastening strap positioned around the leg and connecting the first rigid frame and the at least one stabilizer for fastening the apparatus to the leg; a first positioning device attached to the first rigid frame and a second positioning device attached to the second rigid frame; a tension-applying spring attached to and positioned between the two positioning devices, the tension-applying spring positioned in a specific location and orientation with respect to the knee by the positioning devices, to generate forces and moments about the knee over a range of motion for performance of the mechanical pivot shift test on the knee, wherein at least one of the forces and moments is a valgus torque on the knee, and wherein the mechanical pivot shift test evaluates the knee based on kinematic response of the knee to the generated forces and moments; and at least two sensors configured to record the translational and rotational positions of a tibia and a femur of the leg over the range of motion, the recorded translational and rotational positions of the tibia and femur of the leg over the range of motion being used for calculating a stiffness matrix for the knee, the stiffness matrix describing displacements and rotations of the knee in response to the forces and moments applied to the knee.