Baastrup's sign (kissing spines): A neglected condition in paleopathology

New joint formation on vertebral spinous processes, so-called Baastrup's sign or "kissing spines", is a common condition in present-day populations. Paleopatologists, however, have not paid much attention to this manifestation, although some have claimed that this degenerative disease may be indicative of strenuous activities. Here, we report three cases of Baastrup's sign identified in a French post-medieval cemetery, and discuss the possible relationship between the condition and the other pathological changes the skeletons exhibit. Comparison with previously published cases permits some consideration of the etiology of the disease. Our findings question the possible relationship between Baastrup's sign and vertebral ankylosis, as well as the influence of border shifting on the expression of the condition. Moreover, the condition appears to be a possible diagnostic feature of severe forms of rickets/osteomalacia. Contrariwise, no certain relationship between Baastrup's sign and activity can be asserted. Further large sample studies would contribute to gaining information about the prevalence of such a condition in past populations, and to ascertain whether or not it constitutes a useful skeletal marker for the reconstruction of activities in ancient societies.