---
title: "Updating the joints in the VST"
canonical: "https://help.vicon.com/space/ProCalc16/12649859/Updating%20the%20joints%20in%20the%20VST"
format: markdown
---
Several of the default labeling templates, including the one that is supplied for CGM2.3, use a hinge joint (a single degree-of-freedom joint) at the knee. Hinge joints work well to constrain the VST when it’s used for labeling only, but because CGM uses a ball joint (three degrees of freedom) for all joints, you must update the labeling template (VST) to use ball joints.


    **To update the joints in a VST:**


1. Load a static trial and create a new subject based on the labeling template.
2. Reconstruct and label the static trial.
3. Run a **Kinematic Fit** operation on the trial.  
The current segments and joints are fitted to the marker data.
4. In the **Subjects Resources** pane, expand the subject node and then expand the **Joints** node to display the joints in the template.
  The hinge joints are clearly labeled with a **1** symbol.
5. Select the hinge joints, then right-click and select **Unlink Joint**.   
The symbols change from 1 to 6 to indicate that the hinge joints have been replaced with 6-degree of freedom joints:
6. Re-link these joints using the **Link Segments** tool in the Labeling Template Builder. To do this, on the **Subject Preparation Tools** pane, in the **Labeling Template Builder** section, select **Ball Joint** and click **Link**:
  A tip next to the mouse pointer prompts you to select the parent segment.
7. In the **Subjects Resources** pane, expand the **Segments** node of the subject.
8. Click on the **L_Femur** segment to select it.   
You are prompted to select the child segment.
9. Click on the **L_Tibia** segment.   
The list of joints now shows that the **L_Femur_L_Tibia** joint is now a ball joint with the symbol **3**.
10. Repeat Steps 8-9 for the right side.
11. Right-click the subject and select **Save Labeling Skeleton as Template**.
12. Select a new name for the template, then save.   
The template has now been updated with ball joints instead of hinge joints for the knees.