• Mariah Balmaceno-Criss, Renaud Lafage, Daniel Alsoof, Mohammad Daher, David Kojo Hamilton, Justin S Smith, Robert K Eastlack, Richard G Fessler, Jeffrey L Gum, Munish C Gupta, Richard Hostin, Khaled M Kebaish, Eric O Klineberg, Stephen J Lewis, Breton G Line, Pierce D Nunley, Gregory M Mundis, Peter G Passias, Themistocles S Protopsaltis, Thomas Buell, Justin K Scheer, Jeffrey P Mullin, Alex Soroceanu, Christopher P Ames, Lawrence G Lenke, Shay Bess, Christopher I Shaffrey, Frank J Schwab, Virginie Lafage, Douglas C Burton, Bassel G Diebo, Alan H Daniels, and International Spine Study Group (ISSG).
• Department of Orthopedics, Warren Alpert Medical School of Brown University, East Providence, RI.
• Spine. 2024 Jun 1; 49 (11): 743751743-751.

Study DesignRetrospective review of prospectively collected data.ObjectiveTo investigate the effect of lower extremity osteoarthritis on sagittal alignment and compensatory mechanisms in adult spinal deformity (ASD).BackgroundSpine, hip, and knee pathologies often overlap in ASD patients. Limited data exists on how lower extremity osteoarthritis impacts sagittal alignment and compensatory mechanisms in ASD.Patients And MethodsIn total, 527 preoperative ASD patients with full body radiographs were included. Patients were grouped by Kellgren-Lawrence grade of bilateral hips and knees and stratified by quartile of T1-Pelvic Angle (T1PA) severity into low-, mid-, high-, and severe-T1PA. Full-body alignment and compensation were compared across quartiles. Regression analysis examined the incremental impact of hip and knee osteoarthritis severity on compensation.ResultsThe mean T1PA for low-, mid-, high-, and severe-T1PA groups was 7.3°, 19.5°, 27.8°, and 41.6°, respectively. Mid-T1PA patients with severe hip osteoarthritis had an increased sagittal vertical axis and global sagittal alignment ( P <0.001). Increasing hip osteoarthritis severity resulted in decreased pelvic tilt ( P =0.001) and sacrofemoral angle ( P <0.001), but increased knee flexion ( P =0.012). Regression analysis revealed that with increasing T1PA, pelvic tilt correlated inversely with hip osteoarthritis and positively with knee osteoarthritis ( r2 =0.812). Hip osteoarthritis decreased compensation through sacrofemoral angle (β-coefficient=-0.206). Knee and hip osteoarthritis contributed to greater knee flexion (β-coefficients=0.215, 0.101; respectively). For pelvic shift, only hip osteoarthritis significantly contributed to the model (β-coefficient=0.100).ConclusionsFor the same magnitude of spinal deformity, increased hip osteoarthritis severity was associated with worse truncal and full body alignment with posterior translation of the pelvis. Patients with severe hip and knee osteoarthritis exhibited decreased hip extension and pelvic tilt but increased knee flexion. This examines sagittal alignment and compensation in ASD patients with hip and knee arthritis and may help delineate whether hip and knee flexion is due to spinal deformity compensation or lower extremity osteoarthritis.Copyright © 2024 Wolters Kluwer Health, Inc. All rights reserved.

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