Elsevier

Journal of Biomechanics

Volume 61, 16 August 2017, Pages 250-257
Journal of Biomechanics

Short communication
Incorporating the length-dependent passive-force generating muscle properties of the extrinsic finger muscles into a wrist and finger biomechanical musculoskeletal model

https://doi.org/10.1016/j.jbiomech.2017.06.026Get rights and content

Abstract

Dynamic movement trajectories of low mass systems have been shown to be predominantly influenced by passive viscoelastic joint forces and torques compared to momentum and inertia. The hand is comprised of 27 small mass segments. Because of the influence of the extrinsic finger muscles, the passive torques about each finger joint become a complex function dependent on the posture of multiple joints of the distal upper limb. However, biomechanical models implemented for the dynamic simulation of hand movements generally don’t extend proximally to include the wrist and distal upper limb. Thus, they cannot accurately represent these complex passive torques. The purpose of this short communication is to both describe a method to incorporate the length-dependent passive properties of the extrinsic index finger muscles into a biomechanical model of the upper limb and to demonstrate their influence on combined movement of the wrist and fingers. Leveraging a unique set of experimental data, that describes the net passive torque contributed by the extrinsic finger muscles about the metacarpophalangeal joint of the index finger as a function of both metacarpophalangeal and wrist postures, we simulated the length-dependent passive properties of the extrinsic finger muscles. Dynamic forward simulations demonstrate that a model including these properties passively exhibits coordinated movement between the wrist and finger joints, mimicking tenodesis, a behavior that is absent when the length-dependent properties are removed. This work emphasizes the importance of incorporating the length-dependent properties of the extrinsic finger muscles into biomechanical models to study healthy and impaired hand movements.

Introduction

The forces produced by soft tissue structures that surround a joint (including passive muscles) play a crucial role in the control and stabilization of dynamic movements of low mass and inertia systems. Experimental work on biomechanical systems ranging from insect legs to human wrists (Charles and Hogan, 2012, Hooper et al., 2009, Souza et al., 2009, Wu et al., 2012) has demonstrated that passive viscoelastic forces, and the joint torques that result, influence dynamic movement trajectories of low mass systems more than the momentum and inertia of the segments.

Comprised of 27 bones with masses ranging between 0.002 and 0.04 kg (Le Minor and Rapp, 2001, McFadden and Bracht, 2003, Mirakhorlo et al., 2016, Saul et al., 2015), the hand is a small mass and inertia system. As a result, the inclusion of passive viscoelastic forces are critical for the simulation of controlled dynamic movements of the hand and fingers (Esteki and Mansour, 1997, Kamper et al., 2002). Passive viscoelastic forces in the hand are produced by soft tissue structures, either those that act within the hand (e.g., ligaments, joint capsules, skin, and intrinsic finger muscles) or the extrinsic finger muscles, which originate proximally, cross the wrist, and attach distally on the fingers (Knutson et al., 2000, Kuo and Deshpande, 2012). Because the force a muscle produces depends on length, it varies as a function of the posture of every joint the muscle crosses. Thus, forces produced by the passive extrinsic finger muscles are a complex, multi-dimensional function of joint postures of the distal upper limb (Bhardwaj et al., 2011, Knutson et al., 2000, O'Driscoll et al., 1992, Richards et al., 1996).

Biomechanical models that are implemented for dynamic simulations of finger movements include passive torques about each finger joint; however, most commonly these models exclude the wrist and distal upper limb (e.g. Babikian et al., 2016, Brook et al., 1995, Esteki and Mansour, 1997, Goislard de Monsabert et al., 2012, Kamper et al., 2002, Li and Zhang, 2009, Sancho-Bru et al., 2003, Sancho-Bru et al., 2001). While previous simulation work integrating the wrist and hand included active muscle properties that varied with proximal joint posture, the passive viscoelastic torques about each finger joint were defined as a function of a single joint, independent of other joint postures (Adamczyk and Crago, 2000). Here, we incorporate the length-dependent passive forces of the extrinsic index finger muscles into a biomechanical model of the hand and demonstrate their influence on combined passive movements of the wrist and hand.

