characterization of the pediatric shoulder’s...

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Introduction Motor vehicle crashes, especially side impacts, are a leading cause of death and disability to the pediatric population as they account for approximately 50% of pediatric trauma [1]. Sixteen percent of children were non-fatally injured while 32% of children have died as a result of vehicle side impacts [2]. According to the Crash Injury Research Engineering Network (CIREN), children involved in side impact crashes are more likely to suffer severe injuries to the head and thorax [1]. The placement of the head and thorax during impact has been shown to be heavily dependent on the response of the shoulder mechanism [3]. Due to the need to increase safety in automobiles, the automotive community has been actively researching methods to prevent injury during car accidents. Potential improvements must first be tested to verify that they reduce injury. This is done through the use of anthropomorphic test devices (ATDs), which provide a method for analyzing the injuries involved in a vehicle crash [1]. However, the data used to design pediatric ATDs is derived and scaled from adults and animal surrogates and it is uncertain whether they are accurate for the child population [4]. In addition, the dynamic response of the pediatric shoulder, which plays an important role in the response of the head and neck during impact, has not been researched and modeled into pediatric ATDs. ……………………………………. Objectives Perform quasi-static, noninvasive shoulder displacements on adult volunteers to define the adult shoulder’s stiffness Perform quasi-static shoulder stiffness testing and dynamic, noninvasive impacts on adult post mortem human subjects Perform quasi-static shoulder stiffness testing on pediatric volunteers Define a correlation between quasi-static and dynamic stiffnesses and find the pediatric shoulder’s response to dynamic loading conditions Methods The right shoulders of six adult volunteers were quasi-statically displaced in four directions: medially, anteromedially, posteromedially, and inferiorly. A combination of motion testing using a point-cluster technique to measure 6-degree-of-freedom motion of the shoulder; resistive loading using a load cell to measure the shoulder’s resistance to quasi-static loading; and electromyography (EMG) recordings to measure the activation of the shoulder muscles during loading was utilized. In each subject, reflective markers were placed on the upper right arm, both acromions, the manubrium, and the medial and lateral epicondyles of the right elbow. Surface electrodes were applied to the latissimus dorsi, upper trapezius, anterior and posterior deltoids, biceps brachii, and pectoralis major. The right shoulders of each subject were quasi-statically displaced using a hand- held force applicator. A load cell attached to the applicator recorded the forces during the motion while an 8-camera Vicon motion capture system tracked and recorded the shoulder’s motion. During the test, electrodes measured the activity of the shoulder muscles during loading. …………………………… Characterization of the Pediatric Shoulder’s Resistance to Lateral, Anterolateral, Posterolateral, Inferior, and Superior Loading Conditions Brian Suntay 1 , Kevin Moorhouse 2 , Ajit Chaudhari 1 , John Borstad 1 , John Bolte IV 1 1 The Ohio State University, 2 National Highway Traffic Safety Administration -0.5 0 0.5 1 1.5 2 2.5 -10 0 10 20 30 40 50 60 70 Displacement (mm) Force (N) Subject 1 Subject 2 Subject 3 Subject 5 Subject 6 -20 0 20 40 60 80 -20 0 20 40 60 80 100 120 140 Displacement (mm) Force (N) Subject 1 Subject 2 Subject 3 -5 0 5 10 15 20 25 -5 0 5 10 15 20 25 Displacement (mm) Force (N) Subject 1 Subject 2 Subject 3 Subject 4 Subject 5 Subject 6 -1 0 1 2 3 4 5 -10 0 10 20 30 40 50 Displacement (mm) Force (N) Subject 1 Subject 2 Subject 3 Subject 4 Subject 5 Subject 6 -5 0 5 10 15 -5 0 5 10 15 20 25 Displacement (mm) Force (N) Subject 1 Subject 2 Subject 3 Subject 4 Subject 5 Subject 6 Figure 1. Force applicator and guide that can be adjusted to the four desired directions. Figure 3. (Top) Subject 3 seated on the bench. Force applicator and guide set to the medial/lateral direction; (Bottom Left) Close up view of subject 3 upper arm reflector cluster, acromion marker, manubrium marker, and anterior deltoid and biceps brachii EMG electrodes; (Bottom Right) Close up view of the posterior shoulder of subject 3. Results and Discussion Figure 2. Electrode placement: latissimus, trapezius, deltoid, biceps, pectoralis. Figure 4. Plot of force vs. deflection for the purely medial loading condition. Figure 5. Plot of force vs. deflection for the inferior loading condition. Figure 6. Plot of force vs. deflection along the x-axis for the posteromedial loading condition. Figure 7. Plot of force vs. deflection along the y-axis for the posteromedial loading condition. Figure 8. Plot of force vs. deflection along the x-axis for the anteromedial loading condition. LAT INF PM PM AM Y-Axis Z-Axis X-Axis Y-Axis X-Axis Subject 1 20.58 1.616 3.519 10.33 1.769 Subject 2 26.32 1.318 2.416 9.209 2.041 Subject 3 17.41 0.9067 1.383 8.455 1.430 Subject 4 1.545 12.16 1.392 Subject 5 19.87 1.783 9.250 1.263 Subject 6 17.40 0.7784 2.834 0.9818 Table 1. Stiffnesses (N/mm) for the subjects’ shoulders calculated as the slope of the linear fit to the force-displacement curves. Stiffnesses were calculated for the shoulders for each of the loading conditions. The response of each subject’s shoulders appear to follow a similar pattern. The force- displacement curves of the shoulders appear to be almost linear and there is little variation in the stiffness of each subject’s shoulder, with the exception of subject 6. The inferior loading condition data for subjects 4-6 has not yet been processed. An abnormal curve was observed in subject 4’s lateral data and was omitted. The abnormality of the curve’s shape might be due to an error in the tracking of the reflective markers. Conclusion The method for quasi-statically and noninvasively measuring the force-displacement characteristics of the shoulder seems promising. However, more subjects need to be tested before moving on to pediatric subjects. References 1.Brown, J. K., Jing, Y., Wang, S., & Ehrlich, P. F. (2006). Patterns of severe injury in pediatric car crash victims: Crash Injury Research Engineering Network database. Journal Of Pediatric Surgery, 41(2), 362-367. 2.Klinich, K. D., & Burton, R. W. (1993). Injury patterns of older children in automotive accidents. 3.Neale, M. S., Hardy, B. J., & Lawrence, G. J. L. (2005). Development and evaluation of a biofidelic shoulder for the IHRA (JARI) pedestrian model. 4.Franklyn, M., Peiris, S., Huber, C., & Yang, K. H. (2007). Pediatric material properties: a review of human child and animal surrogates. Critical Reviews in Biomedical Engineering, 35(3-4), 197-342.

