Abstract
BackgroundThe 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.MethodsWe 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.ResultsThe 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).ConclusionsThe 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.
Highlights
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
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
Data are Measurements of the OC4D and occipitocervical distance (OCD) The mean value of the OC4D in the neutral position was 69.0 ± 6.9 mm, which was not significantly different from the OC4D measured in flexion (68.9 ± 6.8 mm) or extension (68.1 ± 6.9 mm; P > 0.05)
Summary
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. During occipitocervical fixation and fusion, it is important to confirm that the occiput remains in a neutral balanced position in relation to the cervical spine. In the context of our present study, we considered that a normal occipital-cervical distance is likely important for avoiding over-distraction injuries to the cranial nerves and spinal cord during OCF. The C4 vertebral body, with a landmark at the mid-cervical level, is less affected by upper cervical spine motion/rotation, which makes it a more effective and versatile landmark for defining the occipitocervical neutral position during fusion surgery [5]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
