Posterior Arch Defect of the Atlas Associated to Absence of Costal Element of Foramen Transversarium from 16th-Century Sardinia (Italy)

STUDY DESIGN: A paleopathological case of posterior arch defect of the atlas associated to the absence of costal element of the foramen transversarium. OBJECTIVE: In living patients as well as in postmortem analysis it should be difficult to distinguish between a congenital and an acquired anomaly. Any anomaly in the anatomy of atlas should be taken into consideration by clinicians, surgeons, radiologists, and anatomists in order to avoid misinterpretations and clinical complications. SUMMARY OF BACKGROUND DATA: Posterior arch defect has a current occurrence of approximately 4%. Posterior arch schisis is attributed to the defective or absent development of the cartilaginous preformation of the arch rather than a disturbance of the ossification. The absence of costal element of the foramen transversarium has an incidence of ranging from 2% to 10% and is attributed to a developmental defect or to variations in the course of the vertebral artery. METHODS: The skeleton of a man aged 20-30 years, brought to light in the plague cemetery of 16th century Alghero (Sardinia), showed anomalies of the atlas, consisting in failure of the midline fusion of the 2 hemiarches with a small gap and an open anterior foramen trasversarium on the left side. A macroscopic, radiological, and stereomicroscopic study was carried out. RESULTS: The study allowed to rule out a traumatic origin of the defects and to diagnose an association of 2 congenital anomalies. CONCLUSION: Osteoarchaeological cases provides with a valuable opportunity to examine and describe variations in the anatomy of the atlas.