visual3d:tutorials:kinematics_and_kinetics:foot_and_ankle_angles
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| visual3d:tutorials:kinematics_and_kinetics:foot_and_ankle_angles [2024/07/17 15:23] – sgranger | visual3d:tutorials:kinematics_and_kinetics:foot_and_ankle_angles [2025/03/04 19:06] (current) – [Create 3 projected landmarks] wikisysop | ||
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| ===== Purpose ===== | ===== Purpose ===== | ||
| - | 1. Discuss the minimal marker placement for a single segment foot\\ | + | 1. Discuss the minimal marker placement for a single segment foot: **[[# |
| + | 2. Discuss the right-hand rule and its application to defining joint angles: **[[# | ||
| - | **[[#Foot_Segment_-_Marker_Placement|Foot Segment | + | 3. Create a simple foot definition which can be used for kinetic calculations: |
| - | 2. Discuss the right-hand rule and its application | + | 3. Use three different methods |
| + | **[[# | ||
| - | **[[#Ankle_Angle_Explained|Ankle Angle Explained]]**\\ | + | **[[#Virtual_Foot_Method_2_-_Normalize_to_Proximal_Segment|Method 2 - Normalized to proximal segment]]** |
| - | 3. Create a simple foot definition which can be used for kinetic calculations\\ | + | **[[# |
| - | + | ||
| - | + | ||
| - | **[[# | + | |
| - | + | ||
| - | 3. Use three different methods to define the foot for kinematic calculations: | + | |
| - | + | ||
| - | + | ||
| - | [[# | + | |
| - | + | ||
| - | [[# | + | |
| - | + | ||
| - | [[# | + | |
| ===== Discussion ===== | ===== Discussion ===== | ||
| - | There are many ways to define the foot. With a simple single segment foot, two feet are often used.\\ | + | There are many ways to define the foot. With a simple single segment foot, two feet are often used: |
| 1) The first foot is used for kinetic calculations, | 1) The first foot is used for kinetic calculations, | ||
| 2) The second foot (often referred to as Virtual Foot) is used for kinematic calculations. The segment coordinate system of the kinematic foot is defined in such a way that the joint angle has a more clinically relevant meaning.\\ | 2) The second foot (often referred to as Virtual Foot) is used for kinematic calculations. The segment coordinate system of the kinematic foot is defined in such a way that the joint angle has a more clinically relevant meaning.\\ | ||
| - | |||
| There is no set definition of neutral ankle angle, but neutral is approximately when the foot is flat on the floor and the shank segment is vertical. Since the angle joint and toe target are not parallel to the floor, an initial offset is introduced in the ankle angle. The segment coordinate system of the kinematic foot is defined to remove this initial offset and create a more clinically relevant ankle joint angle. | There is no set definition of neutral ankle angle, but neutral is approximately when the foot is flat on the floor and the shank segment is vertical. Since the angle joint and toe target are not parallel to the floor, an initial offset is introduced in the ankle angle. The segment coordinate system of the kinematic foot is defined to remove this initial offset and create a more clinically relevant ankle joint angle. | ||
| - | This tutorial will explain 3 ways to define a kinematic only foot. Keep in mind, there is no default Visual3D foot definition, and the correct definition is dependent on your laboratory' | + | This tutorial will explain 3 ways to define a kinematic only foot. Keep in mind, there is no default Visual3D foot definition, and the correct definition is dependent on your laboratory' |
| Note that although segments are defined using different proximal and distal landmarks, all segments are tracked using the same targets (RFT1, RFT2, RFT3). Also, since these feet are kinematic only, the radius is irrelevant and can be set to 0.1. | Note that although segments are defined using different proximal and distal landmarks, all segments are tracked using the same targets (RFT1, RFT2, RFT3). Also, since these feet are kinematic only, the radius is irrelevant and can be set to 0.1. | ||
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| ===== Foot Segment - Marker Placement ===== | ===== Foot Segment - Marker Placement ===== | ||
| - | | | + | |__**The minimal useful marker set is as follows: |
| The **placement of the calcaneous marker** is then very important. The height of the calcaneous marker relative to the height of the toe marker defines dorsi-plantar flexion in the standing posture. Medial lateral placement of the calcaneous marker is important because the sagittal plane of the foot is defined by the calcaneous marker, the toe marker, and the virtual ankle center. | The **placement of the calcaneous marker** is then very important. The height of the calcaneous marker relative to the height of the toe marker defines dorsi-plantar flexion in the standing posture. Medial lateral placement of the calcaneous marker is important because the sagittal plane of the foot is defined by the calcaneous marker, the toe marker, and the virtual ankle center. | ||
