Lumbar and cervical viscoelastic disc replacement: Concepts and current experience

Area of Science:

• Spinal biomechanics
• Biomaterials engineering
• Orthopedic surgery

Background:

• Ideal lumbar and cervical discs offer six degrees of freedom and tri-planar motion.
• Current artificial disc designs exhibit significant heterogeneity despite aiming for physiologic function.
• Second-generation total disc replacements are non-articulating viscoelastic implants.

Purpose of the Study:

• To review available artificial disc implants, focusing on second-generation designs.
• To detail the concepts and functional results (experimental and clinical) of these implants.
• To identify challenges and define future objectives for artificial disc technology.

Main Methods:

• Literature review of experimental and clinical studies on artificial disc replacements.
• Analysis of implant designs, materials, and biomechanical principles.
• Evaluation of functional outcomes and mobility control.

Main Results:

• Significant heterogeneity exists in lumbar and cervical artificial disc designs.
• Non-articulating viscoelastic implants aim to replicate shock absorption and stiffness.
• Challenges include material selection, component integration, and bone anchoring.

Conclusions:

• Further research is needed on materials for viscoelastic cushions and component interfaces.
• Optimizing bone anchoring remains a critical consideration for monobloc prostheses.
• New objectives must be defined for movement quality and mobility control in artificial discs.