Evaluating fixation techniques to prevent subsidence in cervical corpectomy models using low and high-density...

Area of Science:

• Spinal surgery
• Biomechanical engineering
• Orthopedic research

Background:

• Spinal subsidence is a frequent complication following multisegment corpectomies.
• Fixation methods are crucial for preventing subsidence, alongside cage characteristics.

Purpose of the Study:

• To compare the efficacy of three fixation methods—anterior fixation (AF), posterior fixation (PF), and circumferential fixation (CF)—in preventing spinal subsidence.
• To evaluate fixation performance in both osteoporotic (low-density bone) and normal (high-density bone) models.

Main Methods:

• Utilized low-density (LDB) and high-density (HDB) polyurethane blocks to simulate osteoporotic and normal bone.
• Performed static mechanical tests (maximum compressive load, bending moment, stiffness) and dynamic fatigue tests.
• Quantified the amount of subsidence for each fixation method under different bone densities.

Main Results:

• In LDB models, maximum compressive load and stiffness significantly decreased in the order CF > PF > AF. CF showed significantly less subsidence (0.65 ± 0.10 mm) compared to PF (7.5 ± 1.58 mm) and AF (2.3 ± 1.59 mm).
• In HDB models, maximum compressive load and stiffness also decreased in the order CF > PF > AF. Subsidence was minimal (<1 mm) across all fixation methods.
• Anterior fixation (AF) demonstrated comparable effectiveness to other methods in high-density bone models.

Conclusions:

• Circumferential fixation (CF) is superior in preventing subsidence in osteoporotic bone models after corpectomy.
• Anterior fixation (AF) is a viable option for patients with high bone quality (normal bone density).
• For patients with low bone quality, CF provides more stable fixation and may reduce the risk of subsidence and instrumentation failure.