The size and density of muscle and subcutaneous adipose tissue are independently associated with the risk of mortality in older women with different hip fracture types.

Abstract

Aims: To investigate whether the size and density of proximal femur muscle and surrounding subcutaneous adipose tissue (SAT) are associated with the risk of mortality in older women with different hip fractures (HF) types, as well as to assess how this association changes over time following the fracture.

Methods: CT images and data from 378 female patients with low-energy acute HF were retrospectively collected between January 2020 and July 2022, with an average follow-up of four years. The cross-sectional area and density of the gluteal muscle around the hip, thigh muscle, and adjacent SAT were measured. Cox proportional hazard models were used to assess mortality risk adjusted for covariates in different HF types.

Results: At the end of the follow-up period, 58 had died, and 320 had survived. The mean age at death for non-surviving patients (84.5 ± 7.9 years) was significantly higher than that of surviving patients (72.1 ± 10.6 years). In the femoral neck fracture (FNF) group, the size and density of the gluteus medius and minimus muscles (G.Med/MinM), as well as thigh muscle density, were negatively associated with mortality (P < 0.05). In the intertrochanteric fracture (ITF) group, the mid-thigh SAT (MSAT) area and density were negatively and positively correlated with mortality, respectively. Gluteal muscle size was inversely associated with mortality at one year and beyond following a HF. The MSAT area was inversely associated with mortality within 2 years after HF, while the MSAT density was positively correlated with mortality during the 1-2 years following the fracture.

Conclusions: In different HF groups, the size and density of proximal femur muscles and surrounding SAT demonstrated varying associations with post-fracture mortality in older women, independent of age, BMI, and clinical risk scores.