Association between varus thrust and foot alignment and flexibility in knee osteoarthritis

Area of Science:

• Orthopedics
• Biomechanics
• Gait Analysis

Background:

• Medial knee osteoarthritis (KOA) is often associated with abnormal gait patterns, specifically varus thrust (VT).
• Preventing KOA progression is critical, and VT is a key factor to address.
• The relationship between VT and foot biomechanics, including alignment and flexibility, remains unclear, despite evidence of foot pronation in KOA patients.

Purpose of the Study:

• To investigate the association between varus thrust (VT), foot alignment, and foot flexibility in individuals with knee osteoarthritis (KOA).

Main Methods:

• Gait analysis using inertial sensors was employed to quantify VT differences between the affected and unaffected knees in 20 patients with unilateral KOA (grades III-IV).
• Measurements included foot alignment parameters and the arch stiffness index to assess foot flexibility.
• Statistical analyses were performed to determine correlations between VT, foot alignment, and flexibility.

Main Results:

• Varus thrust (VT) was significantly more pronounced in the knee with osteoarthritis (KOA) compared to the contralateral knee.
• No significant correlation was found between VT and foot alignment.
• A significant positive correlation was observed between VT and the arch stiffness index, indicating a link between foot flexibility and VT (r=0.642, p=0.003).

Conclusions:

• Foot flexibility appears to be a more critical factor than foot alignment in influencing varus thrust (VT) in knee osteoarthritis (KOA) patients.
• Clinical assessment for VT in KOA should include evaluation of foot flexibility alongside foot alignment during physical therapy interventions.
• Further research with larger cohorts and advanced statistical methods is recommended to confirm these findings.