The sections below described how to:

Opening a Model

There are several ways to open a musculoskeletal model written in the OpenSim format (file type: .osim), described in the sections below:

From the File Menu 

you could either drag the file from the Windows Explorer and drop it on the Toolbar of the OpenSim application (if the application is already open) or you can use the File menu as described below.

  1. Click File → Open Model… from the OpenSim main menu bar. 

  2. In the window that appears, locate and select the desired model, and then click Open as shown in the figure above.

  3. After loading a model, its name will appear in the model drop down menu, located in the toolbar, and in the Navigator window.



If you want to open a model that you've loaded recently in the GUI, click File → Recent Files >. This will show a list of up to 10 most recently used models.

Drag and Drop

You can also open model files by dragging the file from the Windows Explorer (Windows) or Finder (Mac OS) and dropping it on the tool bar of the OpenSim GUI (shown in the image on the left).

Saving a Model

To save a copy of a model: 


There are several ways to save a model.

  1. To save a model to the file it came from, select File → Save Model... from the OpenSim main menu bar or Right Click on the model in the navigator and choose Save.
  2. To save a model to a new file, select File → Save Model... or Right Click on the model in the Navigator window and choose Save As... In the dialog box that appears, enter a name into the File name textbox, and then click Save.


  • If the model was loaded from a file created in an earlier version of OpenSim (3.3 or earlier) you will be warned before saving the model to a 4.0 file format as you will not be able to use earlier versions of OpenSim with the saved model file. Consider using Save As functionality if you don't want to modify your model file.





To save a model to the file it came from use File → Save Model... and OpenSim will save the current model in the application. You could also choose File → Save All to save all the models currently open in the application to disk.

Closing a Model

There are several ways to close a model:

  1. Right mouse click on the desired model and select Close.
  2. Navigate to the File menu and choose Close Model or Close All. Selecting Close Model will close the current model. Select Close All will close all loaded models.
  3. If you have made changes to the model, you'll be asked if you want to save or discard the changes.