The scans revealed Johnson has a slight strain in the medial ligament, which is likely to see him sidelined for 3-4 weeks.
Johnson injured his knee during the first quarter of the Tigers' loss to the Swans on Sunday.
Johnson has been in excellent form this season and is ranked in the top five Richmond players for disposals, handballs and tackles after 10 rounds.
Johnson sidelined with knee injury
Richmond skipper Kane Johnson will miss the next 3-4 weeks with a knee injury.