Robert E Elliott1, Omar Tanweer2. 1. Mainline Healthcare Neurosurgery, Newtown Square, Pennsylvania, USA. Electronic address: robertelliottmd@gmail.com. 2. Department of Neurosurgery, New York University Langone Medical Center, New York, New York, USA.
Abstract
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. CONCLUSION: 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.
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. CONCLUSION: 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.
Authors: Carlos A Palancar; Daniel García-Martínez; Davorka Radovčić; Susanna Llidó; Federico Mata-Escolano; Markus Bastir; Juan Alberto Sanchis-Gimeno Journal: J Anat Date: 2020-05-21 Impact factor: 2.921