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Does Removing the Spinal Tether in a Porcine Scoliosis Model Result in Persistent Deformity?: A Pilot Study

  • Symposium: Early Onset Scoliosis
  • Published:
Clinical Orthopaedics and Related Research®

Abstract

Background

Using a tethering technique, a porcine model of scoliosis has been created. Ideally, tether release before placement and evaluation of corrective therapies would lead to persistent scoliosis.

Questions/purposes

Does release of the spinal tether result in persistent deformity?

Methods

Using a unilateral spinal tether and ipsilateral rib cage tethering, scoliosis was initiated on seven pigs. The spinal tether was released after progression to a Cobb angle of 50°. Biweekly radiographs were taken for 18 weeks after tether release to evaluate longitudinal changes in coronal and sagittal Cobb angles. Postmortem fine-cut CT scans were used to evaluate vertebral and disc wedging and axial rotation; results were compared to a previously published data set of 11 animals euthanized before release of the tether (control group).

Results

Radiographic analysis demonstrated two responses to tether release: a persistent deformity group and an autocorrective group. Differences between these two groups included number of days with the tether in place before reaching a Cobb angle of 50° and degree of deformity immediately after scoliosis induction. CT analysis of the tether release versus tether intact groups demonstrated progression in vertebral body wedging without differences in apical rotation.

Conclusions

With the appropriate inducing parameters, release of the spinal tether does not systematically result in deformity correction. Tether release resulted in a reduction in Cobb angle in the first several weeks followed by steady curve progression. Deformity progression was confirmed using detailed CT morphometric analysis.

Clinical Relevance

The tether release model will be used to evaluate corrective nonfusion technologies in future investigations.

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Acknowledgments

We thank Anthony Siconolfi and Amanda Vega for their help with animal care and management.

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Authors and Affiliations

  1. Department of Orthopedic Surgery, NYU Hospital for Joint Diseases, 380 2nd Avenue, Suite 1001, New York, NY, 10010, USA

    Ashish Patel MD, Frank Schwab MD, Renaud Lafage BS, Virginie Lafage PhD & Jean Pierre Farcy MD

  2. Orthopaedic Department, SUNY Downstate Medical Center, Brooklyn, NY, USA

    Ashish Patel MD

Authors
  1. Ashish Patel MD
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  2. Frank Schwab MD
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  3. Renaud Lafage BS
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  4. Virginie Lafage PhD
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  5. Jean Pierre Farcy MD
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Corresponding author

Correspondence to Ashish Patel MD.

Additional information

One or more of the authors (FS) has received funding from a grant from Medtronic Sofamor Danek, Inc (Minneapolis, MN).

Each author certifies that his or her institution approved the animal protocol for this investigation and that all investigations were conducted in conformity with ethical principles of research.

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Patel, A., Schwab, F., Lafage, R. et al. Does Removing the Spinal Tether in a Porcine Scoliosis Model Result in Persistent Deformity?: A Pilot Study. Clin Orthop Relat Res 469, 1368–1374 (2011). https://doi.org/10.1007/s11999-010-1750-5

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  • DOI: https://doi.org/10.1007/s11999-010-1750-5

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