# Knee Kinematics During Curved Walking

## TL;DR

This study finds that walking along curved paths requires greater knee rotation than straight walking, with sharper curves needing even more rotation.

## Contribution

The study introduces a novel analysis of knee joint rotational patterns during curved walking in older adults.

## Key findings

- Maximum knee flexion angles were significantly lower during curved walking compared to straight walking.
- Knee internal rotation increased during curved walking, with sharper curves requiring larger rotation angles.
- Curved walking demands a greater range of knee joint rotation than straight walking.

## Abstract

Objective

Walking in a straight line is considered the simplest form of locomotion for healthy individuals. However, in daily life, the ability to walk along curved paths is essential for tasks such as avoiding obstacles and turning corners. Evaluating gait patterns that involve directional changes along curved trajectories offers a more ecologically valid assessment of functional mobility, thereby contributing to the development of rehabilitation strategies that are better aligned with daily living activities. The present study aimed to investigate differences in knee joint rotational angles between straight and curved walking in older adults, using the point cluster technique. Furthermore, the study sought to determine whether distinct knee rotational patterns exist between gentle and sharp curved walking, both categorized under curved walking.

Methods

A total of 40 community-dwelling older adults participated in the study. Each participant performed one trial of straight walking, gentle curve walking (with a curvature radius of 2 meters), and sharp curve walking (with a curvature radius of 1 meter). During each walking condition, reflective markers attached to the body were recorded at a sampling frequency of 100 Hz. From the recorded trajectories of the reflective markers, knee joint angles for flexion-extension, abduction-adduction, and internal-external rotation were calculated.

Results

The maximum flexion angle was 45.3 ± 10.1° during straight walking, 19.1±9.8° during gentle curve walking, and 23.5 ± 11.7° during sharp curve walking, with a significant difference observed by ANOVA (p < 0.01). Additionally, post hoc multiple comparisons showed significant differences between straight walking and gentle curve walking (p < 0.01), straight walking and sharp curve walking (p<0.01), and gentle curve walking and sharp curve walking (p < 0.05).

The maximum external rotation angle was 8.4 ± 7.17° during straight walking, −2.3 ± 7.6° during gentle curve walking, and −5.8 ± 8.2° during sharp curve walking, with a difference observed by ANOVA (p < 0.05). Additionally, post hoc multiple comparisons showed significant differences between straight walking and gentle curve walking (p < 0.05).

Conclusion

During walking along a curved path, individuals adopt a gait strategy that involves internally rotating the knee joint prior to entering the curve. The internal rotation angle of the knee joint during the early stance phase was greater in sharp curve walking than in gentle curve walking, indicating that a smaller curvature radius requires a larger internal rotation angle. These findings suggest that curved walking demands a greater range of knee joint rotation compared to straight walking.