The 31-year-old Japanese rider suffered his injury when he fell while training on a motocross bike at a Barcelona circuit in January.
His recovery is taking longer than expected, and MotoGP specialist Dr Xavier Mir has advised him to keep it unstressed for a further week in order to speed the healing process.
That could compromise his participation in the first test of the season, which runs from February 3-4 for CRTs only and then for a further three days with the MotoGP prototypes.
CRT squad Avintia confirmed Aoyama as a full-time rider in 2013 in November last year.
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