Freehand Ultrasound to Evaluate Scapular Kinematics in People With Paraplegia

Specific Aims:

Aim 1: Compare the freehand ultrasound (FUS) and skin-based markers methods with a
well-established and accurate dynamic biplanar fluoroscopy combined with model-based tracking
techniques to evaluate scapular kinematics.

Hypothesis 1: Throughout the arm elevation and weight relief raise, FUS measurements will
have lower standard error of measurement, greater intra-rater repeatability, and better
agreement with biplanar fluoroscopy techniques than skin-based method for scapular tilting,
upward rotation, and external rotation.

Aim 2: Establish the convergent validity of FUS and skin-based markers method by describing
the relationship between scapular kinematics and established measures of shoulder pain and
pathology.

Hypothesis 2: Individuals with paraplegia diagnosed with more severe shoulder pain and signs
of shoulder pathology will have reduced scapular posterior tilt, upward rotation, and
external rotation during arm elevation and weight relief raise tasks compared to those with
less shoulder pain and pathology.

Aim 3: Characterize the effect of lesion level on scapular behavior during arm elevation and
weight relief raise tasks.

Hypothesis 3: When compared to individuals with low-level paraplegia, individuals with
high-level paraplegia will have decreased posterior tilt, upward rotation, and external
rotation during arm elevation and weight relief raise tasks.

Study Procedure

- Human Subjects Ten individuals with paraplegia aged from 18 to 65 years old will be
recruited for Aim 1, 2, and 3. An additional 30 individuals with paraplegia will be
recruited for Aim 2 and 3. The participants will be dichotomized between high-level
group (at T7 and above) and low-level group (below T7).[3] Inclusion Criteria include
the level of your spinal cord injury is determined as paraplegia more than one year ago.
Use the manual wheelchair as the primary means of mobility (>80% of mobility). Subjects
do not have a history of fractures or dislocations in the shoulder from which they have
not fully recovered and do not have an implant/pacemaker in the torso and dominant arm,
Subjects with neurologic deficit in the arm will be excluded, as these would impact
scapular kinematics. Subjects with a history of traumatic injury to the upper limb that
has not fully recovered and those with syrinx or complex regional pain syndrome
involving the arms will be excluded as this could also affect our measures but be
unrelated to dynamic scapular movement. Subjects who have impaired cognition or
difficulty reading the informed consent will also be excluded. Based on literature and
our previous experience, we expect at least 50% of the SCI population to have shoulder
pain. We will determine the prevalence of shoulder pain as subjects are recruited.
Participants may be recruited through the research registry for the Center of
Rehabilitation Outcomes Research or Clinical Neuroscience Research Registry at
Rehabilitation Institute of Chicago.

- Methods and Procedures

General questionnaire Basic demographics including age, gender, height, weight will be
recorded. We will also record disability type, lesion level, motor scores (using the
International Standards for Neurological Classification), date of injury, and handedness.

Motion capture Participants will transfer to a customized chair equipped with an adjustable
guide bar in the sagittal, coronal, and scapular plane. The chair is designed to ensure
consistency in arm movement from rest to elevated positions. Height and depth-adjustable pads
and adjustable straps will provide supports to isolate the scapular kinematics and minimize
trunk movement. Participants will wear a slim-fit white tank top or remove their shirt to
allow for placing the markers on the trunk and dominant arm. Marker placement, determined by
the International Society of Biomechanics,[4] will include the following bony landmarks: C7,
T8, anterior sternoclavicular (sternum), xyphoid, acromion, lateral epicondyle, medial
epicondyle, and greater trochanter. These markers allow measurement of trunk and upper arm
movement during trials. A custom designed orthogonal attachment with markers allows tracking
of the US probe through space during scanning. A custom-made triangular triad, with three
reflective markers, will be attached to the flat superior bony surface of the acromion
process. For each subject, a static capture of all markers will be collected in the standard
anatomical neutral position to create the reference trial between the triad coordinate system
and scapular coordinate system determined by the markers placed on the acromial angle, root
of the scapular spine, and inferior angle. After the static capture, the markers on the
acromial angle, root of the scapular spine, and inferior angle will be removed. Triad
attachment will remain on the acromion process during the dynamic trial. Movement of the
subject and ultrasound probe will be collected using a motion capture system.

Freehand ultrasound technique One operator will perform all ultrasound scanning. Imaging will
consist of scanning of the scapula. Ultrasound video files will be collected during the
trial. Scapular scanning consists of positioning the ultrasound probe along the spine and
medial border of the scapula. The ultrasound probe will be fully contacted and manually held
on different points along the scapular spine and medial border during the dynamic trials.
Ultrasound gel is applied to the skin overlaying the scapula and the probe is oriented to
maintain visualization of the border of the scapula in the image.

Dynamic biplanar fluoroscopy and model based tracking technique Study will take place at the
Northwestern Memorial Hospital (NMH) where equipped a number of Siemens/Philips bi-planar
fluoroscopic imaging systems, managed by Dr. Ellen Kruk. The equipments include Siemens Artis
Zee biplane, Siemens Neurostar biplane, Philips Allura FD20 fluoroscopic imaging systems
located at interventional radiology. 64-sliced Siemens Definition or Sensation computer
tomography (CT) scanners or Siemens 3T magnetic resonance imaging (MRI) scanner will also be
utilized to obtain the bone models of humerus and scapula.

