Dickens becoming the sixth first team regular to be ruled out with injury and Leeds Tykes boss Phil Davies will now welcome 24-year-old Natal Sharks scrum-half Ryan Walker from South Africa and 22-year-old loose head prop Steve Millard from London Welsh.
Walker was part of the Natal Sharks development squad that toured England last winter and was understudy to Springbok Craig Davidson at the Sharks.
Millard actually spent pre-season with the Tykes before returning to London Welsh where he has played for 18 months.