An alternative to hip replacement surgery may be in sight. In the Proceedings of the National Academy of Sciences, researchers reveal how it may be possible to use a patient's own stem cells to grow new cartilage in the shape of a hip joint.
Furthermore, the team - including researchers from Washington University School of Medicine in St. Louis, MO - says it is possible to program the newly grown cartilage to release anti-inflammatory molecules, which could stave off the return of arthritis - the most common cause of hip pain.
According to the National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS), osteoarthritis is the primary cause of hip joint damage that requires hip replacement surgery, causing severe pain and disability.
Hip replacement surgery, also known as arthroplasty, involves surgically removing the diseased part of the hip and replacing it with new, prosthetic parts. Each year in the United States, more than 332,000 hip replacement surgeries are performed.
While effective, study co-author Farshid Guilak, Ph.D., a professor of orthopedic surgery at Washington University, and colleagues note that doctors are wary about hip replacement surgery in patients under the age of 50.
They explain that hip prosthetics usually last less than 20 years, so it is likely that younger patients will one day require a second hip replacement. Replacing a worn prosthetic hip joint is complex, and it can increase patients' risk of infection and cause damage to the surrounding bone.
As such, there is a need for an alternative to hip replacement surgery, and Guilak and colleagues believe they may have found one.
Arthritis return could be prevented with gene therapy method
In their study, the researchers describe how new cartilage can be grown from a patient's own stem cells, which are extracted from fat under the skin.
The new cartilage is grown to cover a 3-D, synthetic scaffold that can be molded into the exact shape of a patient's hip joint.
- Osteoarthritis is the most common form of arthritis
- Between 2008-2011, around
30.8 million peoplein the U.S. had osteoarthritis
- In 2011, osteoarthritis accounted for around 80 percent of all hip replacement surgeries in the U.S.
This cartilage-covered scaffold can be implanted onto the surface of the patient's damaged hip joint. The team explains that this could alleviate pain caused by arthritis and, for some patients, it could delay or halt hip replacement surgery.
The scaffold was created using around 600 biodegradable bundles of fiber that are woven together, producing a hardy fabric that has the ability to work like normal cartilage.
"As evidence of this, the woven implants are strong enough to withstand loads up to 10 times a patient's body weight, which is typically what our joints must bear when we exercise," says study co-author Franklin Moutos, Ph.D., vice president of technology development at Cytex Therapeutics Inc.
What is more, the researchers explain how, by inserting a gene into the newly grown cartilage, they can trigger the release of anti-inflammatory molecules that have the potential to stop arthritis from returning.
"When there is inflammation, we can give a patient a simple drug, which activates the gene we've implanted, to lower inflammation in the joint," explains Guilak. "We can stop giving the drug at any time, which turns off the gene."
He adds that this gene therapy component is key; increased levels of inflammatory molecules in a joint can increase pain and damage cartilage. Having the ability to reduce levels of these molecules can protect the newly grown cartilage and promote long-term functioning.
The researchers believe their novel implant may one day provide a much-needed alternative to hip replacement surgery for the millions of patients with osteoarthritis - many of whom are younger patients aged 45-65.
"We envision in the future that this population of younger patients may be ideal candidates for this type of biological joint replacement."
Study co-author Bradley Estes, Ph.D., Cytex Therapeutics Inc.
The team says the implants are now being tested in animal models, and if they are successful, they could reach human testing within the next 3-5 years.