A Chicago-area woman has become the first in the world to fitted for a Triton “smart ankle,” a prosthetic that she can adjust using a smartphone app.

Vernita Jefferson, 73, is a longtime resident of the Chatham neighborhood. She was diagnosed with peripheral arterial disease in 2007, and had her left leg amputated below the knee due to lack of blood flow.

She was fitted with a standard prosthetic four months after the surgery, but had trouble getting around and doing all the activities she’s refused to give up: spending time with her five children and 20 grandchildren, swimming, and singing in the choir at Mount Moriah Missionary Baptist Church.

The foot is one of the most complex areas of the body, containing 25% of the body’s 206 bones as well as numerous muscles, ligaments and nerves. This means it’s very difficult for a prosthetic to allow the same range of motion as a natural foot.

What makes the new prosthetic, which Jefferson has had since last month, special is that it mimics the foot and ankle’s ability to adjust heel height. It’s controlled by a microprocessor and syncs via Bluetooth, so Jefferson can make adjustments simply by touching a button on her phone. It also has built-in sensors and makes some automatic adjustments based on how quickly or slowly Jefferson is walking and how much force is being placed on the prosthetic.

This allows Jefferson to walk on a wider range of surfaces and even drive. She used to need a walker just to make her way to the corner store; now, she makes the trip easily with the aid of just a cane.

Jefferson — a self-professed “shoe lover” — can even wear some high heels, instead of being limited to gym shoes.

Jefferson spends some of her time mentoring other amputees, and told the Chicago Tribune March 4 that she hopes the new technology will give more accessibility to a wide range of people.

“It makes a huge difference just to walk up and down stairs,” she said.