Procedures Ten participants will be tested for Aim 1, 2, and 3 in NMH and additional 30
participants will be tested for Aim 2 and 3 in Biodynamics and Muscle Fiber Laboratories at
Rehabilitation Institute of Chicago. For dynamic trial, each participant will perform arm
elevation (AE) and weight relief raise (WR) trials in a random order. For AE trial, subjects
will be in their own chairs. Subjects will elevate the arm from neutral to 150° in the
sagittal, coronal, and scapular plane (30° anterior to the frontal plane). Subjects will use
their own wheelchair during data acquisition for the WR trial, which entails lifting and
holding the buttocks off the seat with an elbow locked position.[5, 6] A metronome at a
frequency of 0.3 Hz will guide AE and WR trials. Once the subjects are on pace with the
metronome, the researcher will trigger the ultrasound and motion capture systems
simultaneously. Subjects will be given a rest period after each trial to prevent fatigue.
Three dynamic trials will be collected in each task. For testing Aim 1 in NMH, ten out of the
40 subjects will visit the department of interventional radiology at the NMH for the dual
fluoroscopy testing and a CT scan. The dual fluoroscopic imaging system may track the
shoulder joint while the subject performs arm elevation and weight relief push-up trials.

Arm elevation trials The participants may be in their own chair for performing the arm
elevation protocols. A guide bar will be placed in the sagittal, coronal, and scapular plane.
Prior to the start of the protocols, we will ask the participant to wear a slim-fit white
tank top or remove their shirt to allow for placing the motion sensors on the skin of the
participants' thorax, scapula, and upper arm. The participants will be asked to keep the
dominant arm by the side. Bony points of the shoulder will be marked. The ultrasound probe
will be used to sweep over the surface of the shoulder. The participants may be asked to stay
in this position while up to three readings (ultrasound scans). The participants will be then
asked to elevate the arm to a flexed position. Bony landmarks on the shoulder will be marked.
The ultrasound probe will be used to sweep over the surface of the shoulder while the
participants have risen and lowered the arm. The participants may also be asked to complete
similar motions while holding a weight. The participants can stop at any time if they
experience any pain. The participants will be provided rest periods to prevent fatigue. Video
cameras or photo cameras may be used to record scapular movement and the experiment setup.
The soft-tissue and bone surface around the glenohumeral joint and scapula will be monitored
with ultrasound during movement. These trials will take up to 60 minutes to complete.

Weight relief push-up trials The participants will be asked to keep both arms straight while
you push-up in your own chair. The participants may be asked to repeatedly hold the push-up
position while up to three readings (ultrasound scans). The ultrasound probe will be used to
sweep over the surface of the shoulder while performing the push-up. The participants can
stop at any time if they experience any pain. The participants will be provided rest periods
to prevent fatigue. These trials will take up to 60 minutes to complete.

The participants will have the optional to examine the scapular movement measured using
bi-planar fluoroscopy ⎯ a dynamic X-ray imaging device. The participants' shoulder joint
movement will be recorded during arm elevation and weight relief push-up. Before or after the
bi-planar fluoroscopic imaging, a research staff will send the subjects to NMH Radiology for
CT scan or Center for Translational Imaging for MRI scan. The CT/MRI scan will be used to
construct the scapular and humeral models and provide the position and orientation of the
bones. If feasible the same visit/day will include dual fluoroscopy performed at NMH.
Otherwise a second visit will be arranged for the fluoroscopy. A qualified radiology staff
from Department of Interventional Radiology will perform the dual fluoroscopy. This study
will compare the in vivo scapular movement between the FUS and biplanar fluoroscopy. Entire
protocol will last up to three hours. A urine pregnancy test will be done for woman subject
before the fluoroscopy test.

Shoulder pain and pathology measures We will evaluate shoulder pain using Wheelchair Users
Shoulder Pain Index (WUSPI): The WUSPI is a 15-item self-report instrument that measures
shoulder pain intensity in wheelchair users during various functional activities of daily
living, such as transfers, wheelchair mobility, dressing, overhead lifting, and sleeping. [7]
Each item is scored using a 10 cm visual analog scale anchored at the ends with the
descriptors of "no pain" and "worst pain ever experienced." Individual item scores are summed
to arrive at a total index score. The WUSPI is valid and reliable - test-retest reliability
of the total index score was 0.99 and Cronbach's alpha (internal consistency) was 0.98.[8] A
standardized physical examination has been previously used in our study and consists of
common clinical test such as palpation over the bicipital groove/biceps tendon, Neer
impingement test, Hawkin's-Kennedy test, and O'Brien's test for the labrum and
acromioclavicular joint.[9] For each item, the sign/symptom of pain is scored as either
absent (0), equivocally present (1), or definitely present (2).[9] Items are summed to create
a total score.

Inclusion Criteria:

- Above 18 years old

- Have paraplegia as a result of a spinal cord injury morn than one year;

- Able to perform push-ups independently and raise the arm above the head;

- Self-propel a manual wheelchair as the primary means of mobility

Exclusion Criteria:

- Have history of fractures or dislocations in the shoulder, elbow, or wrist from which
you have not fully recovered;

- Have upper limb pain as a result of a complex regional pain syndrome;

- Have a implant or pacemaker within the torso or upper arm;

- Pregnant female.