The mechanics of polymethylmethacrylate augmentation

Area of Science:

• Orthopedics
• Biomedical Engineering
• Spine Surgery

Background:

• Osteoporosis commonly causes vertebral compression fractures.
• Percutaneous cement augmentation is a technique used to treat these fractures.
• Concerns exist that augmentation may alter spinal biomechanics, potentially leading to further fractures.

Purpose of the Study:

• To investigate the biomechanical effects of polymethylmethacrylate augmentation on spinal segments.
• To determine if augmentation alters stiffness and strength after vertebral compression fractures.
• To compare outcomes between pure moment and eccentric compression loading.

Main Methods:

• Twelve thoracic spinal segments were tested.
• Segments were divided into pure moment and eccentric compression groups.
• Baseline stiffness, strength after initial fracture, and strength after a second fracture post-augmentation were measured.

Main Results:

• Polymethylmethacrylate augmentation did not alter segment stiffness before or after the procedure.
• Augmentation did not significantly change the strength measured at initial versus subsequent fractures.
• Eccentric compression loading resulted in lower strength compared to pure moment loading.

Conclusions:

• Kyphoplasty augmentation does not negatively impact the stiffness or strength of multilevel spinal segments.
• Eccentric compression poses a greater risk to spinal strength than pure moments during mechanical testing.