Leach hurt his knee twice while fielding during England's first test victory in Hyderabad and he missed the last two matches where India bounced back to take a 2-1 lead in the series.
"I'm going to have an operation to get the rest of the swelling out because it's not budging," Leach told BBC Radio 5 Live.
"It was quite an unfortunate one. It was the second ball of the first innings in the field, so that whole game I was playing with this knee problem.
"I obviously knocked it a few times throughout that game and it has just created a long period of recovery. I need to get the operation done and then hopefully I can get back to playing cricket."
England do not play another test series until the home summer when they host the West Indies in July, soon after the Twenty20 World Cup, while his county team Somerset begin their new season in April.
"I'd love to have a run of playing cricket and getting into a bit of a rhythm again and hopefully that can happen again once I've got this sorted," Leach added.
In Leach's absence, Shoaib Bashir has stepped up for the tourists in the first innings of the fourth test with figures of 4-84 so far as he ripped through the top order to restrict India to 219-7, trailing England by 134 runs.
