Accuracy and reliability of length measurements on three-dimensional computed tomography using open-source OsiriX...

Area of Science:

• Orthopedics
• Medical Imaging
• Biomechanical Engineering

Background:

• Three-dimensional computed tomography (3D-CT) is increasingly used for bone and joint anatomy research.
• Manual processing of CT data for 3D imaging requires validation to minimize systematic and random errors.

Purpose of the Study:

• To evaluate the accuracy and reliability of length measurements on 3D-CT using OsiriX software.
• To compare 3D-CT measurements with gold-standard physical measurements.

Main Methods:

• 14 frozen pig knees underwent 3D-CT scans with five transosseous holes in the femur.
• Lengths between tunnel orifices were measured using digital calipers (gold standard) and OsiriX software.
• Measurements were taken by two observers across two trials to assess reliability and reproducibility.

Main Results:

• Mean differences between OsiriX and caliper measurements were under 0.1 mm, with maximum differences below 0.3 mm.
• No significant differences were found between OsiriX measurements and real measurements (p=0.544 and 0.622).
• Intraclass correlation coefficients (ICC) were very high, indicating excellent agreement between trials and replicates (ICC=0.998 and 0.999).

Conclusions:

• Length measurements on 3D-CT using OsiriX are accurate and highly reliable for kinematic analysis of knees.
• OsiriX software provides a valid alternative to direct physical measurements, with accuracy within 0.3 mm.