In late 1958, Yves Cotrel, a 33-year old French scoliosis physician and surgeon, embarked on a tour of the major scoliosis surgery centers in the United States and Canada. Mr. and Mrs. Richard Eaton of New York City, who were connected with the French Medical Corps during World War II, paid his way.
Cotrel started his tour at New York City’s Hospital for Ruptured and Crippled (now Hospital for Special Surgery) at the Margaret Caspary scoliosis clinic with the legendary John R. Cobb. Cobb, who had designed and finished one of the most important studies about scoliosis and its causes, collecting data from thousands of patients—mostly poliomyelitis children—was, at the time, using a turnbuckle plaster jacket in combination with spinal fusion to treat his patients. Harrington’s rod, which was in its final development stages in 1958 and was soon to be commercialized by Zimmer, was, in Cobb’s view, “weird” and “completely crazy.”
Cobb’s foundational studies, however, which were highly accurate, have stood the test of time and remain in use today as a simple, reliable method for measuring the angle of spine curvature known as the “Cobb angle.”
Cotrel’s next stop was Pasadena, California, and Joe Risser. Joseph C. Risser, one of the giants upon whose shoulders Harrington, Moe, Winter, Luque and, later, Cotrel would stand on, first made his mark on spine surgery in 1936 when he and his colleagues described scoliosis’s progression in untreated patients. They meticulously documented the gradual increase in deformity between the ages of 5 years and 10 years, and accelerated growth and deformity between the ages of 10 years and 15 years.
Eleven years later, 1947, Risser described how spinal development and the iliac apophysis are related. By 1958, the year Cotrel visited him, a grading system based on his observations was used across the United States. Risser had, according to Cotrel, so much scoliosis knowledge and experience that he decided to extend his stay beyond the planned month.
That same year and, yes, while Cotrel was visiting, Risser gave his daughter away in marriage to a brilliant young surgeon from Mexico City, Eduardo Luque.
After Pasadena, Cotrel went to Minneapolis visiting with John Moe at the Twin Cities Spine Center. Cotrel later said of Moe, “I was immediately captivated by this large smiling giant. He wasn’t dogmatic about his ideas and readily accepted those of others with curiosity, consideration, and interest—even those of a young surgeon from another country just passing through. I had rarely encountered such an open mind in my earlier experiences.” As he did with Risser in California, Cotrel extended his stay in Minneapolis to learn “what was and what was not to be done.”
That year, 1958, John Moe, who was a prolific writer, wrote an endorsement of facet fusion, thorough decortication, and the use of autologous bone to more reliably achieve bone fusion. He would later co-create the King-Moe classification system for adolescent idiopathic scoliosis.
Cotrel returned to the l’Institut Calot de Berck sur Mer, France, a changed surgeon.
With everything he learned rattling around in his head Dr. Cotrel created, with the help of Mr. Belembert’s workshop, a system for testing, prototyping and eventually fabricating many of his ideas.
Between 1959 and 1975 Belembert’s workshop grew into a manufacturer and supplier of such products as EDF plasters for early-onset scoliosis; an active preoperative continuous traction system; a spinal surgery table for perioperative correction; a tension band plating of the tibia with autologous grafting—the tension band being fixed with hooks at the ends, a dynamometric outrigger for scoliosis correction (precursor of the Harrington method); and a device for transverse traction (DTT) that was used in combination with the Harrington rod.
In 1973 the workshop was renamed Sofamor (SOciété de FAbrication de Matériaux Orthopédique) with Raoul Lanoy, better known among Sofamor employees, as “the doctor” serving as head engineer.
In 1975, at the age of 50, Cotrel suffered three cardiac arrests and retired from active surgery. Product development, through Sofamor, which now employed his daughter Doctor Marie-Hélène Plais-Cotrel, and son M. Philippe Cotrel, became his focus.
Between 1976 and 1983, in collaboration with Professor Jean Dubousset of Hôpital St. Vincent de Paul (Paris), Cotrel created a revolution in spinal deformity treatment and changed the surgical approach to spinal deformity forever. It was a set of 3D implants capable of correcting the spine in three dimensions, that we know today as the CD Instrumentation and Implant set.
