General Session: Adult Spinal Deformity

Presented by: J. Andres-Bergos - View Audio/Video Presentation (Members Only)

Author(s):

J. Scheer(1), J. Andres-Bergos(2), R. Lafage(2), F. Schwab(2), J. Smith(3), G. Mundis(4), R. Hostin(5), C. Shaffrey(3), C. Ames(6), D. Burton(7), H.J. Kim(2), S. Bess(8), M. Gupta(9), V. Lafage(2), International Spine Study Group (ISSG)

(1) Northwestern University Feinberg School of Medicine, Department of Neurological Surgery, Chicago, IL, United States
(2) Hospital for Special Surgery, Spine Service, New York, NY, United States
(3) University of Virginia Medical Center, Charlottesville, VA, United States
(4) Scripps Clinic Torrey Pines, La Jolla, CA, United States
(5) Baylor Scoliosis Center, Plano, TX, United States
(6) San Francisco Medical Center, University of California, San Francisco, CA, United States
(7) University of Kansas Medical Center, Department of Orthopaedic Surgery,, Kansas City, KS, United States
(8) NYU Langone Medical Center, New York, NY, United States
(9) Washington University School of Medicine, Department of Orthopaedic Surgery, St. Louis, MO, United States

Abstract

Introduction: Recent sagittal plane analyses have proposed age-adjusted alignment thresholds. However, the impact of these thresholds on post-operative HRQL has not been investigated. This study aims to compare clinical outcomes of patients undergoing surgical reconstruction based on their achievement to age-adjusted alignment parameters in a two years follow-up.

Methods: This multicenter prospective study collects data of consecutive patients with thoracolumbar spinal deformity. A total of 343 adult patients (mean age = 57±15) undergoing surgical correction with a complete follow-up of two years were included. Patients were divided in three groups based on age-adjusted threshold achievement. Stratification was performed as follows: patients reaching age-adjusted threshold ±10 years (matched), patients over-corrected (over) and patients under-corrected (under). For these groups, three different age-adjusted thresholds were assessed; Pelvic Tilt (PT), Pelvic Incidence minus Lumbar Lordosis (PI-LL) and Sagittal Vertical Axis (SVA). Clinical outcomes included actual values and offset from age-adjusted norms were compared between groups at two years follow-up in terms of Oswestry Disability Index (ODI), Short Form 36 questionnaire - physical component summary (SF36-PCS) and Scoliosis Research Society questionnaire (SRS-22).

Results: Average sagittal profile values within the assessed population were: PT=23.3˚± 11, PI-LL=15˚ ± 21, SVA=65mm±77. Two years after surgical reconstruction all measured sagittal parameters showed significant improvement with 25.9% (PT), 23.1% (PI-LL) and 32.9% (SVA) of patients matching their age-alignment threshold. Analysis of each independent parameter showed similar clinical outcomes across the three groups of patients (matched/over/under) in the case of PT and PI-LL. However, SVA assessment demonstrated worse HRQOL for patients under-corrected compared to those either matching their age-adjusted threshold or over-corrected; there was no significant difference between overcorrected patients and those matching an age-adjusted SVA. In addition, patients with SVA over-corrected were significantly older (53.7 vs. 54.2 and 62.4 y/o, p< 0.05). Table: Post-operative groups of patients who were under-corrected, matched or over-corrected based on their age-adjusted alignment thresholds.

Conclusion: Surgical correction of spine deformity achieves age-adjusted stablished threshold of sagittal parameters for a range of 23-33% patients assessed two years after the procedure. Patients showing under-corrected SVA demonstrated worse clinical outcomes whereas other parameters such as PT or PI-LL remain similar for HRQOL across the groups evaluated. Conversely, SVA matched and over-corrected patients did not show significant HRQOL improvement. However, these results must be carefully interpreted given the established risk of proximal junctional kyphosis (PJK) for patients being over-corrected. Taken together, this study further emphasizes the need of personalized spinal surgical correction plans and demonstrated that over-correction does not bring incremental benefit.

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