Stryker made a roughly $400 million equity investment in CMR Surgical, the companies said October 12. The deal carries an exclusive option for Stryker to acquire 100 percent of CMR's equity, subject to regulatory approvals and closing conditions.

Stryker becomes the exclusive US sales agent for the Versius portfolio. CMR keeps leading development and commercialization everywhere else. Andy Pierce, Stryker's group president for medsurg and neurotechnology, is expected to join the CMR board.

CMR's second-generation Versius Plus cleared FDA late last year. The company says Versius has been used in more than 30,000 surgeries, mostly outside the US. Needham analyst Mike Matson puts the soft tissue robotics market above $12 billion.

The structure buys Stryker a US channel and a look at the numbers before it commits, which is how a strategic hedges against a robot that sells well abroad and stalls in American hospitals.