Proper Techniques for Ancient Skull Surgery

Trepanation—the ancient surgical procedure of creating holes in the cranium—was widely practiced in the late pre-Hispanic Andes to treat traumatic head injuries. However, these ancient practitioners only trepanned a small fraction of the total number of cranial fractures. To better understand the system of health-related care in which trepanation was enmeshed, this article investigates the techniques used, patterns in placement, and distribution across the population of trepanation at a mortuary complex in the south-central Andean highlands. Original data from a sample of 569 individuals who lived during the late Middle Horizon and early Late Intermediate Period (ca. 800–1200 CE) demonstrated 136 examples of trepanation among 92 individuals, 62 of whom also exhibited cranial fractures (67.4%). Trepanation usage, survivorship, and association with fracture increased between the Middle Horizon and Late Intermediate Period, concurrent with an increase in cranial trauma. The group with both trepanation and fracture skews more male and has a higher rate of cranial modification than the general population, but this is associated with their higher risk of cranial trauma. This treatment was most successful not when trepanations were placed directly adjacent to the fracture, but in indirect association. Additionally, incisions were more frequently placed on the left side of the cranium regardless of their association with fractures, except in infants, among whom trepanations were placed in locations where fontanelles had recently closed. When compared with contemporaneous populations, these findings evidence commonalities and shared techniques between groups who were otherwise in conflict.