Hassan Fthimnir M, Mohanty Sarthak, Lewerenz Erik, Mikhail Christopher, Stephan Stephen R, Platt Andrew, Bakhsheshian Joshua, Lee Nathan J, Reyes Justin L, Greisberg Gabriella, Lombardi Joseph M, Sardar Zeeshan M, Lehman Ronald A, Lenke Lawrence G
Department of Orthopaedic Surgery, The Och Spine Hospital/Columbia University Irving Medical Center, New York, NY.
Department of Orthopaedic Surgery, Massachusetts General Hospital/Harvard Medical School, Boston, MA.
Clin Spine Surg. 2025 Jun 20. doi: 10.1097/BSD.0000000000001868.
Single-center retrospective cohort study.
To determine if the 4-rod construct (4RC) is protective against the occurrence of rod fractures when compared with the 3-rod construct (3RC) in adult spinal deformity (ASD) patients with long fusions to the sacrum.
Past studies have explored the different outcomes in subjects with dual-rod versus multirod constructs. There is a lack of literature distinguishing the ramifications of 3RC versus 4RC, particularly in the prevalence of rod fractures and rod fractures requiring subsequent revision surgery as a result of pseudarthrosis.
ASD patients undergoing long instrumented fusions to the sacrum were dichotomized between the 3RC and 4RC cohorts. Outcomes of interest include the occurrence of rod fractures (RFs) and RFs requiring revision (RFR). Two-tailed independent-sample t test with Welch's correction and χ2/Fisher exact test were used for continuous and categorical variables, respectively. Multivariable logistic regression analysis was performed to assess whether the 4RC is protective against rod fractures when compared with the 3RC.
One hundred forty-five patients with a minimum 2-year follow-up were included (3RC=57, 4RC=88). Four RC had a greater body mass index (BMI) (P=0.002), longer operating room (OR) time (P=0.002), greater estimated blood loss (EBL) (P=0.002), total instrumented levels (TIL) (P=0.028), and more 3-column osteotomies (3COs) performed (P=0.028). Four RC had greater baseline coronal vertical axis (CVA) (28.2±24.9 vs. 18.5±16.9 mm, P=0.006) and sagittal vertical axis (SVA) (55.1±64.8 vs. 30.4±41.8 mm, P=0.006). Three RC had a greater rate of RF (28.1% vs. 14.8%, P=0.0506) and RFR (14.9% vs. 10.2%, P=0.486) when compared with 4RC, but these findings were not statistically significant. After controlling for BMI, the use of 3-column osteotomies, total instrumented levels, change in coronal alignment (∆CVA), change in sagittal alignment (∆SVA), use of bone morphogenetic protein, and number of interbody fusions, 3RC was associated with 4.93× greater odds of experiencing RFs (P=0.0078). However, significance fell short when adjusting for the occurrence of RFR [OR=2.58 (0.60-11.19), P=0.2067].
ASD patients having long fusions to the sacrum with 4RC across the lumbosacral junction are shown to be at lesser risk of developing rod fractures but not revision surgery as compared with 3RC at 2-year follow-up.
单中心回顾性队列研究。
确定在成人脊柱畸形（ASD）患者中，与三棒结构（3RC）相比，四棒结构（4RC）在长节段融合至骶骨时是否能预防棒体骨折的发生。
既往研究探讨了双棒与多棒结构患者的不同结局。缺乏区分3RC与4RC影响的文献，尤其是在棒体骨折的发生率以及因假关节形成导致需要后续翻修手术的棒体骨折方面。
接受长节段融合至骶骨的ASD患者被分为3RC和4RC队列。感兴趣的结局包括棒体骨折（RFs）的发生以及需要翻修的棒体骨折（RFR）。连续变量和分类变量分别采用经韦尔奇校正的双尾独立样本t检验和χ²/费舍尔精确检验。进行多变量逻辑回归分析，以评估与3RC相比，4RC是否能预防棒体骨折。
纳入了145例至少随访2年的患者（3RC组=57例，4RC组=88例）。4RC组患者的体重指数（BMI）更高（P=0.002），手术时间（OR）更长（P=0.002），估计失血量（EBL）更多（P=0.002），融合节段总数（TIL）更多（P=0.028），且进行的三柱截骨术（3COs）更多（P=0.028）。4RC组患者的基线冠状面垂直轴（CVA）更大（28.2±24.9 vs. 18.5±16.9 mm，P=0.006）和矢状面垂直轴（SVA）更大（55.1±64.8 vs. 30.4±41.8 mm，P=0.006）。与4RC组相比，3RC组的RF发生率更高（28.1% vs. 14.8%，P=0.0506），RFR发生率更高（14.9% vs. 10.2%，P=0.486），但这些结果无统计学意义。在控制了BMI、三柱截骨术的使用、融合节段总数、冠状面排列变化（∆CVA）、矢状面排列变化（∆SVA）、骨形态发生蛋白的使用以及椎间融合器的数量后，3RC组发生RFs的几率高出4.93倍（P=0.0078）。然而，在调整RFR的发生情况后，差异无统计学意义[比值比（OR）=2.58（0.60 - 11.19），P=0.2067]。
在2年随访时，与3RC相比，在腰骶交界处采用4RC进行长节段融合至骶骨的ASD患者发生棒体骨折的风险较低，但翻修手术风险无差异。
