Midfielder Green, who has had operations on broken fingers and a fractured metatarsal already this season, had his troublesome shoulder fixed on Tuesday.
Defender Leacock, who has been out since early November with a persistent groin problem, also went under the knife and another midfielder Zadkovich had a groin operation in his native Australia.
Only last week, forward Steve Davies had a screw inserted in his foot to help repair a damaged metatarsal and he, along with midfielder Miles Addison (foot), Green, Leacock and Zadkovich, is out for the rest of the season.
Manager Nigel Clough is hopeful that all five players will be fit for the start of pre-season training in July.
"I think they will be okay in time," he said. "Miles' foot injury is probably less straightforward than the others and we have to be careful with Dean purely because of the length of time he has been out."