Intradiscal pressure measurements: A challenge or a routine?

Area of Science:

• Biomechanics
• Biomedical Engineering

Background:

• Intradiscal pressure (IDP) is a critical biomechanical parameter for spinal disc research.
• Existing IDP sensors vary in size and measurement principles, with limited data on inter-sensor reliability and the impact of insertion.
• Species-specific differences in disc size and mechanics are significant but their influence on sensor measurement effects is understudied.

Purpose of the Study:

• To evaluate inter-sensor reliability for IDP measurement using two different transducer sizes.
• To investigate the influence of sensor insertion and size on measured IDP across different species.
• To provide guidance on sensor selection for accurate IDP assessment.

Main Methods:

• In vitro study using bovine and caprine spinal discs.
• Simultaneous measurement of IDP with two pressure transducers (Ø1.33 mm and Ø0.36 mm) under three loading periods.
• Assessment of sensor insertion effects by alternating transducer insertion and recording pressure changes.

Main Results:

• High inter-sensor reliability was observed when sensors were used simultaneously (ICC: 0.964-0.999).
• Sensor size significantly influenced measured IDP during insertion tests, particularly in caprine specimens.
• A pressure increase of 0.31-0.64 MPa was noted in caprine discs upon larger sensor insertion, indicating a species-dependent effect.

Conclusions:

• While sensors show high reliability for simultaneous IDP measurement, their size impacts readings upon insertion.
• Sensor selection is critical, especially for smaller disc sizes, to avoid measurement artifacts.
• Further research should consider species-specific biomechanics and sensor characteristics for accurate IDP quantification.