CHRI Investigator Feature
One of CHRI’s newest faculty investigators is Matthew Halanski, MD, who came to CHMC and UNMC in February as Chief of Pediatric Orthopaedic Surgery. Dr. Halanski entered the medical profession out of a passion for research and discovery. He has developed a nationally and internationally recognized track record in pediatric orthopedics research that began in Residency, continued through Fellowship, and onward into his previous position on the faculty of the University of Wisconsin-Madison. He was attracted to Omaha by the opportunity for more protected research time, as well as CHRI’s research resources. While Dr. Halanski’s research program spans from basic science to clinical studies, three research tracks that Dr. Halanski described in our recent interview demonstrate a variety of strategies for innovative treatment of orthopaedic disorders in children.
Immobilization casts for treatment of fractures may not appear to be a natural target for technology and innovation, but some of Dr. Halanski’s most visible and well-published research has been on developing devices and techniques to improve cast safety. During the application of a cast, plaster’s exothermic hardening process can create enough heat to burn the skin. Dr. Halanski and colleagues developed a technique to infuse the casting material with a thermosensitive dye, so that when it approaches a temperature that risks burning, the material changes color to alert the clinician. Injury can also happen at time of cast removal, when the skin can be injured by abrasion or burn by the hot saw blade. Dr. Halanski and colleagues tested strategies to alleviate this risk. One was incorporating a blade-resistant strip applied along the length of the cloth stockinette before application of the casting material. A more recent invention uses a conductive silver-impregnated stockinette that allows triggering of an alarm system that can be added to any commercially available cast saw. A patent is pending, and there are plans to evaluate this alarm system in a clinical trial. Dr. Halanski is continuing to innovate in this space since arriving in Omaha, by pairing with Dr. Hani Haider, PhD, UNMC Orthopaedic Surgery, to develop devices that can alleviate pressure sores under casts.
Another line of research for the Halanski team is innovating early childhood treatments for clubfoot. Standard treatment, called the Ponseti Method, starts with serial casting which obtains foot correction and is then followed by the bracing. Bracing is a strategy to avoid relapse, and requires the child wear a brace nightly until age 4. Those that relapse in spite of bracing typically undergo a tendon transfer surgery, where the tendon is moved from one side of the foot to the other and attached to bone. Dr. Halanski points out considerable evidence that this treatment program may be suboptimal for many patients, as some patients may be over-braced and despite bracing, still go on to recur. Dr. Halanski is working with Dr. Haider to explore clinical measures that may allow early identification of those whose bracing is no longer needed or is ineffective. This would allow a more individually-tailored treatment strategy if this relapse risk could be identified much earlier. For those children in which bracing is ineffective or not well tolerated, Dr. Halanski’s team has investigated performing tendon transfers at a much younger age to serve as a prophylaxis, which may eliminate years of bracing. However, one main concern for early surgery: babies’ bones are not yet hardened, and it is unknown how well a tendon can be successfully transferred to a non-ossified bone. Dr. Halanski and colleagues developed a novel animal model utilizing newborn pigs to study this question. Initial investigations using this model with standard tendon transfer techniques demonstrated ill effects on subsequent bone growth. This has led the team to investigate alternate, less destructive tendon transfer techniques which appear promising. Overall, the hope with this line of inquiry is to diminish the burdensome bracing phase or eliminate it altogether for many patients.
The research track where Dr. Halanski’s studies seem to delve most deeply into basic biology revolves around discovering and understanding surgical interventions that promote targeted bone growth. “One of the biggest problems that underlies many of the disorders we treat in pediatric orthopedics is diminished skeletal growth,” he explains. “If one side of a bone is not growing as fast as the other side you get a crooked bone. If one entire limb is growing slower than the other you get a leg length difference. Uneven growth is a hallmark of many things we end up treating with surgery: limb deformities, scoliosis, acetabular dysplasia (hip dysplasia). We have many ways of slowing down growth: from restricting growth with plates and screws, to drilling or scraping out the GOOD growth plate, or even removing sections of bone to shorten them. However, we still haven’t figured out a clinically useful way to speed up growth.”
Over 50 years ago it was shown that bone growth could be stimulated in horses by transverse division of the periosteum, the fibrous layer that surrounds the bone. Decades later, a clinical trial in children with unequal leg lengths showed it is possible to lengthen the shorter leg by making multiple periosteal divisions in the tibia, femur, and fibula – however, this was a highly invasive surgery . The mechanism of this growth response has been up for debate; the prevailing theory says the periosteum serves as a mechanical tether, so cutting it simply frees the bone tissues to grow unrestrained. Others have postulated that the accelerated growth is nothing more than a response to local inflammation and increased blood flow to the area. Dr. Halanski and colleagues at UW-Madison began investigating this question experimentally using various animal models. Through elegant surgical techniques, mechanical modeling and testing, and the first-time use of second harmonic generation imaging to visualize the periosteum’s collagen fibers on growing bones, before and after surgical treatment, it became evident that the “mechanical tether theory” is insufficient to explain growth acceleration.
Looking forward, Dr. Halanski comments, “That finding has branched our research into two questions. One is to ask, ‘What is the actual mechanism?'” He and his lab continue to look for this answer. “The other question is, ‘Regardless of the mechanism can we resect the periosteum in a non-invasive manner?’” Over the past few years, Dr. Halanski has collaborated with a team at the University of Michigan to develop a novel “knifeless” ultrasound technique that is able to cut the periosteum. Further optimization of this non-surgical method in both small and large animal models could set the stage for human clinical trials and open new possibilities to treat orthopaedic disorders in children.
- Limpaphayom N and Prasongchin P. Surgical technique: Lower limb-length equalization by periosteal stripping and periosteal division. Clinical Orthopaedics and Related Research. 2011; 469(11):3181-9.
by Matthew Sandbulte, CHRI Grant Writer | October 14, 2019