The science of mechanical devices for orthopedic use is called biomechanics or orthopedic biomechanics.

Here's why:

* Biomechanics is the study of the mechanics of living organisms. It combines biology and mechanics to analyze the movement and function of the human body.

* Orthopedic biomechanics specifically focuses on the mechanics of the musculoskeletal system. It examines how bones, muscles, tendons, ligaments, and joints interact to produce movement and support the body.

So, when we talk about the design and function of devices like prosthetics, braces, and implants, we're using the principles of orthopedic biomechanics.