The 29-year-old suffered the problem over the summer but was still expected to be fit in time for the start of the season.
Manager Nigel Adkins was delighted to see Kebe finally back on the training ground but does not yet know when he will be fit for selection.
"Jimmy's been on the training ground, involved with the first team this week and he's trained very hard," Adkins told the club website.
"It's a good progression for him. Hopefully he's going to be back available for me to select very soon."