A Lifesaving Implant for Thoracic Insufficiency

Robert Campbell

Harland-Smith lecturer Robert Campbell, Director of the Center for Thoracic Insufficiency Syndrome, Children's Hospital of Philadelphia, began his talk on surgical anatomy by telling the orthopaedic residents - "forget everything you know about scoliosis". He then discussed the anatomical basis of disease, an innovative device based on a fresh anatomical perspective, and the tribulations of surgical innovation at the patient and the FDA level. He ended by quoting the pioneer surgeon John Cobb who said in 1958: "In the future study of scoliosis, it will be necessary to keep our eye on the patient and not on the curve".

Bob is globally recognized for developing the VEPTR, the vertical expandable prosthetic titanium rib, which is a lifesaving implant for young children with severe deformities of the spine and chest wall. Andrew Howard had the opportunity to discuss surgical innovation with Bob and hear the advice of a master innovator.

Q - Dr. Campbell, where did the idea for this device come from?

A - It starts with a patient. He was six months old and dying on a ventilator in the ICU from thoracic insufficiency. Had been to Austin, to Houston, had a tracheotomy, frequently arrested. Interestingly the standard approach then was something called a Toronto chest wall splint. That didn't work. He needed more chest volume so he could aerate his lungs. We planned an opening wedge thoracotomy but I needed a device to expand the chest wall - to hold it open. I sat down the night before and planned an improvised solution using Steinmann pins bent around the ribs. Physiologically, it worked. Technically, it was very difficult. I knew we needed to revise our implant as the baby grew - so the device was invented just for this youngster. I was motivated because I knew I was doing the revision myself. I found out later how many orthopaedic surgeons had turned this patient down!

Q - So you designed a device?

A - There are three crucial points to innovation. The device comes last. The critical first point is to reduce the problem to an anatomic and mechanistic understanding. The second is to come up with a surgical approach to that anatomical problem. It is only at the final stage that we design the device. In this child's case we need a 3 dimensional functional appreciation of the problem. It's not a bent spine that needs straightening. The problem is low chest volume and an absent chest well - which makes the pump mechanism of the diaphragm ineffective. The surgical solution is an expansion thoracoplasty - like an opening wedge between the ribs. And the device has to be a better, safer means of creating and maintaining that volume. So I designed the VEPTR to do that.

Q - How long did it take to design the device?

A - The first VEPTR took me 18 months of concentrated work. Two or three hours a day, plus travel, probably 2000 hours of my time in total. I considered it a Manhattan project - we had this revision surgery coming up. I had the advantage of two years of engineering school - so I had some basics. I could design the joints and do all my own drawings - to the point that they are ready for manufacture. Make sure these are signed, notarized, dated, detailed. These days you can send them to a technician and create computerized models and templates very quickly.

Q - And then you had it manufactured?

A - It's never easy. I remember talking to Zimmer, an orthopaedic giant, early on. When they asked me to estimate the market size, I said 'one kid'. They lost interest pretty quickly. I found a company called Techmedica, whose main business was custom hip and knee implants. When they heard the patient story they agreed to manufacture the device as a one off in return for publicity. I insisted that the publicity had to be tasteful - only at six weeks postop - only with the patient well - so we scheduled the surgery.

Q - Any other hurdles to deal with?

A - Oh yes. Just before surgery - the device was not ready - the fit between expanding components was not precise, and the engineers wanted to add a plastic bushing. I didn't like that idea, because of wear debris. I wanted to convert a rectangular cross section to a t-shape. I cancelled the clinic and flew out to Techmedica to meet three engineers and the CEO in the boardroom. The engineers all told me a t-shaped slide was too complex to machine. By then I knew the company a bit and I asked them to call in Malcolm, a lathe worker, from the shop floor. He came into the boardroom in his bib overalls and I showed him my revised drawings and asked if he could machine it. He said yes, and the CEO backed the lathe worker. They worked four weeks day and night to have it ready - it worked for that patient and has been the basis of the design ever since.

Q - How many patients now?

A - About 500 patients of my own, and growing by 5% to 10% every year. The VEPTR is used all around the world - over 4000 have been implanted.

Q - What about regulatory approval?

A - Before we did the first one, we went to the local institutional review board. They approved a custom device for a lifesaving indication. The case went well, the company's publicist did a good job - 125 newspapers and national TV coverage - this was in 1989 before the internet - I was even reading about it in supermarket tabloids. So the floodgates opened then and patients from everywhere showed up. The second patient was approved by the IRB. The third patient - I was at the review board for this one, the sister, the nun, on our hospital's IRB looked me in the eye and said "Dr. Campbell, the jig is up." She couldn't approve a third similar device as unique, as a one off - and she was right. I called the company and said we need to talk to the FDA. I called the FDA and left a message. I had just lit a fuse.

Q - What is the FDA story?

A - A nice guy from the FDA called me back in the middle of a busy clinic. Turns out it was Dr. Thomas Callaghan - the chief of medical devices. He was a biologist from Yale and he really liked kids. Pretty soon I was meeting him - holding the Xray up to the light - showing him the VEPTR - he asked "Do these kids die?" and I said yes, so he said "then let's go ahead with that".

Q - And how many years to full approval with that encouraging start?

A - Fourteen years. About 10,000 Bob Campell hours.

Q - Worth it?

A - Absolutely.

Q - Other twists and turns?

A - Of course. Techmedica closed in 1994 and I ended up with 800 pounds of manufacturing dies in my office and 30 kids with devices in. That is where Synthes picked up the product and they continue with it. Synthes helped us with the multicentre premarket trial from the 1990s on. In 2002 the FDA asked for control patients, for the first time. We had to challenge this as unethical - this is a fatal condition for some of these kids. We submitted historical controls gathered through the scoliosis research society. This was rejected by the FDA. The premarket approval application was withdrawn, and the application resubmitted as a humanitarian device exemption. That means establishing proven safety and probable benefit, when treating a potentially fatal condition. That is how VEPTR is approved in the US. In other countries the indications are not so tight.

Q - Where are things today?

A - A very exciting stage. I moved from San Antonio to CHOP (Children's Hospital of Philadelphia) two years ago. Our new centre of excellence at CHOP has 16 physicians including cardiovascular surgeons, geneticists, pulmonologists, general surgeons, otolaryngologists, and more. I am the referee and all ideas are welcome. We are using 3D MRI and other technologies to refine our understanding of thoracic function; and working on new operations and new devices.

Q - Advice?

A - Perseverance. I always had a very powerful guardian angel in the background. I always looked for internal champions - in my university, at the company, at the FDA.

Q - Final Words?

A - I mean this. Anyone who wants help navigating the FDA for a surgical device, contact me. I am ready to help any surgeon with that. I have learned a lot.

Andrew Howard

Figure 1 The Vertical Expandable Prosthetic Titanium Rib (VEPTR) device. It can be configured to span from rib to rib (1a), from rib to spine (1b.) or from rib to pelvis (1c.)

Figure 1a

Figure 1b

Figure 1c

Figure 2 A radiograph showing the device in a patient. It expands the chest wall, and can be extended multiple times as the child grows, with an outpatient surgical procedure. 2a - preoperative. 2b - postoperative. Note the opening wedge thoracotomy creating a much higher thoracic volume on the left, concave, side.

Figure 2a

Figure 2b