MEMPHIS, Tenn. (AP) — A cruise in the Bahamas should've been the trip of a lifetime for Gail Blayde, but all it did was remind her how badly her knees hurt.

"I couldn't even enjoy my cruise. I stayed in the cabin a lot," said the 61-year-old Whitehaven resident.

Long a vibrant, active woman who had worked at FedEx, Blayde was stricken with osteoarthritis in her knees in her late-50s. She needed medication to ease the pain and relied on a walker, cane or motorized wheelchair to get around. She couldn't sleep and had so much trouble moving that her husband Louis took over the household chores.

The disappointing cruise spurred her to action. After computerized tomography scans showed the degenerative disease had worn away the cartilage in both knees, causing painful bone-on-bone friction, Blayde turned to an increasingly common option: knee-replacement surgery.

But hers wasn't the usual joint-replacement procedure. Blayde became one of the first Memphis-area residents to benefit from custom-made knee implants crafted with the help of 3D-printing technology.

"It's basically a custom-designed knee replacement," said Dr. Peter B. Lindy, the surgeon with East Memphis Orthopedic who performed the procedures on Blayde.

The advance is significant given the growing prevalence of knee-replacements in the U.S., especially among aging Baby Boomers — a generation that grew up playing sports and heads into retirement with expectations of continued activity.

Between 1999 and 2008, the number of knee replacements performed annually more than doubled, to about 615,000, and by 2010, some 4.7 million people were living with one, according to studies published in the Journal of Bone and Joint Surgery.

By 2030, when the youngest Boomers are entering retirement, some 3.48 million knees will be replaced annually, according to projections presented at a meeting of the American Academy of Orthopaedic Surgeons.

The new process, developed by a Billerica, Massachusetts, company, ConforMIS, incorporates CT scans of a patient's knee, hip and ankle. Proprietary software converts the two-dimensional scan data into a three-dimensional map,or model, of the patient's knee and bone geometry, correcting for deformities.

A 3D printer then crafts the wax mold used to form the metal components of the customized knee implants.

Long-term studies evaluating the ConforMIS process are underway, but no results have been posted yet, according to a National Institutes of Health website.

Lindy, one of the first Memphis surgeons to operate using the process, said the custom implants are superior to off-the-shelf components in the same way tailor-made suits fit better than those purchased straight off store racks.

"If it fits the patient better, it makes the patient more comfortable," he said.

Under the traditional process, surgeons had to select among a range of fixed, standardized sizes for the femoral and tibial implants that make up the metal components of the knee replacement.

Because of individual variations, the standardized implants sometimes are too large, overhanging the bone, or small, leaving areas of bone unprotected. They also can be aligned improperly.

"Everyone's a few degrees different," Lindy said.

As with tailor-made suits, the custom knee replacements formerly cost more than off-the-shelf implants. But steady cost reductions in 3D printing technology have erased the difference, Lindy said.

The benefits have been obvious for Blayde, who had one knee replaced in June and the other on her birthday in August.

"Before (the surgeries) I didn't want to do anything but sit around the house," she said.

"I told her I felt her every pain," added Louis, 66, pastor of a local church.

Blayde also said she was glad to get off the pain pills. "I'm not one to like to take medication," she said.

With her pain gone and mobility back, Blayde and her husband plan to get out more and travel again.

"I like to go. I like to move," she said.

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Information from: The Commercial Appeal, http://www.commercialappeal.com