Fujishiro Takashi, Hayama Sachio, Obo Takuya, Nakaya Yoshiharu, Nakano Atsushi, Usami Yoshitada, Nozawa Satoshi, Baba Ichiro, Neo Masashi
1Department of Orthopedic Surgery, Osaka Medical College, Takatsuki; and.
2Department of Orthopedic Surgery, First Towakai Hospital, Takatsuki, Osaka, Japan.
J Neurosurg Spine. 2021 Apr 30;35(1):8-17. doi: 10.3171/2020.10.SPINE201723. Print 2021 Jul 1.
Kyphotic deformity resulting from the loss of cervical lordosis (CL) is a rare but serious complication after cervical laminoplasty (CLP), and it is essential to recognize the risk factors. Previous studies have demonstrated that a greater flexion range of motion (fROM) and smaller extension ROM (eROM) in the cervical spine are associated with the loss of CL after CLP. Considering these facts together, one can hypothesize that an indicator representing the gap between fROM and eROM (gROM) is highly useful in predicting postoperative CL loss. In the present study, the authors aimed to investigate the risk factors of marked CL loss after CLP for cervical spondylotic myelopathy (CSM), including the gROM as a potential predictor.
Patients who had undergone CLP for CSM were divided into those with and those without a loss of more than 10° in the sagittal Cobb angle between C2 and C7 at the final follow-up period compared to preoperative measurements (CL loss [CLL] group and no CLL [NCLL] group, respectively). Demographic characteristics, surgical information, preoperative radiographic measurements, and posterior paraspinal muscle morphology evaluated with MRI were compared between the two groups. fROM and eROM were examined on neutral and flexion-extension views of lateral radiography, and gROM was calculated using the following formula: gROM (°) = fROM - eROM. The performance of variables in discriminating between the CLL and NCLL groups was assessed using the receiver operating characteristic (ROC) curve.
This study included 111 patients (mean age at surgery 68.3 years, 61.3% male), with 10 and 101 patients in the CLL and NCLL groups, respectively. Univariate analyses showed that fROM and gROM were significantly greater in the CLL group than in the NCLL group (40.2° vs 26.6°, p < 0.001; 31.6° vs 14.3°, p < 0.001, respectively). ROC curve analyses revealed that both fROM and gROM had excellent discriminating capacities; gROM was likely to have a higher area under the ROC curve than fROM (0.906 vs 0.860, p = 0.094), with an optimal cutoff value of 27°.
The gROM is a highly useful indicator for predicting a marked loss of CL after CLP. For CSM patients with a preoperative gROM exceeding 30°, CLP should be carefully considered, since kyphotic changes can develop postoperatively.
颈椎生理前凸消失（CL）导致的后凸畸形是颈椎椎板成形术（CLP）后一种罕见但严重的并发症，识别其危险因素至关重要。既往研究表明，颈椎较大的前屈活动范围（fROM）和较小的后伸活动范围（eROM）与CLP术后CL消失相关。综合考虑这些因素，可以推测代表fROM与eROM之间差距的指标（gROM）在预测术后CL消失方面非常有用。在本研究中，作者旨在探讨脊髓型颈椎病（CSM）行CLP术后CL明显消失的危险因素，包括将gROM作为一种潜在预测指标。
将因CSM接受CLP的患者，根据末次随访时与术前测量相比C2至C7矢状面Cobb角丢失是否超过10°，分为CL丢失（CLL）组和无CL丢失（NCLL）组。比较两组患者的人口统计学特征、手术信息、术前影像学测量以及通过MRI评估的椎旁肌形态。在中立位和屈伸位侧位X线片上检查fROM和eROM，并使用以下公式计算gROM：gROM（°）=fROM - eROM。使用受试者工作特征（ROC）曲线评估各变量区分CLL组和NCLL组的效能。
本研究纳入111例患者（手术时平均年龄68.3岁，男性占61.3%），CLL组和NCLL组分别有10例和101例患者。单因素分析显示，CLL组的fROM和gROM显著大于NCLL组（分别为40.2°对26.6°，p<0.001；31.6°对14.3°，p<0.001）。ROC曲线分析显示，fROM和gROM均具有良好的区分能力；gROM的ROC曲线下面积可能高于fROM（0.906对0.860，p = 0.094），最佳截断值为27°。
gROM是预测CLP术后CL明显丢失的一个非常有用的指标。对于术前gROM超过30°的CSM患者，应谨慎考虑行CLP，因为术后可能会出现后凸改变。
