Anatomical axis validation of lower extremity for different deformities: A radiological study

Area of Science:

• Orthopedic surgery
• Radiology
• Biomechanical analysis

Background:

• Accurate knee alignment assessment is crucial for orthopedic procedures.
• Existing methods for measuring lower limb and knee axes may have limitations.
• Establishing a reliable correlation between different radiographic techniques is essential for clinical practice.

Purpose of the Study:

• To derive an objective relationship between local knee axis measurements from short anteroposterior (AP) roentgenograms and lower limb axis measurements from orthoroentgenograms.
• To validate the reliability and accuracy of using short AP X-rays for knee alignment assessment.

Main Methods:

• Radiographs of 114 patients were analyzed by two independent raters.
• Measurements included lower limb axis on orthoroentgenogram and local knee axis on cropped short AP X-ray.
• Intra-rater and inter-rater reliabilities were assessed using intra-class correlation coefficients (ICCs).
• Three models were developed to correlate different anatomical and mechanical axes.

Main Results:

• Rater 2 demonstrated perfect reliability (ICCs > 0.90) for all measurements.
• First measurements were more consistent than second measurements.
• Strong positive correlations were observed across all three models, with an exception in varus cases.

Conclusions:

• The derived correlation between short AP X-rays and orthoroentgenograms for knee alignment is comparable to previous studies.
• This standardized correlation can serve as a reliable template for future research.
• Findings can aid knee surgeons in making more accurate interpretations using local knee axis measurements.