Anterior cervical graft and plate load sharing

Area of Science:

• Orthopedic Surgery
• Biomechanical Engineering
• Spinal Fusion Research

Background:

• Anterior cervical discectomy and fusion (ACDF) is a standard surgical procedure.
• Anterior cervical plates are often used in ACDF to stabilize the spine.
• Concerns exist regarding whether the plate shields the interbody bone graft from mechanical loading, potentially hindering fusion.

Purpose of the Study:

• To quantify the load-sharing mechanism between an interbody bone graft and an anterior cervical plate.
• To determine if the anterior plate acts as a load-sharing or load-shielding device during ACDF.

Main Methods:

• Mechanical testing was performed on six cadaveric calf spines.
• Simulated ACDF with an interbody bone graft was conducted, both with and without an anterior plate.
• Load-displacement data were analyzed to calculate graft-plate load distribution under axial compression.

Main Results:

• The anterior plate was found to share mechanical load with the interbody graft.
• As axial load increased, the percentage of load transmitted through the graft decreased (53% to 41%).
• However, the absolute magnitude of load transmitted through the graft increased (24 N to 37 N), with minimal intervertebral strain (<6%).

Conclusions:

• In single-level ACDF, the anterior cervical plate functions as a load-sharing device.
• This load-sharing role is crucial for promoting bone graft consolidation and successful fusion.
• Findings support the clinical observation of effective graft consolidation in ACDF procedures using anterior plates.