The frenetic activities of many baby boomers have left them with worn-out knees that need replacement surgery – and months of recovery time. Partial replacement surgery, however, can prove to be a faster and less painful method.

Nancy Strk is among millions of baby boomers whose knees taught them growing older can be a real pain. She used a cane due to a worn-out knee.

"The pain is getting worse, so I'm just afraid that it's deteriorating more," Strk said in an interview before undergoing a new repair technique.

The cushioning cartilage was gone in one part of Strk's knee, said Dr. Geoffrey Westrich, an orthopedic surgeon at the Hospital for Special Surgery in New York City.

"One the inside, the medial part of the knee, she's completely bone-on -bone," Westrich said.

Surgeons have commonly fixed the problem with a total knee replacement. The top and bottom of the knee are shaved down and replaced with metal alloy and plastic. That is major surgery that can require up to three months of recovery time.

However, a partial knee replacement can get patients back on their feet much sooner. Only part of the damaged knee is repaired, meaning 75 percent less bone and cartilage is removed.

"There's less blood loss, there's less pain after surgery, and people really functionally recover a lot better," Westrich said.

Strk was a good candidate for partial knee replacement because only the inside of her knee was injured, Westrich said. "She has no pain on the outside, and that looks good. And she has no pain under the knee cap, and that looks good," he said before the surgery.

Five weeks after the procedure, Strk has tossed her cane and started playing with her grandchildren, pain free. She can't even tell the replacement parts are there, Strk said.

"It's great. I feel like a new person," Strk said.