颅脊角在枕颈融合术矢状面平衡重建中的应用价值

Values of spino-cranial angle in sagittal balance reconstruction in occipitocervical fusion

中文关键词:  颅脊角  寰枢椎  枕颈融合  矢状面平衡  颈椎参数

英文关键词:Spino cranial angle  Atlantoaxial spine  Occipitocervical fusion  Sagittal balance  Cervical parameters

中文摘要:

  【摘要】 目的：探讨颅脊角（spino-cranial angle，SCA）在枕颈融合术（occipitocervical fusion，OCF）中矢状面平衡调控、术后矢状面平衡评估中的应用价值及其与颈椎矢状面参数的相关性。方法：回顾性分析55例枕颈交界区不稳采用OCF治疗的患者，其中男30例，女25例，年龄18~70岁（45.2±11.9岁），随访时间≥12个月。在术前及末次随访时的X线片上测量SCA、枕颈角（O-C2 angle，O-C2A）、T1倾斜角（T1 slope，T1S）、颈椎前凸角（cervical lordosis，CL）、颈椎矢状面垂直轴（cervical sagittal vertical axis，cSVA）、T1S-CL等颈椎矢状位参数，分析SCA与其他矢状位参数之间的关系。以T1S-CL值将患者分为平衡组（≤20°）和失衡组（＞20°），使用受试者操作特征曲线（receiver operating characteristic，ROC）确定矢状位平衡的术前最佳SCA截断值（86.65°），根据最佳截断值将患者分为低SCA组（SCA＜86.65°，n=35）和高SCA组（SCA≥86.65°，n=20）。两组间年龄、性别、手术时间、手术节段和失血量无统计学差异（P>0.05）。测量并比较术前及末次随访时低SCA组和高SCA组各矢状位参数，同时对比两组临床结局评分，包括日本骨科协会（Japanese Orthopaedic Association，JOA）评分和颈椎功能障碍指数（neck disability index，NDI），评估SCA与临床结局的关系。结果：SCA与CL（r=-0.74）、T1S-CL（r=0.61）、T1S（r=-0.54）及cSVA（r=0.35）均具有显著相关性（P＜0.05），而与O-C2A相关性较差（r=0.23，P=0.19）。术前低SCA组相比于高SCA组O-C2A、T1S、CL更大，并且在末次随访时除O-C2A（5.86°±14.76° vs 14.13°±8.86°）外，低SCA组其余颈椎矢状位参数的改善幅度均显著大于高SCA组。两组术后末次随访时JOA评分均较术前明显升高、NDI评分均较术前明显降低；高SCA组术前JOA评分更低、NDI评分更高，且末次随访时JOA、NDI评分改善程度均不及低SCA组。结论：SCA以86.65°为最佳截断值，可有效预测OCF术后的颈椎矢状面平衡及临床预后状态，是评估该手术疗效的优质矢状面参数。其中，术前低SCA患者术后矢状位序列改善更显著，临床结局更优；而高SCA可作为术前生活质量不佳的预警信号。需注意SCA与O-C2A相关性较弱，难以直接为OCF术前固定角度的个体化规划提供参考依据。

英文摘要:

  【Abstract】 Objectives: To explore the application value of spino-cranial angle(SCA) in sagittal balance regulation during occipitocervical fusion(OCF) surgery and sagittal balance assessment after surgery, as well as its relationship with other cervical sagittal parameters. Methods: A total of 55 patients with instability in the occipitocervical junction region were included in this study, all of whom were treated with OCF and were followed up ≥12 months. There were 30 males and 25 females, aged 18-70 years, with a mean of 45.2±11.9 years. On the preoperative and final follow-up X-rays, cervical sagittal parameters were measured, such as SCA, O-C2 angle(O-C2A), T1 slope(T1S), cervical lordosis(CL), cervical sagittal vertical axis(cSVA), and T1S-CL. The relationships between SCA and other sagittal parameters were analyzed. Setting T1S-CL=20° as sagittal balance， the patients were divided into balance group and imbalance group, and the optimal SCA cut-off value for sagittal balance before operation was confirmed to be 86.65° using receiver operating characteristic(ROC) curve analysis. According to the optimal SCA cut-off value, the patients were divided into low SCA group(SCA<86.65°, n=35) and high SCA group(SCA≥86.65°, n=20). There was no significant difference between the two groups in age, gender, operative time, operative segment, and blood loss(P>0.05). The sagittal parameters before operation and at final follow-up were measured and compared between the two groups, meanwhile, clinical outcome scores including Japanese Orthopaedic Association(JOA) scores and neck disability index(NDI) were also compared to evaluate the relationship between SCA and clinical outcomes. Results: There was a significant correlation between SCA and CL(r=-0.74), T1S-CL(r=0.61), T1S(r=-0.54) and cSVA(r=0.35)(P<0.05). However, the relationship between SCA and O-C2A was poor(r=0.23, P=0.19). The low SCA group had higher O-C2A, T1S, and CL compared to the high SCA group before operation, and at final follow-up, the low SCA group had greater values of change except for O-C2A(5.86°±14.76° vs 14.13°±8.86°). Regarding clinical outcomes, both groups demonstrated significant postoperative improvements in JOA scores and reductions in NDI scores compared to preoperative levels. However, the high SCA group exhibited lower preoperative JOA scores and higher NDI scores, with smaller improvements in JOA scores and smaller reductions in NDI scores at final follow-up compared to the low SCA group. Conclusions: The SCA with an optimal cutoff value of 86.65° can effectively predict cervical sagittal balance and clinical prognostic outcomes after OCF. It serves as a high-quality sagittal parameter for evaluating the surgical efficacy. Specifically, patients with low preoperative SCA exhibit more significant improvements in postoperative sagittal alignment and better clinical outcomes, whereas high SCA can act as an early warning signal for poor preoperative quality of life. Notably, the correlation between SCA and O-C2A is weak, making it difficult to directly provide a reference for the individualized planning of preoperative fixation angles in OCF.