|Year : 2017 | Volume
| Issue : 2 | Page : 95-99
Prevalence of ponticulus posticus of the first cervical vertebra: A digital radiographic study
Poornima Govindraju, Talkad Subbaiah Mahesh Kumar
Department of Oral Medicine and Radiology, Rajarajeswari Dental College and Hospital, Bengaluru, Karnataka, India
|Date of Submission||02-Dec-2016|
|Date of Acceptance||17-Oct-2017|
|Date of Web Publication||9-Nov-2017|
Department of Oral Medicine and Radiology, Rajarajeswari Dental College and Hospital, Bengaluru - 560 074, Karnataka
Source of Support: None, Conflict of Interest: None
| Abstract|| |
Introduction: Ponticulus posticus is an anomaly located on the first cervical vertebra which can be appreciated on the lateral cephalogram that is mostly neglected by the dentists. Aims and Objectives: To assess the prevalence of ponticulus posticus and its relationship with gender and age. Materials and Methods: A sample of 580 patients' lateral cephalograms were retrieved from the archives of the department (Sirona Orthophos XG 5). Seventy-nine lateral cephalograms were excluded, and only 501 lateral cephalograms were taken with the age range of 8 to 60 years. Each digital radiograph was inspected for the presence and absence of ponticulus posticus and further evaluated for both the partial and complete form using Sidexes software and the results were statistically analyzed. Results: Ponticulus posticus was observed in 14.4% of the patients, among which 2.8% had complete and 11.6% had partial type; 59.7% were females and 40.3% were males. Conclusion: Ponticulus posticus is not an uncommon anomaly; therefore, lateral cephalogram should be carefully examined to check for the presence of this anomaly.
Keywords: Anomaly, lateral cephalogram, ponticulus posticus
|How to cite this article:|
Govindraju P, Mahesh Kumar TS. Prevalence of ponticulus posticus of the first cervical vertebra: A digital radiographic study. J Indian Acad Oral Med Radiol 2017;29:95-9
|How to cite this URL:|
Govindraju P, Mahesh Kumar TS. Prevalence of ponticulus posticus of the first cervical vertebra: A digital radiographic study. J Indian Acad Oral Med Radiol [serial online] 2017 [cited 2018 Jan 21];29:95-9. Available from: http://www.jiaomr.in/text.asp?2017/29/2/95/217909
| Introduction|| |
In clinical orthodontics, the most common diagnostic radiographs used are panoramic and lateral cephalometric radiographs. Significant cervical spine pathology can be detected on this routine lateral cephalogram. In young patients, the most common index used to measure the growth potential is the cervical vertebrae maturation index (CVMI), where often the cervical spine pathology is omitted and inadequate attention is paid to this region. Ponticulus posticus is one such anatomical anomaly of the first cervical vertebra (the atlas) that is omitted on the lateral cephalogram. It appears as a small bony bridge which is formed between the posterolateral portion of the superior margin of the posterior arch of the atlas and the posterior portion of the superior articular process.,
Ponticulus posticus is seen commonly in the lower primates. Its history dates back to the 12th century, when it was reported that these anatomical structures were found in the human skeletons. The earliest description of the structure was given by Cleland in 1861,, and the first writings on ponticulus posticus was by Louis Bolk, a Dutch anatomist, in 1906. This was insignificant until the spine surgeons showed concern toward this anomaly during the insertion of screws into the lateral mass of the atlas. In literature, ponticulus posticus has been referred to as pons posticus, arcuate foramen, Kimmerle anomaly, foramen sagitale, canalis arteriae vertebrates, retroarticular vertebral artery ring, foramen atlantoideum, and retroarticular canal of the atlas.,
Many studies have shown an association of ponticulus posticus with migraine. Because ponticulus posticus is intimately related to the atlanto-occipital membrane (where the spine and skull meet) and this membrane, in turn, is attached to the dura mater, small tensions exerted on the dura causing posterior circulation ischemia and cervicogenic headache, which in turn results in excruciating pain in migraine., Its prevalence has been reported to be between 5.14 and 37.83% in the Western population [Table 1]., Radiographically, Miki et al. have classified ponticulus posticus into three types:
|Table 1: Prevalence of complete ponticulus posticus as reported in literature|
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Full type: It forms a complete bony ring;
Incomplete type: Some portions of the bony ring are defective;
Calcified type: There is a linear or amorphous calcification.
