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Historic Discoveries Meet Modern Techniques in Limb Length and Deformity Reconstruction at St. Croix Orthopaedics
Thor Heyerdahl was the visionary explorer at the helm of the 1947 Kon-Tiki voyage. He believed civilization flourished through the exchange of ideas between nations and organized expeditions to demonstrate the possibility of contact between ancient cultures separated by oceans. He never imagined his voyages would also connect present-day nations separated by ideology, revealing the surgical discoveries of a brilliant physician working in isolation on the Siberian steppes.
The practice of Mark Dahl, MD, of St. Croix Orthopaedics, is founded on these discoveries. His international expertise in the relatively new field of limb length and deformity reconstruction is grounded in the medical innovation Heyerdahl unintentionally brought to light — and complemented by Dr. Dahl’s award-winning work as a 3-D sculptor of the human form. Supported by the medical resources of the HealthEast Care System, Dr. Dahl is the only surgeon in the Upper Midwest offering these complex and delicate reconstruction procedures.
“Heyerdahl assembled multinational crews for his voyages,” Dr. Dahl explains. “Among them were a Russian doctor, Yuri Senkevich, and an Italian climber, Carlo Mauri. Mauri injured his leg in a climbing accident that left it shortened and chronically infected, even after 20 corrective operations by Italian surgeons. When Dr. Senkevich and Mauri met on one of Heyerdahl’s expeditions, Dr. Senkevich offered to introduce Mauri to Gavriil Ilizarov, a Russian surgeon who was pioneering bone-lengthening and correction techniques unknown to Western medicine. Mauri crossed the Iron Curtain with Dr. Senkevich in the early 1980s and was treated by Dr. Ilizarov. When Mauri’s Italian surgeons examined his healed leg, they were astonished. Compared with Dr. Ilizarov’s techniques, Western methods for lengthening bones were antiquated and riddled with complications. The Italians invited Dr. Ilizarov to Milan to present his methods and later studied with him in Siberia.”
Dr. Dahl followed the medical trail blazed by Heyerdahl’s crew. After his residency, Dr. Dahl designed his own three-year program to study limb lengthening in Italy, working with surgeons at universities in Verona, Lecco and Milan. His Italian mentors introduced him to Dr. Ilizarov, paving the way for Dr. Dahl to spend two months training with Dr. Ilizarov at the Russian Ilizarov Scientific Center for Restorative Traumatology and Orthopaedics in Kurgan, Russia. As he developed expertise in this emerging field, Dr. Dahl found that the nuanced lengthening and corrective surgical techniques also enhanced his abilities in the state-of-the-art knee, ankle and hip replacement segment of his practice.
“Modern surgical techniques for limb lengthening are largely based on Dr. Ilizarov’s work,” Dr. Dahl says. “During the course of 50 years, this brilliant man invented multiple limb-lengthening methods based on distraction osteogenesis, the body’s ability to spontaneously regenerate tissue. Without Heyerdahl’s expedition to bring Mauri and Dr. Senkevich together, Dr. Ilizarov’s techniques might never have come to light.”
This boy was treated for osteosarcoma. When the bone tumor was removed, his bone was replaced with a donor bone. The allograft became infected, and the weakened femur fractured, resulting in bone loss of 25 cm.
Minor limb-length discrepancies are relatively common. If any correction is needed, it can be handled nonsurgically. Discrepancies of an inch or more, however, place extra pressure on joints and increase degenerative arthritis. The main causes of limb-length discrepancy requiring surgical treatment include previous fractures, bone infection, bone diseases, and bone deformities, such as bowed or crooked legs, or asymmetric limbs.
Bone-lengthening and corrective treatment is appropriate for older children and adults with normal neurologic status and good health. Surgical lengthening is not appropriate for elderly or diabetic populations, or patients with severe neurologic conditions or other health risks that could interfere with their ability to grow new bone. Additionally, Dr. Dahl stresses that corrective procedures are too invasive and costly to be used for cosmetic corrections.
Surgical technology has advanced dramatically in the past 10 years, but treatments continue to incorporate the many methods and techniques developed by Dr. Ilizarov. His percutaneous corticotomy procedure cuts bone into two segments while preserving the bone’s blood supply, allowing it to grow. The external fixation device used by Dr. Ilizarov is still used to suspend and adjust treated limbs. The frame is attached to the bone with wires and threaded pins. Gradually, the cut bone is pulled apart, stimulating new bone and tissue growth. Dr. Ilizarov’s techniques resculpt the living human musculoskeletal system, saving limbs, lengthening bones, correcting bone deformities, filling defects in bones and regenerating missing lengths of bone — a procedure called bone transport.
The external fixator enables extraordinary results, but the treatment is lengthy and painful. Risks include infection at the site of the wires and pins, and stiffness in adjacent joints.
Dr. Dahl removed the allograft and treated the infection with antibiotic beads. Afterward, he cut the surviving bone in two locations and used an external fixator to lengthen and transport the bone.
In the mid-’90s, German surgeon Rainer Baumgart developed a new device to advance limb lengthening while reducing the risks and discomfort of the external fixator. Drawing on his undergraduate studies in aerospace engineering, Dr. Baumgart designed a completely implantable telescopic rod with a tiny motor operated by radiofrequency waves. This FITBONE device lengthens the bone from within, without need for an external device. Patients treated with the FITBONE maintained better muscle mass, motion and comfort — and infection complications dropped.
