Buxton had a scan on his knee earlier this week and also visited a specialist to establish the extent of the problem.
The results of the scan have confirmed Buxton, who scored his fourth goal of the season in the victory over Leeds, will be out until mid-February.
The loss of Buxton comes as a further blow to Rams manager Nigel Clough, who has already seen club captain Shaun Barker ruled out for the entire season with a long-term knee injury.































