thumb implant

Innovations in Implantable Medical Devices

This article previously appeared on ECN Mag

Implantable medical devices have for years made an impact in areas such as cardiology and prosthetics, but numerous recent technology advances are enabling implantables to address areas not always in the spotlight.

These applications include:

  • Customized tracheal stents
  • A non-opioid chronic pain treatment
  • Putting a finger on better implant design
  • Microchips meeting biology
  • Disappearing stents

Stents That Mimic the Real Thing

Narrowing, or stenosis, of the trachea and/or bronchi leads to breathing difficulties and requires specific management through the implantation of a stent.

Ten years ago, Benjamin Moreno, now general director of AnatomikModeling, established IMA Solutions, a company specializing in 3D scanning that diversified into the treatment of medical images and development of customized medical implants for thoracic surgery.

“Physicians were using standard implanted metal or silicone stents to correct all conditions. We identified how to address special needs and offer hope to patients for whom standard prostheses did not fit. It was a large task, and required advanced modeling,” Moreno said, adding that 3D printing at the time was limited in scope.

Following several years of R&D in collaboration with the pulmonology department at Toulouse University Hospital in France, AnatomikModeling successfully developed and implanted several customized stents (Figure 1) that were anatomically identical to patients’ trachea and/or bronchi.

Figure 1: AnatomikModeling developed custom that were anatomically identical to patients’ trachea and/or bronchi. (Image Source: AnatomikModeling)

The new prostheses are custom-made in three steps, according to Moreno:

  • First, a 3D reconstruction of the patient’s airways is produced from CT-scan images.
  • The virtual reconstruction then is used to create a mold, which undergoes a quality control step using an Artec Space Spider 3D scanner to compare to the designed 3D model.
  • Finally, a patient-specific prosthesis is manufactured from medical grade silicone elastomer and the imaging goes to a 3D printer to create and manufacture the insert.

“Our goal is to make the entire process from initial scanning to final customized implant totally digital,” Moreno said.

The prosthesis is implanted by conventional bronchoscopy with the help of a prosthesis pusher in the operating room under general anesthesia. In addition, the rigidity of the stent can be calculated as a function of the stenosis.

The researchers have finished the feasibility stage trials and are now implanting the devices in volunteer patients who have little or no alternatives. Trials are being conducted in France.

AnatomikModeling’s focus is to introduce the technology to the full European market. Meanwhile, Moreno says that the company hopes to link with a U.S. medical silicon device manufacturer to conduct trials in the States and also to obtain full global certification.

Tiny Implant for Chronic Pain

A peripheral nerve that has been damaged due to trauma or surgery often will begin to misfire causing consistent pain. For many years, the main solution for this was prescription of opioid drugs.

In 2016, Bioness, Inc. launched the StimRouter Neuromodulation System (Figure 2), the first FDA-cleared, minimally invasive, long-term neuromodulation medical device indicated to treat chronic pain of a peripheral nerve origin. It also has been approved to treat chronic pain in Europe and Canada.

“Before us, the only alternatives to using opioids were temporary nerve blocks, nerve destroying ablation procedures, or spinal cord stimulation that involves implanting pacemaker-type devices that have wires implanted in the dorsal column of the spine,” said Mark Geiger, global director of marketing for implantables at Bioness.

 

Figure 2: The StimRouter Neuromodulation System is the first FDA-cleared, minimally invasive, long-term neuromodulation medical device indicated to treat chronic pain of a peripheral nerve origin. (Image Source: Bioness)

Part of the implant is a “pulse generator” the size of a hockey puck powering the system, and it affects the body on a global scale instead of just the area where pain is occurring.

It is a percutaneous implant requiring about a half-centimeter incision. With ultrasound guidance, a doctor can find the specific peripheral nerve causing the pain, stimulate it, get feedback from the patient, and then implant a tiny lead near that nerve. The end of the lead is left under the skin and a transmitter in the form of a small patch is placed over the implant. This powers the lead through the skin with a wave of energy that is sent to the tip of the implant near the nerve.

