Marseille man Ekongolo suffered fractured knees in a car crash in Yaounde on Friday.
On Monday, Cameroon tweeted their support for the defender, before announcing that Galatasaray's Chedjou had been called up as a replacement.
Chedjou played a key part in World Cup qualification for the finals in Brazil, and featured against both Mexico and Croatia at the tournament.
He was not included for any of the AFCON qualifiers, but has now been called into Volker Finke's 24-man party, which will have to be cut by one before the finals get underway in Equatorial Guinea on January 17.
Cameroon, four-time winners of the competition, have been drawn in Group D alongside Mali, Guinea and the Ivory Coast.
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