(CBS4) – She nearly lost an arm when she was shot at Columbine High School in 1999, but doctors saved her life and her limb. Twenty one years later, Kacey Ruegsegger Johnson is recovering from another complex surgery.

This time, she is hoping to finally live pain free.

READ MORE: Suzanne Morphew Murder: Judge Decides To Move Forward With Trial, Barry Morphew Pleads Not Guilty

Kacey Ruegsegger Johnson (credit: CBS)

“The shooters came into the library and they were yelling and laughing,” Kacey said.

She explained she was trying to hide when she was blasted with a shotgun fired by one of the Columbine gunmen.

“It completely shattered the top of my right arm, and the x-ray looks like a cloud of dust,” Kacey told CBS4 Health Specialist Kathy Walsh.

With donated bone, metal and screws, a surgeon at Presbyterian/St. Luke’s Medical Center (PSL) rebuilt her shoulder back then.

“He knew it wouldn’t give me a lot of function, but it would let me have two arms,” she said.

Kacey married and has four children. She wrote a book about her survival, but she could never move on from her injury.

READ MORE: Denver West High School Reunites After 10 Years

(credit: Kacey Ruegsegger Johnson)

“The pain’s just always been there,” she said.

“Imagine a bomb going off in your shoulder,” said Dr. Kareem Sobky, Orthopedic surgeon with OrthoONE at PSL. That’s how he described Kacey’s devastating injury.

Sobky said Kacey got cutting-edge surgery 21 years ago, but the joint had shifted causing painful bone on bone.

In March at PSL, Sobky did what is called a reverse shoulder replacement.

CBS4’s Kathy Walsh interviews Dr. Kareem Sobky. (credit: CBS)

“We attach the ball to the old socket and the new socket to where the old ball existed,” explained Sobky.

Three months later, Kacey said her arm is already functioning better than it has in 20 years.

“Now, I’m moving higher to the front and higher to the side,” she said moving her arm. “I’m reaching up and flipping on light switches, opening doors.”

MORE NEWS: Denver School Board Votes To Censure Tay Anderson

Kacey will always carry the scars, what she calls her tattoos of survival. But with her new shoulder, she is hoping she will finally be free of the pain.