Orthopaedics
Spine Research

Spine Research

The spine research program has focused on understanding the anatomy, biomechanics and biology of the spine and how this may be used to improve our scoliosis care. Development of innovative treatment methods, the mechanobiology of growth, the biomechanical function of spine ligaments and biomechanics of instrumentation insertion have been recently investigated.

A crucial difference between pediatric and adult orthopaedic biomechanics is growth. A new collaborative basic science research program between the Divisions of Orthopaedic Surgery and Developmental Biology on the regulation of the skeletal growth plates has been started at Cincinnati Children's. This program is designed to study physiological growth and, subsequently, patterns of abnormal growth as a result of changes to these regulatory pathways.

More than most other branches of medicine, mechanics is central to orthopaedics. Therefore, the mechanobiology of growth is a primary research interest, especially as it impacts the clinical treatment of skeletal deformities. We have designed and fabricated a spine staple based on the premise that some scoliosis may be surgically arrested or corrected much less invasively than with spinal fusion by modifying spine growth. The initial work was published in Spine (May 20, 2005). A company, SpineForm LLC, was created to develop, test and commercialize the spinal staple. 

With the help of a Cincinnati Children's Trustee Grant in 1994, we began animal studies on endoscopic approaches to scoliosis correction. We initially validated that thoracoscopic discectomy improved spine flexibility as well as traditional discectomy in which the chest was split open (Spine, 1998). 

More recently we defined the normal pressures exerted on the growth plate using novel microelectromechanical (MEMS) stress sensors that we fabricated in our lab in collaboration with the University of Cincinnati’s Micro / Nano Engineering group and support from grants from the trustees and Scoliosis Research Society. 

We also quantified the structural features of spine growth plate tissues from scoliosis patients. With these tissues, we have determined that growth activity remains in the spine even in patients with severe deformities. In November 2009, the FDA conditionally approved its first pediatric orthopaedic investigational device exemption (IDE) for studying the SpineForm spine staple in children.  This landmark IDE approval is also the first for a spine growth modulation device by any regulatory body in the world.  Our next steps are to obtain national and international investigator agreements, site agreements and site IRB approvals. 

The Division of Orthopaedics is one of the leaders in endoscopic spinal surgery in children, performing hundreds of cases in children and adolescents. In cooperation with Ethicon Endo-Surgery and the Cincinnati Children's teleconferencing center, we have performed live interactive surgical procedures that were viewed by spine surgeons nationally and internationally. We conducted the first international training course in VATS to correct spinal deformities for the University of Tokyo. We are currently performing VATS spinal instrumentation and fusion for correction of scoliosis in select cases.

With support and collaboration of the Cincinnati Children's Research Foundation, Department of Surgery and Ethicon, we invented and developed devices and procedures to modify spine growth and biomechanical tests to evaluate their effect on spine motion. The implants may correct adolescent idiopathic scoliosis using an entirely endoscopic technique. The prototype work was presented to the 2003 Scoliosis Research Society where it won the prestigious Hibbs Award for clinical research, and was published in Spine in 2005. Since then, a mechanism of action of this implant was determined by histomorphometric studies of the structure of vertebral growth plates. This work was published in the major refereed journal of the American Academy of Orthopaedic Surgeons, the Journal of Bone and Joint Surgery (Am) in March 2009. This was a collaborative effort with the Cincinnati Children's Division of Pathology. Techniques to assess biological changes to growth plate and disc are being developed in collaboration with the Division of Developmental Biology at Cincinnati Children's.

To determine major differences between the spine biomechanics of humans and animal models, we directly measured in vivo compressive stresses in quadruped intervertebral discs. Microelectromechanical sensors (MEMS) were designed and fabricated in collaboration with UC Electrical Engineering. The sensors were also used to measure stresses bilaterally in vitro to determine the biomechanical effects of implant insertion. A computational model, using finite element analysis (FEA), is being developed with Mechanical Engineering at the University of Cincinnati. The model simulates mechanical tests on spinal segments and will be used to evaluate the effect of implant and design changes on the load-displacement characteristics and the stresses in the disc.

