B-twin expandable spinal spacer for posterior lumbar interbody stabilization: mechanical testing

Area of Science:

• Orthopedic Surgery
• Biomedical Engineering
• Spinal Fusion Techniques

Background:

• Posterior lumbar interbody fusion is common for degenerative disc disease.
• Current methods often sacrifice posterior structures and risk dural sac injury.
• A new expandable spacer aims to overcome these limitations.

Purpose of the Study:

• To introduce and evaluate a novel, expandable spacer for posterior lumbar interbody fusion.
• To assess the biomechanical properties of the B-twin ESS spacer.
• To determine its suitability for clinical application in spinal fusion.

Main Methods:

• Laboratory testing of an isolated spacer under controlled loading conditions.
• Strength and fatigue tests using an artificial model.
• Evaluation of pullout resistance and ultimate compression strength in cadaveric specimens.

Main Results:

• The single spacer demonstrated high yield (2660 N) and ultimate (4313 N) forces.
• Fatigue testing showed an endurance limit of 931 N at 5 million cycles.
• The bone-spacer interface exhibited strong pullout resistance (556 N) and ultimate compressive strength (3399 N for a pair).

Conclusions:

• The B-twin ESS spacer is biomechanically sound for spinal fusion.
• It is expected to withstand physiological loads and resist migration or subsidence.
• This novel device offers a potentially safer alternative for posterior lumbar interbody fusion.