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The thumb carpometacarpal joint: curvature morphology of the articulating surfaces, mathematical description and mechanical functioning

Dathe H., Dumont C., Perplies R., Fanghänel J., Kubein-Meesenburg D., Nagerl H., Wachowski M. M.

Acta of Bioengineering and Biomechanics

2016

Vol. 18, no. 2

103--110

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°. 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.

Badania antropometryczne kończyny górnej oraz pomiar siły ścisku dłoni i kciuka

Łopatka M., Guzik-Kopyto A., Michnik R., Rycerski W.

Aktualne Problemy Biomechaniki

2012

z. 6

93--98

Analiza kinematyki ruchu kciuka podczas pisania krótkich wiadomości tekstowych (sms)

Michnik R., Sacha E.

Aktualne Problemy Biomechaniki

2009

z. 3

161--166

W artykule przedstawiono metodologię badania kinematyki ruchu kciuka w czasie pisania wiadomości tekstowych sms, z użyciem wybranego modelu telefonu komórkowego. Do badań wykorzystano optoelektroniczny system APAS do trójwymiarowej analizy ruchu, natomiast do porównania otrzymanych wyników wykorzystano autorski program, napisany w środowisku Matlab™.

In this paper the methodology of analysis of thumb kinematics during writing the short message sms was presented. To obtain the kinematics it was used the APAS system and to compare the results it was used the program written in Matlab™ environment.