Multiselect Listbox On User Form

I have created a user form with a multiselect listbox. The user form displays a checkbox to the left of each ListBox item that can be selected. Once selected the user clicks the SAVE button on the user form and the results are stored in a single cell on an excel workbook. The user form contains several other buttons that allow the user to view the NEXT and PREV records stored on the excel worksheet. If a checkmark is placed next to the option Shear and the Save button clicked, the word Shear would be recorded in the 7th column, current row of the worksheet. If the user checks several boxes like: Flexion and Lateral Bending, the 7th column of that row would store Flexion; Lateral Bending. The macro inserts a semicolon space between multiple selected items.

When the user clicks the PREV or NEXT button on the user form to go an existing record I am having difficulty getting the correct checkboxes to be selected to reflect the contents of the 7th column, current row. The ListBox control is named GeneralInjuryMechanisms. The code that I currently have for this section of the macro is as follows:

Dim strInput As String, strOutput As String
Dim varZz As Varient, i As Integer
GeneralInjuryMechanisms.Clear 'Clear the existing ListBox options
AddRegionalMechanisms 'Recreate ListBox options based on current record in column 7
strInput = Cells(r, 7).Value ' i.e. cell on worksheet with Flexion; Lateral Bending
varZz = Split(strInput, "; ") 'create array of values using "; " as delimiter.
For i = LBound(varZz) To UBound(varZz) ' loop through values...................