Only highly experienced limb-lengthening surgeons who have handled thousands of cases qualify to use implantable devices. Dr. Dahl trained with Dr. Baumgart and was one of only two American surgeons approved to use the FITBONE devices for leg lengthening and stump lengthening. Of the 1,000 cases handled globally using the FITBONE, many were performed by Dr. Dahl and his American colleague, John Birch, MD. Although the German manufacturer of the FITBONE has not yet completed the Food and Drug Administration (FDA) application and approval process, a similar implantable lengthening device, the PRECICE, developed by an American company, keeps the technology available. A handful of carefully selected American surgeons are approved to use the PRECICE device. Dr. Dahl is among them and has used the PRECICE in approximately 100 procedures since it was released a year and a half ago.
“Implantable technology takes the treatments Dr. Ilizarov developed and makes them so much more comfortable for our patients,” Dr. Dahl says. “Both FITBONE and PRECICE are wonderful products. We continue to use the FITBONE on a case-by-case basis with special application and approval from the FDA, as the FITBONE stump-lengthening device for trauma amputation patients is the only one of its kind available.”
Dr. Dahl and his staff have now fully incorporated the PRECICE technology, which is FDA-approved.
Dr. Dahl recently treated a Special Forces officer who had stepped on an improvised explosive device in Afghanistan, losing both legs and part of one arm.
“He has one amputation at mid-thigh and another that is at his hip and too short to be fit with a prosthesis,” explains Dr. Dahl. “Without a prosthesis for both legs, this young man would not be able to walk. I am able to lengthen the stump side femur enough to accommodate a prosthesis by using the shorter FITBONE lengthener.”
Finally, the FITBONE was used to lengthen the femur, and the PRECICE was used to lengthen the tibia to complete the correction, restoring normal function.
Lengthening or deformity correction for children with congenital discrepancies cannot always be achieved in one surgery because only 20 percent of the original bone can be lengthened in a single procedure. For patients missing 8–14 inches of bone, treatment may require multiple procedures over several years.
After a bone is fully lengthened and healed, internal devices are removed from the bone marrow in an outpatient procedure.
“We do a tiny incision through the end of the bone, using a sleeve to protect the joint,” Dr. Dahl explains. “A tool is threaded into the device, the screws are removed, and we slide the device out.”
Internal fixators have not replaced external fixators, which remain necessary for the correction of the most severe deformities, such as recurrent clubfoot. However, implantable devices provide an improved treatment option for appropriate patients. Internal fixator devices reduce, but do not eliminate, complications of bone-lengthening and deformity correction. Complications include delay in bone healing, premature bone healing, axial deviation during lengthening, muscle contractures and weakness, and rarely, nerve damage.
The stages of each surgery are meticulously plotted in advance using computer graphics.
“We calculate for angles that we have to correct, the length that we have to achieve, and predict the way the bone might deform if the unexpected happens,” Dr. Dahl says. “Keep in mind that soft tissues don’t adapt as well to lengthening as bone does. Nerves can stretch as much as 30 percent, and muscles will stretch up to 15 percent. Ligaments are less responsive, and cartilage doesn’t handle pressure well. For these reasons, our most challenging predictions are anticipating how hips, knees and ankles will react to lengthening in children with congenital shortened legs. Planning these surgeries is like planning a trip up the Amazon. You have to predict and plan for the bends in the river so you can avoid them.”
“Years ago,” says Dr. Dahl, “when patients had broken legs that healed crooked and short and angulated in traction, there weren’t options available to improve their outcomes. There was only the hope that someday, maybe someone would find a solution. I believe there may be thousands of people who, like Carlo Mauri in his day, may not be aware that treatment is available. Today we can offer more than hope; we have corrections to benefit these patients.”
Heyerdahl’s expeditions were founded on the belief that nations were enriched through the exchange of knowledge. His crew’s interactions reflected this spirit of generosity, opening doors that brought Dr. Ilizarov’s work to light and prompted the multinational collaboration of European, Russian and American surgeons to develop new treatment options to correct bone injuries and deformities. Dr. Dahl honors this spirit of generosity by holding tutorial education programs for surgeons worldwide, at Woodwinds Health Campus, Gillette Children’s Specialty Healthcare and High Pointe Surgery Center.
International collaboration: Dr. Dahl performed the first two FITBONE surgeries with the assistance of Canadian John Birch, MD, and Dr. Rainer Baumgart, the German inventor of the FITBONE motorized telescopic nail.
“Orthopaedic means ‘straight child,’” says Dr. Dahl, reflectively. “It reminds me that I was drawn to medicine out of a desire to help people by reducing their pain and enriching their lives. The correction of bone deformities requires a combination of geometry, physiology, surgical expertise, artistry and attention to detail. For me, the most exciting aspect of my work is the improvement we have seen in patient outcomes. At one time, the ability to merely lengthen the bone was considered success. Today, successful outcomes are about more than lengthening. Through improved devices, advances in surgical techniques, and our fantastic HealthEast team of nurses, operating teams and physical therapists, we can offer treatment that is far less painful, and outcomes that restore quality of life to these patients.”
Dr. Dahl is a partner at St. Croix Orthopaedics, practicing through the HealthEast Care System at Woodwinds Health Campus, Gillette Children’s Specialty Healthcare and High Pointe Surgery Center. To refer a patient or schedule an appointment, contact Dr. Dahl at 651-439-8807 or visit www.stcroixortho.com.
Source: MD News October 2013, Twin Cities Edition