Structural properties of the axis studied in cadaveric specimens

Area of Science:

• Orthopedic surgery
• Anatomy
• Radiology

Background:

• The axis (C2 vertebra) is crucial for spinal stability.
• Understanding its internal structure is vital for treating axis fractures.
• Age-related bone density changes may impact axis biomechanics.

Purpose of the Study:

• To investigate the internal structural properties of the axis using peripheral quantitative computed tomography (PQCT).
• To assess age-related differences in axis bone density.
• To inform potential revisions of dens fracture classification and fixation techniques.

Main Methods:

• Peripheral quantitative computed tomography (PQCT) scans were performed on 20 fresh cadaveric axis specimens.
• Serial scans were acquired in three planes.
• Bone density (PQCT values) was compared between the dens (Region 1) and the anterior body of the axis (Region 2), and analyzed based on age (<40 vs. >40 years).

Main Results:

• The dens (Region 1) demonstrated significantly higher PQCT values than the anterior axis body (Region 2).
• A progressive decrease in PQCT values was observed with increasing age.
• Specimens from individuals younger than 40 years had significantly higher PQCT values than those older than 40 years.
• Decreased bone density areas were larger and more extensive in older specimens compared to younger ones.

Conclusions:

• Age significantly impacts the internal structural properties of the axis, particularly bone density.
• The observed age-related decrease in bone density, especially around the dens, may necessitate a re-evaluation of current dens fracture classification systems.
• Current fixation techniques for axis fractures might need reconsideration in light of these structural age-related changes.