Standardized initial head position in cervical range-of-motion assessment: reliability and error analysis

Area of Science:

• Biomechanics
• Orthopedics
• Medical Device Technology

Background:

• Accurate measurement of cervical spine range of motion (ROM) is crucial for diagnosing and managing spinal conditions.
• Existing methods for assessing cervical ROM may have limitations in precision and reliability.
• The OSI CA-6000 Spinal Motion Analyzer is a device designed for quantitative ROM assessment.

Purpose of the Study:

• To evaluate the clinical reliability and precision of the OSI CA-6000 Spinal Motion Analyzer for cervical spine ROM measurements.
• To assess the impact of a novel procedure designed to minimize variability and quantify error sources.
• To determine the accuracy of the CA-6000 in measuring rotation, lateral bending, and flexion-extension in pain-free individuals.

Main Methods:

• Twenty asymptomatic subjects underwent repeated ROM measurements by two examiners.
• Standardized subject positioning and a novel measurement protocol were employed.
• Interclass correlation coefficients (ICCs) were calculated to assess reliability, alongside systematic and random error analysis.

Main Results:

• The CA-6000 demonstrated high reliability for rotation (ICC 0.93-0.97) and lateral bending (ICC 0.93-0.97).
• Acceptable reliability was found for flexion-extension (ICC 0.75-0.93).
• Estimated clinical errors were approximately 4.5 degrees, with minimal systematic errors related to placement or posture.

Conclusions:

• The modified CA-6000, with standardized positioning, is a precise and reliable tool for measuring active cervical ROM across three Cartesian axes.
• The instrument allows for highly repeatable measurements with minimal variation between trials.
• While effective for rotation and lateral bending, the design for flexion-extension measurement could benefit from further improvement.