Biomechanics and Motion Analysis

Development, Validation and Clinical Application of a Quantitative Method for Thumb Trapeziometacarpal Joint

Principal Investigator: William P. Cooney, M.D.
Project Coordinator: Diana Hansen — hansen.diana@mayo.edu

Figure 1: In-vivo setup for the quantitative measurement of the trapeziometacarpal joint

The purpose of this study was to develop and validate a method for assessing the maximal workspace of the thumb’s trapeziometacarpal (TMC) joint motion in vivo using an electromagnetic tracking device (Fig. 1).

Due to the intricate anatomical structures at the base of the thumb, it is difficult to clinically measure the motion of the TMC joint. Movement patterns of the thumb make the current methods of measuring thumb joint motion difficult and are not for objective documentation of thumb motion or thumb impairment. Currently, measurement of the range of thumb motion is limited to flexion-extension and abduction-adduction planes at the metacarpal (MCP) and interphalangeal (IP) joints. However, if such motions take place simultaneously or are combined with a more complex joint such as occurs at the TMC joint, it becomes difficult, if not impossible, to evaluate the precise kinematics of the thumb (Fig. 2).

Figure 2: The predictive curve of the extreme circumduction of the TMC joint to form the maximal working space of the first metacarpal head motion (a), predictive paths of abd/adduction and flexion/extension of the TMC joint (b).

In vitro results indicated that the spherical model, as measured by the electromagnetic tracking system, was a reliable tool for assessing the movement of the TMC joint. The in vivo collection of 20 healthy subjects, 10 with repeated measurements, indicated that the quantitative model as measured by the electromagnetic tracking device, to be a reliable tool for assessing the range of motion (ROM) of the TMC joint. The collection of data from patients with osteoarthritis of the TMC joint are being measured pre and post-operatively currently. The study is also being extended to collect data on patients with a longer post-operative time.