A Minimally Invasive Cage for Spinal Fusion Surgery Utilizing Superelastic Hinges

An innovative shape memory alloy actuated cage has been developed for spinal fusion surgery. Spinal fusion surgery is performed on people suffering from low back pain. The viscoelastic spinal disc between the two vertebrae can degenerate in some fashion, such as herniation, and the space needs to be restored to relive the pressure on the nerves within the lower back. There are two main parts to a spinal disc, the annulus fibrosis and the nucleolus. The annulus fibrosis is a cartilaginous structure and is of interest to preserve. Therefore a minimally invasive cage utilizing superelastic elements has been developed. Furthermore, the cage safety and efficacy has been proven and will be presented here. Within this work, the efficacy and longevity of the cage will be presented. To this end, ASTM testing for spinal implants has been conducted on an electromechanical test system capable of inducing simultaneous axial and torsional forces.

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A Minimally Invasive Cage for Spinal Fusion Surgery Utilizing Superelastic Hinges

Volume 1: Development and Characterization of Multifunctional Materials; Modeling, Simulation and Control of Adaptive Systems; Integrated System Design and Implementation ◽

10.1115/smasis2013-3144 ◽

2013 ◽

Cited By ~ 1

Author(s):

Walter Anderson ◽

Christoph Haberland ◽

Mohammad Elahinia

Keyword(s):

Minimally Invasive ◽

Spinal Fusion ◽

Bone Growth ◽

Selective Laser Sintering ◽

Low Back ◽

Structural Elements ◽

Disc Space ◽

Dual Purpose ◽

Fusion Surgery ◽

Spinal Fusion Surgery

A prototype cage implant for spinal fusion surgery has been designed and developed. Spinal fusion surgery is sometimes performed to alleviate low back pain. The cage implant is a spacer that sits in between two vertebrae to allow for bone growth and fusion, all while relieving compression of the spinal cord. The cage implant is minimally invasive in nature, utilizing embedded nitinol hinges as dual purpose actuators and assembly structural elements. The cage implant utilizes elliptical shaped nitinol hinge pins as actuators to allow the cage to be in a straightened before deployment and manipulate its shape to an oblong octagon once within the disc space. A new modeling technique was developed to aid with the design of the nitinol ellipses. The model is MATLAB based and accounts for the non Mises behavior of nitinol through a correction factor for mapping the effective stress and strain. A nitinol rod and an elliptical geometry were examined experimentally and show the robustness of the developed model. These experiments were conducted to design the nitinol hinges for the cage implant. The cage implant is made of two different materials, nitinol hinge actuators and the containing titanium structural segments. The nitinol hinge actuators are completely enclosed within the medical grade titanium segments through the use of selective laser sintering.

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Combined Paresthesia and Subperception Spinal Cord Stimulator Therapy for Management of Persistent Pain After Spinal Fusion Surgery for Congenital Scoliosis

Pain Management Case Reports ◽

10.36076/pmcr.2021/5/33 ◽

2021 ◽

pp. 33-36

Author(s):

James C. Burns

Keyword(s):

Spinal Cord ◽

Chronic Pain ◽

Back Pain ◽

Case Report ◽

Spinal Fusion ◽

Congenital Scoliosis ◽

Low Back ◽

Spinal Cord Stimulator ◽

Fusion Surgery ◽

Spinal Fusion Surgery

Background: A significant number of patients who undergo spinal fusion surgery are managed in chronic pain clinics for low back pain or what is commonly described as failed back surgery syndrome (FBSS). There are a multitude of reasons for chronic long standing back pain after surgery, and the etiology is often multifactorial involving both preoperative and postoperative risk factors. In patients with scoliosis, it has been shown that fusion with Harrington rods extending into the lumbar region is associated with increases in postoperative back pain, especially with fusions to the L4-L5 region. Spinal cord stimulation (SCS) is a recognized treatment for this condition after repeat surgery or when conservative treatments have failed. Case Report: This case report describes the use of SCS with combination therapy in the management of severe low back pain after thoracolumbar fusion with Harrington rods in a patient with congenital scoliosis. After a failed trial of conservative medical management, a spinal cord stimulator capable of delivering combination traditional paresthesia with subperception and burst stimulation was placed. Regarding the choice of SCS therapy, there is a vast array of choices including traditional paresthesia, paresthesia-free, subperception, microburst, or combination treatment. The latter is capable of delivering multiple therapies over time designed to provide more thorough and longer-lasting relief. Conclusion: Simultaneous traditional paresthesia and subperception waveform therapy might offer superior pain relief in comparison to therapies utilizing a sing=le waveform. Further studies are needed to evaluate the use of combination over traditional SCS therapy for the treatment of axial back pain secondary to FBSS. Key words: Chronic pain, combination therapy, congenital scoliosis, neuromodulation, spinal cord stimulator, spinal fusion

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