[Variability of muscular and articular forces of the thumb. Comparison of three results during lateral grip].
The aim of this paper is to describe three different laboratory studies of muscular and articular forces in the thumb and to compare and discuss their results in term of constraints (forces and moments) at the carpometacarpal joint during key pinch. Imaging techniques such as biplanar roentgenograms or computer tomography imaging were used on cadaver hands and magnetic resonance imaging on living hands in order to determine bone dimensions, muscle and tendon forces, directions, and centres of rotation. Mechanical models of free bodies with three to five links were created. Problems of balancing of static forces were solved using different methods (electromyography, systematic combination of muscular forces or optimization method). The results in terms of muscular forces or constraints at the carpometacarpal joint showed a strong variability (one to three depending on method and hypothesis). However the three studies all showed subluxation of the carpometacarpal joint balanced by joint constraints. Finally, it was demonstrated using magnetic resonance imaging, that results were strongly influenced by the exact point of application of the forces.
Lbath
F
F
Laboratoire de mécanique des solides, INSA, Bâtiment 304, 69621 Villeurbanne, France.
Rumelhart
C
C
Comtet
J J
JJ
D001696:Biomechanical Phenomena; D004576:Electromyography; D018737:Hand Strength / Q000502:physiology*; D006801:Humans; D008279:Magnetic Resonance Imaging; D008662:Metacarpophalangeal Joint / Q000033:anatomy & histology* / Q000000981:diagnostic imaging / Q000502:physiology*; D008954:Models, Biological; D009119:Muscle Contraction / Q000502:physiology*; D016059:Range of Motion, Articular / Q000502:physiology*; D012399:Rotation; D013933:Thumb / Q000033:anatomy & histology* / Q000000981:diagnostic imaging / Q000502:physiology*; D014057:Tomography, X-Ray Computed