Dathe, Henning and Dumont, Clemens and Perplies, Rainer and Fanghaenel, Jochen and Kubein-Meesenburg, Dietmar and Naegerl, Hans and Wachowski, Martin M. (2016) The thumb carpometacarpal joint: curvature morphology of the articulating surfaces, mathematical description and mechanical functioning. ACTA OF BIOENGINEERING AND BIOMECHANICS, 18 (2). pp. 103-110. ISSN 1509-409X,
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Purpose: The purpose is to present a mathematical model of the function of the thumb carpometacarpal joint (TCMCJ) based on measurements of human joints. In the TCMCJ both articulating surfaces are saddle-shaped. The aim was to geometrically survey the shapes of the articulating surfaces using precise replicas of 28 TCMCJs. Methods: None of these 56 articulating surfaces did mathematically extend the differential geometrical neighbourhood around the main saddle point so that each surface could be characterised by three main parameters: the two extreme radii of curvature in the main saddle point and the angle between the saddles' asymptotics (straight lines). Results: The articulating surfaces, when contacting at the respective main saddle points, are incongruent. Hence, the TCMCJ has functionally five kinematical degrees of freedom (DOF); two DOF belong to flexion/extension, two to ab-/adduction. These four DOF are controlled by the muscular apparatus. The fifth DOF, axial rotation, cannot be adjusted but stabilized by the muscular apparatus so that physiologically under compressive load axial rotation does not exceed an angle of approximately +/- 3 degrees. Conclusions: The TCMCJ can be stimulated by the muscular apparatus to circumduct. The mechanisms are traced back to the curvature incongruity of the saddle surfaces. Hence we mathematically proved that none of the individual saddle surfaces can be described by a quadratic saddle surface as is often assumed in literature. We derived an algebraic formula with which the articulating surfaces in the TCMCJ can be quantitatively described. This formula can be used to shape the articulating surfaces in physiologically equivalent TCMCJ-prostheses.
| Item Type: | Article |
|---|---|
| Uncontrolled Keywords: | METACARPAL JOINT; OSTEOARTHRITIS; FEMALE; thumb; saddle surfaces; curvature morphology; quantitative description; thumb kinematics |
| Subjects: | 600 Technology > 610 Medical sciences Medicine |
| Divisions: | Medicine > Lehrstuhl für Kieferorthopädie |
| Depositing User: | Dr. Gernot Deinzer |
| Date Deposited: | 15 Mar 2019 08:46 |
| Last Modified: | 15 Mar 2019 08:46 |
| URI: | https://pred.uni-regensburg.de/id/eprint/2673 |
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