Design and Analysis of Different Locking Mechanisms for Stand-alone Posterior Lumbar Cage Implant

Abstract

Spinal implants are commonly used in the treatment of spinal disorders and injuries. Spine surgery for interbody fusion using intervertebral cages has become a prescribed method to treat degenerative disc disease and spondylolisthesis. Interbody fusion cages restore disc height by replacing the degenerated disc. Cage design, the material and the surgical approach play significant roles in a successful clinical outcome. A cage implant provides stability for functional spinal units; however, this is accomplished with rods and plates that require additional penetration and space in vertebrae. Hence, stand-alone cage devices are being used, but the designs and their effectiveness are still investigational. This work aims at designing intervertebral cage models with a self-locking mechanism. Four prospective designs for the locking mechanism are proposed. The design is modeled using SOLIDWORKS®. The mechanical analysis was performed on the modeled implants using ANSYS. The material of the implant is titanium, based on its proven biomechanical properties. The dimensions of the cage implant were chosen to best suit the lumbar L4/5 Intervertebral Disc (IVD). Analysis of results indicates that the proposed designs with the locking mechanism withstand load and provide stability to functional spinal units. The modeled cage implants with the proposed locking mechanism show prospective results from mechanical analysis and proceed further for biomechanical testing.

Keywords:
Intervertebral Disc; Spinal Implant; Biocompatible; Finite Element Analysis

HIGHLIGHTS

• Design of Artificial Inter Vertebral Discs with self-locking mechanism.

• Elimination of rods and plates that require additional penetration and space in vertebrae.

• Stress-Strain Analysis of the proposed designs.

• Results show that proposed design would provide stability for functional spinal units.