In September 1985 Raymond Roy-Camille implanted the first CD with pedicle screws with Christian Mazel. In 1987 Claude Argenson was the first to use the CD in fractures.
Yves Cotrel, who had heard that Howmedica’s largest distributor in the United States, Stuart Medical in Greensburg, Pennsylvania, was distributing European sourced spinal implants and instrumentation, booked a flight to Pittsburgh, about 40 miles from Greensburg, to pay Abe Glasser and Stuart Medical a visit.
Abe Glasser, Stuart Medical and the One and Only Julius Falcon
High schooler Julius Falcon started working for Abe and Gloria Glasser’s medical distribution company in 1969. He would walk over to their warehouse, work the dock, stock goods and between 1969 and 1973, through college (the legendary Slippery Rock University in Butler County, Pennsylvania) Falcon worked on and off at the Glasser’s company.
Abe had been a U.S Navy pharmacist mate during World War II and, in 1951 with his wife Gloria, started Stuart Medical. He started selling band aids to Pittsburgh area hospitals. Over the years he and Gloria added literally everything a hospital could possibly need and by 1979 were employing more than 200 people in their Greensburg warehouse.
Falcon, a wrestler in high school and an athletic trainer in college who absolutely loved kinesiology, anatomy, athletic training, and all of his orthopedic courses, was working at 84 Lumber as a manager trainee when, in 1979, he stopped by Stuart Medical to chat with his long-time, on-and-off employer, Abe Glasser.
”So, Abe and I had a great conversation,” remembers Julius. “He asked me, ‘Julius, do you know anything about scoliosis?’ I said, “Yeah we learned about that in school. There’s C shaped curves, there’s S shaped curves. But you know that’s just the curve from one side when you look into your body from the side, you’ve got a kyphosis and lordosis.”
“Abe’s eyes were bugging out of his head. I was throwing out terms that he had heard about, but he didn’t know anything about.”
There was a very specific reason Abe asked Julius that question. And that reason was John Moe, the very same surgeon who, 21 year earlier, had trained a young Yves Cotrel at the Twin Cities Spine Clinic and Fairview Hospital in Minnesota.
Doctors Moe, Robert Winter, David Bradford, and the other surgeons at the clinic were Stuart Medical customers.
Moe was stuck in U.S. Customs at La Guardia airport and had called Abe for help. Moe was returning from the Werner Wicker Kilnik in Bad Wildungen, Germany, where he was observing Klaus Zielke perform anterior spine surgery using a novel set of instruments and implants. Klaus gave Moe a set, which Moe hand-carried onto the plane. When he landed in New York and declared the spine surgery instruments and implants to U.S. customs, the agents stopped him cold.
Abe had the required licenses for importing medical devices, so he was able to pop Moe and the Zielke VDS loose.
Which is roughly when Julius Falcon providentially showed up, giving Abe an impromptu scoliosis lecture.
Abe said to Julius, “Oh you got to come down here and work with me.” And the rest, in actual fact, is spine history. Falcon came on board and would stay with Abe and Gloria’s Stuart’s Medical for the next 20 years.
Between 1979 and 1986, the largest spinal implant and instrument supplier in the world was Greensburg, Pennsylvania-based Stuart Medical—the only company selling the Zielke VDS (manufactured by ULRICH in Frankfort, Germany) and, later, Sofamor’s revolutionary Cotrel-Dubosset (CD) system in the United States.
The practice of spine surgery was beginning to find its legs.
Falcon remembers it was an intense and remarkable time in his life. “My beeper would go off, I would call in and Abe would say, ‘Julius we’re going to catch a flight, we’re going to Germany to watch Dr Zielke do surgery. Okay?’ And a day later, I’m sitting with Abe on that aircraft. One trip, I remember, a young kid comes walking up the aisle, introduces himself to Abe and says, ‘Are you Mr. Glasser?’ ‘Yes’. He goes, ‘Well, I’m Randy Betz, one of the doctors that’s going to Germany to observe Dr Zielke doing surgery.’ Dr. Betz was 33 years old at the time.
