• HeyHwee Weng DennisHWDUniversity Orthopedics, Hand and Reconstructive Microsurgery Cluster (UOHC), National University Health System, Singapore.Yong Loo Lin School of Medicine, National University of Singapore, Singapore., Hui Wen Tay, Gordon Chengyuan Wong, Kimberly-Anne Tan, Eugene Tze-Chun Lau, Seng Juong Wong, Ka-Po Gabriel Liu, and Hee-Kit Wong.
• University Orthopedics, Hand and Reconstructive Microsurgery Cluster (UOHC), National University Health System, Singapore.
• Spine. 2021 Aug 1; 46 (15): E832-E839.

Study DesignA retrospective, radiographic comparative study conducted in a single academic institution.ObjectiveThis study aims to compare fulcrum extension with conventional extension imaging to determine maximum "hip lordosis" (HL), an important novel patient-specific parameter in spinal realignment surgery, as well as understand the extension capabilities of the lower lumbar spine, which together, are key contributors to whole-body balancing.Summary Of Background DataRecent literature recognizes the hip as an important contributor to whole-body lordosis beyond a compensator for spinal imbalance.MethodsPatients >45 years' old with mechanical low back pain due to degenerative spinal conditions were included and grouped based on the imaging performed-fulcrum or conventional extension. All imaging was performed using EOS under standardized instructions and visual aids. Radiographic parameters include global lumbar angle (GLA), inflexion-S1 (Inf-S1) angle, segmental lumbar angles, pelvic incidence (PI), sacral slope (SS), pelvic tilt (PT), femoral alignment angle (FAA), HL and spinocoxa angle (SCA). Unpaired t test was used to compare between radiographic parameters.ResultsOne hundred patients (40 males and 60 females, mean age 63.0 years) underwent either fulcrum or conventional extension EOS® imaging. Both groups had comparable baseline radiographic parameters. Fulcrum extension gave a larger mean GLA (-60.7° vs. -48.5°, P = 0.001), Inf-S1 angle (-58.8° vs. -48.8°, P = 0.003), SCA (-36.5° vs. -24.8°, P < 0.001), L4/5 and L5/S1 lordosis (-20.7° vs. -17.7°, P = 0.041, and -22.3° vs. -17.1°, P = 0.018, respectively), compared to conventional extension. PI, SS, PT, FAA, and HL were similar between both extension postures.ConclusionFulcrum extension, compared to conventional extension, is better at generating lordosis in the lower lumbar spine, thus improving preoperative assessment of stiffness or instability of the lumbar spine. Both extension methods were equally effective at determining the patient-specific maximum HL to assess the flexibility and compensation occurring at the hip, potentially guiding surgical management of patients with degenerative spines.Level of Evidence: 3.Copyright © 2021 Wolters Kluwer Health, Inc. All rights reserved.

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