The 30-year-old had been recruited to fill the role left by the departure of former United under-18 boss Paul McGuinness. McKenna is set to officially start his role on Monday, but had already started working at Carrington on Thursday.
McKenna had started out his playing career with Enniskillen United in his native Northern Ireland before joining Tottenham, but was forced to retire early after picking up a persistent hip problem.
He is viewed as one of England’s best up-and-coming coaches and this move is undoubtedly a coup for United, who are looking to restore their academy to its former high standards, churning out talented players for the senior side at an unmatched rate.
At Spurs, McKenna guided the under-18 side to the semi-finals of the FA Youth Cup in 2015, impressing fans and fellow coaches alike by admitting that winning matches was not the priority for him at youth level.
Instead, he said that his priority was to get his players to the level where they needed to be in order to make the transition up to Mauricio Pochettino’s first-team plans, as well as looking for ‘standout players’ to fit the manager’s style of play.
United could benefit from such a meticulous approach, with the likes of Marcus Rashford and Timothy Fosu-Mensah having already made the giant leap from under-18 level to first-team action in the space of a season last term.