Title: A Proposed New ObstacleSet Algorithm for Modeling Deltoid
1A Proposed New Obstacle-Set Algorithm for
Modeling Deltoid
Tiffany Xu Mentor Dr. Brian Garner
2Presentation Outline
- I, Introduction to muscle modeling and why
that is needed? - II, Application areas of muscle modeling.
- III, Introduction to four mostly used muscle
modeling methods. - IV, Studies carried out using the obstacle-set
model. - Description of muscle modeling using obstacle-set
model. - Difficulties encountered in modeling deltoid.
- V, A new obstacle-set model.
- Algorithm/methods.
- Results/comparison with data from other studies.
- Advantage of the new obstacle-set model.
- VI, Conclusion.
- VII, Questions.
3Introduction to Muscle Modeling
- In order to understand how each muscle works to
influence our body behavior, all the following
factors need to be studied - Point of force application
- Direction of force application
- Force magnitude
- But, not all of those factors could be obtained
directly, which is why computer simulation of
muscle activity emerges as a popular method to
approximate the muscle moment arm.
Through out the study of muscle mechanics, muscle
moment arm is an eternal topic. Proper
representation of muscle paths in musculoskeletal
models is important for accurately modeling the
magnitude and line-of-action of muscle forces.
4Applications of Muscle Modeling
- Biomechanics (North Carolina State University,
ergonomics research) - Computer graphics
- 1 Patria A. Hume, Justin Keogh and Duncan Reid,
The Role of Biomechanics in Maximizing Distance
and Accuracy of Golf Shots. Sports Med
2005,35(5) 429-449. - 2 Arpad Illyes, Rita M. Kiss, Shoulder Muscle
Activity During Pushing, Pulling, Elevation and
Overhead Throw. Journal of Electromyography and
Kinesiology 15(2005) 282-289. - 3 Marcus G. Pandy, Computer Modeling and
Simulation of Human Movement. Annual Reviews of
Biomedical Engineering, 2001. 3245-73.
5Straight-line model
Four Mostly Used Muscle Wrapping Methods
Centroid line model
3D model via finite element algorithm
Obstacle-set model
Difficulty of Simulating the Muscle Path Tension
between desire to have model accuracy, and desire
to have simplicity and computational efficiency.
6Obstacle-set Model
- The muscle path in this method is formed by
several segments of straight lines and curved
lines joined together by via points. And the
anatomical constrains are modeled by cylinder,
sphere, stub, or other combination of those
geometries.
7Obstacle-set Model Has A Limitation in Modeling
Broad Muscle
- However, modeling some broad muscles crossing
joints with wide ranges of motion can be
difficult owing to - Broad muscles are modeled with multiple bands.
- Each bands path is computed independently.
- The independent bands of the deltoid have a
tendency to slip around to unrealistic positions
behind the sphere.
8New Obstacle-set Algorithm --improvement was made
The aim of this study was to develop a new
obstacle-set algorithm that accounts for
connectivity between muscle fibers, that will
keep the fibers staying on the surface of the
obstacle-set without any slip.
9New Obstacle-set Algorithm for Modeling Deltoid
- Origin sites on a fixed clavicle/scapula bone,
and insertion sites on a moving humerus, were
defined. - A sphere obstacle was defined to represent
anatomy underneath the deltoid. - Reference planes were specified.
- Fixed angles between the path and reference
planes were chosen to reflect the breadth of the
deltoid muscle between bands. - Minimum-distance path of each muscle band around
the sphere and within a path plane was
calculated.
10New Obstacle-set Algorithm for Modeling Deltoid
The muscle paths were then applied onto the bone
structure reconstructed from the Visible Human
Project data.
Anterior, medial, and posterior muscle path
planes and their orientation reference planes
and their orientations.
Sphere as the obstacle
11Process of Simulation
60o
0o
30o
- Move/rotate the humerus
- Orientation of the anterior muscle path plane
determined - Orientation of the medial and posterior muscle
path planes changed - Minimum length of each muscle path computed
- Above steps repeated to find the orientation
value of the anterior muscle path plane which
minimized the sum of the path lengths
12Results of the New Obstacle-set Model
- No slip.
- Computational time was less than a millisecond.
- Wide range of shoulder joint motion.
- Realistic configurations of the hypothetical
deltoid.
13Results of the New Obstacle-set Model
Why Say It Is Realistic?
Abduction moment arm for anterior, medial and
posterior deltoid from this new obstacle-set
model, compared with experimental data from other
two studies.
-- Obstacle-set -- Liu -- Otis
1/3, Moment arm of anterior deltoid during
abduction
14Results of the New Obstacle-set Model
-- Obstacle-set -- Liu -- Otis
-- Obstacle-set -- Liu -- Otis
2/3, Moment arm of medial deltoid during abduction
3/3, Moment arm of posterior deltoid during
abduction
15Advantage of the New Obstacle-set Algorithm
- Advantages of this algorithm include
- simplicity
- realism
- computational efficiency
- connectivity between muscle fibers taken into
account - flexible algorithm, so that an arbitrarily large
number of muscle bands could be used to model
broad muscles.
16Conclusion
Compared to other modeling methods, the new
obstacle-set algorithm, is not only simple and
fast, but also flexible and realistic. This
improved obstacle-set model, handles the problem
of slip that happened in the original one. The
derived connectivity algorithm keeps the fibers
of a broad muscle staying on surface of the
sphere-shaped obstacle, which makes the new
obstacle-set model robust. Comparison to the
experimental data reveals a good approximation of
the moment arm. But more experimental data needs
to be studied and compared with, so that the
realisticness of this new model could be
improved.
17Thank you! Any Questions?
References 1 Garner B.A., Pandy M.G., The
Obstacle-Set Method for Representing Muscle Paths
in Musculoskeletal Models. Computer Methods in
Biomechanics and Biomedical Engineering, Vol. 3,
pp. 1-30. 2 Silva S. Blemker and Scott L. Delp,
Three-Dimensional Representation of Complex
Muscle Architectures and Geometries. Annals of
Biomedical Engineering, Vol. 33, No. 5, May 2005
pp.661-673. 3 Garner, B. A. and Pandy, M.G., A
kinematic model of the upper limb based on the
visible Human Project dataset. Computer Methods
in Biomechanics and Biomedical Engineering. 4
Brian A. Garner and Marcus G. Pandy,
Musculoskeletal Model of the Upper Limb Based on
the Visible Human Male Dataset. Computer Methods
in Biomechanics and Biomedical Engineering, Vol.
4, pp.93-126. 5 JC Otis, CC Jiang, TL
Wickiewicz, MG Peterson, RF Warren and TJ
Santner,Changes in the moment arms of the rotator
cuff and deltoid muscles with abduction and
rotation. Department of Biomechanics, Hospital
for Special Surgery, New York, N.Y. 10021.