Randal Betz, M.D., prior professor of orthopedic surgery at Temple University School of Medicine, former Chief of Staff and Medical Director of the Spinal Cord Injury Program at Shriners Hospital for Children in Philadelphia and an internationally renowned researcher and author, remembers those early trips well.
“Abe Glasser would sponsor us to go to Germany,” he recalls. “In 1986 that was my first real exposure to anterior spine surgery. In my fellowship I never saw the front of the spine. It was a real eye opener to see Zielke perform anterior spine surgery.”
“Zielke was a very powerful man. No one told him anything. His staff was petrified of him. Technically, he was superb. It was an eye opener on how medicine in Europe was being practiced. Zielke himself is very gracious good thinker, very good technician.”
David Krauss from Pittsburgh, who was a well-known spine surgeon, attended the visit to Dr Zielke’s clinic at the same time and when he returned to Pittsburgh, Randal Betz joined him to do the first case using Zielke instrumentation. Dr Kraus in turn came to Philadelphia to assist Randal Betz with his first Zielke case.
Dr. Betz remembers that the Zielki System “Was a skinny (3.2mm) threaded rod, with a lot of nuts. Basically, it was a pedicle screw or vertebral body screw threaded rod and with these nuts. You had to rotate the nuts to move the spine along. He had a derotation device, actually a lordosing device which increased the lordosis in the spine. We know today, in 2022, that was wrong. But it worked because you took the discs out. We didn’t have good cages then or used bone graft so trying to maintain the lordosis was actually the right thing to do. Serendipitously it worked. It was a huge advance for patients with myelodysplasia.”
One of the more unique aspects of the Zielke system was that 3.2mm rod. Why 3.2mm?
The answer is John Moe. According to Falcon, “When John Moe and Klaus Zielke began their relationship, John Moe had a tremendous respect for Zielke and called Paul Harrington on the phone and said, “Paul, there’s this young German doctor I want you to meet. He really understands scoliosis and he’s got a great idea here. I would love for you to meet with him, and you guys should speak about things.” Zielke, with Moe’s introduction, traveled to Houston, Texas, to meet John Harrington. Zielke developed so much respect for Harrington that he made his threaded rod a 3.2mm, or 1/8 of an inch, in his honor.” 3.2 mm was the diameter of the Harrington compression rod used on the transverse processes.
The Zielke VDS system for anterior spine surgery was an immediate hit although Abe would not sell it unless surgeons completed training. Once “certified” by Zielke or a surgeon well versed in the system (John Moe, for example) surgeons were allowed to purchase the Zielke system for about $35,000. Abe did have loaner sets but shipped them out only on a case by case basis. That policy would later face a severe test from Memphis-based Danek Medical.
Klaus Zielke’s system was a modification of a 1964 system developed by Allen Dwyer of Australia, who performed one of the first posterior releases, resecting the ligament and capsular structures overlying the facet joints on the concave side and excising any fibrous and boney ankylosis between the lamina, followed by corrective instrumentation via an anterolateral approach. Unfortunately, Dwyer’s system didn’t de-rotate the spine and patients experienced a high rate of late curve progression and cable fracture due to pseudarthrosis.
Zielke’s innovation was a ventral derotation spondylodesis [VDS] system.
Sapporo, Japan’s Kyoshi Kaneda also developed a modification of Dwyer’s system which was a two-rod system to function as an anterior multi-segmental construct to treat thoracolumbar and lumbar scoliosis.
In 1976, Mexico City’s Eduardo Luque developed segmental spinal instrumentation based on the principle of lateral bending as the predominant corrective force. The rods were fixed proximally and distally with sublaminar wires. After excising any contracted structures on the concave side and performing facetectomies on both sides, the wires that encircled the lamina and the rod at each segment was tightened to straighten the spine in the coronal plane.
Then came Cotrel-Dubosset.
In 1984, Yves Cotrel visited Greensburg to see Glasser. “One day, Mr. Glasser said to me, ‘Julius, I have a French guy coming here. His name’s Dr Cotrel. I want you to take a look at what he has,’” recalls Falcon.
