Simulated Ankle Equinus Affects Knee Kinematics During Gait.

Area of Science:

• Biomechanics
• Gait Analysis
• Orthopedics

Background:

• Distinguishing gait compensations from true abnormalities is crucial for effective intervention in neuromuscular disorders.
• Ankle equinus, a common gait deviation, can influence other joint kinematics.
• Understanding these relationships aids in targeted treatment planning.

Purpose of the Study:

• To investigate the impact of isolated ankle equinus on knee kinematics during the initial contact phase of gait.
• To determine the threshold of ankle equinus that elicits compensatory knee flexion.

Main Methods:

• Ten healthy subjects underwent 3D motion analysis under five conditions: shoe alone and with ankle foot orthosis simulating 10°, 20°, and 30° of plantar flexion.
• Repeated-measures ANOVA analyzed differences in knee flexion at initial contact across conditions.
• Primary outcome measure was knee flexion angle at initial contact.

Main Results:

• Simulated ankle equinus greater than 10° consistently resulted in increased knee flexion at initial contact.
• Observed knee flexion ranged from 7° to 22° with simulated equinus.
• A clear pattern of increased knee flexion was identified as a compensation for simulated ankle equinus.

Conclusions:

• Increased knee flexion at initial contact appears to be a compensatory strategy for ankle equinus exceeding 10°.
• For ankle equinus of 10° or less, observed knee flexion may indicate a true gait deviation.
• Findings have significant implications for cerebral palsy treatment, differentiating compensation from abnormality to optimize gait interventions.