3D-printed implants are a “real step forward” in spinal surgery

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Vincent Fiere (Hospital Jean Mermoz, Lyon, France) performed the world’s first spinal surgery (anterior lumbar interbody fusion) with a three-dimensional (3D) printed customised cage (UNiD, Medicrea). He speaks to Spinal News International about the potential role of 3D-printed implants in spinal surgery.

What are the potential advantages of using a 3D printer to create spinal implants? 

The advantages are numerous, which include:

 
A custom-made anatomical spinal implant matching the individual spinal parameters as according to the most recent studies on spinal sagittal balance restoration.

 
The surgeon can achieve a predetermined simulated 3D strategy: restoration of harmonious sagittal and coronal balance, lordosis, disc height, and foramen opening. For example, an asymmetrical lumbar intervertebral body device (unavailable in standard ranges) can be designed to treat coronal and sagittal imbalance.

 
A device that, in fusion applications, will offer the best possible 3D structure for the bone to grow into.

 
The best fit for the native shape at the junction between implant and anatomy. For an intervertebral body device, the press-fit with the UNiD is excellent.

 
Perfect 3D scaling, which increases the contact surface bone/implant with better chance of integration.

How was the 3D printer used to create the UNiD ALIF cage?

The device was planned and designed using a 3D reconstruction of the lumbar spine of the patient, and this reconstruction was created using pre-operative lumbar CT scan. The device was designed to match the endplates morphology, the anterior/posterior and lateral dimensions of the vertebrae and the height and angle I had planned to restore. The implant was then 3D printed from PEKK (polyether ketone ketone) according all the planning data.

Was the procedure to implant the cage any different from that to implant a “normal” cage?

After standard preparation of the inner intervertebral space and initial height restoration, I used a PEKK customised template to check the cage sizing was satisfactory. In this first case, we prepared three different cage’s heights and finally used the largest one, which was our best case scenario.

The preop simulated implantation in Surgimap [a clinical imaging tool] revealed itself to be was satisfactory and the 3D laser fritting technology was impressively efficient; the customised cage exactly reproduced the anatomical details of patient’s vertebral plates and the scale was correct.

 


What condition was the procedure for and what have been the outcomes so far?

The patient was being treated for lumbar and radicular chronicle pain (due to L5-S1 degenerative disc disease) that was resistant long-term medical treatment. They had a lack of lordosis (type 1 sagittal spine missing 12 degrees lordosis at this level) and foraminal stenosis. We had satisfactory results at three months postoperative point.

What are the potential risks of using 3D printing to create implants?

There are no specific risks as long as surgeons and industry work together in the patient’s interest. The current enthusiasm around the 3D printing label must not drag us away from our initial goal of improving the patient’s life.

Do you think 3D-printed implants will be cost-effective?

Yes. Not only do 3D-printed implants have the potential to bring high-end technology to improve the patient outcome but they also may have a considerable impact on the economics of our arena. Reduced inventory needed for each surgery implies reduced logistic work at all levels. That should benefit everyone in the chain from the manufacturer to the patient.

Which patients do you think will receive the most benefit from having 3D-printed implants?

If we realise everybody is different with a specific unique spine, all patients could benefit. More pragmatic for the moment would be a selection of patient with asymmetrical 3D imbalance, large reconstructions surgeries for tumours, paediatric spinal reconstruction, or oversized patients.

Do you think 3D printing could be a “game changer” in terms of how implants are made?

Sure. On an industrial point of view it seems a real forward step changing the line of production and inventory management but I am just a basic spinal surgeon.

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