Department of Spine Surgery, Affiliated Hospital of Southwest Medical University, No. 25 Taiping Street, Luzhou City, 646000, China.
BMC Musculoskelet Disord. 2020 Jun 15;21(1):385. doi: 10.1186/s12891-020-03398-9.
The aim of the present study was to describe and measure the occipital-cervical distance by a novel method utilizing the occiput-C4 distance (OC4D) in normal subjects, as a proposed tool to guide restoration of vertical dislocations of the occipitocervical region in patients with basilar invaginations and for performing standardized testing of occipitocervical constructs.
We analyzed neutral, flexion, and extension lateral cervical spine radiographs of 150 asymptomatic subjects (73 males and 77 females) that were judged to be normal. The mean age of the included asymptomatic subjects was 48.0 ± 8.4 years old (range 20-69 years old; 48.4 ± 10.2 years old for males and 47.6 ± 6.4 years old for females). The OC4D was defined as the shortest distance from the center of the C4 vertebral body to the McGregor's line. Occipitocervical distances (OCDs) were measured and analyzed its correlation with OC4Ds. Two spine surgeons each performed three measurements of the OC4D and OCD from each asymptomatic subject, from which our reported average values were derived. The height, weight, and body mass index (BMI) of each subject were recorded and analyzed for their correlations with the OC4D and OCD.
The OC4Ds from neutral, flexion, and extension lateral cervical spine radiographs were 69.0 ± 6.9, 68.9 ± 6.8, and 68.1 ± 6.9 mm, respectively. There was no significant difference in the OC4D values among neutral, flexion, and extension lateral cervical spine radiographs (P > 0.05). The neutral, flexion, and extension OCDs were 23.0 ± 4.8, 27.6 ± 6.0, and 13.8 ± 4.7 mm, respectively. In particular, the neutral OCD was significantly different from those in flexion and extension lateral cervical spine radiographs (P < 0.001). There was no significant correlation between OC4D and OCD in neutral, flexion, and extension (P > 0.05 for all). There were positive correlations between OC4D and height, as well as OC4D and weight, in neutral, flexion, and extension lateral cervical spine radiographs (P < 0.001 for all). Furthermore, the intra-class correlation coefficients for inter- and intra-observer reliabilities of OC4Ds in neutral, flexion, and extension lateral cervical spine radiographs were significantly higher than those for OCDs (P < 0.001).
The OC4D represents a novel measurement for estimating the occipital-cervical distance that is not affected by changes in neutral, flexion, and extension positions. Hence, the OC4D may serve as a valuable parameter and intra-operative tool to guide vertical restoration during occipitocervical fusion (OCF) for patients with altered occiput-cervical anatomy.
本研究旨在描述并测量正常受试者枕颈距离，提出利用枕骨- C4 距离（OC4D）作为一种工具，以指导基底凹陷患者枕骨颈椎区垂直脱位的复位，并对枕骨颈椎结构进行标准化测试。
我们分析了 150 名无症状受试者（73 名男性和 77 名女性）中立位、屈伸侧颈椎侧位片的影像学资料，这些受试者被认为是正常的。纳入的无症状受试者平均年龄为 48.0 ± 8.4 岁（年龄 20-69 岁；男性为 48.4 ± 10.2 岁，女性为 47.6 ± 6.4 岁）。OC4D 定义为 C4 椎体中心到麦格雷戈线的最短距离。测量枕颈距离（OCD）并分析其与 OC4D 的相关性。两位脊柱外科医生分别对每个无症状受试者的中立位、屈伸侧颈椎侧位片进行了三次 OC4D 和 OCD 的测量，我们报告的平均值就是由此而来。记录每位受试者的身高、体重和体重指数（BMI），并分析其与 OC4D 和 OCD 的相关性。
中立位、屈伸侧颈椎侧位片的 OC4D 值分别为 69.0 ± 6.9、68.9 ± 6.8 和 68.1 ± 6.9mm，差异无统计学意义（P > 0.05）。中性、屈伸位 OCD 值分别为 23.0 ± 4.8、27.6 ± 6.0 和 13.8 ± 4.7mm，差异有统计学意义（P < 0.001）。中性位 OCD 与屈伸位差异有统计学意义（P < 0.001）。在中立位、屈伸位时 OC4D 与 OCD 无明显相关性（P > 0.05）。OC4D 在中立位、屈伸位与身高、体重呈正相关（P < 0.001）。中立位、屈伸位颈椎侧位片 OC4D 的组内相关系数（ICC）明显高于 OCD（P < 0.001）。
OC4D 是一种新的枕颈距离测量方法，不受中立位、屈伸位变化的影响。因此，OC4D 可能成为指导伴有枕骨-颈椎解剖结构改变的枕颈融合术（OCF）中垂直复位的有价值的参数和术中工具。
