{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,10,22]],"date-time":"2026-10-22T02:40:07Z","timestamp":1792636807384,"version":"4.5.0"},"reference-count":34,"publisher":"MDPI AG","issue":"4","license":[{"start":{"date-parts":[[2025,2,12]],"date-time":"2025-02-12T00:00:00Z","timestamp":1739318400000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["JCM"],"abstract":"<jats:p>Background\/Objectives: Both poor bone quality and paraspinal sarcopenia have been suggested as risk factors for proximal junctional kyphosis (PJK) at the upper instrumented vertebra (UIV) following long-segment thoracolumbar fusion. Methods: Adults \u226550 with a T1-6 UIV were identified, and data were gathered on pre- and postoperative spinopelvic parameters, bone quality (using Hounsfield units and vertebral bone quality score), and paraspinal cross-sectional area at L3 and the UIV. PJK was defined by a \u226510\u00b0 increase in the proximal junctional angle. Cox regressions were performed to identify PJK risk factors; PJK was subdivided into types 1\u20133 based on the Yagi\u2013Boachie classification. Results: In total, 15\/76 patients (median age 66; 72.4% female) experienced PJK; 10 experienced type 1, 4 experienced type 2, and one experienced type 3. Univariable Cox regression showed that PJK was negatively correlated with total paraspinal muscle CSA at the UIV (HR 0.74\/100 mm2; 95% CI [0.57, 0.6]; p = 0.02). Lower total paraspinal CSA at L3 (HR 0.94\/100 mm2; p = 0.07) and higher postoperative global tilt (HR 1.03; p = 0.09) also trended toward significance. Similarly, type 1 PJK was predicted by smaller total paraspinal CSA at the UIV (HR 0.64\/100 mm2; [0.45, 0.92]; p = 0.02). Paraspinal CSA was not predictive of type 2 PJK, but lower HU at the UIV and UIV + 1 trended toward significance (HR 0.98\/unit; p = 0.16). A comparison of type 1 and 2 PJK showed a higher average of paraspinal CSA and a lower average of HU at the UIV. Conclusions: Global alignment and paraspinal sarcopenia were most predictive of PJK, though paraspinal sarcopenia was only predictive of type 1. Type 2 may be better predicted by bone quality.<\/jats:p>","DOI":"10.3390\/jcm14041207","type":"journal-article","created":{"date-parts":[[2025,2,12]],"date-time":"2025-02-12T08:05:42Z","timestamp":1739347542000},"page":"1207","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":5,"title":["The Paraspinal Sarcopenia at the Upper Instrumented Vertebra Is a Predictor of Discoligamentous but Not Bony Proximal Junctional Kyphosis"],"prefix":"10.3390","volume":"14","author":[{"ORCID":"https:\/\/orcid.org\/0000-0001-8012-860X","authenticated-orcid":false,"given":"Zach","family":"Pennington","sequence":"first","affiliation":[{"name":"Department of Neurologic Surgery, Mayo Clinic, Rochester, MN 55905, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Anthony L.","family":"Mikula","sequence":"additional","affiliation":[{"name":"Department of Neurologic Surgery, Mayo Clinic, Rochester, MN 55905, USA"},{"name":"Department of Neurosurgery, University of California San Francisco, San Francisco, CA 94143, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0009-0007-3609-7229","authenticated-orcid":false,"given":"Abdelrahman","family":"Hamouda","sequence":"additional","affiliation":[{"name":"Department of Neurologic Surgery, Mayo Clinic, Rochester, MN 55905, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Maria","family":"Astudillo Potes","sequence":"additional","affiliation":[{"name":"Department of Neurologic Surgery, Mayo Clinic, Rochester, MN 55905, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Ahmad","family":"Nassr","sequence":"additional","affiliation":[{"name":"Department of Orthopaedic Surgery, Mayo Clinic, Rochester, MN 55905, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Brett A.","family":"Freedman","sequence":"additional","affiliation":[{"name":"Department of Orthopaedic Surgery, Mayo Clinic, Rochester, MN 55905, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Arjun S.","family":"Sebastian","sequence":"additional","affiliation":[{"name":"Department of Orthopaedic Surgery, Mayo Clinic, Rochester, MN 55905, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Jeremy L.","family":"Fogelson","sequence":"additional","affiliation":[{"name":"Department of Neurologic Surgery, Mayo Clinic, Rochester, MN 55905, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Benjamin D.","family":"Elder","sequence":"additional","affiliation":[{"name":"Department of Neurologic Surgery, Mayo Clinic, Rochester, MN 55905, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2025,2,12]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"1082","DOI":"10.1097\/01.brs.0000160842.43482.cd","article-title":"Adult Scoliosis: Prevalence, SF-36, and Nutritional Parameters in an Elderly Volunteer Population","volume":"30","author":"Schwab","year":"2005","journal-title":"Spine"},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"301","DOI":"10.1007\/s00132-018-3536-5","article-title":"Realignment Surgery in Adult Spinal Deformity","volume":"47","author":"Diebo","year":"2018","journal-title":"Orthopade"},{"key":"ref_3","doi-asserted-by":"crossref","unstructured":"Yan, C., Li, Y., and Yu, Z. 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