Effect of Finger Posture on the Tendon Force Distribution Within the Finger Extensor Mechanism

Abstract

Understanding the transformation of tendon forces into joint torques would greatly aid in the investigation of the complex temporal and spatial coordination of multiple muscles in finger movements. In this study, the effects of the finger posture on the tendon force transmission within the finger extensor apparatus were investigated. In five cadaver specimens, a constant force was applied sequentially to the two extrinsic extensor tendons in the index finger, extensor digitorum communis and extensor indicis proprius. The responses to this loading, i.e. fingertip force/moment and regional strains of the extensor apparatus, were measured and analyzed to estimate the tendon force transmission into the terminal and central slips of the extensor hood. Repeated measures analysis of variance revealed that the amount of tendon force transmitted to each tendon slip was significantly affected by finger posture, specifically by the interphalangeal (IP) joint angles (p < 0.01). Tendon force transmitted to each of the tendon slips was found to decrease with the IP flexion. The main effect of the metacarpophalangeal joint angle was not as consistent as the IP angle, but there was a strong interaction effect for which MCP flexion led to large decreases in the slip forces (> 30%) when the IP joints were extended. The ratio of terminal slip force: central slip force remained relatively constant across postures at approximately 1.7:1. Force dissipation into surrounding structures was found to be largely responsible for the observed force-posture relationship. Due to the significance of posture in the force transmission to the tendon slips, the impact of finger posture should be carefully considered when studying finger motor control or examining injury mechanisms in the extensor apparatus.

Using kinematic reduction for studying grasping postures. An application to power and precision grasp of cylinders

“…Hand posture introduces constraints on the strength that can be exerted to complete a given task (Domalain et al, 2008;Rossi et al, 2012;Shivers et al, 2002;Watanabe et al, 2005), and affects the distribution of contact pressure and comfort rating (Aldien et al, 2005;Youakim, 2009). Hand posture also affects tendon loads and excursions, and stresses on adjacent tissues such as synovial membranes and nerves (An et al, 1983;Lee et al, 2008), which is associated with the risk of developing work-related musculoskeletal disorders (WMSD) (Laoopugsin and Laoopugsin, 2012;Wells et al, 1994). When attempting to prevent WMSD, different interventions are performed, such as controlling postures, lowering the required grasp force or changing the shape and size of the grasped surface, among others (Harih, 2014;Kroemer, 1989).…”

Hand Posture Prediction Using Neural Networks within a Biomechanical Model

“…The latest hand biomechanical models were developed for very different and specific purposes [7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23], namely to understand the role of anatomical elements, to study the causes and effects of pathologies, to plan rehabilitation, to simulate surgeries, to analyse the energetics of human movement and athletic performance, to design prosthetics and biomedical implants, and to design functional electric stimulation controllers, to name a few. To simulate a task, these models need the hand posture, the forces on the hand and their application points as inputs, and they allow the estimation of the muscle forces needed to perform the task.…”

Towards a Realistic and Self-Contained Biomechanical Model of the Hand

“…These too are quantitative analyses performed on dynamic models. Recent models do not differ much from the ones developed before 2000 (Fok & Chou, 2010;Kamper et al, 2006;Kurita et al, 2009;Lee et al, 2008aLee et al, , 2008bQiu et al, 2009;Roloff et al, 2006;Sancho-Bru et al, 2001, 2003a, 2003b, 2008Valero-Cuevas, 2000;Valero-Cuevas et al, 2000, 2005Vigouroux et al, 2006Vigouroux et al, , 2008Wu et al, 2010). All models present a similar configuration.…”

“…By the year 2000, few threedimensional models had been developed (Biryukova & Yourovskaya, 1994;Casolo & Lorenzi, 1994;Chao et al, 1976;Chao & An, 1978;Esteki & Mansour, 1997;Mansour et al, 1994;ValeroCuevas et al, 1998), and none of them modelled the complete hand. Since 2000, many three-dimensional biomechanical models can be found in literature, having been developed for very different purposes (Fok & Chou, 2010;Kamper et al, 2006;Kurita et al, 2009;Lee et al, 2008aLee et al, , 2008bQiu et al, 2009;Roloff et al, 2006;Sancho-Bru et al, 2001, 2003a, 2003b, 2008Valero-Cuevas, 2000;Valero-Cuevas et al, 2000, 2005Vigouroux et al, 2006Vigouroux et al, , 2008Wu et al, 2010): to understand the role of the different anatomical elements, to understand the causes and effects of pathologies, to simulate neuromuscular abnormalities, to plan rehabilitation, to simulate tendon transfer and joint replacement surgeries, to analyse the energetics of human movement and athletic performance, to design prosthetics and biomedical implants, to design functional electric stimulation controllers, to name a few. These models, however, do not differ much from the ones developed before 2000, and many limitations are still evident.…”