General Session: Adult Spinal Deformity

Presented by: A.J. Buckland - View Audio/Video Presentation (Members Only)

Author(s):

J.F. Baker(1), L.M. Day(2), J.H. Oren(3), M.J. Moses(4), G.W. Poorman(5), A.J. Buckland(6), P.G. Passias(6), V. Lafage(7), F.J. Schwab(8), S. Bess(9), T.J. Errico(6), T.S. Protopsaltis(6)

(1) Auckland City Hospital, Department of Orthopaedic Surgery, Auckland, New Zealand
(2) SUNY Downstate College of Medicine, New York, NY, United States
(3) SBH Health System, Bronx, Orthopedic Surgery, Bronx, NY, United States
(4) NYU Langone Medical Center, New York, NY, United States
(5) Hospital for Joint Diseases at NYU Langone Medical Center, Department of Orthopaedic Surgery, New York, NY, United States
(6) Hospital for Joint Diseases at NYU Langone Medical Center, New York, NY, United States
(7) Hospital for Special Surgery, Spine Research, New York, NY, United States
(8) Hospital for Special Surgery, Spine Service, New York, NY, United States
(9) Denver International Spine Center, Denver, CO, United States

Abstract

Background: Surgical correction for adult spinal deformity (ASD) can be achieved with various grades of osteotomies, which are necessary when there is a significant mismatch in pelvic incidence minus lumbar lordosis (PI-LL) on standing radiographs. While computed tomography (CT) and/or magnetic resonance imaging (MRI) are routinely obtained prior to ASD surgery, the utility of these modalities in assessing flexibility for preoperative planning is unknown. The aim of this study was to examine the potential contribution of CT and MRI in planning for sagittal deformity correction.

Purpose: To evaluate the ability of CT and MRI to provide useful information about lumbar flexibility for planning ASD corrections.

Study Design/Setting: Retrospective review of an adult spinal deformity database.

Patient Sample: 122 ASD patients undergoing ≥ 3 levels of spinal fusion.

Outcome Measures: Preoperative lateral radiograph and supine CT and/or MRI spinopelvic parameters including lumbar lordosis (LL), PI-LL, and operative data including osteotomy grade.

Methods: Patients were included from a single institution adult spinal deformity database. Standing full-body stereotactic radiographs and supine lumbar CT and/or MRI were analyzed. Patients were grouped by the number of previously fused lumbar segments (0; 1-2; 3-4 levels).

Results: 122 patients were included. In patients with both CT and MRI available (n=45), there was no significant difference in LL from each (p=0.17). Mean LL was significantly different between standing radiographs and supine imaging (32.2° vs 38.4°, p< 0.001). Those with no previous segments fused had a greater change in mismatch than those who had either 1-2 or 3-4 segments previously fused, (7.7° vs 4.0° vs. 4.7°, p=0.13). When supine flexibility was considered, 44/122 (36%) patients had an increase in LL of >10°, 18 converted from PI-LL>30° to < 30°and 15 converted >20° to < 20°, potentially eliminating the need for a higher grade osteotomy. There were 4/18 patients whose PI-LL decreased to < 30° and underwent a three-column osteotomy (3CO) anyway.

Conclusions: Alignment is often overlooked when reviewing advanced imaging modalities. Supine MRI and CT are useful in determining lumbar flexibility for planning ASD surgery. A change in PI-LL mismatch on supine imaging can obviate the need for a more invasive 3CO. In addition to standing radiographs, alignment should be assessed on supine imaging modalities where available as this may enhance surgical planning and reduce surgical morbidity.

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