EXCLUSIVE

Adidas could be facing stiff penalties after an employee's grisly injury at Kanye West's Calabasas office -- where his Yeezys are designed -- is being investigated by OSHA ... TMZ has learned.

We broke the story ... an Adidas employee was working on Yeezy shoes 2 months ago when a massive 3D printer fell over onto his foot. He was so badly injured he had to be airlifted to the hospital. Sources at the Calabasas complex say people have been "hush hush" about his condition, but word is the foot may have been amputated.

We're told the Occupational Safety and Health Association is now trying to determine if there were any workplace violations that caused the accident. If they find any willful or repeated safety violations, Adidas could face fines up to $129k per violation.