Activity-Related Variation in Pathologies of the Patella among Native American Groups
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This study explores pathologies affecting the patella among skeletal collections from six North American archaeological groups. Given the location of the patella in the knee joint and attachment sites of the quadriceps femoralis tendon (QFT) and the patellar ligament (PL), changes in this bone may reflect muscle development and joint degeneration from activities involving the lower extremities. The archaeological groups examined were Archaic through Historic hunter-gatherers, Middle and Late Mississippian agriculturalists, and Historic horticulturalists. The groups spanned the Eastern Woodlands, Great Plains, and Texas regions. For each patella examined, the frequency of moderate to severe expressions of QFT and PL entheses on the anterior surface of the patella and of lipping on the margins of the articular surface was recorded, as was the presence of coalesced porosity, surface osteophytes, and eburnation on the articular surface. The following five research questions were explored: 1) Do individuals within an archaeological group exhibit variation in patellar pathologies? 2) Do patellar pathologies exhibit variation within a group by factors such as sex, age, or temporal component? 3) Do patellar pathologies vary between groups? 4) If individual, within-group, or between-group variation exists, what causes it? 5) Can examination of this variation be used to identify subsistence practices or division of labor in prehistoric groups? Significant variation in patellar pathologies was found within all six archaeological groups. Furthermore, patterning of these pathologies was found to vary by sex, age, and temporal component. Division of labor was implicated as an underlying factor of significant sex differences. While geographical region could not account for the differences between groups, subsistence regime did correspond to the patterning in coalesced porosity between groups. Coalesced porosity was extremely high in agricultural groups. This degenerative condition, is caused by a prolonged, habitual kneeling posture, which is commonly adopted by agriculturalists while processing maize. While not accounted for in this study, variation among horticulturalists and hunter-gatherers may be more reflective of mobility than of subsistence regime. The ability to identify activity patterns via a single skeletal element may prove useful in archaeological cases of commingled, unprovenienced, or poorly preserved/highly fragmented remains. The results of this analysis indicate that unique signatures of entheses and articular surface and margin changes are found both within and between groups. Differences in activity can account for some of this variation, and analysis of this type can provide valuable information on prehistoric lifeways.