Relationship Between Hip Flexion and Ankle Dorsiflexion During Swing Phase in Chronic Stroke Patients

Background: During the clinical examination of stroke patients, it is common to observe that involuntary hip flexion occurs during voluntary ankle dorsiflexion (synkinesia). This suggests that there is a relationship between these two joints. We hypothesized that there may be a relationship between hip and ankle flexion during swing phase of the gait cycle. The objective of this study was to determine if there is a biomechanical relationship between peak hip flexion and peak ankle dorsiflexion during the swing phase of the gait cycle following stroke.

Method: The paretic lower limbs of 60 patients with stroke were evaluated using clinical tests and 3D-gait analysis. The clinical assessment included muscle strength, spasticity and passive range of ankle motion. The gait analysis focused on sagittal frontal and transverse kinematic gait parameters during swing.

Findings: A stepwise-linear-regression indicated that peak hip flexion and gait speed were the only 2 parameters which accounted for peak ankle dorsiflexion. There was also a significant negative correlation between peak hip flexion and peak ankle dorsiflexion during swing, and a significant positive correlation between hip flexor and ankle dorsiflexor muscle strength.

Interpretation: These results suggest that the biomechanical behaviour of hip and ankle joints during the swing phase of the gait cycle is linked in patients with stroke. They also suggest that two strategies exist: if sufficient ankle dorsiflexion is present, less hip flexion is required (distal-strategy) whereas if dorsiflexion is reduced, it is compensated for by an increase in peak hip flexion (proximal-strategy).