The effects of bite line deviation on lateral cervical radiographs when upper cervical joint dysfunction exists: a...

Area of Science:

• Orthopedics
• Radiology
• Biomechanics

Background:

• Accurate assessment of cervical lordosis is crucial for diagnosing spinal conditions.
• Inconsistent bite line positioning during lateral cervical radiography can introduce errors.
• Understanding upper cervical joint motion is essential for reliable imaging.

Purpose of the Study:

• To evaluate the impact of inconsistent bite line positioning on cervical radiographic measurements.
• To propose additional imaging protocols when consistent bite line maintenance is challenging.
• To highlight potential measurement errors in cervical lordosis assessment.

Main Methods:

• Lateral cervical radiographs (neutral, flexion, extension) were obtained from 20 subjects.
• Radiographic measurements assessed relative motion in the atlantal-occipital (AO) and atlantal-axial (AA) joints.
• Paradoxical motion and excessive extension at the AO joint were specifically analyzed.

Main Results:

• Average relative AO flexion was -0.9 degrees and extension was 12.0 degrees.
• Average relative AA flexion was 8.5 degrees and extension was 2.8 degrees.
• 60% of subjects showed paradoxical AO joint motion during flexion, with 10 also exhibiting excessive AO extension.

Conclusions:

• Dynamic cervical flexion and extension radiographs are advised when bite line deviation occurs.
• These dynamic views help calculate upper cervical spinal joint tolerances.
• Failure to account for bite line deviation can result in up to 20.3% measurement error in cervical lordosis.