“The patient feels a very pleasant, light, stimulation instead of a pain signal, and has a programmer so now the patient is in charge of their own pain management,” Geiger said. “We have patients playing basketball, working, weightlifting, running, just getting their lives back. The patch is replaceable and the power source is rechargeable just like a cell phone.”

Geiger added that the FDA took the unusual step of granting Bioness “very broad approval” for the StimRouter.

Thumbs Up on This Implant

Alejandro Badia, M.D., F.A.C.S., is one of the few American surgeons who embrace the concept of joint replacement for the thumb.

The internationally renowned hand and upper-limb surgeon found BioPro, a technically superior implant design, which he started using exclusively several years ago.

“Rather than standard one-piece CMC implant designs, the BioPro implant offers a modular, two-piece design to better match patient’s anatomy,” according to Dr. Badia. “The basal joint in osteoarthritis is at the base of the thumb. It’s the second most common place for disabling arthritis in the hand. It’s not only painful, but saps grip strength; you can’t even turn a car key.”

The BioPro Modular Thumb Implant (Figure 3) incorporates two important features for an anatomically correct fit. The medial offset head aligns with the true center of the trapezium, ensuring proper joint alignment. The 15-degree varus angle stem allows the head to maintain good contact with the socket during flexion or opposition, minimizing chances of dislocation.

Dr. Badia, founder of the Badia Hand to Shoulder Center in Doral, Florida, and of OrthoNOW, a network of orthopedic urgent care centers in the U.S., continues to educate both patients and other physicians about alternatives available for better treatments.

Figure 3: The BioPro Modular Thumb Implant incorporates a medial offset head and a 15-degree varus angle stem to ensure proper alignment. (Image Source: BioPro)

Bionic Arms Closer to Reality

Dries Braeken is a biomedical scientist and currently the group manager of a project at imec that is trying to stimulate tissue using electronic microchips in healthcare applications—a tiny, implanted link that will allow an artificial arm/hand to actually “feel.”

Braeken explained that the chip side of this “bionic arm” was part of a program under the Defense Advanced Research Projects Agency (DARPA), a research agency of the U.S. Department of Defense. The program is called HAPTIX, which stands for Hand Proprioception and Touch Interfaces.

The goal of the program is to create a prosthetic hand that moves and provides sensations just like a natural hand. The project imec was involved in wanted to do so by interfacing directly with the nerves instead of the muscles, to connect the biological and artificial circuitry through a permanent, implanted link that sends and reads electrical signals in two directions.

“Every single movement, action, and reaction we do with a living arm is second nature,” Braeken said. “To reconstruct that intuitive communication is extremely complicated. Our body is a very efficiently made organism that is extremely complex as far as how signals are sent to and from the brain. In this instance, the place for the chip to be inserted is the nerve bundle of the upper arm or shoulder. It has to be extremely small and it must interface with the existing nerve bundle that controls the lost arm.”

The chip is wrapped in a special moisture proof material and then fixed directly to the specific nerves. It connects them to their sister command links within the artificial appendage.

“We can make chips that can do virtually anything,” Braeken added. “We’ve been doing that for more than 30 years. The growing range of smarter consumer electronics is basically running the world today, but once you start combining them with the human body it’s a whole different world. You meet new challenges, need new materials, new protection, new checks and balances. That’s where the real challenge is: combining microchips and biology.”

The chip currently is in the animal modeling stage with limited human testing.

Bioresorbable Drug-Eluting Stents

A common way to treat coronary artery disease is to use drug-eluting stents. Coated, standard metal stents do the job, but are not perfect because, while the drug elution lasts three to six months, metal stents remain for life. As many as 3 percent of patients suffer adverse affects because of metal stents each year.

They can’t have normal MRI heart tissue scans and a surgeon must do a special type of invasive discovery if additional artery disease progresses. Now, REVA Medical is changing that with a bioresorbable scaffold (stent), as shown in Figure 4.

Bionic Arms Closer to Reality

Dries Braeken is a biomedical scientist and currently the group manager of a project at imec that is trying to stimulate tissue using electronic microchips in healthcare applications—a tiny, implanted link that will allow an artificial arm/hand to actually “feel.”

