Lower Limb Malrotation Is Regularly Present in Long-Leg Radiographs Resulting in Significant Measurement Errors

Area of Science:

• Orthopaedic Surgery
• Radiology
• Biomechanical Analysis

Background:

• Weight-bearing long-leg radiographs are standard in orthopaedic surgery.
• Radiographic measurements are sensitive to leg rotation, potentially leading to inaccuracies.

Purpose of the Study:

• To investigate the prevalence of rotational errors in long-leg radiographs.
• To quantify the impact of malrotation on key angular measurements of the femur and tibia.

Main Methods:

• 100 consecutive long-leg radiographs were analyzed using Paley's method.
• Leg rotation was assessed via fibular overlap.
• Angular parameters including mLPFA, mLDFA, AMA, mMPTA, mLDTA, and mFA-mTA were measured and corrected for rotation.

Main Results:

• An average internal rotation of 8 degrees was observed, with a range from 29 degrees internal to 22 degrees external rotation.
• Mean differences in measured parameters after rotational correction ranged from 0.4 to 1.7 degrees.
• All assessed angular parameters were significantly influenced by lower limb malrotation.

Conclusions:

• Malrotation is a frequent issue in long-leg radiographs.
• Accurate measurement of lower limb alignment requires verification of correct rotational positioning.
• Standardized rotational assessment is essential for reliable orthopaedic surgical planning.