Spinal Implant Monitors Spinal Fusion Healing

Source: Medical Xpress

Researchers create a spinal implant to monitor spinal fusion healing

Spinal fusion can treat multiple disorders of the spinal cord. The procedure involves fusing two vertebrae together. Furthermore, surgeons also often use a cage for providing support where the disc was formerly between the vertebrae. However, what if the spine’s healing could be supported in more than one way through those cages?

The researchers at the University of Pittsburgh Swanson School of Engineering are working on creating a patient-specific 3D-printed smart metamaterial implant. The implants will double as sensors for monitoring spinal healing. A detailed paper on their work was published recently in the journal Advanced Function Materials.

Assistant professor of civil and environmental engineering Amir Alavi said real-time biofeedback can be given with the help of a simple implant.

He said,

Smart implants can provide real-time biofeedback and offer many therapeutic and diagnostic benefits

But it is very challenging to integrate bulky circuits or power sources into the small area of implants. The solution is to use the implant matrix as an active sensing and energy-harvesting medium. That’s what we’ve been focused on.

Alavi’s iSMaRT lab led the research. Moreover, Intelligent Structural Monitoring and Response Testing had made another class of multifunctional mechanical materials. They have their own sensors, which record and relay important information. For example, information about pressure and stress on its structure. These meta tribomaterials, also called self-aware materials can generate their own power. In addition, they can be used for multiple sensing and monitoring applications.

Material Design

The design of the material causes contact electrification between the conductive and dielectric microlayers under pressure. It creates an electric charge that relays information linked with the condition of the material matrix. Moreover, it inherits the outstanding mechanical tunability of regular metamaterials naturally. The power, which is generated through the built-in triboelectric nanogenerator mechanism eliminates the requirement for a separate source of power. Furthermore, a tiny chip is used in recording the data regarding the cage pressure. It is also an important indicator of healing. Additionally, a portable ultrasound can be used for reading the data without any invasive procedures.

The proposed cage senses capabilities uniquely and is also made of material, which is highly tunable. Moreover, it can be customized according to the needs of the patient.

Alavi explained,

Spinal fusion cages are being widely used in spinal fusion surgeries, but they’re usually made of titanium or PEEK polymer materials (a semi-crystalline, high-performance engineering thermoplastic) with certain mechanical properties

The stiffness of our metamaterial interbody cages can be readily tuned. The implant can be 3D-printed based on the patient’s specific anatomy before surgery, making it a much more natural fit.

Successful Testing of the Implant

The team tested the device successfully in human cadavers. Moreover, they are looking to move on to animal models after this. And since the material is tunable and scalable to a great extent, the design of the smart sensor can be adapted and applied to various medical devices in the future. For example, cardiovascular stents or components, are used for knee and hip replacements.

Alavi said,

This is a first-of-its-kind implant that leverages advances in nanogenerators and metamaterial to build multifunctionality into the fabric of medical implants

This technological advancement is going to play a major part in the future of implantable devices.

The paper was published in Advanced Functional Materials: “Patient-Specific Self-Powered Metamaterial Implants for Detecting Bone Healing Progress”


Developing new and smart medical devices are a need. Especially implants that have novel properties with advance functions. The concept of “self-aware implants” has been proposed here. It will enable the development of a new generation of multifunctional metamaterial devices that can be implanted. Moreover, the devices respond to the environment. In addition to empowering themselves and monitoring their conditions.

All these functions are obtained by integrating nano energy harvesting with mechanical metamaterial paradigms. Moreover, these functions are achieved with the help of nano energy harvests.

Multiple aspects of the concept have been highlighted by the development of proof-of-concept interbody spinal cage implants. Additionally, these implants have self-powering, self-sensing, and mechanical tuning abilities. The bench-top testing is done through synthetic biomimetic and human cadaver spine models. It helps with the evaluation of the electrical and mechanical performance of the patient-specific implants.


The results of the self-aware cage implants show that they can diagnose the process of bone healing. It can be done with the help of signals generated through built-in mechanisms of contact-electrification. The current and voltage generated by the implants under compression forces of spine models reach 9.2V and 4.9 nA. They empower low-power electronics and serve as triboelectric nanogenerators.


The aim of the proposed technology is to make a revolution in implantable devices and to get better surgical outcomes.

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Dr. Armash Shahab is a dentist with a bachelor's degree from Dow University of Health Sciences. She is skilled in general dentistry and is an experienced medical content writer. She also works as a Science Instructor for Little Medical School, which is a STEM-based learning program for kids. Her future plans are to work for the betterment of dentistry for the underprivileged in Pakistan, apply for postgraduation, and specialize in Paediatric Dentistry.


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