With this background, the present study was intended to investigate the prevalence and morphological features of ponticulus posticus and to identify any possible gender and age predominance with the prevalence of ponticulus posticus in an Indian population comprising patients reporting to our institute for orthodontic treatment who were all healthy and free of any systemic or musculoskeletal problems.
| Materials and Methods|| |
The study was carried out in the Department of Oral Medicine and Radiology. A sample of 580 patients' lateral cephalograms were retrieved from the archives of the department (Sirona Orthophos XG 5). To obtain data from a normal population, 79 lateral cephalometric radiography of patients with cleft palate, craniofacial syndromes, poor quality image, mastoid projection over the posterior arch of atlas, and missing data were excluded. After implementing the exclusion parameters criteria, 501 cephalometric radiographs (298 females and 203 males) with clearly visible skull base and age range of 8–60 years were included in the study. Each digital radiograph was inspected for the presence and absence [Figure 1] of ponticulus posticus and further evaluated for both the partial [Figure 2] and complete [Figure 3] form using Sidexes software and the results were statistically analyzed.
| Results|| |
The sample consisted of a total of 580 patients' lateral cephalograms, of which 79 radiographs were not of good quality and were excluded from the study. Of the remaining 501 patients, 201 (40.1%) were males and 300 (59.9%) were females [Table 2]. The age group of the study sample varied from 10 to 60 years with increased percentage observed in 11–20 years (56.5%) [Table 2]. The prevalence of ponticulus posticus was seen in 72 patients (14.4%) in 501 radiographs. Out of the 72 patients who had ponticulus posticus, 58 (11.6%) patients showed partial ponticulus posticus, 14 (2.8%) patients showed complete ponticulus posticus which was statistically significant (<0.001) [Table 3] and [Table 4] and [Graph 1]. In the total sample, the ponticulus posticus was observed in 72 (14.4%) patients, of which 29 (40.3%) were males and 43 (59.7%) were females [Table 5]. Prevalence of ponticulus posticus was observed more in the 11–20 years (56.5%) age group followed by 21–30 years (38.7%) [Table 6] and [Graph 2].
|Table 4: Prevalence of different forms of ponticulus posticus using Chi square Goodness of Fit test|
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|Table 5: Comparison of the gender-wise prevalence of ponticulus posticus using Chi Square test|
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|Table 6: Comparison of the prevalence of ponticulus posticus in different age groups|
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| Discussion|| |
Ponticulus posticus is a common anomaly which can be seen on two-dimensional radiographs such as lateral cephalogram whose anatomical importance is unknown. It has been suggested that this anomaly i.e., arcuate foramen acts as an additional lateral extension for the attachment of the posterior atlanto-occipital membrane in quadrupeds (early primates), however, in humans it has disappeared as the vertical loading of superior articular process of atlas supports the head. Overlooking this anomaly can result in complications during cervical spine surgery.
In the western population, the prevalence of ponticulus posticus has been reported to be 5.1–37.8%. It is a common anatomical variant and is estimated to occur in approximately 3–18% of the population. In our study, the total prevalence of ponticulus posticus was 14.4%, which was almost similar to about 15.8% in a study done by Kendrick et al. and Young et al., in which the prevalence was 15.50%, as well as Prescher et al. which was around 11.00%. Schilling et al. found a slightly higher prevalence of approximately 19.3%. A study done among Koreans revealed an overall prevalence of ponticulus posticus of 26% on CT and 14% using lateral cephalograms which was similar to our results., The possible causes for this ponticulus posticus can be congenital, genetic, ossification due to age or external mechanical factors.
Complete ponticulus posticus has been found to be between 2.6% and 14.3% in radiological and between 3.4% and 15% in osteological studies.,,,,, Our study revealed a prevalence of 2.8% cases of complete ponticulus posticus, which was similar to the study done by Mudit et al. Female predominance has been described more often in literature, with higher prevalence of 10.6% in female patients than 8.71% in males; a similar pattern was noted in our study. This finding was in accordance to the study done by Mudit et al. This is in contrast to the study done by Sharma et al. where the authors showed male predominance, the reason for which can be difference in sample size and sample distribution.
Partial ponticulus posticus was found to be present in 11.6%. In the present study it was found that partial ponticulus posticus is common in females i.e., (52%) than males (48%), which is similar to the results of Stubbs in a study of arcuate foramen and its variability in distribution related to different race and sex. Taitz and Nathan studied 672 atlas vertebras, of which 25.9% had a partial posterior bridge and 7.9% a complete bony bridge. They found partial bony bridges predominate in younger age groups (10–30 years) and complete bony bridges in the older age groups (30–80 years), however, in the present study, the prevalence of ponticulus posticus was between 11 and 30 years, which is similar to the study by Mudit et al.,
Although the possibility that the calcification of the bony bridge progresses over time from an incomplete bony arch to complete ossification has been described by Paraskevas et al., this study found no clear relationship with age because we found three cases of children under 10 years of age with complete ossification and 4 cases with partial ossification. Thus, while ossification is most likely a gradual process, its initiation is not likely to be related to the age of the patient. This would confirm the findings of Lamberty and Zivanovic, who observed ponticulus posticus cartilage in fetuses and children. The limitations of the study were that the lateral cephalogram cannot determine if the anomaly is unilateral or bilateral, and that the study was done retrospectively; hence, future studies should be done prospectively considering the clinical feature of headache, especially migraine.
| Conclusion|| |
Ponticulus posticus is not an uncommon anomaly, therefore, lateral cephalograms should be carefully examined to check for the presence of this anomaly before screw placement in the lateral mass of the atlas to avoid vertebral artery injury. If this anomaly in lateral cephalogram is detected or suspected, a three-dimensional imaging modality such as CBCT or CT scan is needed for that purpose.
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Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2], [Figure 3]
[Table 1], [Table 2], [Table 3], [Table 4], [Table 5], [Table 6]