Abstract: Instrument systems for performing total ankle arthroplasties comprise an instrument adapter, a talus reaming guide and a talar trial system. The instrument adapter comprises a coupler for attaching to a robotic surgical arm, an extension arm extending from the coupler, a talus resection block attached to the extension arm, including a talus cutting guide surface, and an interface for receiving another instrument. The talus reaming guide comprises a second attachment member for coupling to the interface, and a reaming hoop for confining movement of a reamer. The talar trial system comprises a talar adapter for connecting to the interface, and a talar trial couplable to the talar adapter, the talar trial including a talar bearing surface. The talus resection block can serve as a universal instrument adapter for mounting the talus reaming guide, the talar trial system and a tibia resection block for performing a total ankle arthroplasty.