WEST PALM BEACH, Fla. — Risk for knee osteoarthritis (OA) and knee replacement surgery was higher in individuals with obesity and sarcopenia than those having either condition on its own. Individuals with sarcopenic obesity had about a 50% greater likelihood of knee replacement than those with nonsarcopenic obesity and more than twice the likelihood of surgery than those with sarcopenia alone, according to research presented at the World Congress on Osteoarthritis (OARSI) 2026 Annual Meeting.

“Our findings indicate that muscle strengthening should be recognized as a strategy of equal importance to weight management in the management strategies for knee osteoarthritis,” presenter Zhipeng Wang of Nanfang Hospital and Zhujiang Hospital at Southern Medical University in Guangzhou, China, told attendees.

The results also suggest that assessing patients’ body composition, rather than their BMI alone, may be more useful in identifying patients at higher risk for knee OA and knee replacement surgery, Alison Chang, MS, DPT, PhD, a professor of physical therapy and human movement sciences at Northwestern University Feinberg School of Medicine in Chicago, told Medscape Medical News. Chang, who was not involved in the research, added that the findings should be interpreted cautiously, given methodological limitations related to how sarcopenia was defined and assessed in the patient cohorts.

The researchers analyzed data from 372,972 individuals in the UK Biobank to compare knee replacement surgery rates in those with sarcopenia and obesity, those with sarcopenia but not obesity, those with obesity but not sarcopenia, and those with neither sarcopenia nor obesity.

They assessed sarcopenia based on grip strength combined with appendicular lean mass relative to height squared, and obesity was determined based on BMI. They validated their findings in a separate cohort from the Osteoarthritis Initiative (OAI) and then calculated the associations of knee replacement with each of the three conditions (sarcopenia, obesity, and both). In the OAI cohort, however, sarcopenia was defined using the SARC-F and the chair stand test.

In accordance with previous research, individuals with obesity alone had nearly three times the risk for knee replacement surgery compared to those without obesity or sarcopenia (hazard ratio [HR], 2.86; P < .001). Risk for knee replacement in those with only sarcopenia was also higher than in those without sarcopenia or obesity (HR, 1.6; P < .001). But likelihood of knee replacement was more than four times greater in those with sarcopenia and obesity than with neither (HR, 4.53; P < .001).

When the researchers compared individuals with sarcopenic obesity with those with only one or the other condition, the risk for knee replacement surgery was 56% higher than in those with nonsarcopenic obesity (HR, 1.56; P < .001) and more than double in those with only sarcopenia (HR, 2.73; P < .001). Those with sarcopenia alone also had about half the risk for knee replacement than those with obesity alone (HR, 0.55; P < .001).

Reliability of Sarcopenia Assessment Questioned

Following the presentation, one commenter raised questions about the reliability of grip strength as a proxy for measuring sarcopenia and suggested that alternative assessments, such as a DEXA scan, may provide a more robust determination of sarcopenia. Chang agreed, noting that grip strength may be influenced by hand OA and “and therefore reflect multijoint osteoarthritis burden rather than true sarcopenia.”

The SARC-F and chair stand test “rely on lower extremity function and may be affected by knee pain and stiffness, meaning they may capture knee symptoms rather than underlying muscle status,” Chang said. “This raises the possibility that the observed association could partly reflect underlying joint disease rather than sarcopenia itself. Furthermore, neither cohort includes DEXA-based measures of muscle mass, limiting the ability to identify true sarcopenia.” Regardless, however, the findings do suggest that management of knee OA “should emphasize preserving or improving muscle alongside weight reduction,” Chang said.

Jessica Johnson, PT, a physical therapist at UW Health in Madison, Wisconsin, also acknowledged that grip strength may not be the best measure for this population given the high overlap between knee and hand OA, but “we don’t really have a perfect tool,” she said in an interview. “Imaging is helpful in identifying cross-sectional area or volume, but it doesn’t describe muscle quality.”

Sarcopenic obesity is about more than simply biomechanics and load given that muscle is a secretory organ, Johnson elaborated. “Both cardiovascular training and resistance training are essential tools in improving muscle quality,” she said, but it’s difficult to measure muscle quality since it can include mitochondrial density, mitochondrial efficiency, myofilament strength, and other factors.

“Muscle quality affects metabolic efficiency and insulin sensitivity and acts as a metabolic sink for carbohydrate storage,” Johnson said. “Whereas muscle area or volume could describe muscle hypertrophy, whether myofibrilar or sarcoplasmic, it may also be affected by fat infiltration and hydration level.”

Regardless of the way sarcopenia was assessed in this study, however, the results remain “encouraging for the prescription of resistance training for patients with knee osteoarthritis,” Johnson said.

No external funding was noted for the study. Wang, Chang, and Johnson had no relevant financial relationships to disclose.

Tara Haelle is a science/health journalist based in Dallas.