Hi,
SEP report can only show count. The best way is to pull the logs for the computer which are running with the old definitions and select those computer and update the virus definitions from the SEPM console.
To pull the logs,
1.Open SEPM console
2.click on
Monitors Tab .
3.Select Log type - Computer status.
4.Time range - Current Month.
5.Below that you can see the definition date, select the date which you want.
Now click on the view logs. Now you can see the list of the computers and it's detail discription.
From the results you can select the all computer and run Update content command.
You can see the command results on Command status tab.