A joint company, SpineForm LLC, was formed with medical device development company E-Prime LLC. We have US and international patents, including continuations issued in 2009 on the novel spine staple implant system. Implant modifications were tested in bench and live models in an independent, GLP laboratory. After the generous support of the Cincinnati business community and the work of nationally recognized regulatory consultants, the FDA granted a conditional investigational device exemption in October 2009. 

 

In cooperation with Depuy Spine Inc., we have completed the development of an anterior implant instrumentation system to correct spinal deformities in children. The Frontier instrumentation system has been designed with both open and endoscopic anterior scoliosis correction in mind. The operative technique varies depending on the type of scoliosis to be treated, as well as the approach. The technique and indications continue to be defined, and advancements should be anticipated.

 

Hemiepiphysiodesis is one of least invasive and most effective procedures to correct limb deformity in children. Since 1993, the Division of Orthopaedics at Cincinnati Children’s Hospital Medical Center has helped translate limb growth modulation techniques to scoliosis correction. Our preclinical studies on endoscope spine staple hemiepiphysiodesis have earned the top research award at the Scoliosis Research Society (Hibbs Award) in 2003. In November 2009, the FDA approved the Cincinnati Children’s HemiBridge Spine Clip for an investigational device exemption (IDE) study in humans (2009). This marks the FDA’s first IDE approval for a pediatric orthopaedic device. Human use should begin on children with scoliosis at two sites in 2010 and expand to approximately 10 sites thereafter. If growth modulation is as successful in the spine as it is in the limbs, our device has strong potential to eliminate most spinal fusions in growing children with scoliosis. Our minimum surgery device aims to correct the growth of a scoliotic spine rather than fuse it into a long solid column. In collaboration with Cincinnati Children’s, the HemiBridge spine clip technology is licensed to SpineForm, a start-up company in Cincinnati.

 

Several members of the Spine Center are also members of the Growing Spine Study Group (GSSG), dedicated to the treatment of progressive early onset spinal deformities. The treatment of progressive scoliosis in very young children has been a difficult problem to address. Both nonoperative treatment such as bracing and casting and operative care such as growing rod and vertical expandable prosthetic titanium rib (VEPTR) carry a high rate of complications in this young population with progressive curves. Furthermore, definitive fusion of the entire deformity at an early age can also lead to growth-related problems including short trunk, thorax and crank-shaft phenomenon as well as respiratory problems. Indications for different types of treatments are unclear. Recent studies from Cincinnati Children’s and others have shown good early results for patients being treated with dual growing rods in children with early onset scoliosis (EOS).

Additional treatments addressing early onset spinal deformity related diseases have promising results as well, but need to be reviewed for long-term outcomes. The significance of this multicenter study is to obtain a large number of patient data to compare all treatments for children with this severe, challenging problem. It is important to know how different surgical techniques compare to each other as well as to nonoperative care and / or observation to better understand the problem and determine the best way to treat these children with the least amount of surgery necessary. This multicenter study will evaluate the long-term clinical and radiographic outcomes of EOS and other early onset spinal and chest wall deformities in a large population of patients.

 

In a collaborative effort with the Division of Pulmonary Medicine, the Division of Orthopaedics has been approved by the Growing Spine Study Group (GSSG) executive committee to submit a proposal to study early onset scoliosis curves with evidence of obstructive lung disease (OLD). Prior pulmonary focus on scoliosis has been on restrictive lung disease (RLD) in which lung size is diminished by a small thoracoabdominal cavity. This shows up on pulmonary function tests (PFTs) as a reduced forced vital capacity (FVC). Obstructive lung disease may be even more common than restrictive disease in scoliosis, and is typically caused by the spine compressing against the right bronchus. In obstructive lung disease it takes a child longer to exhale against their compressed bronchus, which is evident on PFTs as a low forced expiratory volume in the first second (FEV1).

Our initial findings of a retrospective chart review at Cincinnati Children's showed that OLD is relatively common in thoracic scoliosis curves, especially those with loss of normal kyphosis. Amazingly, children with OLD of <70 percent FEV1 can be completely corrected within one week after scoliosis surgery by intentionally creating kyphosis during surgical correction. The larger multisite study will increase the number of cases for review, and has the potential to produce new standard-of-care guidelines for the surgical treatment of scoliosis for children with obstructive lung disease.

 

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