An employee was working on a car with a tire removed. While holding a wrench with his right hand on the lower slide bolt of the vehicle's brake caliper and using his left hand to hit the end of the wrench to break the bolt free, the bolt loosened and he hit his left index finger on the lower control arm of the vehicle's suspension system. The impact caused a fracture to his left index fingertip and a degloving that resulted in amputation at the distal knuckle.