Segal Dale N, Ball Jacob, Fletcher Nicholas D, Yoon Eric, Bastrom Tracey, Vitale Michael G
Department of Orthopaedic Surgery, Harvard Medical School, Boston, MA, USA.
Department of Orthopaedic Surgery, Columbia Universityl, New York, NY, USA.
Spine Deform. 2022 Mar;10(2):377-385. doi: 10.1007/s43390-021-00413-4. Epub 2021 Sep 16.
Typically, selection of lowest instrumented vertebra (LIV) in Adolescent Idiopathic Scoliosis (AIS) is based on the coronal radiograph; however, increasing evidence suggests that fusions proximal to the stable sagittal vertebrae (SSV) on the lateral radiograph can result in distal junctional kyphosis (DJK). The purpose of this study is to compare rates of DJK in patients with AIS that have a discordance between the Lowest Touched Vertebra (LTV) and the SSV and to identify risk factors for developing DJK.
Patients with AIS Lenke type 1, 2 and 3 curves treated with a posterior spinal fusion were separated into two groups. Group 1 had SSV that was proximal to the LTV whereas group 2 had SSV that was distal to the LTV. Comparisons were made for patients that were fused to the SSV(a), LTV(b) or between(c). Distal junctional angle (DJA) > 5° and increasing kyphosis at the end of the fusion construct were evaluated as risk factors for DJK.
The rate of DJK was 0.0% in group 1a, 1b, and 1c compared to 4.3%, 18.5% and 10.0% in groups 2a, 2b and 2c, respectively(p < 0.001). The rate of DJK was 22.9% when the distal junctional angle(DJA) > 5° versus 1.4% when the DJA < 5°(p < 0.001).
There was a low risk for progression of DJK when the SSV was proximal to the LTV, however, those with SSV distal to the LTV represent a high-risk group. Importantly, the development of DJK occurred almost exclusively in patients with LIV at the thoracolumbar junction which demonstrates that surgeons need to be cautious when ending fusions at T11, T12, and L1 in patients at high risk for DJK. Furthermore, having a distal junctional angle 5° or greater increased the risk of developing DJK by roughly 16-fold. At a minimum of 5-year follow-up, the development of DJK did not appear to adversely impact SRS outcomes or revision rates.
通常，青少年特发性脊柱侧凸（AIS）中最低融合椎（LIV）的选择基于冠状位X线片；然而，越来越多的证据表明，在侧位X线片上，融合至稳定矢状椎（SSV）近端可能导致远端交界性后凸（DJK）。本研究的目的是比较LIV与SSV不一致的AIS患者中DJK的发生率，并确定发生DJK的危险因素。
接受后路脊柱融合治疗的AIS Lenke 1型、2型和3型曲线患者被分为两组。第1组的SSV位于LTV近端，而第2组的SSV位于LTV远端。对融合至SSV（a）、LTV（b）或两者之间（c）的患者进行比较。将远端交界角（DJA）>5°以及融合结构末端后凸增加评估为DJK的危险因素。
第1组a、b、c亚组的DJK发生率为0.0%，而第2组a、b、c亚组分别为4.3%、18.5%和10.0%（p<0.001）。当远端交界角（DJA）>5°时，DJK发生率为22.9%，而DJA<5°时为1.4%（p<0.001）。
当SSV位于LTV近端时，DJK进展风险较低，然而，SSV位于LTV远端的患者属于高危组。重要的是，DJK几乎仅发生在胸腰段交界区LIV的患者中，这表明对于有DJK高风险的患者，外科医生在T11、T12和L1处结束融合时需谨慎。此外，远端交界角≥5°会使发生DJK的风险增加约16倍。在至少5年的随访中，DJK的发生似乎并未对SRS结局或翻修率产生不利影响。
