Spinal Growth Modulation with Use of a Tether in an Immature Porcine Model

Newton, Peter O.; Upasani, Vidyadhar V.; Farnsworth, Christine L.; Oka, Richard; Chambers, Reid C.; Dwek, Jerry; Jung Ryul Kim; Perry, Andrew; Mahar, Andrew T.
December 2008
Journal of Bone & Joint Surgery, American Volume;Dec2008, Vol. 90-A Issue 12, p2695
Academic Journal
Background: Spinal growth modulation by tethering the anterolateral aspect of the spine, as previously demonstrated in a nonscoliotic calf model, may be a viable fusionless treatment method for idiopathic scoliosis. The purpose of the present study was to evaluate the radiographic, histologic, and biomechanical results after six and twelve months of spinal growth modulation in a porcine model with a growth rate similar to that of adolescent patients. Methods: Twelve seven-month-old mini-pigs underwent instrumentation with a vertebral staple-screw construct connected by a polyethylene tether over four consecutive thoracic vertebrae. The spines were harvested after six (n = 6) or twelve months (n = 6) of growth. Monthly radiographs, computed tomography and magnetic resonance imaging scans (made after the spines were harvested), histologic findings, and biomechanical findings were evaluated. Analysis of variance was used to compare preoperative, six-month postoperative, and twelve-month postoperative data. Results: Radiographs demonstrated 14° ± 4° of coronal deformity after six months and 30° ± 13° after twelve months of growth. Coronal vertebral wedging was observed in all four tethered vertebrae and progressed throughout each animal's survival period. Disc wedging was also created; however, in contrast to the findings associated with vertebral wedging, the tethered side was taller than the untethered side. Magnetic resonance images revealed no evidence of disc degeneration; however, the nucleus pulposus had shifted toward the side of the tethering. Midcoronal undecalcified histologic sections showed intact bone-screw interfaces with no evidence of implant failure or loosening. With the tether cut, stiffness decreased and range of motion increased in lateral bending away from the tether at both time-points (p < 0.05). Conclusions: In this porcine model, mechanical tethering during growth altered spinal morphology in the coronal and sagittal planes, leading to vertebral and disc wedging proportional to the duration of tethering. The resulting concave thickening of the disc in response to the tether was not anticipated and may suggest a capacity for the nucleus pulposus to respond to the compressive loads created by growth against the tether. Clinical Relevance: Multilevel flexible tether placement may provide a growth-modulating mechanism for scoliosis correction while maintaining disc health. Understanding the response of the growing vertebrae and discs in this proposed method of fusionless scoliosis treatment remains paramount.


Related Articles

  • Computerized Tomographic Morphometric Analysis of Subaxial Cervical Spine Pedicles in Young Asymptomatic Volunteers. Rao, Raj D.; Marawar, Satyajit V.; Stemper, Brian D.; Yoganandan, Narayan; Shender, Barry S. // Journal of Bone & Joint Surgery, American Volume;Sep2008, Vol. 90-A Issue 9, p1914 

    Background: Although cervical spine pedicle screws have been shown to provide excellent fixation, widespread acceptance of their use is limited because of the risk of injury to the spinal cord, nerve roots, and vertebral arteries. The risks of pedicle screw insertion in the cervical spine can be...

  • transversectomy.  // Taber's Cyclopedic Medical Dictionary (2009);2009, Issue 21, p2365 

    A definition of the term "transversectomy," which refers to the excision of a transverse vertebral process, is presented.

  • Choice Spine Launches Major System into Lucrative Pedicle Screw Spine Market.  // Biomedical Market Newsletter;1/28/2012, Vol. 21, p1 

    The article informs that Choice Spine, a spine manufacturer has launched Starfire Pedicle Screw System. It mentions that this system enables the surgeons to treat lumbar conditions, post traumatic spine instability and scoliosis. It further informs about the features of the Starfire System which...

  • The future of cervical spine surgery may focus on motion preservation. Brockenbrough, Gina // Orthopedics Today;Feb2009, Vol. 29 Issue 2, p57 

    This article looks at the future of dynamics in cervical spine surgery and challenges in this area.

  • Lateral Lumbar Interbody Fusion. Pawar, Abhijit; Hughes, Alexander; Girardi, Federico; Sama, Andrew; Lebl, Darren; Cammisa, Frank // Asian Spine Journal;2015, Vol. 9 Issue 6, p978 

    The lateral lumbar interbody fusion (LLIF) is a relatively new technique that allows the surgeon to access the intervertebral space from a direct lateral approach either anterior to or through the psoas muscle. This approach provides an alternative to anterior lumbar interbody fusion with...

  • PERSPECTIVE. Hee Kit Wong // Orthopedics Today;Jul2011, Vol. 31 Issue 7, p26 

    The author comments on the study by Miyako Suzuki wherein Suzuki found that, in determining whether using local bone graft is as effective as iliac crest bone graft in case of L4 degenerative spondylolisthesis, there are fusion rates of 90% and 85%, respectively, in single-level instrumented cases.

  • Corrective Osteotomies in Spine Surgery. Gill, J. Brian; Levin, Andrew; Burd, Tim; Longley, Michael // Journal of Bone & Joint Surgery, American Volume;Nov2008, Vol. 90-A Issue 11, p2509 

    The article presents a review of corrective osteotomies in spine surgery. The histories and operative techniques for Smith-Petersen, pedicle subtraction, and cervical extension osteotomies are covered. A discussion of vertebral column resection is also included. The indications for the different...

  • Foraminal Endoscopic Spine Surgery For Painful Degenerative Conditions of the Lumbar Spine: Focus on Endoscopic Decompression of Lateral recess stenosis. Yeung, Anthony T. // Internet Journal of Minimally Invasive Spinal Technology;Supplement III, p25 

    An abstract of the article "Foraminal Endoscopic Spine Surgery for Painful Degenerative Conditions of the Lumbar Spine: Focus on Endoscopic Decompression of Lateral Recess Stenosis," by Anthony T. Yeung is presented.

  • Tratamiento por vía anterior de las lesiones inestables de la columna toracolumbar. Palapa García, Leobardo Roberto; Vallejo, Sergio Anaya; Martínez, Gustavo Casas // Acta Ortopedica Mexicana;sep/oct2002, Vol. 16 Issue 5, p245 

    Objective. 1. To describe to the post-operating clinical evolution of the patients with unstable injuries thoracolumbars. 2. To determine the stability of the unstable injuries thoracolumbars treated by anterior approach. 3. To correlate the proportion of invasion to the spinal conduit and the...


Read the Article


Sorry, but this item is not currently available from your library.

Try another library?
Sign out of this library

Other Topics