Biomechanical Behavior of Injected Cement Spacers versus Traditional Cages in Low-Density Lumbar Spine under...

Area of Science:

• Orthopedic surgery
• Biomechanical engineering
• Spine research

Background:

• Osteoporosis increases risks with traditional interbody cages.
• Injected cement spacers are an alternative, primarily used in cervical spine surgery.
• Lumbar spine surgery presents unique challenges for interbody device stability.

Purpose of the Study:

• To compare the biomechanical performance of cement spacers and traditional cages in lumbar spine surgery.
• To evaluate the influence of bone density and vertebral geometry on device performance.
• To determine the suitability of cement spacers for osteoporotic lumbar spine stabilization.

Main Methods:

• Axial compression testing on 20 human cadaveric lumbar segments (low-density bone).
• Comparison of stiffness, failure load, and displacement between cement spacers (n=10) and traditional cages (n=10).
• Analysis of the impact of bone density, vertebral geometry, and spacer contact area.

Main Results:

• Cement spacers exhibited higher stiffness and significantly less displacement (p < 0.001) than traditional cages.
• Both groups showed similar failure loads.
• Cage performance correlated with bone density and vertebral height; cement spacers showed no such correlations.

Conclusions:

• Cement spacers provide a stiffer lumbar interbody construct with reduced failure displacement compared to traditional cages.
• Cement stabilization is less sensitive to bone density, making it potentially advantageous for patients with weaker vertebrae.
• Cement spacers may offer a safer alternative to cages, especially given the challenges of cage insertion and potential bone damage.