(Reuters) - Intuitive Surgical Inc <ISRG.O> on Tuesday posted fourth-quarter profit that beat Wall Street expectations, but cautioned that growth in use of its da Vinci surgical robots will be slower next year at the same time research and development costs will increase.

Intuitive also announced an accelerated plan to buy back $2 billion of its common stock, and shares were up 1 percent at $673 after hours.

On a conference call with investors, Intuitive said procedures using the da Vinci system rose 15 percent year-over-year in 2016, but that growth will slow to between 9 and 12 percent this year due to changes in hospital trends and competitive factors.

The company also said its pro forma gross profit margins will drop modestly to between 69 and 71 percent this year, compared with 71.6 percent in 2016, due to higher spending on research and development, unfavorable foreign exchange rates and other factors.

For the fourth quarter, Intuitive reported adjusted earnings of $6.09 per share, compared with the average Wall Street estimate of $5.99, according to Evercore ISI.

(Reporting by Deena Beasley in Los Angeles; Editing by Matthew Lewis)