ARLINGTON — Even after three arthroscopic surgeries, the cartilage in Bob Deans knees had deteriorated to the point that even sitting still could be excruciatingly painful.It was like there was ground up glass inside my knees, Dean said. My lifestyle was to the point where I was hardly walking. If I was going to go upstairs, I would put on a sweatshirt that had pockets so that I could carry everything up with me. You do stupid things to avoid walking 20 feet.An active 60-year-old, Dean had trouble doing the simple things he loved, like walking his dog or playing basketball with his grandkids. So last summer the Arlington man looked into a double knee replacement. But instead of choosing traditional, off-the-shelf implants, Dean was among the first in the country to receive custom total knee implants designed with 3D printing technology.What makes more sense? Make the human fit the appliance or make the appliance fit the human? Dean said.More than 600,000 knee replacements are performed annually in the United States, according to the Agency for Healthcare Research and Quality.Traditional knee implants come in only seven sizes. Surgeons choose the one that is the closest match and then make cuts to the leg bones above and below the knee to make the implant fit. But using appropriately-sized implants, created from 3D mapping of the patients knees, reduces the amount of leg bone that needs to be removed during surgery, which means less bleeding, and also lessens a patients recovery time, said Dr. Bruce Bollinger, an orthopedic surgeon at the Custom Joint Center in Fort Worth who performed Deans surgery last summer.Bollinger called the custom implants, which help surgeons avoid having to make sizing compromises that can lead to pain and flexibility problems for their patients, a major improvement over the current universal knee replacement system that universally fits no one.One size doesnt fit allBecause of how much bone is typically removed, Bollinger said it isnt uncommon for patients in their 50s to be told to wait until they are in their mid-60s to undergo traditional knee replacement. The worry was that the doctors would have less bone to work with when that younger patient came back in for a replacement in 15 or so years.There is no knee we are going to put in that will last 30 years. The younger you are, the shorter period of time it may last and the less bone I have to work with for replacement surgery after that, said Bollinger, who said multiple replacement implants could result in leg amputation. We have had to come up with something as an alternative.ConforMIS iTotal CR Knee Replacement System is that alternative, Bollinger said. The system was approved by the U.S. Food and Drug Administration in 2011 but it only became available commercially in October 2012.Bollinger, who served on a surgery advisory board for ConforMIS and was among the first surgeons in Tarrant County to use the iTotal system, said he has performed nearly 200 custom knee implant surgeries during the past three years.Custom knee replacement may cost a patient about $6,000 compared to $3,500-$4,000 for a traditional knee replacement, Bollinger estimated.Yes, it is going to be more expensive than standard off-the-shelf implants because of all the engineering, but the trade off is, if these implants last five to 10 years longer, it is worth the expense, Bollinger said.3D printing technology is helping transform healthcare, allowing doctors to provide patients with a variety of custom fit replacement body parts such as dental implants, prosthetic limbs and even large segments of skull. Nightmare storiesThe medical staff at the Custom Joint Center in Fort Worth relied on CT scans of Deans hips, knees and ankles to create implants that would realign Deans legs, which had become bowed, to where they had been before his knees deteriorated. Those scans were also used to create a wax mold that helped Massachusetts-based ConforMIS create metal and plastic implants that were the same shape as Deans forensically reconstructed knees. The 3D mapping is also used to create cutting guides for surgeons to use that are specific to their patient.Dean said his recovery time was shorter than expected. He was able to stop using a walker two weeks after surgery.Anyone who knows someone who has had knee surgery will give you nightmare stories about how hard it was and how hard recovery was and how they are using a cane and limping two years after surgery, said Dean, whose mother also had knee replacement surgery in her 60s.His quality of life has also improved greatly. Dean recently started working at a car dealership, where he walks three to five miles a day helping customers. Thats something he couldnt have done before without suffering tremendous pain.I can walk again. Im riding a bike, said Dean, adding that he has since lost about 25 pounds. I feel vibrant now. Ive got energy. Its a wonderful thing.