Thigh Muscle Composition and Its Relationship to Functional Recovery Post Hip Fracture Over Time and Between Sexes

Abstract

Background: Computed tomography (CT)-scan measures of muscle composition may be associated with recovery post hip fracture.

Methods: In an ancillary study to Baltimore Hip Studies Seventh cohort, older adults were evaluated at 2 and 6 months post hip fracture. CT-scan measures of muscle were acquired at 2 months. Short Physical Performance Battery (SPPB) was measured at 2 and 6 months. Generalized estimating equations were used to model the association of muscle measures and physical function, adjusting for age, sex, body mass index, and time postfracture.

Results: Seventy-one older adults (52% males, age 79.6 ± 7.3 years) were included. At 2-months, males had greater thigh cross-sectional area (CSA, p < .0001) and less low-density muscle (p = .047), and intermuscular adipose tissue (p = .007) than females on the side of the fracture, while females performed better on the SPPB (p = .05). Muscle measures on the fractured side were associated with function at 2 months in both sexes. Participants with the lowest tertile of muscle CSA difference at 2-months, indicating greater symmetry in CSA between limbs, performed better than the other 2 tertiles at 6-months. Males performed worse in functional measures at baseline and did not recover as well as females (p = .02).

Conclusion: CT-scan measures of muscle CSA and fatty infiltration were associated with function at 2-months post hip fracture and with improvement in function by 6 months. Observed sex differences in these associations suggest that rehabilitation strategies may need to be adapted by sex after hip fracture.

Keywords: Computed tomography (CT scan); Physical function; Sex differences.