Swelling After Knee Injury May Hinder Healing

FRIDAY, Aug. 31 (HealthDay News) -- The swelling that normally occurs when a joint is injured may interfere with healing after knee injuries, researchers say.

Publishing in the September issue of Arthritis & Rheumatism, Duke University researchers identified two immune system proteins -- interleuken-1 and tumor necrosis factor -- produced by the body during swelling that blocked the healing of a damaged pig meniscus. The meniscus is a type of cartilage inside the knee joint that acts as a shock absorber between the thigh bone and lower leg bone. Almost 15 percent of all athletic injuries to the knee involve the meniscus. Over time, wear and tear on this cartilage contributes to osteoarthritis.

Medical treatments could be used to block interleuken-1 and tumor necrosis factor and help heal knee injuries and osteoarthritis, the researchers said.

"There already is a drug that blocks the effects of tumor necrosis factor that is used widely and effectively in patients with rheumatoid arthritis, the form of the disease caused by body's own immune system attacking the joint," senior researcher Farshid Guilak said in a prepared statement. "Another drug also exists that blocks IL-1 that is being used for rheumatoid arthritis and is currently undergoing clinical trials for osteoarthritis."

The Duke team exposed pig knees to varying levels of the two proteins. As they increased the dose amount, the meniscus tissue became less able to repair itself. The range of concentrations in the experiment match those found in the joints of humans with rheumatoid arthritis and osteoarthritis.

The majority of meniscus injuries are tears in the tissue. If the tear is small and occurs outside the meniscus, it can be repaired surgically, although surgical repairs are not always effective. A large tear may mean surgeons have to remove the torn tissue entirely, which speeds the progression of osteoarthritis.

These findings, the team said, could result in a targeted, less invasive way to manage meniscus damage.

More information

To learn more about meniscal injuries, visit A Patient's Guide to Meniscal Injuries.