While total hip replacement surgery—also known as total hip arthroplasty (THA)—may improve pain, mobility, and quality of life for most recipients, it is an invasive surgical procedure that can cause significant damage to the surrounding muscle, and some patients continue to experience persistent muscular problems, according to a press release from the American Physiological Society.

The release notes that a team of cross-institutional researchers have found that a patent’s susceptibility to inflammation in the muscle may be a measurable marker that can be used to predict how well patents will recover from joint replacement surgery and to identify those patients who may need a specialized rehabilitation plan.

Their study, called “Muscle Inflammation Susceptibility: A Prognostic Index of Recovery Potential After Hip Arthroplasty?” was published recently in the American Journal of Physiology – Endocrinology and Metabolism. In it, they note that a muscle’s ability to regenerate is critical to a patient’s outcome following hip-replacement surgery, and that chronic inflammation is known to inhibit muscle repair and may be a sign of problems to come, according to the release.

In the article, researchers conducted two studies to measure inflammation levels and make predictions about which patients would have a harder time recovering after hip-replacement surgery.

First, they compared two types of hip-replacement patients—those having surgery due to osteoarthritis (THA) and those having surgery due to a trauma that caused hip fracture (HFX)—with healthy controls to measure inflammation levels near affected muscles and throughout the body. They found that the HFX patients had higher system-wide levels of inflammation than THA patients or controls, and that many of  THA group’s measurements were not significantly different from than the control group patients, the release explains.

Researchers in the second study measured the presence of TNF-like weak inducer of apoptosis (TWEAK)—a substance that signals impaired muscle tissue formation and increased loss of muscle mass—among the THA patients. The presence of TWEAK suggests that a patient may have high muscle inflammation susceptibility (MuIS), which is an indicator that may predict which patients will have poor muscle-regeneration outcomes after hip-replacement surgery, the release explains.

Then, the researchers divided THA patients into positive (MuIS+) or negative (MuIS-) groups based on the amount of inflammation that was found in their gluteus maximus—the muscle that surrounds and supports the injured hip, the release continues. They found that patients in the MuIS+ group had significantly higher levels of inflammation and suppressed muscle regeneration before surgery than patients in the MuIS- group, according to the release.

“The results suggest MuIS status at the time of surgery may be a powerful determinant of recovery potential independent of age and BMI,” the researchers write, in the release.

“We suspect MuIS+ patients may be in need of a rehabilitation program that is more intensive…than usual care to overcome MuIS. If this proves to be the case, identifying MuIS+ patients at the time of surgery may enable clinicians to make an informed decision regarding post-surgery rehabilitation, essentially facilitating a personalized rehabilitation medicine approach,” they add.

[Source: American Physiological Society]