| - | \\ | ||
| + | CA< | ||
| + | ST< | ||
| + | SMH< | ||
| + | VMH< | ||
| + | VMB< | ||
| + | PM< | ||
| + | FMB< | ||
| + | SMB< | ||
| - | CA< | ||
| - | ST< | ||
| - | SMH< | ||
| - | VMH< | ||
| - | VMB< | ||
| - | PM< | ||
| - | FMB< | ||
| - | SMB< | ||
| * As previously mentioned, Visual3D does not have a default marker set or segment definition. It is therefore important to keep in mind that the marker set and segment definitions described in this tutorial as solely provided as an example. There are a number of alternatives for marker placement and segment definition. | * As previously mentioned, Visual3D does not have a default marker set or segment definition. It is therefore important to keep in mind that the marker set and segment definitions described in this tutorial as solely provided as an example. There are a number of alternatives for marker placement and segment definition. | ||
| ==== Create a Kinetic Right Foot Segment ==== | ==== Create a Kinetic Right Foot Segment ==== | ||
| + | This is a simple representation of the foot that is adequate for many of the Kinematic and Kinetic calculations in Visual3D. It is not, however, adequate for the calculation of the ankle joint angle. | ||
| - | This is a simple representation of the foot that is adequate for many of the Kinematic and Kinetic calculations in Visual3D. It is not, however, adequate for the calculation of the ankle joint angle. | + | If using the **Sample Data** |
| - | |**1. Create the Right Foot Segment:**\\ \\ < | + | |**1. Create the Right Foot Segment:**|In the **Segments** tab, select //Right Foot// in the Segment Name box.\\ Click on the **Create Segment** button| |
| + | |**2. In the Right Foot tab, Enter these values**|**Define Proximal Joint and Radius | ||
| + | |**3. Click on Build Model and Close Tab before proceeding**|A 3D image of a foot will appear distal to the shank.| | ||
| + | |{{: | ||
| ===== Virtual Foot Method 1 - Heel to Toe ===== | ===== Virtual Foot Method 1 - Heel to Toe ===== | ||
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| In this tutorial we consider the Ankle Joint Center to be the distal end of the shank segment: | In this tutorial we consider the Ankle Joint Center to be the distal end of the shank segment: | ||
| - | |**1. Create Right Ankle Joint Center (RAJC):**\\ \\ < | + | |**Create Right Ankle Joint Center (RAJC):**| |
| - | + | |Click the **Landmarks** | |
| - | |**2. Create Right Toe Joint Center (RTOE) at the same height as the heel marker:**\\ \\ < | + | |{{:RAJC.jpg}}| |
| + | |**Create Right Toe Joint Center (RTOE) at the same height as the heel marker:**| | ||
| + | |Click **Landmarks** button and then select **Add New Landmark**|**Landmark Name:** RTOE\\ **Define Orientation Using: | ||
| + | |{{: | ||
| \\ | \\ | ||
| Once the Ankle Joint Centers have been created, the Foot segments can now be defined. | Once the Ankle Joint Centers have been created, the Foot segments can now be defined. | ||
| Line 102: | Line 95: | ||
| Note: This definition assumes that the heel, toe, and ankle center define the sagittal plane of the foot. Care must be taken to place the heel marker carefully. Any medial/ | Note: This definition assumes that the heel, toe, and ankle center define the sagittal plane of the foot. Care must be taken to place the heel marker carefully. Any medial/ | ||
| - | |**3. Create Right Virtual Foot Segment: | + | |**3. Create Right Virtual Foot Segment: |
| ==== Rotating the Virtual Foot Segments ==== | ==== Rotating the Virtual Foot Segments ==== | ||
| Line 116: | Line 109: | ||
| Note: this definition assumes that the posture in the standing trial is to be considered an ankle angle of zero degrees regardless of the actual posture. | Note: this definition assumes that the posture in the standing trial is to be considered an ankle angle of zero degrees regardless of the actual posture. | ||
| - | |**6. Create Right Virtual Foot Segment: | + | |**6. Create Right Virtual Foot Segment: |
| **NOTE** Since the two segment coordinate systems are perfectly aligned the segments have identical orientation in the standing trial and hence have a joint angle of zero degrees.\\ | **NOTE** Since the two segment coordinate systems are perfectly aligned the segments have identical orientation in the standing trial and hence have a joint angle of zero degrees.\\ | ||
| Line 140: | Line 133: | ||
| Create 3 landmarks (RLA_Floor, RMA_Floor, RFT1_Floor) that are the projection of the 3 markers used to define the foot onto the floor. | Create 3 landmarks (RLA_Floor, RMA_Floor, RFT1_Floor) that are the projection of the 3 markers used to define the foot onto the floor. | ||
| - | |**1. Create RLA_Floor: | + | |**1. Create RLA_Floor: |
| - | |**2. Create RMA_Floor: | + | |**2. Create RMA_Floor: |
| - | |**3. Create RFT1_Floor: | + | |**3. Create RFT1_Floor: |
| ==== Create the Virtual Foot Segment ==== | ==== Create the Virtual Foot Segment ==== | ||
visual3d/tutorials/kinematics_and_kinetics/foot_and_ankle_angles.1721229833.txt.gz · Last modified: 2024/07/17 15:23 by sgranger