Objective To investigate the associations of six-degree-of-freedom (6-DOF) continuous gait characteristics of the hip, knee, and ankle joints and dual-task cost (DTC) with fall risk in hospitalized older adults under single-task walking and dual-task walking (DTW) conditions with different cognitive loads.
Methods A total of 156 older patients admitted to Taikang Xianlin Drum Tower Hospital, Nanjing, from May 2024 to June 2025 were enrolled. Patients aged ≥60 years who were conscious, able to walk independently for >10 m, and willing to participate were included. Patients who were unable to complete the walking tests because of severe trauma or other conditions, whose falls were caused by external violence or acute diseases, or who declined participation were excluded. Demographic characteristics and lower-limb six-degrees of freedom gait data were collected at baseline during single-task walking and three DTW conditions, including (100-1) DTW, (100-7) DTW, and digit-memory DTW, and DTC was calculated. Falls were recorded during a one-year follow-up. Depending on data distribution, between-group comparisons were performed using the independent-samples t test or Mann-Whitney U test. Continuous six-degrees of freedom gait curves were compared using one-dimensional statistical parametric mapping (SPM1D), and receiver operating characteristic analysis was used to evaluate the discriminative ability of DTC for fall risk.
Results Among the 156 patients, 46 experienced falls, corresponding to a fall rate of 29.5%. During single-task walking, no significant between-group differences were observed in gait speed (t=0.342), gait cycle (Z=0.312), step length (Z=0.734), or cadence (t=0.354) (all P>0.05). Under all three DTW conditions, the fall group showed lower gait speed, step length, and cadence and a longer gait cycle (all P<0.05). DTC was significantly higher in the fall group during (100-1) DTW, (100-7) DTW, and digit-memory DTW (t=3.885, 4.221, and 5.112, respectively; all P<0.001). Analysis of the six-degrees of freedom gait curves showed reduced upward displacement of both knees in the fall group. The minimum SPM{t} values for the left knee during single-task walking, (100-1) DTW, (100-7) DTW, and digit-memory DTW were −4.3, −4.7, −4.6, and −5.6, respectively, while those for the right knee were −2.5, −3.7, −4.7, and −5.2, respectively (all P<0.01). Right-knee extension angles were greater in the fall group, with corresponding maximum SPM{t} values of 4.6, 5.2, 6.1, and 6.3, respectively (all P<0.05). Under DTW conditions, ankle extension angles were greater in the fall group during several phases of the gait cycle; the maximum SPM{t} values were 3.7 for the left ankle and 5.8 for the right ankle during (100-1) DTW, 5.0 for the right ankle during (100-7) DTW, and 4.1 for the right ankle during digit-memory DTW. In addition, the right-hip abduction angle was greater in the fall group during 7%–73% of the gait cycle in (100-7) DTW [maximum SPM{t}=2.93, P<0.01] and during 8% to 71% of the gait cycle in digit-memory DTW [maximum SPM{t}=2.89, P<0.01]. During digit-memory DTW, the left-knee abduction angle was greater during 67%–94% of the gait cycle [maximum SPM{t}=2.16, P=0.014]. The left-ankle adduction angle was also greater during 26%–65% of the gait cycle in (100-1) DTW [maximum SPM{t}=4.40] and during 26% to 32% and 40% to 65% of the gait cycle in (100-7) DTW [maximum SPM{t}=4.20].
Conclusions Compared with single-task walking, dual-task walking may further reveal gait abnormalities in older patients at risk of falls, characterized by deterioration in conventional gait parameters, increased DTC, and altered 6-DOF movement patterns of the hip, knee, and ankle joints during specific phases of the gait cycle. Continuous 6-DOF gait analysis combined with DTC may provide objective kinematic evidence for identifying fall risk in hospitalized older adults.