When Common Becomes Uncommon

Baastrup’s disease, or kissing spine, is a degenerative spinal condition marked by abnormal contact between the spinous processes of adjacent vertebrae. Although frequently diagnosed in older clinical populations, where it is often found in association with other spinal diseases, it remains underreported in the palaeopathological record. This study presents a case of co-occurring Baastrup’s disease, L5 sacralization and swayback syndrome, in an adult male from a 6th–7th century CE burial at San Pietro al Natisone, northeastern Italy. The observed changes reflect the combined effects of age-related degeneration and biomechanical stress associated with the presence of a lumbosacral transitional vertebra (LSTV). Our findings support the hypothesis that congenital anomalies such as LSTVs can predispose individuals to abnormal spinal mechanics and secondary degenerative changes. This case also emphasizes the diagnostic value of examining posterior vertebral elements in archaeological samples and highlights the importance of interpreting Baastrup’s disease within the broader context of spinal degeneration.