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Page 1: Characterization of the Pediatric Shoulder’s …ibrc.osu.edu/wp-content/uploads/2013/12/Suntay_OSBMEC.pdfIntroduction Motor vehicle crashes, especially side impacts, are a leading

IntroductionMotor vehicle crashes, especially side impacts, are a leading cause of death and disability to the

pediatric population as they account for approximately 50% of pediatric trauma [1]. Sixteen percent

of children were non-fatally injured while 32% of children have died as a result of vehicle side

impacts [2]. According to the Crash Injury Research Engineering Network (CIREN), children

involved in side impact crashes are more likely to suffer severe injuries to the head and thorax [1].

The placement of the head and thorax during impact has been shown to be heavily dependent on the

response of the shoulder mechanism [3].

Due to the need to increase safety in automobiles, the automotive community has been actively

researching methods to prevent injury during car accidents. Potential improvements must first be

tested to verify that they reduce injury. This is done through the use of anthropomorphic test

devices (ATDs), which provide a method for analyzing the injuries involved in a vehicle crash [1].

However, the data used to design pediatric ATDs is derived and scaled from adults and animal

surrogates and it is uncertain whether they are accurate for the child population [4]. In addition, the

dynamic response of the pediatric shoulder, which plays an important role in the response of the

head and neck during impact, has not been researched and modeled into pediatric ATDs.

…………………………………….

Objectives• Perform quasi-static, noninvasive shoulder displacements on adult volunteers to define the

adult shoulder’s stiffness

• Perform quasi-static shoulder stiffness testing and dynamic, noninvasive impacts on adult post

mortem human subjects

• Perform quasi-static shoulder stiffness testing on pediatric volunteers

• Define a correlation between quasi-static and dynamic stiffnesses and find the pediatric shoulder’s

response to dynamic loading conditions

MethodsThe right shoulders of six adult volunteers were quasi-statically displaced in four directions:

medially, anteromedially, posteromedially, and inferiorly. A combination of motion testing using a

point-cluster technique to measure 6-degree-of-freedom motion of the shoulder; resistive loading

using a load cell to measure the shoulder’s resistance to quasi-static loading; and electromyography

(EMG) recordings to measure the activation of the shoulder muscles during loading was utilized.

In each subject, reflective markers were placed on the upper right arm, both acromions, the

manubrium, and the medial and lateral epicondyles of the right elbow. Surface electrodes were

applied to the latissimus dorsi, upper trapezius, anterior and posterior deltoids, biceps brachii, and

pectoralis major. The right shoulders of each subject were quasi-statically displaced using a hand-

held force applicator. A load cell attached to the applicator recorded the forces during the motion

while an 8-camera Vicon motion capture system tracked and recorded the shoulder’s motion.

