• Deokcheol Lee, Tomofumi Kuroki, Takuya Nagai, Keisuke Kawano, Kiyoshi Higa, Syuji Kurogi, Hideaki Hamanaka, and Etsuo Chosa.
• Department of Orthopaedic Surgery, University of Miyazaki, Miyazaki, Japan.
• Spine. 2022 Jan 15; 47 (2): E46E57E46-E57.

Study DesignA retrospective analysis of a prospective, non-randomized cohort dataset.ObjectiveTo cross-sectionally examine the prevalence of sarcopenia and the association between spine-pelvic deformity and skeletal muscle volume loss and ectopic fat infiltration into lumbar paravertebral muscles (PVMs) in patients who underwent lumbar surgery.Summary Of Background DataMuscle quality deterioration has been considered the main pathology of sarcopenia, reducing muscle strength directly. The qualitative deterioration as well as volume loss in PVM, which contributes significantly to core body extension, might cause aging-related spine deformity.MethodsIn total, 184 patients were included. Sarcopenia was diagnosed at baseline, and all patients underwent whole-body X-ray. The amount of fat in lumbar PVM was evaluated with the Goutallier classification in magnetic resonance imaging findings. The expression of adipogenesis- and atrophy-promoting factors in PVM was evaluated with quantitative polymerase chain reaction.ResultsIn total, 36.1% of adults aged ≥60 years were diagnosed with sarcopenia. The values of skeletal muscle indexes of the limb and trunk were inversely correlated with the sagittal vertical axis, pelvic tilt (PT), and pelvic incidence minus lumbar lordosis (PI-LL) values. The PT and PI-LL were greater, PVM area was smaller, and Goutallier grade was greater in sarcopenic adults than in non-sarcopenic older adults. Additionally, the PVM area correlated with the LL value, and Goutallier's grade correlated with the PT and PI-LL values. Moreover, the amount of ectopic fat in PVMs inversely correlated with skeletal muscle indexes. The expression levels of atrophy gene-1 and muscle ring-finger protein-1 did not differ between the groups and did not correlate with the PVM area. In contrast, the expression of Pparg and Cebpa was upregulated in sarcopenic older adults, where it correlated with Goutallier's grade.ConclusionThe volume loss of skeletal muscle, including lumbar PVM, and ectopic fat infiltration into the PVM, may cause the lumbo-pelvic deformity.Level of Evidence: 3.Copyright © 2021 The Author(s). Published by Wolters Kluwer Health, Inc.

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