Design of a Novel Kresling Origami Lumbar Disc Replacement for Degenerative Disc Disease

Abstract

Though it is normal for spinal discs to show signs of wear and deterioration with age, this process may result in degenerative disc disease (DDD), causing pain, stiffness, and even physical deformity. DDD affects 40% of people aged 40 years old and increases to 80% for those aged 80 years or older. Lumbar disc replacements (LDRs) are commonly used as a surgical intervention for DDD. Unfortunately, currently marketed LDRs present a myriad of problems that lead to a clinical failure rate of up to 26% at a two-year follow-up report. Patients with underlying conditions such as diabetes experience even higher rates of clinical failure. Root causes for complications include incorrect sizing of the implant, lack of mobility, and material choices that do not allow for proper integration into the body. Our project proposes a novel design that will replicate the properties of natural lumbar discs and mitigate these complications. This design consists of porous titanium (Ti-6AL-4V)/chitosan sponge composite endplates that can be loaded with compounds to prevent infection and accelerate fusion with the vertebrae surrounding the LDR. A polyurethane Kresling Origami-inspired insert will be sandwiched in between the endplates, allowing the LDR to adjust its size for optimal fitting and provide shock absorption, stability, and mobility to the spinal column. Methods for executing this design are also proposed, along with mechanical and biological tests to be conducted. This paper is the first part in a series of studies that will culminate in assembling and testing the final LDR.