Researchers discovered that people with psoriatic arthritis—a condition causing joint pain and skin problems—are nearly twice as likely to experience muscle loss compared to healthy people. In this study of 109 people, scientists used ultrasound to measure leg muscles and found that 41% of arthritis patients had significant muscle loss, compared to only 22% of healthy controls. The good news? Ultrasound imaging proved to be a simple, practical way to detect this muscle loss early. Understanding this connection could help doctors identify and treat muscle loss before it becomes a serious problem for arthritis patients.

The Quick Take

  • What they studied: Whether people with psoriatic arthritis lose muscle mass more often than healthy people, and whether ultrasound could be used to detect this muscle loss
  • Who participated: 54 people with psoriatic arthritis and 55 healthy people without the condition, all between ages 18-65, matched by age, gender, and body weight
  • Key finding: Muscle loss occurred in 41% of arthritis patients versus 22% of healthy people—nearly double the rate. Ultrasound measurements of leg muscles accurately identified who had muscle loss
  • What it means for you: If you have psoriatic arthritis, you may want to discuss muscle health with your doctor. Regular strength exercises and monitoring might help prevent or slow muscle loss, though more research is needed to confirm the best prevention strategies

The Research Details

This was a cross-sectional study, which means researchers took a snapshot in time by comparing two groups of people at the same moment. They recruited 54 patients with psoriatic arthritis and 55 healthy control participants who were similar in age, gender, and body weight. This matching approach helps ensure that differences found were due to the arthritis, not other factors.

Researchers measured several things: basic measurements like height and weight, muscle strength using a grip test, walking speed over 4 meters, and detailed ultrasound images of the thigh muscles. They also used a special X-ray technique called DEXA to measure total body muscle mass. For the arthritis patients, they assessed disease severity using multiple scoring systems to understand how active their condition was.

This research approach is important because it establishes whether a real difference exists between arthritis patients and healthy people regarding muscle loss. By using ultrasound—a safe, affordable imaging method—researchers demonstrated a practical tool that doctors could use in regular clinics without expensive equipment. The cross-sectional design provides a clear snapshot, though it cannot prove that arthritis causes muscle loss, only that the two occur together more frequently in arthritis patients.

The study’s strengths include careful matching of control participants to arthritis patients, use of multiple measurement methods (ultrasound, strength testing, and DEXA scanning), and assessment of disease activity using established medical scales. The moderate sample size of 109 people is reasonable for this type of study. Limitations include the inability to determine cause-and-effect relationships and the focus on a single time point rather than following people over time.

What the Results Show

The most striking finding was that muscle loss (sarcopenia) occurred in 22 of 54 arthritis patients (40.7%) compared to only 12 of 55 healthy controls (21.8%). This means arthritis patients were nearly twice as likely to have significant muscle loss. When researchers measured specific thigh muscles using ultrasound, they found that arthritis patients with muscle loss had noticeably thinner muscles in three key areas: the rectus femoris (front thigh muscle), vastus intermedius (deep thigh muscle), and overall quadriceps (thigh muscle group).

The ultrasound measurements proved valuable for diagnosis. Researchers identified specific thickness measurements that could reliably identify muscle loss: the right rectus femoris at 1.11 centimeters, left rectus femoris at 1.11 centimeters, right vastus intermedius at 1.17 centimeters, and left vastus intermedius at 1.19 centimeters. These measurements could serve as diagnostic cutoff values for doctors to use.

Interestingly, muscle loss was associated with two factors: lower body weight (BMI) and longer disease duration—meaning people who had arthritis for many years were more likely to have muscle loss. However, muscle loss was not connected to how severe the arthritis was at the time of testing, suggesting that the muscle loss develops gradually over time rather than being directly caused by current disease activity.

The study found that muscle loss was not associated with several factors researchers initially suspected might be important: current disease activity scores, skin lesion severity, age, gender, smoking, alcohol use, blood inflammation markers, vitamin D levels, or history of falls. This suggests that muscle loss in arthritis patients may develop through different mechanisms than the active inflammation of the disease itself.

This research adds to growing evidence that people with inflammatory arthritis conditions experience muscle loss more frequently than the general population. Previous studies have shown similar patterns in rheumatoid arthritis and other inflammatory conditions. This study is notable for being one of the first to systematically examine this connection in psoriatic arthritis specifically and for demonstrating that ultrasound is a practical diagnostic tool—a finding that could make screening easier in clinical practice.

The study’s main limitation is its cross-sectional design, which shows that muscle loss and arthritis occur together but cannot prove that arthritis causes the muscle loss. The study was conducted at a single time point, so researchers couldn’t track changes over time. The sample size, while adequate, was relatively modest. Additionally, the study didn’t investigate potential mechanisms explaining why arthritis patients lose muscle, such as reduced physical activity levels or nutritional factors. The findings may not apply equally to all arthritis patients, as the study included only those with psoriatic arthritis.

The Bottom Line

If you have psoriatic arthritis, discuss muscle health with your rheumatologist or doctor. Consider asking about ultrasound screening for muscle loss, especially if you’ve had arthritis for several years. Engage in regular strength-training exercises as tolerated, focusing on leg muscles. Ensure adequate protein intake and maintain a healthy body weight. These recommendations are based on logical reasoning from this study’s findings, though more research is needed to confirm the best prevention and treatment strategies (moderate confidence level).

People with psoriatic arthritis should pay attention to these findings, particularly those who have had the condition for many years. Doctors treating arthritis patients should consider screening for muscle loss. People with other inflammatory arthritis conditions may also benefit from similar monitoring. This research is less directly relevant to people without arthritis, though maintaining muscle mass is important for everyone’s health.

Muscle loss appears to develop gradually over years of arthritis, not suddenly. Benefits from strength training and lifestyle changes typically take 4-8 weeks to become noticeable, with more significant improvements over 3-6 months of consistent effort. However, preventing muscle loss is likely easier than regaining lost muscle, so early intervention is important.

Want to Apply This Research?

  • Track weekly strength-training sessions (sets, reps, and exercises performed) and body weight. Record any changes in leg strength or ability to climb stairs, walk distances, or rise from a chair. Monitor these metrics monthly to identify trends.
  • Add two 20-30 minute strength-training sessions per week focusing on leg exercises (squats, lunges, leg presses, or resistance band work). Include protein-rich foods at each meal (aim for 25-30 grams per meal). Schedule a discussion with your doctor about muscle health monitoring.
  • Set monthly reminders to assess functional strength (time to walk 4 meters, ability to rise from a chair, grip strength). Track body weight weekly. Schedule quarterly check-ins with your healthcare provider to discuss muscle health and adjust exercise programs as needed. Consider requesting ultrasound measurements annually to objectively track muscle thickness changes.

This research provides important information about muscle loss in psoriatic arthritis patients, but it should not replace professional medical advice. The findings are from a single study and represent a snapshot in time rather than proof of cause-and-effect. Before starting any new exercise program or making significant dietary changes, consult with your doctor or rheumatologist, especially if you have psoriatic arthritis or other chronic conditions. This information is for educational purposes and should be discussed with your healthcare provider to determine what’s appropriate for your individual situation.