Document Type
Article
Publication Date
2010
College/Unit
Statler College of Engineering and Mining Resources
Department/Program/Center
Mechanical and Aerospace Engineering
Abstract
Background
The development of osteoarthritis (OA) in the hand results in increased joint stiffness, which in turn affects the grip strength. The goal of the present study is to theoretically analyze the muscle forces in a thumb in response to the increased joint stiffness.
Methods
The thumb was modeled as a linkage system consisting of a trapezium, a metacarpal bone, a proximal and a distal phalanx. Nine muscles were included in the model: flexor pollicis longus (FPL), extensor pollicis longus (EPL), extensor pollicis brevis (EPB), abductor pollicis longus (APL), flexor pollicis brevis (FPB), abductor pollicis brevis (APB), the transverse head of the adductor pollicis (ADPt), the oblique head of the adductor pollicis (ADPo), and opponens pollicis (OPP). Numerical tests were performed using an inverse dynamic approach. The joints were prescribed to an angular motion at one degree-of-freedom (DOF) each time with all other DOFs of the joints being mechanically constrained, while the muscle forces in response to the joint motions were predicted. The normal joint stiffness was assumed to be 0.05, 0.10, and 0.15 N m/rad for interphalangeal (IP), metacarpophalangeal (MCP), and carpometacarpal (CMC) joint, respectively. The joint stiffness was assumed to increase by 50% and 100%, simulating the biomechanical consequences of OA.
Results
Our simulations indicated that the increase in joint stiffness induced substantial increases in muscle forces, especially in the EPL and FPL muscles in response to IP, MCP, or CMC extension/flexion motions.
Conclusions
Because the strength of the muscles in the fingers is limited, the muscles will not be able to overcome joint resistance if joint stiffness is increased to its limit due to OA. This may contribute to the reduced range of motion typically seen in OA.
Digital Commons Citation
Wu, John Z.; Li, Zong-Ming; Cutlip, Robert G.; and An, Kai-Nan, "A simulating analysis of the effects of increased joint stiffness on muscle loading in a thumb" (2010). Faculty & Staff Scholarship. 2834.
https://researchrepository.wvu.edu/faculty_publications/2834
Source Citation
Wu, J.Z., Li, Z., Cutlip, R.G. et al. A simulating analysis of the effects of increased joint stiffness on muscle loading in a thumb. BioMed Eng OnLine 8, 41 (2009). https://doi.org/10.1186/1475-925X-8-41
Comments
© 2009 Wu et al; licensee BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.