Frontal knee alignment: three-dimensional marker positions and clinical assessment

Area of Science:

• Orthopedics
• Biomechanics
• Radiology

Background:

• Accurate assessment of lower limb mechanical alignment is crucial for diagnosing and managing knee osteoarthritis (OA).
• Traditional methods like weight-bearing long-leg radiographs are considered the gold standard but can be resource-intensive.
• Exploring non-invasive, dynamic, or static imaging alternatives is essential for efficient clinical practice.

Purpose of the Study:

• To evaluate the validity of static three-dimensional (3-D) gait analysis for measuring the hip-knee-ankle angle.
• To assess the accuracy of an inclinometer in measuring tibial alignment.
• To compare these measurements against the established mechanical axis determined by radiographs in individuals with knee OA.

Main Methods:

• Weight-bearing long-leg radiographs were used to determine the lower-limb mechanical axis.
• Three-dimensional (3-D) gait analysis was employed to measure the hip-knee-ankle angle in a static standing position.
• An inclinometer was utilized to measure tibial alignment.
• These measurements were compared in eleven individuals (20 knees) diagnosed with radiographic knee osteoarthritis.

Main Results:

• The mean mechanical axis for the cohort was 0.7° ± 7.2° (range: -13° to 16°).
• Both tibial alignment (inclinometer) and hip-knee-ankle angle (3-D gait analysis) showed correlation with the mechanical axis.
• The correlation between the hip-knee-ankle angle and the mechanical axis was stronger than that of tibial alignment.

Conclusions:

• Static 3-D gait analysis provides a valid estimation of knee mechanical alignment.
• Inclinometer measurements are also a valid method for estimating tibial alignment.
• These techniques offer promising, potentially more accessible, alternatives for assessing knee mechanical alignment in clinical settings.