Sarcopenic knee osteoarthritis is a specific phenotype associated with higher frailty

Purpose: Sarcopenia, an age-dependent loss of skeletal muscle mass, is a major risk factor for falls in older adults. A potential coexisting risk factor for falls in persons with sarcopenia that was not adequately addressed in earlier studies is knee osteoarthritis (OA). The coexistence of these 2 conditions, defined as sarcopenic OA, may exacerbate the risk of falls through the OA-sarcopenia interaction. This study aimed to investigate the relationship between sarcopenic OA and fall experience in older adults. Methods: Older adults with knee pain were divided into 4 phenotype groups according to the presence of sarcopenia and radiographic knee OA (i.e., Kellgren and Lawrence grade ≥ 2): isolated sarcopenia, isolated knee OA, sarcopenic knee OA, and control (i.e., non-sarcopenia with non-knee OA) groups. Fall experience in the prior 12 months was assessed using questionnaires. Binary and ordinal logistic regression analyses were performed to assess the relationship between the 4 phenotypes and any fall (≥ 1 fall) or recurrent falls (≥ 2 falls) after adjustment for age, sex, and body mass index. Results: We included 298 patients (age: 60-90 years, 78.9% women) in this study. Of these, 27 (9.1%) had sarcopenic knee OA, 12 (4.0%) had isolated sarcopenia, and 166 (55.7%) had isolated knee OA. Patients with sarcopenic knee OA had 4.70 times (95% confidence interval: 1.08, 20.5) higher odds of recurrent falls than those with isolated sarcopenia and isolated knee OA. Conclusions: Sarcopenic knee OA may be a specific phenotype associated with higher frailty. A thorough investigation of the interaction between sarcopenia and OA may provide novel insights into the pathomechanics of recurrent falls.