Hills Jeffrey, Mundis Gregory M, Klineberg Eric O, Smith Justin S, Line Breton, Gum Jeffrey L, Protopsaltis Themistocles S, Hamilton D Kojo, Soroceanu Alex, Eastlack Robert, Nunley Pierce, Kebaish Khaled M, Lenke Lawrence G, Hostin Richard A, Gupta Munish C, Kim Han Jo, Ames Christopher P, Burton Douglas C, Shaffrey Christopher I, Schwab Frank J, Lafage Virginie, Lafage Renaud, Bess Shay, Kelly Michael P
Department of Orthopedic Surgery, University of Texas, San Antonio, Texas.
Division of Orthopedic Surgery, Scripps Clinic, La Jolla, California.
J Bone Joint Surg Am. 2024 Dec 4;106(23):e48. doi: 10.2106/JBJS.23.00372. Epub 2024 Sep 18.
Our understanding of the relationship between sagittal alignment and mechanical complications is evolving. In normal spines, the L1-pelvic angle (L1PA) accounts for the magnitude and distribution of lordosis and is strongly associated with pelvic incidence (PI), and the T4-pelvic angle (T4PA) is within 4° of the L1PA. We aimed to examine the clinical implications of realignment to a normal L1PA and T4-L1PA mismatch.
A prospective multicenter adult spinal deformity registry was queried for patients who underwent fixation from the T1-T5 region to the sacrum and had 2-year radiographic follow-up. Normal sagittal alignment was defined as previously described for normal spines: L1PA = PI × 0.5 - 21°, and T4-L1PA mismatch = 0°. Mechanical failure was defined as severe proximal junctional kyphosis (PJK), displaced rod fracture, or reoperation for junctional failure, pseudarthrosis, or rod fracture within 2 years. Multivariable nonlinear logistic regression was used to define target ranges for L1PA and T4-L1PA mismatch that minimized the risk of mechanical failure. The relationship between changes in T4PA and changes in global sagittal alignment according to the C2-pelvic angle (C2PA) was determined using linear regression. Lastly, multivariable regression was used to assess associations between initial postoperative C2PA and patient-reported outcomes at 1 year, adjusting for preoperative scores and age.
The median age of the 247 included patients was 64 years (interquartile range, 57 to 69 years), and 202 (82%) were female. Deviation from a normal L1PA or T4-L1PA mismatch in either direction was associated with a significantly higher risk of mechanical failure, independent of age. Risk was minimized with an L1PA of PI × 0.5 - (19° ± 2°) and T4-L1PA mismatch between -3° and +1°. Changes in T4PA and in C2PA at the time of final follow-up were strongly associated (r 2 = 0.96). Higher postoperative C2PA was independently associated with more disability, more pain, and worse self-image at 1 year.
We defined sagittal alignment targets using L1PA (relative to PI) and the T4-L1PA mismatch, which are both directly modifiable during surgery. In patients undergoing long fusion to the sacrum, realignment based on these targets may lead to fewer mechanical failures.
Therapeutic Level III . See Instructions for Authors for a complete description of levels of evidence.
我们对矢状面排列与机械并发症之间关系的理解正在不断发展。在正常脊柱中，腰1-骨盆角（L1PA）决定了前凸的程度和分布，并且与骨盆入射角（PI）密切相关，而胸4-骨盆角（T4PA）与L1PA相差4°以内。我们旨在研究恢复至正常L1PA以及胸4-L1PA不匹配的临床意义。
对一个前瞻性多中心成人脊柱畸形登记数据库进行查询，选取接受了从胸1-胸5区域至骶骨固定手术且有2年影像学随访资料的患者。正常矢状面排列的定义如先前针对正常脊柱所述：L1PA = PI×0.5 - 21°，且胸4-L1PA不匹配 = 0°。机械性失败定义为严重的近端交界性后凸（PJK）、移位的棒材骨折，或在2年内因交界性失败、假关节形成或棒材骨折而进行再次手术。使用多变量非线性逻辑回归来确定L1PA和胸4-L1PA不匹配的目标范围，以将机械性失败的风险降至最低。根据C2-骨盆角（C2PA），使用线性回归确定T4PA变化与整体矢状面排列变化之间的关系。最后，使用多变量回归评估术后初始C2PA与1年时患者报告结局之间的关联，并对术前评分和年龄进行校正。
纳入的247例患者的中位年龄为64岁（四分位间距，57至69岁），其中202例（82%）为女性。无论方向如何，偏离正常L1PA或胸4-L1PA不匹配均与机械性失败风险显著升高相关，且与年龄无关。当L1PA为PI×0.5 -（19°±2°）且胸4-L1PA不匹配在-3°至+1°之间时，风险降至最低。末次随访时T4PA的变化与C2PA的变化密切相关（r² = 0.96）。术后较高的C2PA与1年时更多的残疾、更多的疼痛和更差的自我形象独立相关。
我们使用L1PA（相对于PI）和胸4-L1PA不匹配定义了矢状面排列目标，这两者在手术期间均可直接调整。在接受长节段至骶骨融合手术的患者中，基于这些目标进行重新排列可能会减少机械性失败的发生。
治疗性III级。有关证据水平完整描述，请参阅作者须知。
