A new software tool for fast and repeatable joint biomechanic analysis

This paper describes a method for a computerized analysis of diarthroid joints. The software implements reliable functions to study the shapes of the articulating surfaces through 2D arbitrary sections and geometrical fitting of lines/conics to quantify ligament behaviour through the computation of elongation, strain and orientation during the recorded motion. The software also allows for the computation of the most classical kinematic parameters, such as helical axes, instantaneous rotations and displacements, centers of rotation or pivot points of motion. In addition, new functional-anatomical features, such as distance maps, contact areas tracking, and tools to validate functional hypothesis on the joint mechanism are possible in an interactive environment which display the 3D behaviour of the acquired or selected joint structure. An easy interface also allows non-expert users to analyse the joint biomechanics and a test-demo is available freeware at http://www.studyioint.org. This approach represents a generalization of the analysis of several cadaveric joints, and its preliminary versions were used for kinematic and anatomical investigations about normal and pathological knees or shoulders. It provides a standard method for a complete analysis of joints or model predictions.