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Evaluation of Limited Screw Density Pedicle Screw Constructs in Posterior Fusions for Adolescent Idiopathic Scoliosis

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Abstract

Study design

Retrospective case series.

Objectives

To compare radiographic and clinical outcomes in posterior spine fusions with pedicle screw instrumentation of varying screw densities in the treatment of adolescent idiopathic scoliosis (AIS).

Summary of background data

Posterior spinal fusion with pedicle screw instrumentation is the mainstay of surgical treatment for AIS. The most commonly used construct consists of screws placed at every level on the concave side of the deformity and nearly every level on the convex side. However, some surgeons have begun using constructs with fewer pedicle screws. The literature comparing outcomes of these differing pedicle screw constructs is limited.

Methods

Fifty-two consecutive cases of posterior spinal fusions for AIS performed by four surgeons were reviewed. High screw density constructs were used in 26 cases and limited screw density constructs in 26 cases. Construct characteristics and radiographic measurements were compared preoperatively and at last follow-up. Operative time and estimated costs were also evaluated. Student t tests were used to compare the groups with p <.05 considered significant.

Results

There was no significant difference in magnitude of correction for the high versus limited screw density group initially (38.5° vs. 34.9°, p =.093) or at final follow-up (36.9° vs. 32.2°, p =.054). Sagittal alignment, coronal balance, and translation of the major apical vertebra were comparable and stable in both groups. The high versus limited screw density group utilized significantly more pedicle screws (16.8 vs. 11.6 screws, p <.0001), had longer operative times (309 vs. 267 minutes, p =.007), and had additional estimated direct costs of $5,800.

Conclusions

Excellent curve correction, stability, and balance can be achieved using fewer screws than commonly used in posterior pedicle screw fusions for AIS. Operative time is reduced, and risk and cost are decreased with the use of limited screw density constructs.

Level of Evidence

III.

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Author information

Authors and Affiliations

  1. Department of Pediatric Orthopaedics, Helen DeVos Children’s Hospital, 35 Michigan Street NE, Suite 4150, Grand Rapids, MI, 49503, USA

    John W. Kemppainen MD

  2. Department of Orthopedic Surgery Biostats, Akron Children’s Hospital, Orthopaedics, Suite 7200, One Perkins Square, Akron, OH, 44308, USA

    Melanie A. Morscher PT, Mark J. Adamczyk MD & Todd F. Ritzman MD

  3. Biostats, Inc., 501 Wood Street North, East Canton, OH, 44730, USA

    M. David Gothard MS

Authors
  1. John W. Kemppainen MD
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  2. Melanie A. Morscher PT
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  3. M. David Gothard MS
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  4. Mark J. Adamczyk MD
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  5. Todd F. Ritzman MD
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Corresponding author

Correspondence to Todd F. Ritzman MD.

Additional information

Author disclosures: JWK (none); MAM (none); MDG (none); MJA (none); TFR (none).

The authors are especially grateful for the help provided by Jessica Kemppainen, PhD (University of Akron, Akron, OH), for manuscript consultation and Amy Krahe, MPT (Akron Children’s Hospital), for manuscript preparation.

This work was supported in part from donations received by Akron Children’s Hospital Foundation, specifically for orthopedic research and education.

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Kemppainen, J.W., Morscher, M.A., Gothard, M.D. et al. Evaluation of Limited Screw Density Pedicle Screw Constructs in Posterior Fusions for Adolescent Idiopathic Scoliosis. Spine Deform 4, 33–39 (2016). https://doi.org/10.1016/j.jspd.2015.07.010

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  • DOI: https://doi.org/10.1016/j.jspd.2015.07.010

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