Dr Creaney trained in the London Deanery at various hospitals including The Royal London, The Royal National Orthopaedic Hospital in Stanmore, The Olympic Medical Institute, Pure Sports Medicine and DMRC Headley Court which is a military rehabilitation hospital.
Upon becoming a Consultant in 2009 Dr Creaney worked in Sheffield before taking a substantive consultant post at University Hospital Birmingham. This NHS hospital also serves as the main Royal Centre for Defence Medicine (RCDM) where injured soldiers are treated. Dr Creaney has worked as a doctor in elite sport with rugby teams and as a medical officer at the Commonwealth Games in Manchester (2002), World Student Games in Bangkok (2007), UK Schools Games (2008) and the London Olympics (2012).
Since 2005, Leon has served as a team and event doctor with UK Athletics and has travelled with teams to Jordan, Czech, Moscow, Lithuania and Rieti, Italy.