During the test, electrodes measured the activity of the shoulder muscles during loading.

……………………………

Characterization of the Pediatric Shoulder’s Resistance to Lateral, Anterolateral,

Posterolateral, Inferior, and Superior Loading Conditions

Brian Suntay1, Kevin Moorhouse2, Ajit Chaudhari1, John Borstad1, John Bolte IV1

1The Ohio State University, 2National Highway Traffic Safety Administration

-0.5 0 0.5 1 1.5 2 2.5-10

0

10

20

30

40

50

60

70

Displacement (mm)

Fo

rce

(N

)

Subject 1

Subject 2

Subject 3

Subject 5

Subject 6

-20 0 20 40 60 80-20

0

20

40

60

80

100

120

140

Displacement (mm)

Fo

rce

(N

)

Subject 1

Subject 2

Subject 3

-5 0 5 10 15 20 25-5

0

5

10

15

20

25

Displacement (mm)

Fo

rce

(N

)

Subject 1

Subject 2

Subject 3

Subject 4

Subject 5

Subject 6

-1 0 1 2 3 4 5-10

0

10

20

30

40

50

Displacement (mm)

Fo

rce

(N

)

Subject 1

Subject 2

Subject 3

Subject 4

Subject 5

Subject 6

-5 0 5 10 15-5

0

5

10

15

20

25

Displacement (mm)

Fo

rce

(N

)

Subject 1

Subject 2

Subject 3

Subject 4

Subject 5

Subject 6

Figure 1. Force applicator and guide that can

be adjusted to the four desired directions.

Figure 3. (Top) Subject 3 seated on the bench. Force applicator and guide set to the medial/lateral

direction; (Bottom Left) Close up view of subject 3 upper arm reflector cluster, acromion marker,

manubrium marker, and anterior deltoid and biceps brachii EMG electrodes; (Bottom Right) Close

up view of the posterior shoulder of subject 3.

Results and Discussion

Figure 2. Electrode placement: latissimus,

trapezius, deltoid, biceps, pectoralis.

Figure 4. Plot of force vs. deflection for the

purely medial loading condition.

Figure 5. Plot of force vs. deflection for the

inferior loading condition.

Figure 6. Plot of force vs. deflection along

the x-axis for the posteromedial loading

condition.

Figure 7. Plot of force vs. deflection along

the y-axis for the posteromedial loading

condition.

Figure 8. Plot of force vs. deflection along

the x-axis for the anteromedial loading

condition.

LAT INF PM PM AM

Y-Axis Z-Axis X-Axis Y-Axis X-Axis

Subject 1 20.58 1.616 3.519 10.33 1.769

Subject 2 26.32 1.318 2.416 9.209 2.041

Subject 3 17.41 0.9067 1.383 8.455 1.430

Subject 4 1.545 12.16 1.392

Subject 5 19.87 1.783 9.250 1.263

Subject 6 17.40 0.7784 2.834 0.9818

Table 1. Stiffnesses (N/mm) for the subjects’

shoulders calculated as the slope of the linear

fit to the force-displacement curves.

Stiffnesses were calculated for the shoulders

for each of the loading conditions.

The response of each subject’s shoulders appear to follow a similar pattern. The force-

displacement curves of the shoulders appear to be almost linear and there is little variation in

the stiffness of each subject’s shoulder, with the exception of subject 6. The inferior loading

condition data for subjects 4-6 has not yet been processed. An abnormal curve was observed in

subject 4’s lateral data and was omitted. The abnormality of the curve’s shape might be due to

an error in the tracking of the reflective markers.

ConclusionThe method for quasi-statically and noninvasively measuring the force-displacement

characteristics of the shoulder seems promising. However, more subjects need to be tested

before moving on to pediatric subjects.

References1.Brown, J. K., Jing, Y., Wang, S., & Ehrlich, P. F. (2006). Patterns of severe injury in pediatric car crash victims: Crash Injury Research

Engineering Network database. Journal Of Pediatric Surgery, 41(2), 362-367.

2.Klinich, K. D., & Burton, R. W. (1993). Injury patterns of older children in automotive accidents.

3.Neale, M. S., Hardy, B. J., & Lawrence, G. J. L. (2005). Development and evaluation of a biofidelic shoulder for the IHRA (JARI)

pedestrian model.

4.Franklyn, M., Peiris, S., Huber, C., & Yang, K. H. (2007). Pediatric material properties: a review of human child and animal surrogates.

Critical Reviews in Biomedical Engineering, 35(3-4), 197-342.