Impact of skeletal muscle mass on complications following expander breast reconstruction

Sarcopenia is characterized by skeletal muscle mass (SMM) depletion and decreased muscle power. In two-stage breast reconstruction using a tissue expander, obesity is the main risk factor for postoperative complications. Obese patients with breast cancer and sarcopenia have a hidden lower SMM with a larger body mass index (BMI). This study aimed to investigate the impact of decreased SMM on complications after tissue expander surgery. In this nonrandomized, retrospective cohort study, 157 patients underwent 169 expander indwelling surgeries. Cross-sectional areas (cm²) of skeletal muscles at the third lumbar vertebra were measured on computed tomography (CT) and normalized for height (cm²/m²) to determine the skeletal muscle index (SMI). Subcutaneous and visceral adipose tissue areas were measured in the same slice and normalized for height (cm²/m²) to determine the total adipose tissue index (TATI). The SMI/TATI ratio was calculated as an index of sarcopenic obesity. Postoperative complications occurred in 40 cases (23.7%). In multivariate analysis, a lower SMI/TATI ratio was identified as a significant independent risk factor for complications (P < 0.001, adjusted odds ratio (OR) = 2.28 per 10% decrease). Delayed wound healing was significantly associated with lower SMI/TATI ratio (P = 0.003, OR = 6.33 per 10% decrease) and diabetes (P = 0.044, OR = 7.36). Seroma was significantly associated with high BMI (P < 0.001, OR = 8.00 per 5-kg/m² increase) and blood loss (P = 0.003, OR = 1.18 per 10 g increase). These results show that patients with a large adipose tissue volume and lower SMM (sarcopenic obesity) have more complications after expander surgery than those with high BMI, or TATI alone.