Osteosarcopenia Quietly Fuses Bone and Muscle Loss and Raises Risk of Falls, Fractures and Death

Fragility fractures are a major global health burden. The 2019 Global Burden of Disease study counted 178 million new fractures and 25.8 million years lived with disability, up 65% since 1990. Osteoporosis and sarcopenia often occur together, a state called osteosarcopenia, and this review argues that recognizing the overlap matters because it predicts worse outcomes than either condition alone.

This is a narrative review drawing on international consensus guidelines, large population cohorts, interventional studies and translational research. It covers definitions, epidemiology, pathophysiology, clinical findings, diagnosis and treatment. The text provided was truncated partway through the treatment section, so later material on emerging therapies is only summarized from the abstract.

The authors describe bone and muscle as tightly linked through mechanical loading, myokines (such as myostatin, irisin and IL-6) and bone-derived factors (such as sclerostin, FGF23 and osteocalcin). Aging disrupts this crosstalk through inflammaging, declining sex hormones, IGF-1 and growth hormone, mitochondrial dysfunction, and shifts of mesenchymal stem cells toward fat rather than bone or muscle. Marrow and muscle fat produce palmitic acid, which is toxic to osteoblasts in vitro. Age-related dysregulation of the kynurenine pathway of tryptophan metabolism may reduce beneficial metabolites such as picolinic acid and raise harmful ones. Reported associations include an 18-fold higher likelihood of osteopenia or osteoporosis in people with sarcopenia, and greater risk of functional disability, falls, fractures, frailty, hospitalization and mortality.

Diagnosis combines DXA (T-score ≤ −2.5 for osteoporosis, with some groups including osteopenia) and EWGSOP2-based sarcopenia assessment: SARC-F screening, grip strength or chair stand, gait speed, SPPB or TUG, and lean mass by DXA, BIA, MRI or CT. The authors urge systematic screening in high-risk groups, such as those with prior fragility fractures, recurrent falls, frailty or long-term care residence.

No therapy is approved for osteosarcopenia as such. Osteoporosis drugs follow standard criteria, while sarcopenia care rests on exercise (150 minutes per week of aerobic activity plus resistance training at least twice weekly), protein of 1.2–1.5 g/kg/day, leucine, vitamin D (at least 1000 IU/day), calcium (1000–1300 mg/day) and possibly HMB or creatine. The FrOST trial found 18 months of high-intensity resistance training with protein improved muscle, function and bone density in older men, whereas a 12-week elastic-band program improved function but not bone density in women with osteosarcopenic obesity.

Caveats include inconsistent sarcopenia definitions that produce variable prevalence, DXA lean mass as an imperfect proxy for muscle, limited evidence that bone drugs improve muscle, and a lack of trials testing combined interventions.