Arnette is being evaluated but the rookie is looking at a potential month-and-a-half absence and a stint on injured reserve.
The former Ohio State defender had been playing through the injury and started each of the first three games for the Raiders.
Arnette, 23, was a three-year starter at Ohio State and earned second-team All-Big Ten honors last season before being selected by the Raiders with the No. 19 pick in the draft.
Arnette signed a projected four-year, $13,418,540 rookie contract that includes a $7,318,938 signing bonus. The contract includes a fifth-year for the Raiders to pick up for the 2024 season.
In 2020, Arnette has appeared in three games for the Raiders and recorded 12 total tackles and one pass defense.