Does the Amount of Correction of Sagittal Deformity Really Promote Proximal Junctional Kyphosis? Multivariate Analyses According to Uppermost Instrumented Vertebra Levels

Se-Jun Park; Chong-Suh Lee; Jin-Sung Park; Tae Soo Shin; Il Su Kim; Jeongkeun Kim; Kyung-Chung Kang; Keun-Ho Lee

doi:10.1016/j.wneu.2023.06.095

Does the Amount of Correction of Sagittal Deformity Really Promote Proximal Junctional Kyphosis? Multivariate Analyses According to Uppermost Instrumented Vertebra Levels

World Neurosurg. 2023 Jun 27:S1878-8750(23)00878-1. doi: 10.1016/j.wneu.2023.06.095. Online ahead of print.

Authors

Se-Jun Park¹, Chong-Suh Lee², Jin-Sung Park¹, Tae Soo Shin¹, Il Su Kim¹, Jeongkeun Kim¹, Kyung-Chung Kang³, Keun-Ho Lee⁴

Affiliations

¹ Department of Orthopedic Surgery, Spine Center, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, South Korea.
² Department of Orthopedic Surgery, Haeundae Bumin Hospital, Busan, South Korea.
³ Department of Orthopedic Surgery, Kyung Hee University Hospital, Kyung Hee University School of Medicine, Seoul, Republic of Korea.
⁴ Department of Spine Center, Barunsesang Hospital, Seongnam, Gyeonggi-do, Republic of Korea. Electronic address: keun118@naver.com.

PMID: 37385442
DOI: 10.1016/j.wneu.2023.06.095

Abstract

Background: The present study assumed that the effects of deformity correction amounts on proximal junctional kyphosis (PJK) development after long deformity surgery would vary according to uppermost instrumented vertebrae (UIV) levels. Our study was to reveal the association between the amount of correction and PJK according to UIV levels.

Methods: Adult spinal deformity patients aged >50 years who underwent thoracolumbar fusion (≥4 levels) were included. PJK was defined by proximal junctional angles ≥15°. Presumed demographic and radiographic risk factors for PJK were evaluated including parameters regarding the correction amount such as postoperative change in lumbar lordosis and postoperative offset grouping, the value associated with age-adjusted pelvic incidence-lumbar lordosis mismatch. The patients were divided according to UIV levels of T10 or above (group A) and T11 or below (group B). Multivariate analyses were performed separately for both groups.

Results: The present study included 241 patients (74 for group A and 167 for group B). PJK developed in approximately half of all patients within an average of 5 years of follow-up. For group A, only body mass index (P = 0.002) was associated with PJK. No radiographic parameters were correlated. For group B, postoperative change in lumbar lordosis (P = 0.009) and offset value (P = 0.030) were significant risk factors for PJK development.

Conclusions: The correction amount of sagittal deformity increased the risk of PJK only in patients with UIV at or below T11. However, it was not associated with PJK development in patients with UIV at or above T10.

Keywords: Overcorrection; Proximal junction kyphosis; Uppermost instrumented vertebra.