11/7/2018: The expected time to recoup an investment is long. There are two FDA routes. One is called 510K, which means there was a similar instrument prior to 1976. This process takes an average of 2.4 years (0.5 to 7.7 years)*
The other is worse for something new. The Pre-Market Approval (PMA) includes clinical trails and takes an average of 8.5 years ( 2.9 to 24.5 years)*
Then consider time to market, sell and defend product liability and you have your answer.
I have a US patent on method to prevent infections in total joint surgery. There is no interest from the implant manufacturers since they project 50 to 150 million dollars and 10 years to get market approval. No thanks.
*J Bone Joint Surg. 2017.Volume 99, Issue 6. page 26.