Section snippets

Dynamic biomechanical model

A dynamic biomechanical model was developed in OpenSim v3.2 (Delp et al., 2007) by adapting an existing dynamic model of the upper extremity (Saul et al., 2015). The original model included the kinematics of the shoulder, elbow, and wrist, without additional degrees of freedom distal to the wrist. As described previously (Blana et al., 2016), the kinematics of the original model were augmented to include degrees of freedom for digits 1 (thumb) through 5 (pinky finger) (Fig. 1). Mass and inertia

Results and discussion

Simulation of length-dependent passive force-generating properties of extrinsic finger muscles yielded coupled movements between the wrist and index finger during dynamic forward simulations (Fig. 3). With the forearm pronated, prescribed wrist flexion produced coordinated MCP extension (initial position: 83° flexion, final position: 21.8° extension) and PIP extension (11.1–1.7° flexion; Fig. 3b–d), mimicking tenodesis (Johanson and Murray, 2002, Su et al., 2005). With the forearm supinated,

Conclusion

Passive torques are critical to achieve controlled and stabilized dynamic free movements of the wrist and fingers (Babikian et al., 2016, Blana et al., 2016, Charles and Hogan, 2012, Kamper et al., 2002). Additionally, passive coupling of the fingers and wrist is a fundamental component of hand function in the severely disabled hand, such as following tetraplegia (Johanson and Murray, 2002, Su et al., 2005). The methods implemented in this study are novel in that they enable incorporation of

Conflict of interest

None.

Acknowledgements

This work was funded by the National Institutes of Health under the Award Numbers R01EB011615, R01HD084009, and T32EB009406. We acknowledge the contributions of Christa Nelson in completing an initial set of simulations that we then expanded to complete the analysis included in the Appendix.

References (34)

  • J.L. Sancho-Bru et al.

    A 3-D dynamic model of human finger for studying free movements

    J. Biomech.

    (2001)
  • T.R. Souza et al.

    Prestress revealed by passive co-tension at the ankle joint

    J. Biomech.

    (2009)
  • F.C. Su et al.

    Movement of finger joints induced by synergistic wrist motion

    Clin. Biomech. (Bristol, Avon)

    (2005)
  • M.M. Wu et al.

    Passive elastic properties of the rat ankle

    J. Biomech.

    (2012)
  • M.M. Adamczyk et al.

    Simulated feedforward neural network coordination of hand grasp and wrist angle in a neuroprosthesis

    IEEE Trans. Rehabil. Eng.

    (2000)
  • E.M. Arnold et al.

    A model of the lower limb for analysis of human movement

    Ann. Biomed. Eng.

    (2010)
  • S. Babikian et al.

    Slow movements of bio-inspired limbs

    J. Nonlinear Sci.

    (2016)
  • Cited by (15)

    • Simulating finger-tip force using two common contact models: Hunt-Crossley and elastic foundation

      2021, Journal of Biomechanics
      Citation Excerpt :

      Through forward dynamic simulations, how contact model (Hunt-Crossley vs. Elastic Foundation) and contact model parameters (target force, contact area, and stiffness) influenced finger-tip forces was examined. A previously described index finger model (Fig. 1a) was used (Binder-Markey and Murray, 2017). Briefly, this model included four extrinsic muscles, one unconstrained degree-of-freedom [metacarpophalangeal (MCP) flexion–extension], and two constrained degrees-of-freedom [proximal interphalangeal (PIP) and distal interphalangeal (DIP) flexion–extension were held constant].

    • The Biomechanical Basis of the Claw Finger Deformity: A Computational Simulation Study

      2019, Journal of Hand Surgery
      Citation Excerpt :

      Musculotendon paths and force-generating properties (both active and passive) of the 4 extrinsic index finger muscles (flexor digitorum superficialis indicis, flexor digitorum profundus indicis, extensor digitorum communis indicis, and extensor indicis proprius) were explicitly defined within the model.23 Net passive torques contributed by intrinsic muscles and soft tissue structures (eg, ligaments, joint capsules, and skin) that cross the MCP, PIP, and DIP joints of the index finger were implemented into the model as 3 torsional spring-dampers, each independently acting about the flexion-extension axis of each joint.23 Consistent with an intrinsic-minus hand,4,9,18 active force-generating properties of the intrinsic finger muscles were excluded from the model.

    View all citing articles on Scopus
    View full text