The prevalence of the ponticulus posticus (arcuate foramen) and its importance in the Goel-Harms procedure: meta-analysis and review of the literature.
OBJECTIVE
We reviewed published radiographic and cadaver series describing the incidence of the anatomical anomaly ponticulus posticus and discuss its relevance to C1 lateral mass screw (C1LMS) insertion.


METHODS
Online databases were searched for English-language articles describing the presence of ponticulus posticus in cadaver and radiographic studies. Forty-four reports describing 21,789 patients (n = 15,542) or bony/cadaver specimens (n = 6247) fulfilled inclusion criteria. Meta-analysis techniques were applied to estimate the prevalence of this anomaly.


RESULTS
The overall prevalence of ponticulus posticus was 16.7%. The anomaly was identified in 18.8% of cadaver, 17.2% of computed tomographic, and 16.6% on radiographic studies. The anomaly composed a complete foramen in 9.3% of patients and was partial/incomplete in 8.7%. It was present bilaterally in 5.4% of cases and unilateral in 7.6%. There was no significant difference in prevalence between males (15.8%) and females (14.6%). Review of that literature demonstrated a dramatic increase in the number of patients treated with C1LMS through the posterior arch since first described in 2002, necessitating recognition of this anomaly when performing the Goel-Harms procedure.


CONCLUSIONS
The atlantal anomaly ponticulus posticus is not rare, occurring in 16.7% of patients in radiographic and cadaver studies. This anomaly may give the false impression that the posterior arch of the atlas is of adequate size to accommodate a C1LMS and may lead to inadvertent vertebral artery injury. Careful assessment via preoperative multiplanar computed tomographic imaging should be performed before consideration of C1LMS implantation.
Mainline Healthcare Neurosurgery, Newtown Square, Pennsylvania, USA. Electronic address: robertelliottmd@gmail.com.
Robert E
RE
Elliott
Department of Neurosurgery, New York University Langone Medical Center, New York, New York, USA.
Omar
O
Tanweer
D000293:Adolescent; D000328:Adult; D017677:Age Distribution; D000368:Aged; D000369:Aged, 80 and over; D001268:Atlanto-Axial Joint / Q000002:abnormalities* / Q000000981:diagnostic imaging / Q000601:surgery*; D001863:Bone Screws; D002102:Cadaver; D005260:Female; D006801:Humans; D007593:Joint Instability / Q000000981:diagnostic imaging / Q000601:surgery*; D008297:Male; D008875:Middle Aged; D019635:Neurosurgical Procedures / Q000379:methods*; D015995:Prevalence; D017678:Sex Distribution; D013124:Spinal Injuries / Q000000981:diagnostic imaging / Q000453:epidemiology* / Q000601:surgery; D009626:Terminology as Topic; D014057:Tomography, X-Ray Computed; D055815:Young Adult
Arcuate foramen; Atlantoaxial; Atlas; C1; C1-2; Goel; Harms; Kimmerle