This study aimed to determine whether changes in phase angle during rehabilitation are associated with clinical outcomes such as activities of daily living (ADL), skeletal muscle index (SMI), and strength in patients with osteoporotic fractures. This retrospective observational study included patients with osteoporotic fractures admitted to convalescent rehabilitation wards.

Changes in phase angle were defined as the difference between the phase angle values at discharge and on admission. The primary outcome was the Functional Independence Measure Motor (FIM-motor) score at discharge.

The secondary outcomes were SMI and handgrip strength at discharge. We used multivariate analysis to adjust for confounding factors and examine the association between changes in the phase angle and outcomes.

We analyzed a total of 115 patients (97 women, mean age 81.0 ± 10.0 years), with a median change in phase angle of 0.0° during hospitalization. We observed increased phase angles in 49 patients (43%), with a median increase of 0.2°.

Multiple regression analysis showed that changes in phase angle were independently associated with FIM-motor score at discharge (β = 0.238, P = 0.027). Changes in phase angle were not significantly associated with SMI (β = 0.059, P = 0.599) or handgrip strength (β = -0.032, P = 0.773) at discharge.

An increased phase angle during rehabilitation was positively associated with ADL improvement in patients with osteoporotic fractures. These findings may help clinicians make informed decisions regarding patient care and treatment strategies for better outcomes.