A Randomized Controlled Trial Assessing the Evolution of the Weight-Bearing Ankle Dorsiflexion Range of Motion Over 6 Sessions of Talus Mobilizations in Older Adults

Design and Experimental Research of 3-RRS Parallel Ankle Rehabilitation Robot

The ankle is a crucial joint that supports the human body weight. An ankle sprain will adversely affect the patient’s daily life, so it is of great significance to ensure its strength. To help patients with ankle dysfunction to carry out effective rehabilitation training, the bone structure and motion mechanism of the ankle were analyzed in this paper. Referring to the configuration of the lower-mobility parallel mechanism, a 3-RRS (R and S denote revolute and spherical joint respectively) parallel ankle rehabilitation robot (PARR) was proposed. The robot can realize both single and compound ankle rehabilitation training. The structure of the robot was introduced, and the kinematics model was established. The freedom of movement of the robot was analyzed using the screw theory, and the robot kinematics were analyzed using spherical analytics theory. A circular composite rehabilitation trajectory was planned, and the accuracy of the kinematics model was verified by virtual prototype simulation. The Multibody simulation results show that the trajectory of the target point is basically the same as the expected trajectory. The maximum trajectory error is about 2.5 mm in the simulation process, which is within the controllable range. The experimental results of the virtual prototype simulation show that the maximum angular deflection error of the three motors is 2° when running a circular trajectory, which meets the experimental requirements. Finally, a control strategy for passive rehabilitation training was designed, and the effectiveness of this control strategy was verified by a prototype experiment.

Association ankle function and balance in community-dwelling older adults

Background and purpose

Ankle function declines with age. The objective of this study was to investigate the association between ankle function and balance in older adults, with a focus on range of motion (ROM) and strength.

Methods

This was a cross-sectional study that included 88 healthy community-dwelling older adults. Ankle mobility was measured while bearing weight (lunge test) and not bearing weight. The plantar-flexor muscle strength was assessed using a hand-held dynamometer. Balance was measured in terms of dynamic balance and mobility (timed up and go test), monopodal and bipodal static balance with open and closed eyes (single-leg stand test and platform measures), and margins of stability (functional reach test). Linear correlation and multiple regression analyses were conducted with a 95% CI.

Results and discussion

Most participants had limited ankle mobility (n = 75, 86%). Weight-bearing ankle dorsiflexion ROM was the strongest predictor of dynamic balance and included general mobility and stability (Radj2 = [0.34]; β = [-0.50]). In contrast, plantar-flexor muscle strength was a significant predictor of static standing balance with open eyes (Radj2 = [0.16–0.2]; β = [0.29–0.34]). Overall, weight-bearing ankle dorsiflexion ROM was a more representative measure of balance and functional performance; however, a non-weight-bearing mobility assessment provides complementary information. Therefore, both measures can be used in clinical practice.

Conclusion

This study supports the concept that ankle mobility contributes to the performance of dynamic tasks, while the plantar-flexor muscle strength helps to develop a standing static balance. Identification of alterations in ankle function is warranted and may assist in the design of tailored interventions. These interventions can be used in isolation or to augment conventional balance training in order to improve balance performance in community-dwelling older adults.