Falcon was fully aware that surgeons were generally uncomfortable with the anterior surgical approach to the spine, especially on children. But, when the Zielke was indicated surgeons got the best results going anteriorly. The big medical centers at the time, Minneapolis, Chicago, New York City, Los Angeles, Philadelphia, were doing anterior spine surgery.
What Cotrel showed both Glasser and Falcon was a posterior approach which could rotate the spine using multiple hooks, different types of hooks, laminar hooks, transverse process hooks, pedicle hooks—which didn’t protrude into the canal.
Falcon was very impressed. “It made great sense to me, and I thought ‘Aha, well, this is going to take off.’”
“Cotrel’s system didn’t have a compression rod, nor a distraction rod. It had two solid rods that were seven millimeters on the OD with, including the knurls. It was a big, 7.0mm heavy thick rod and it was strong. I knew what the fear was about fracture and breakage. The Luque rod was a nice and solid 6.4mm (3/16”) rod. Those didn’t break. When I looked at the ability of Cotrel’s design to compress and distract with multiple hooks of fixation and a safe method of connection—not a sublaminar wire—and surgeons wouldn’t have to go anteriorly as much.”
“The next day Abe wanted to know my thoughts, ‘Julius, what did you think of that system?’ I said, ‘Abe, you have got to get this system.’ And he got angry. ‘Why?! Why?’ I said, ‘Because it does things nothing else does. Why don’t you want it?’ He goes ‘Well, Dr Cotrel only wants us to make 20%.’”
Abe did sign an exclusive distribution agreement for Cotrel’s system (manufactured by Sofamor). The first U.S. surgeons to use it were Dr. Kenton D. Leatherman in 1984 and Dr. Harry L. Shufflebarger in 1985.
Cotrel’s system freed patients from post-operative immobilization and presented spine surgeons with a major advance in scoliosis surgery. As more surgeons were trained, it became obvious that pedicle screws were superior in achieving fixation of all three spinal columns and correcting the deformity in all three dimensions.
Alan Olsen Meets Eduardo Luque
In the latter part of 1985, Alan Olsen, founder of five-year old Danek Medical, who had just merged his company with Warsaw, Indiana-based Biotechnology, Inc. (the combined firms were named Danek Medical) was contacted by one of Biotechnology’s East Coast distributors, John Agricola. A customer, Dr. Ed Simmons, was having issues with the early Zielke rod and screw spinal implants.
Olsen visited Simmons who, as Olsen recalls, starts pulling out X-rays and showing him the structural problems with Zielke’s system. “Dr. Simmons was pointing to different cases, and he says, ‘on this one, the screws are breaking’, ‘on this one, the rod is breaking’. Immediately Olsen started working on a solution, literally creating sketches on the plane ride back to see his business partners and two of Biotechnology founders, LD Beard and orthopedic surgeon George Rapp in Warsaw, Indiana. Rapp immediately put Olsen in touch with Eduardo Luque in Mexico City and in literally days, Olsen was scrubbing in and observing the inimitable Dr. Luque in action.
“Eduardo was bringing out all the stuff he’d been working on, sublaminar wires, pedicle screws and plates. And I’m just eating it up and I’m just absolutely in awe of the fact I’m in the presence of Eduardo Luque,” remembers Olsen. “Luque is the father of totally changing scoliosis spine surgery from Harrington rods to sublaminar wiring. I scrubbed in all these scoliosis cases.”
The gears in Olsen’s head were spinning, which Dr. Luque could clearly see. He turned to Olsen and said, “Before you do anything with this Alan, you need to go see Rich Ashman at Texas Scottish Rite Hospital, because he’s doing testing on various screws and plates.”
Texas Scottish Rite Hospital
There are about 250 children’s hospitals in the United States. A fair number started as “Crippled Children” hospitals and treated, at little or no cost to the family, children afflicted with poliomyelitis, cerebral palsy, spina bifida, scoliosis and other deformities of the musculoskeletal system. The Shriner’s hospital system, Gillette Children’s in Minnesota, the New York Hospital for Crippled Children and Memphis’s St. Jude’s Research Hospital are but four examples. Texas Scottish Rite Hospital had similar origins and had evolved to offer orthopedic care at no cost to families.
