Open Purchase orders - holds the commitments from the financial side

If the Purchase orders are not closed for past years 2014 onwards. In my opinion it holds up the commitments. Hence it is very important to close Purchase orders inorder to  release commitments.

Please confirm if this is correct, and which is the best report or query that displays the impact it has for old open Purchase orders, Do you know of an integrity report that can be run inorder to have buyers close out the POs on time. Please help. Thank you