Reproducible reference frame for in vitro testing of the human vertebrae

Area of Science:

• Biomechanics
• Orthopedic Surgery
• Anatomy

Background:

• Standardized anatomical reference frames are crucial for in vitro biomechanical testing of human vertebrae.
• Current literature lacks a clear consensus on such a reference frame, hindering reproducibility.

Purpose of the Study:

• To define and validate a novel anatomical reference frame for human vertebrae specifically for in vitro biomechanical applications.
• To establish a repeatable alignment procedure for human vertebral specimens.

Main Methods:

• Proposed an anatomical reference frame based on endplate points and posterior wall landmarks.
• Assessed in vitro repeatability with 5 operators on 7 specimens.
• Evaluated feasibility and repeatability in silico using CT-scans.

Main Results:

• In vitro intra-operator repeatability was better than 3° for all angles; inter-operator repeatability was better than 9°.
• Lateral tilt demonstrated the highest repeatability, while anterior-posterior tilt was the least repeatable.
• In silico repeatability using CT-scans was comparable to in vitro results.

Conclusions:

• This work presents the first formally defined and validated anatomical reference frame for human vertebrae in vitro testing.
• Adoption of this reference frame will enhance specimen alignment reproducibility and test load consistency.
• Improved reproducibility will facilitate more accurate in vitro biomechanical testing and comparison with numerical models.