Replacing both knees - at 52

Sitting too much has become the latest health hazard, endangering everything from joints to hearts to blood-sugar levels.

Cheryl Dare, who has tended bar in the Norristown area for the last 23 years, faces the opposite problem. Her daily eight-hour shifts are spent on her feet, in constant motion, and she has the slim figure to show for it.

Yet, at 52, Dare's knees were in such bad shape due to advanced degenerative arthritis she needed to get both replaced recently at Aria 3B Orthopaedic Institute in Langhorne.

"It was getting to the point where I thought I would have to quit," Dare said. "But I really need to work for about 10 more years, and bartending is what I know."

The throbbing pain hit Dare hardest after her long shifts, which made sleeping impossible.

Though the severity of her pain isn't unique, Dare's age is another story. Her surgeon, Robert E. Booth Jr., treats mostly patients in their late 60s and early 70s.

"I'll be 53 in December," Dare said. "I never expected to feel so badly at my age."

Dare was Booth's fourth surgical patient of the morning. The medical director at Aria 3B, Booth at his peak was averaging 1,300 replacements a year. Now he's down to about 1,000.

Forty-five percent of his cases are bilateral, meaning both knees are replaced in one surgery.

High volume is typical in top orthopedic practices. But Booth also is an innovator, having co-designed the first knee replacement specifically for women. Because of their wider hips, women's knees are set at a slightly different angle than men's.

Like most of Booth's patients, Dare had worn out the cartilage on the insides of her knees. Most times, cartilage loss is related to being overweight, but traumatic injuries and genetics also can contribute.

Dare says she comes from a family of "joint nightmares."

"My father had his first knee replacement in his early 50s," she said. "My brother is talking with Dr. Booth about when he should get his knees replaced."

The knee joint is made up of three main components: the bottom of the femur, the top of the tibia, and the patella, or kneecap. The ends of each part are covered with cartilage, a tissue that enables the joint to move easily. More cartilage, called the meniscus, is between the femur and tibia, where it acts as a shock absorber for the joint.

In the early stages, knee pain can be treated with medications, steroid injections, physical therapy, or braces, "which work, but patients never wear," Booth said.

"Once the cartilage starts to degenerate, it's not a matter of strength or motion, it just comes down to the joint being shot," Booth said. "It's like putting a bigger engine in a car with a flat tire; it's not going to make much difference."

The only option left is replacement.

To replace the lost cartilage in Dare's right knee, Booth first removed the damaged surfaces by sawing off the scarred ends of the femur and tibia.

“You’re still putting in metal and plastic implants, but you’re only taking away the surface of the bone,” Booth said.

To anchor the new metal implants, a cement mixture made by Booth’s surgical technician is piped onto the bones. The green cement resembles the texture of Play-Doh and takes about eight minutes to harden.

Next, the patella is removed and replaced with a plastic piece shaped like a button. Finally, a plastic disk is inserted between the metal implants to act as the new meniscus.

Booth finished Dare's first knee in roughly 17 minutes.

Speed doesn't just mean a surgeon can see more patients; infections are less likely the more quickly surgery is completed. Booth estimates his infection rate is 0.3 percent, or three people per 1,000.

Interviewed a few days after surgery, Dare said she was glad she chose to get both knees done at once.

"It's the recovery that's the hard part. It's painful," she said. "I just keep thinking, 'Thank God I did them both' - because I wouldn't come back for the other one."

Bilateral surgeries are attractive for a number of reasons as a single surgical event with one anesthetizing and one hospital stay.

In addition, the rehabilitation period for bilateral surgery is almost the same as it is for one replacement, putting patients with desk jobs out of work for six to eight weeks, as opposed to at least 12 weeks for separate surgeries.

But a longer surgery means greater stress on the cardiovascular system. Booth said it's critical for patients to be carefully screened for heart disease before surgery.

"If you have a bad knee, it may mask cardiac disease because you can't walk far or fast enough to know that you have a bad heart," Booth said.

Plus, as Dare discovered, there is more pain involved with getting both knees done at once.

"It's a bigger biologic insult on the body so the discomfort is greater," Booth said.

Knee replacements appear to be durable, especially for patients who keep their weight under control. After 20 years, 96 percent of Booth's patients report their new knees are holding up well.

"I can't quote 30-year success rates, because no one has really lived with a knee replacement for 30 years," Booth said. "You have to remember that the original population tested was in their mid-70s."

Booth said he urges patients who are overweight to drop pounds before surgery, though that can be difficult for people in too much pain to exercise.

Weight isn't a problem for Dare, who is looking forward to getting back to golfing and keeping up with her 12-year-old daughter.

"My daughter is a pitcher on her softball team," she said, "and I would like to squat down to catch for her."

koshea@philly.com

215-854-2237

@KelOShea