Bone densitometry within titanium lumbar interbody fusion cages: a computed tomography feasibility study.

Area of Science:

• Spinal fusion research
• Medical imaging analysis
• Biomaterials science

Background:

• Lumbar fusion cages are widely used for interbody arthrodesis.
• Titanium cages can impede fusion assessment due to image obscuration.
• Developing reliable methods for evaluating fusion within cages is crucial for treatment comparison.

Purpose of the Study:

• To validate computer tomography (CT)-based density measurements within titanium cages using a phantom model.
• To differentiate CT reconstruction artifacts from actual bone fragmentation or tissue within cages.
• To establish densitometry as a viable outcome measure for cage-augmented fusion.

Main Methods:

• Utilized an anthropomorphic lumbar spine phantom with titanium cages.
• Filled cages with hydroxyapatite equivalent materials of varying densities.
• Imaged specimens with CT and analyzed intracage density using region of interest analysis.
• Evaluated images for artifacts and correlated CT values with true material densities.

Main Results:

• CT-based intracage density measurements strongly correlated with true material densities (r=0.99).
• CT successfully distinguished between bone and fibrous tissue within cages.
• Intracage CT values, though slightly overestimated, were correctable to bone mineral content.
• Artifacts did not significantly affect density measurements or were distinguishable from bone fragmentation.

Conclusions:

• CT-based densitometry is feasible within titanium cages, even with imaging artifacts.
• This technique can reliably assess bone fusion and differentiate artifacts.
• Further research into this method as an outcome assessment tool for spinal fusion is warranted.