Reliability of trunk shape measurements based on 3-D surface reconstructions

Area of Science:

• Orthopedics
• Biomedical Engineering
• Medical Imaging

Background:

• Scoliosis is a spinal deformity characterized by external asymmetry.
• Accurate measurement of trunk surface asymmetry is crucial for scoliosis assessment and management.
• Existing methods may have limitations in capturing the full extent of external deformities.

Purpose of the Study:

• To evaluate the reliability of 3-D trunk surface measurements for characterizing external asymmetry in scoliosis.
• To compare the reliability of measurements obtained from two different postures: anatomical and clavicle positions.
• To assess the sensitivity of trunk surface analysis for monitoring scoliosis progression and surgical outcomes.

Main Methods:

• Repeated trunk surface acquisitions using the Inspeck system were performed on scoliosis patients.
• 3-D trunk models were generated, and various measurements of asymmetry were computed.
• Intraclass correlation coefficients (ICC) and smallest detectable differences were calculated for each measure and posture.

Main Results:

• Reliability for posture A (anatomical) ranged from fair to excellent (ICC 0.91-0.99).
• Reliability for posture B (clavicle) was also good to excellent (ICC 0.85-0.98).
• Trunk surface analysis demonstrated robustness to arm posture changes and reduced errors compared to marker-based methods.

Conclusions:

• 3-D trunk surface measurements provide reliable characterization of external asymmetry in scoliosis.
• While not yet sensitive enough for monitoring natural curve progression, it aids in documenting asymmetry and surgical improvements.
• The anatomical posture offers slightly better reliability due to improved trunk surface coverage.