I recall a similar DC 9 / MD incident many years ago. The pre takeoff control check was completed at the hold; take off clearance was given to 'quickly' follow the departing aircraft, such that the departing jet blast disturbed debris / stones which jammed the elevator which was not detected until rotate.
Follow-on activity including the need for a control check after lining up, and advice as to detect a jammed elevator, vice servotab, in a free moving system.
There may have been regulatory change re ability to fly with one side jammed ( elevator or tab? ) and the need / operation of an automatic control split to continue flight - again a split system may only account for a servotab jam depending on design