Braeken explained that the chip side of this “bionic arm” was part of a program under the Defense Advanced Research Projects Agency (DARPA), a research agency of the U.S. Department of Defense. The program is called HAPTIX, which stands for Hand Proprioception and Touch Interfaces.

The goal of the program is to create a prosthetic hand that moves and provides sensations just like a natural hand. The project imec was involved in wanted to do so by interfacing directly with the nerves instead of the muscles, to connect the biological and artificial circuitry through a permanent, implanted link that sends and reads electrical signals in two directions.

“Every single movement, action, and reaction we do with a living arm is second nature,” Braeken said. “To reconstruct that intuitive communication is extremely complicated. Our body is a very efficiently made organism that is extremely complex as far as how signals are sent to and from the brain. In this instance, the place for the chip to be inserted is the nerve bundle of the upper arm or shoulder. It has to be extremely small and it must interface with the existing nerve bundle that controls the lost arm.”

The chip is wrapped in a special moisture proof material and then fixed directly to the specific nerves. It connects them to their sister command links within the artificial appendage.

“We can make chips that can do virtually anything,” Braeken added. “We’ve been doing that for more than 30 years. The growing range of smarter consumer electronics is basically running the world today, but once you start combining them with the human body it’s a whole different world. You meet new challenges, need new materials, new protection, new checks and balances. That’s where the real challenge is: combining microchips and biology.”

The chip currently is in the animal modeling stage with limited human testing.

Bioresorbable Drug-Eluting Stents

A common way to treat coronary artery disease is to use drug-eluting stents. Coated, standard metal stents do the job, but are not perfect because, while the drug elution lasts three to six months, metal stents remain for life. As many as 3 percent of patients suffer adverse affects because of metal stents each year.

They can’t have normal MRI heart tissue scans and a surgeon must do a special type of invasive discovery if additional artery disease progresses. Now, REVA Medical is changing that with a bioresorbable scaffold (stent), as shown in Figure 4.

 

Figure 4: REVA Medical has developed a bioresorbable scaffold that replaces metal stents in patients suffering from artery disease. (Image Source: REVA Medical)

“The first critical thing in the coronary area is developing the actual bioresorbable material,” according to Reggie Groves, REVA chief executive officer. “Then the stent must be able to be delivered like a normal metal stent. You don’t want to change how any physician puts the stent in.

“You also want the scaffold to be strong through the entire time the patient is healing, and finally, the stent must go away benignly; resorb into the body without any incident. It must be natural and bodily compatible. The average ‘healing’ is four to six months, and what influences how long the stent lasts is how strong and thick you make it. So timing can be controlled by the stent itself.”

The first step was to find a polymer that was best for the application. REVA chose to make Tyrocore the material for their sirolimus-eluting bioresorbable scaffolds. Tyrocore is REVA’s proprietary tyrosine-derived polymer designed specifically for vascular scaffold applications.

After restoration of blood flow, bioresorbable scaffolds support the artery through the healing process and then resorb benignly into the body over a period of time. This resorption is intended to allow the return of natural function of the artery and reduce the risk of adverse events associated with permanent metallic drug-eluting stents.

“REVA Fantom and Fantom Encore are the only coronary bioresorbable scaffolds made from Tyrocore and it is inherently radiopaque, making it visible under X-ray fluoroscopy,” Groves said. “The scaffolds are designed with thin strut profiles while maintaining strength and with distinct ease-of-use features, such as X-ray visibility and expansion with one continuous inflation.”

The REVA product is inserted exactly like any metal stent. It is X-ray visible and the thickness of the polymer is in the range of metal, so it is thinner and easier to work with for physicians.

“We have exclusive rights to the material patent and we manufacture it in-house,” Groves added. “We received the CE certification and our stents are now in use in Europe and Turkey.”

Searching Outside the Box

For this new generation of medical technology, looking “outside of the box” is the norm. The companies mentioned above are among those that are advancing implantable medical device innovations.

With today’s medical technology, the number of true innovators in this category will continue to grow in the coming years.

Leave a Comment

Your email address will not be published. Required fields are marked *