​Oxford United summer signing Frankie Kent will miss the majority of the upcoming season after suffering an anterior cruciate ligament (ACL) injury.The U’s say defender Kent sustained the injury during a pre-season training session and has since undergone a successful operation.AdvertisementAdvertisementAdvertisementThe 30-year-old was Oxford’s only summer signing before they were placed under a transfer embargo by the English Football League earlier this month.Kent arrived at the Kassam as a free agent, having previously played for Hearts, Peterborough and Colchester United.The Oxford players and head coach Aaron Ramsey are currently in Spain as they step-up their preparations for the new League One season.They will open their campaign with an EFL Cup tie against Leyton Orient on 8 August before the League One season begins with a home match against MK Dons a week later.Oxford chairman apologises over transfer embargoOxford bring in former Hearts defender Kent