Rich Ashman, with a Ph.D. in biomechanical engineering from Tulane University, joined Dallas’s Texas Scottish Rite Hospital (TSRH) in late 1984. Joining him in the lab were Drs. Charlie Johnston and Tony Herring. Eventually Ashman would become its hospital’s Director of Research. TSRH was well known for its academic research capabilities and Ashman was joining the hospital as the revolution in spinal surgery was picking up steam.
One of his first tasks was to get an MTS Testing machine (a four-month wait). He was introduced to Mike Sherman, a Bioengineering Masters student at The University of Texas Health Science Center in Dallas and UT-Arlington. Mike had access to an Instron machine at Dallas Veterans Administration Hospital. “Charlie Johnston and I were planning a study of fatigue failure mechanisms of subliminal wiring systems.” Over the next several months Rich, Mike, and Charlie used the VA’s mechanical test machine.
“When I joined Charlie and Tony at Texas Scottish Rite Hospital, our overall objective was to do a deep dive into the mechanical advantages and disadvantages of the available scoliosis instrumentation systems. Our goal was not necessarily to develop a new system, but rather better understand the mechanics of the existing spine implant systems, both from the standpoint of how they could be used to better correct and stabilize deformities and avoid system failures.” [i]
At that time the only posterior systems on the market were the Harrington and the Luque subliminal wire system. Harrington’s system was increasingly being used in different ways than as first designed. Surgeons were bending and contouring the rods and using two hooks on top. They also would add subliminal wires in the center of the construct and wire the rods together. Surgeons were using combinations of Luque sublaminar wiring with Harrington rods.
These new combinations of hooks and wires on multiple vertebrae were loading the rods in ways which exacerbated the known fatigue problems of the Harrington rods. Aside from the fatigue characteristics of these hybrid systems, Ashman and Johnston were interested in how the combinations of hooks and wires affected the overall stiffness of the constructs.
Their interest in overall construct stiffness was developed years earlier when Charlie Johnston and Ashman first met in New Orleans. Ashman’s biomechanical background prior to 1984 was as a faculty member at Tulane primarily studying bone mechanics and bone remodeling. “I met Charlie through Dr. Andy King at Children’s Hospital in New Orleans. Charlie and I subsequently worked on a biomechanical comparison of the Zielke and Dwyer anterior spine instrumentation systems. This work was presented at the Scoliosis Research Society in 1984 and I think it was the first work using construct stiffness as a biomechanical criterion to compare spine systems.”
“We believed overall construct stiffness was key to the bone fusion process. Correction of the deformity was usually primary in the surgeon’s mind, but we were becoming more interested in the spine fusion process, particularly how the implant systems limited motion between vertebrae. One needs to limit motion to achieve fusion, but a construct that is too stiff can cause stress shielding of the bones and limit fusion.”
By mid-1985 they had a decent understanding of the limitations of these hybrid systems and wanted to address not only the fatigue problems caused by the ratchet mechanism of the Harrington rod design, but also improve overall construct stiffness.
“At some point I really started to concentrate on more effective ways to connect rods together. The key was coming up with a connector that provided significant strength, but also small enough to implant.” Sometime within 1985, Ashman came up with a clamp mechanism which would go on to be known as the Crosslink™ connector for spine rods.
Remembers Ashman, “Surgeons at Scottish Rite Hospital performed maybe 20 or so cases using the initial Crosslink connectors with Harrington and Luque rods.” It was a clear improvement over wiring rods together. The TSRH team found the Crosslink connectors improved the overall stiffness and the correctability of the Harrington and Luque rod constructs both in the lab and in surgery. “At some point we began to look at hooks using the same three point shear clamp mechanism.”
By 1985, a few months before Alan Olsen arrived, Ashman had the Crosslink and was exploring the idea of central hooks on a Harrington or plain rod—really to avoid Harrington’s notches which, he knew, were potential fatigue points. “I was just thinking, ‘Okay, we could use a plain rod, and the Crosslink connectors, have hooks that you can place up or down and have the semblance of a complete set for posterior spine correction,” remembers Ashman. He didn’t have all of the instrumentation, but he had the basic implants.
