Incomplete spondylolysis and healing. A study of ancient Canadian Eskimo skeletons.

STUDY DESIGN

Skeletons of ancient Canadian Eskimos subjected to arctic weathering presented an unusual opportunity for direct observation of all stages of spondylolysis.

OBJECTIVE

To explore early stages of incomplete lysis, a phenomenon difficult to observe radiographically.

SUMMARY OF BACKGROUND DATA

Although lumbar spondylolysis most often appears to be a stress fracture that may proceed to complete separation, its early stages have been difficult to visualize.

METHODS

Vertebrae were examined for even minute lytic defects in the general region of pars interarticularis and the results were correlated with age at death.

RESULTS

Spondylolysis was found in 51 individuals, with 110 separate sites (sides) affected. At 34 of these sites, all but two in adolescents or young adults, the lysis was incomplete. Incomplete lysis affected the superior margin of the neural arch more often than the inferior margin, and the right side more often than the left.

CONCLUSION

Spondylolysis first became recognizable as incomplete stress fractures during adolescence, with most progressing to complete lysis in young adulthood. New fractures continued to develop in young adults, but most healed by middle adulthood. After 45 years of age, the overall frequency of spondylolysis declined, indicating that even complete defects occasionally healed.