A cannula assembly for use in robotic surgery is disclosed that includes a robotic cannula having a housing with an open end and a tubular portion extending distally from the housing, the tubular portion being dimensioned to accommodate passage of a surgical instrument having a 12 mm diameter, an adapter assembly configured for engagement within the open end of the cannula housing and including a tubular body with a passage supporting a primary seal dimensioned to accommodate passage of a surgical instrument having a 12 mm diameter, and an insert tube dimensioned to extend through the passage of the body portion of the adapter assembly and the tubular portion of the robotic cannula, the insert tube including a head portion with a passage supporting a secondary seal dimensioned to accommodate a surgical instrument having an 8 mm diameter.
