SPONDYLOLYSIS OF THE SACRUM IN ALASKAN AND CANADIAN INUIT SKELETONS

Spondylolysis of the lower back, particularly that involving the isthm us between the superior and inferior articular processes (pars interar ticularis), is generally attributed to stress fracturing caused by mov ement of the affected vertebra relative to the vertebra below. The fin ding of isthmic spondylolysis in the first vertebra of a fused sacrum is thus unusual and requires explanation. Although unrepresented in th e clinical literature, sacral spondylolysis has been reported for arch aeological specimens and appears to be especially prevalent in North A merican Inuit. A study of 373 Inuit sacra from Alaska and Canada produ ced 16 examples of spondylolysis (eight from each area). All but one o f the affected individuals were male, and nearly all were young adults , many between 18 and 20 years of age. All cases of sacral spondylolys is observed in this study were judged to have resulted from stress fra cturing that occurred while S1 was still unfused, and most appear to h ave been in the process of healing, following fusion of S1 with S2, wh en death occurred. The high frequency observed in these people is attr ibuted to unusual stresses becoming concentrated in the lower back of adolescent males due to such activities as weight lifting, wrestling, kayak paddling, and harpooning, combined with, and perhaps even contri buting to, delayed maturation (S1-S2 fusion) of the sacrum. (C) 1996 W iley-Liss, Inc.