Then the Cotrel-Dubosset system, marketed by Stuart Medical, arrived in the U.S. “Several surgeons at the hospital had seen it presented at a national meeting. It was obviously a complete and well thought out system and the TSRH surgeons ordered it as soon as they could. Shortly after the surgeons at the hospital stated using the CD system. They started coming to me asking for our Crosslink with connectors sized for the larger 7mm CD rods. I had a few sets made but really needed to find someone to take on manufacturing the Crosslink.”
The TSRH Crosslink was a clear improvement over Cotrel-Dubosset’s DTT connector.
“I remember thinking ‘Well, we had some good ideas, but it looks like these guys pretty much, you know, scooped us on whatever we were doing as far as implant development.’ We weren’t having any luck talking with device companies anyway. Several companies we had talked to said they wanted to get out of the spine implant market and weren’t entertaining any new systems. So, I put my system into a cardboard box and stuck it on the shelf.”
Then Ashman gets a call from Tony Herring saying Eduardo Luque has a new implant system with some company in Memphis; “some guy wants to come to Dallas and talk to you about implant testing.”
The “guy” from Memphis was Alan Olsen from Danek.
“Alan Olsen seemed like a nice enough guy, and he had brought Eduardo’s new plate and screw system which they had fabricated in Danek’s Warsaw factory,” remembers Ashman. “The Luque system did not lock the screws to the plate (like Steffee’s system). Rather, the screws pivoted and were also cannulated.”
The idea was to insert the screws down the pedicle, directed by a K wire. Ashman told Olsen that he’d be happy to test the screws, but he also told Olsen just by looking at them they’d have a fatigue problem. “The first threads near the root of the screw were started too abruptly, also the cannulation would make the screw even weaker.” Ashman said the threads needed to be tapered in near the root.
“We had had other companies in and out of the lab. If something was an obvious issue, we would all express our opinions. However, I don’t remember any other company treating our opinions the way Alan did. He gets on the phone to his manufacturing partner, Miles Igo, at the Biotechnology factory in Warsaw and says ‘Stop the presses. We’ve got to redesign the screw.’ Okay.”
Cash was very tight at Danek at the time, but Miles stopped the presses and they made changes.
Alan, who lived in Memphis began stopping by the TSRH lab every couple weeks or so to see how things were going. It was 1986, during one of those visits that Ashman asked Charlie Johnston if they should show Olsen what they’d been previously working on.
“So, I pull out the cardboard box with the Crosslink and the other stuff we’d been working on; we kind of laid it out. Charlie and I talked about our concepts of how the implants would work. How the hooks could be placed up or down on plain rods and how the rods would be locked together both axially and rotationally.”
Remembers Ashman, “Alan Olsen was a Marlboro smoker at the time. We were just talking away and at some point, Alan starts fumbling for his pack, tries to light up a Marlboro, this while stopping us, asking ‘Wait, who have you shown this to? What is the patent status, what else is in the cardboard box.’ Alan was like the worst poker player in the world.”
“And Alan says, ‘I would like to license all this stuff from you, okay? We’ll start with the Crosslink and make that first.’ It was on the market, literally, in less than 30-days after the license agreement was signed.” Ashman and Olsen wrote half of the license agreement, the TSRH lawyers the other half—and it still only came to one page. Danek would manufacture and commercialize it and pay the hospital 5% royalty on net sales. No time limits. No patent requirements. That’s it.
With the Crosslink and more from TSRH on the way, Danek Medical (the future Medtronic Spine) had the beginnings of a full product line for spine surgery.
NEXT: Danek Goes Public, the Loaner Program and Merges with Sofamor.
[i] [Johnston CE, Ashman RB, Sherman MC, Eberly CF, Herndon WA, Sullivan JA, King AGS, Burke SW, “Mechanical consequence of rod contouring and residual scoliosis is sublaminar segmental instrumentation”, J. Ortho. Res., Vol. 5, pp. 206‑216, 1987.]
