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This section describes Plug-in Gait upper body modeling, so you can determine if an upper body model will provide the data you require for your clinical analysis.

The following topics are covered:

For details about the labeling skeleton templates to be used with Plug-in Gait upper body models, see Plug-in Gait labeling skeleton templates (VSTs) in Vicon Nexus.

Outputs from Plug-in Gait upper body model

Use a Plug-in Gait upper body model if you require the kinematic and kinetic calculation outputs listed in the following table. The output variables are prefixed by the appropriate context (L for left or R for right).

Output

Description

Kinematics:

Angles

ElbowAngles

Relative. The angles between the upper arm and the forearm.

HeadAngles

Absolute. The angles between the head and the laboratory coordinate system.

NeckAngles

The angles between head relative to thorax.

ShoulderAngles

Relative. The angles between the upper arm and the thorax.

SpineAngles

The angles between the thorax relative to the pelvis.

ThoraxAngles

Absolute. The angles between the thorax and the laboratory coordinate system.

WristAngles

Relative. The angles between the forearm and the hand.

Kinetics:

Forces

ElbowForce

The force between the upper arm and the forearm.

NeckForce

The force between the head relative to thorax.

ShoulderForce

The force between the upper arm and the thorax.

WristForce

The force between the forearm and the hand.

Moments

ElbowMoment

The moment between the upper arm and the forearm.

NeckMoment

The moment between the head relative to thorax.

ShoulderMoment

The moment between the upper arm and the thorax.

WristMoment

The moment between the forearm and the hand.

Powers

ElbowPower

The power between the upper arm and the forearm.

NeckPower

The power between the head relative to thorax.

ShoulderPower

The power between the upper arm and the thorax.

WristPower

The power between the forearm and the hand.

 

Marker sets for Plug-in Gait upper body modeling

The marker set for Plug-in Gait upper body modeling includes markers for the head, torso, and upper limbs.
There are two variations of the standard marker set for the upper body model:

  • Additional upper arm (UPA) and forearm (FRM) markers
  • No UPA and FRM markers

The UPA and FRM markers are optional; however, using them improves marker tracking during dynamic trials.

Marker placement for Plug-in Gait upper body model

The following images show front, back, and side views to demonstrate where to attach the upper body markers to your patient. You do this before capturing a static trial as described in the Vicon Nexus User Guide. Some markers are shown from two views to help you better determine their position on your patient.

Important

As shown in the following images, some asymmetry is desirable as it helps the auto labeling routine distinguish right from left. For upper body modeling, you can place the UPA and FRM markers asymmetrically. Similarly, avoid symmetrical placement of marker clusters or groups of markers and also ensure markers are asymmetrical within each cluster/group.


The following image shows the front view. The left upper body markers are not labeled; attach markers on that side in a similar way to those on the right (with some asymmetry as described above).

The following image shows the back view. The right upper body markers are not labeled; attach markers in a similar way to those on the left (with some asymmetry as described above).

The following image shows the right side view. The left side view is not shown; attach markers on that side in a similar way to those on the right (with some asymmetry as described above).

The following tables list the markers defined in Plug-in Gait templates for upper body modeling and describe where to place them on the patient:

Head markers

The following table describes the markers positioned on the patient's head. To save time, many users buy a headband and permanently attach markers to it.

Marker label

Definition

Position on patient

LFHD

Left front head

Left temple

RFHD

Right front head

Right temple

LBHD

Left back head

Left back of head (defines the transverse plane of the head, together with the frontal markers)

RBHD

Right back head

Right back of head (defines the transverse plane of the head, together with the frontal markers)

Important

If the back markers cannot be placed level with the front markers, you must configure Plug-in Gait to compensate for this during the subject calibration process. To do this, in the Properties for the Process Static Plugin Gait Model pipeline operation, under Assume Horizontal, select Head.

Torso markers

The following table describes the markers positioned on the patient's torso. The torso markers (C7, T10, CLAV, STRN) define the thorax sagittal plane; therefore, their lateral positioning is most important.

Marker label

Definition

Position on patient

C7

7th cervical vertebra

On the spinous process of the 7th cervical vertebra

T10

10th thoracic vertebra

On the spinous process of the 10th thoracic vertebra

CLAV

Clavicle

On the jugular notch where the clavicles meet the sternum

STRN

Sternum

On the xiphoid process of the sternum

RBAK

Right back

Anywhere over the right scapula
(This marker has no equivalent marker on the left side. This asymmetry helps the autolabeling routine determine right from left on the subject. Placement is not critical as it is not included in the Plug-in Gait model calculations.)

Upper limb markers

The following table describes the markers positioned on the patient's upper body.

Marker labels shown with an asterisk * are optional; however, using them improves marker tracking during dynamic trials.

Marker label

Definition

Position on patient

Left upper limb markers

LSHO

Left shoulder

On the acromio-clavicular joint

*LUPA

Left upper arm

On the upper lateral 1/3 surface of the left arm (Place asymmetrically with RUPA)

LELB

Left elbow

On the lateral epicondyle

*LFRM

Left forearm

On the lower lateral 1/3 surface of the left forearm (Place asymmetrically with RFRM)

LWRA

Left wrist marker A

At the thumb side of a bar attached to a wristband on the posterior of the left wrist, as close to the wrist joint center as possible. Loose markers can be used but for better tracking of the axial rotations, a bar is recommended.

LWRB

Left wrist marker B

At the little finger side of a bar attached to a wristband on the posterior of the left wrist, as close to the wrist joint center as possible. Loose markers can be used but for better tracking of the axial rotations, a bar is recommended.

LFIN

Left finger

Just proximal to the middle knuckle on the left hand

Right upper limb markers

RSHO

Right shoulder

On the acromio-clavicular joint

*RUPA

Right upper arm

On the lower lateral 1/3 surface of the right arm (Place asymmetrically with LUPA)

RELB

Right elbow

On the lateral epicondyle approximating the elbow joint axis

*RFRM

Right forearm

On the lower lateral 1/3 surface of the right forearm (Place asymmetrically with LFRM)

RWRA

Right wrist marker A

At the thumb side of a bar attached symmetrically with a wristband on the posterior of the right wrist, as close to the wrist joint center as possible

RWRB

Right wrist marker B

At the little finger side of a bar attached symmetrically with a wristband on the posterior of the right wrist, as close to the wrist joint center as possible

RFIN

Right finger

Just below the middle knuckle on the right hand