OpenSim

Kathryn Wu and I changed the “hip_flexion_r" first. We made the value higher so that it would raise the whole leg higher. Then we changed the "knee_angle_r" so that the knee would change from 180 degree angle to 90 degree angle. Lastly, we changed the ”ankle_angle_r" so the foot of the leg raise and form a 90 degree andgle with the calf.

I. Musculoskeletal Model of the Lower Extremity-Muscles in a Model

I used the Coordinates panel to view the degrees of freedom of the model. There are 23 degrees of freedom of the model in total. There are 3 degrees of freedom of the right leg. They are flexion, adduction and rotation.

Comparison between the degrees of freedom in the model and the degrees of freedom in your lower limbs:

The simulation does not support moving the same joint for different degrees of freedom atthe same time. For example, in real life, I am able to lift up my right leg while twist it to the right. The model are not able to simulate this process.

An example of a joint motion in the model that has been simplified:

For the knee joint, when you set the reflection to the highest degrees in the panel, it would make the knee appear in an weird angle However, if it is in real life and I bent my knee at that angle, my joint would break. That is the limitation of the model.

II. Joint Angles, Muscle-tendon Lengths, & Moment Arms 

Before I did the simulation, I first plotted the fiber length and knee length in the default position. After I got the graph, I lift up the model's right hip flexion to 45 degrees. Before I plotted the new graph, I took a guess about the change. I assumed that as the right hip was flexed, the fiber-length curve be contracted so that the fiber length would be shorter. Then I plotted the new data and got the graph from the right. The blue line is covered by the green line. But I can tell that after the right hip was flexed, the curve of the fiber length lowered. 

III. Assessment of Hamstrings Length During Crouch Gait

6. Range of Motion

b. Label the times at which heel strike and toe-off occur, and the stance and swing intervals.

c. What is the range of motion for knee flexion during stance phase for normal gait?

Flexion ranges from about 0° (full extension) to 15-20° of flexion.

d. How does knee flexion range of motion for crouch gait compare to that of normal gait?

In crouch gait, the knee flexion range is significantly higher compared to normal gait. Normal gait usually has knee flexion between 0° and 60°, while crouch gait involves knee flexion ranging from 60° to 70°.

1. Which motion is expressed in positive angles: wrist flexion or wrist extension?

Wrist Flexion

2. Which motion is expressed in positive angles: radial deviation or ulnar deviation?

Radial Deviation

3. What are the functions of the Extensor Carpi Ulnaris (ECU) muscle? Check or circle all that apply.

    Ο wrist extension  Ο wrist flexion  Ο radial deviation  Ο ulnar deviation  Ο hip extension

4. What are the functions of the Extensor Carpi Radialis Brevis (ECRB)? Check or circle all that apply.

    Ο wrist extension  Ο wrist flexion  Ο radial deviation  Ο ulnar deviation  Ο hip extension

5. In these plots, given how the model defines the wrist flexion degree of freedom, is wrist extension moment denoted by positive or negative values?

Wrist extension moment can be denoted by positive or negative values based on the adopted sign convention of the model.

6. What happens to the maximum moment of the wrist extensors if the ECU muscle is transferred to the ECRB?

Hint: Remember, one of the goals of the surgery is to increase wrist extension strength. 

Transferring the Extensor Carpi Ulnaris (ECU) muscle to the Extensor Carpi Radialis Brevis (ECRB) location would increase the maximum isometric extension moment of the wrist extensors, shifting the deviation moment from ulnar to radial. 

7. In these plots, is the sign of an ulnar deviation moment positive or negative?

Negative

8. What happens to the maximum moment of the ulnar deviators if the ECU muscle is transferred to the ECRB location?

Shift the maximum moment of the ulnar deviators from ulnar to radial deviation

9. One goal of this tendon transfer surgery is to decrease excessive ulnar deviation. Has your simulated surgery achieved this goal? Why or why not?

Yes. The graph did show that the ulnar deviation has decrases after surgery.

10. What is the peak value of the ECU extension moment before transfer? At what flexion angle does it occur?

 Note: Remember, extension moments are negative on the plots.

(-70, -0.76)

11. What is the peak value of the ECU extension moment after transfer? At what flexion angle does it occur?

(-0.707, -1.93)

Day 1

In the Bioengineering class, we had a OpenSim Soccer Kick Contest to see which team can achieve the maximum speed of a kicked soccer ball using OpenSim. We first followed the instructions and imported the model and use Parameter window to change the variables of the muscles. We put our trials into a google sheets. After 20 minutes of testing, we figured out that the increase of the Hamstrings Muscle Force will cause the decrease of the maximum speed. Other forces are directly proportional to the maximum speed. Kathryn and I decided to make the Hamstrings Mscle Force the minimum and other forces the maximum. Then we got 10.57. However, we figured out there is an unusual pattern of the maximum speed and Turn Right and Left. We started to test it out and found the relationship of the angle and the maximum speed is parabolic. Eventually, the greatest final maximum speed we got is 13.6.

Day 2

The next day, we changed the coordinates as well. After several testings, we got 15.27 as the maximum speed.