Table 3.

Various types of spinal implants, summarized from [30].

Device	Purpose	Materials	Biomechanical Properties	Advantages	Disadvantages
Cage	Used as a stabilizer to distribute forces between vertebral bodies and to restore space between intervertebral and foramina space.	It is typically made from metal, ceramic, plastic, most commonly PEEK, titanium, and stainless steel.	Elastic modulus is similar to bone; radiolucent; good load-sharing; minimally invasive; preserves normal spinal anatomy.	They provide a graft for vertebrae to refuse and heal when the intervertebral disc has failed. Because of their porosity, they allow the bone to grow through them.	Some materials might be hydrophobic and unable to bond to bone for solid fusion.
Pedicle Screws	Provide rigid attachment between vertebrae and rod; allows for precise correction and alignment. Allow the redirection of forces.	Titanium, especially TiAl4V, stainless steel, cobalt-chromium.	High bending and torsional strength; low profile; rigid fixation; improved fusion rates; reduced rates of pseudarthrosis.	They can withstand significant forces and loads which are used in scoliosis.	There is a high possibility of loosening the screw, pulling out, or breaking, that might affect bone healing.
Spinal Rods	Adds stability to spinal implant structure; contoured to the patient’s spine.	Titanium, PEEK, stainless steel, cobalt-chromium, nitinol.	Biocompatible; improved biomechanical properties; minimal artifact on imaging; improved sagittal realignment.	The choice of material provides the patient with a wide range or customized characteristics.	Risk of fatigue, fractures, deformation; notch sensitivity; difficulty in identifying faults or breaks; risk of pseudarthrosis; the possibility of leaving weakness that affects overall durability.
Spinal Plates	Adds stability to spinal implant structure; screws into vertebral bodies to help restore normal alignment.	Titanium, stainless steel.	Rigid fixation; improved fusion rates.	—	—