Men Who Smoke at Lower Risk of Joint Replacement: Study

FRIDAY, July 8 (HealthDay News) — It is well-known that smoking is unhealthy, yet men who smoke are less likely than nonsmokers to require total hip or knee replacement, according to a new study.

The researchers also found that being overweight or doing vigorous physical activity increased the likelihood of joint replacement.

In the study, Australian researchers analyzed the medical records of 11,388 men who were followed from 1996-1999 to March 2007. During that time, 857 of the men had either total knee replacement (59 percent) or total hip replacement (41 percent).

The investigators found that being overweight independently increased the risk of total joint replacement, while smoking lowered the risk. This reduced risk was most evident after 23 years of smoking, and men who smoked 48 years or more were up to 51 percent less likely to undergo joint replacement than men who never smoked, the study showed.

The University of Adelaide researchers also found that vigorous exercise increased the risk of joint replacement in men aged 70 to 74, according to the study published in the July 8 online edition of the journal Arthritis & Rheumatism.

“Our study is the first to demonstrate a strong inverse correlation between smoking duration and risk of total joint replacement. The independent inverse associations of smoking with risk of total joint replacement were evident also after adjusting for major confounders and after accounting for the competing mortality risk in this elderly [group] of men,” study author George Mnatzaganian, a Ph.D. student, said in a journal news release. “Further investigation is needed to determine how smoking impacts the development of osteoarthritis.”

According to the 2007 National Hospital Discharge Survey, about 230,000 Americans had hip replacements and 543,000 had knee replacements that year. Severe osteoarthritis was the most common reason for the procedures.

Need a New Hip? Someday You May Grow Your Own

By Dennis Thompson
HealthDay Reporter

FRIDAY, Aug. 5 (HealthDay News) — In a decade or so, people now clamoring for metal and ceramic replacement joints may instead be able to have a fully functional biological replacement — a joint grown within their own bodies to their specific physiology.

To date, researchers have successfully grown replacement shoulder joints in rabbits, using an implanted biological “scaffold” upon which new cartilage developed, according to a study reported in The Lancet.

“It’s definitely a major step forward,” said Dr. Thomas A. Einhorn, chairman of orthopaedic surgery and a professor of orthopaedics, biochemistry and biomedical engineering at Boston University and a spokesman for the American Academy of Orthopaedic Surgeons. “It’s excellent work.”

However, people with arthritis or degenerative joint conditions should not expect to take advantage of this medical advance any time in the immediate future. Clinical use of the new technology is still a decade or more away, said Einhorn and Dr. James L. Cook, a veterinarian and director of the Comparative Orthopaedic Laboratory at the University of Missouri, and a member of the research team.

“You’re probably looking at the eight- to 10-year mark before it becomes widely available,” Cook said. “I tell everyone we’re working as hard as we can. I get a ton of calls from patients who say, ‘I’ll fly wherever I can, I’ll pay whatever I have to, I’ll sign whatever you want me to. I don’t want metal or plastic. I don’t want an artificial joint.’”

The new process works by implanting in the damaged joint what’s called a bioscaffold, which has been infused with a medication known as transforming growth factor beta-3. The drug encourages the body’s own cells — stem cells included — to become cartilage and bone cells.

The scaffold is made from polycaprolactone, a biodegradable plastic, and hydroxyapatite, a naturally occurring mineral found in bone and teeth.

Researchers removed the entire humeral head — the ball part of ball-and-socket shoulder joints — from rabbits used as test subjects and then implanted the scaffolds to grow a biological replacement for the missing piece.

The study reported that the rabbits implanted with the drug-infused scaffolds were able to use the joints and support themselves with them faster and more consistently than rabbits not given the scaffolds. After four months, a new cartilage surface for the humeral head had grown in place, with no complications or adverse effects, the researchers reported.

“They’ve been able to demonstrate that using a specific type of scaffold that’s been doped with a specific type of growth factor, cells will basically populate the scaffold and create cartilage,” Einhorn said.

Though apparently sound, the process still faces years of testing, mainly because it involves the use of an experimental cell growth factor, Einhorn and Cook said.

“We feel that clinically it works, but there’s still a lot of safety testing on the human side to get [U.S. Food and Drug Administration] approval,” Cook said. “The FDA wants to see it’s safe, it’s the same product every time, and there are no problems with disease transmission or infection.”

Einhorn said the durability of the biological joints also must be considered.

“The stability needs to be tested,” he said. “Is it going to be able to withstand the wear and tear that occurs through use on a daily basis, or is it something that just looks good now but will break down quickly?”

Cook has high hopes that the biological replacement joints will prove superior to the artificial joints now used, providing recipients with a higher degree of function.

“A metal and plastic joint is at its best condition the day you put it in,” he said. “The plastic wears out. Even the metal can wear out. A biological joint can actually improve over time as it adapts to your body.”

And though excited and intrigued by the research, Einhorn warned that people should not get their hopes up too soon.

“It’s not an answer for the middle-aged patient who has arthritis now, but it may be an answer for the middle-aged patient who has arthritis in the next 10 to 20 years,” he said.

Age-Related Memory Loss May Be Reversible, Animal Study Suggests

WEDNESDAY, July 27 (HealthDay News) — Age-related memory problems occur due to declines in the neural networks of a certain area of the brain, but this problem may be reversible, a new study in animals suggests.

Yale University researchers found that the neural networks in the prefrontal cortex of older lab animals have weaker connections and fire less strongly than in younger animals.

The prefrontal cortex is responsible for higher cognitive and executive functions, including working memory. Working memory, which is the basis for abstract thought and reasoning, enables humans to recall information such as where they left their car keys.

The researchers also found that certain compounds — such as one used in a medication that has been approved for treating high blood pressure in adults — helped improve prefrontal cortex neuronal firing rates in older animals, according to the report published July 27 in the journal Nature.

“Age-related cognitive deficits can have a serious impact on our lives in the ‘information age’ as people often need higher cognitive functions to meet even basic needs, such as paying bills or accessing medical care,” study author Amy Arnsten, a professor of neurobiology and psychology and a member of the Kavli Institute for Neuroscience, said in a Yale news release. “These abilities are critical for maintaining demanding careers and being able to live independently as we grow older.”

Researchers note that studies involving animals often fail to produce similar results or benefits in humans.