Precision of lumbar intervertebral measurements: does a computer-assisted technique improve reliability?

Area of Science:

• Orthopedics
• Radiology
• Biomechanical analysis

Background:

• Manual measurement of lumbar intervertebral motion from radiographs has questionable reliability.
• Few studies have compared computer-assisted versus manual measurement reliability for lumbar flexion-extension radiographs.

Purpose of the Study:

• To determine if computer-assisted measurement of lumbar intervertebral motion on flexion-extension radiographs improves reliability compared with digitized manual measurements.

Main Methods:

• Three physicians and three other observers used digitized manual techniques and computer-assisted quantitative motion analysis (QMA) software.
• Measurements included intervertebral rotation, anterior-posterior (AP) translation, and disc height changes (L1-S1).
• Intra- and interobserver reliabilities were calculated using intraclass correlation coefficients and adjusted percent agreement (APA) for instability classification.

Main Results:

• QMA demonstrated substantially higher intra- and interobserver reliability across all measurements (rotation, AP translation, disc height changes) compared to the digitized manual technique.
• QMA was also more reliable for classifying spinal "instability" (defined by AP translation or rotation thresholds).
• Intraobserver APAs for QMA ranged from 87-97%, versus 60-73% for manual; interobserver APAs ranged from 91-96% for QMA, versus 57-63% for manual.

Conclusions:

• Computer-assisted quantitative motion analysis (QMA) software significantly improves the reliability of lumbar intervertebral motion measurements.
• QMA enhances the reliability of classifying spinal instability from flexion-extension radiographs.
• This technology offers a more dependable method for evaluating lumbar spine biomechanics.