Department of Orthopedic Surgery, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea.
Department of Neurological Surgery, New York University, New York, NY.
Spine (Phila Pa 1976). 2023 May 15;48(10):672-682. doi: 10.1097/BRS.0000000000004625. Epub 2023 Mar 13.
Retrospective comparative study.
To assess the relationship of fusion mass bone density on computed tomography (CT) and the development of rod fractures (RFs) and proximal junctional kyphosis (PJK).
Few studies have evaluated the relationship of fusion mass bone density to mechanical complications.
A retrospective review of adult spinal deformity patients who underwent thoracolumbar three-column osteotomy from 2007 to 2017 was performed. All patients underwent routine 1-year CT imaging and had at least 24 months follow-up. Posterior fusion mass bone density was evaluated by measuring hounsfield unit (HU) on CT in three different regions [upper instrumented vertebra (UIV), lower instrumented vertebra, and osteotomy site], and were compared between patients with and without mechanical complications.
A total of 165 patients (63.2 years, 33.5% male) were included. Overall PJK rate was 18.8%, and 35.5% of these underwent PJK revision. There was significantly lower density of posterior fusion mass at the UIV in patients who experienced PJK compared with patients without PJK (431.5HU vs. 537.4HU, P =0.026). Overall RF rate was 34.5% and 61.4% of these underwent revision for RFs. Among 57 patients with RFs, 71.9% had pseudarthrosis. Fusion mass density did not differ between patients with or without RFs. However, in RF patients with pseudarthrosis, there was significantly higher bone mass density near the osteotomy compared with those without pseudarthrosis (515.7HU vs. 354.2HU, P =0.012). There were no differences in radiographic sagittal measures between the patients with and without RF or PJK.
Patients with PJK tend to have less dense posterior fusion mass at the UIV. Fusion mass density does not correlate with RF, but greater bone density near the osteotomy was correlated with accompanying pseudarthrosis in patients with RFs. Assessing density of posterior fusion mass on CT may be helpful in assessing risk for PJK and provide insight as to the causes of RFs.
回顾性对比研究。
评估 CT 上融合块骨密度与内固定棒断裂（RFs）和近端交界性后凸（PJK）的关系。
很少有研究评估融合块骨密度与机械并发症的关系。
对 2007 年至 2017 年间接受胸腰段三柱截骨术的成人脊柱畸形患者进行回顾性研究。所有患者均接受常规 1 年 CT 成像，并随访至少 24 个月。通过在 CT 上测量三个不同区域（上固定椎、下固定椎和截骨部位）的亨氏单位（HU）来评估后路融合块骨密度，并比较有和无机械并发症的患者之间的骨密度。
共纳入 165 例患者（63.2 岁，33.5%为男性）。总体 PJK 发生率为 18.8%，其中 35.5%行 PJK 翻修。与无 PJK 的患者相比，发生 PJK 的患者 UIV 处的后路融合块密度明显较低（431.5HU 比 537.4HU，P =0.026）。总体 RF 发生率为 34.5%，其中 61.4%因 RF 行翻修。在 57 例 RF 患者中，71.9%为假关节形成。有和无 RF 的患者之间的融合块密度没有差异。然而，在伴有假关节形成的 RF 患者中，靠近截骨处的骨量密度明显高于无假关节形成的患者（515.7HU 比 354.2HU，P =0.012）。RF 或 PJK 患者之间的影像学矢状位测量值无差异。
发生 PJK 的患者 UIV 处的后路融合块密度较低。融合块密度与 RF 无关，但 RF 患者中靠近截骨处的骨密度较大与伴随的假关节形成相关。在 CT 上评估后路融合块的密度可能有助于评估 PJK 的风险，并为 RF 的发生原因提供深入了解。
