The 82nd Annual Meeting of the American Association of Physical Anthropologists (2013)

Secular change in the knee joint and the effects of obesity


Department of Anthropology, Texas State University

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In America, there have been well-documented trends of rising obesity in the past 30 years and a steady increase in stature during the 20th century. Proposed explanations for these increases in body weight and stature include improvements in nutrition, healthcare, sanitation, and socioeconomic status, as well as reduced incidence of infectious disease during early growth. Of interest to anthropologists is how excessive body weight affects the skeletal system. The purpose of this study is to: (1) determine if there is a secular change in the articular surfaces of the knee joint, and (2) examine if secular changes in body weight are reflected in the size and shape of the articular surfaces of the knee joint. Twenty-one measurements from the femur and tibia were collected and analyzed from 174 skeletons from the Terry Collection, Bass Collection, and the Texas State Collection. Body Mass Index (BMI) was calculated for each individual. The data was then subjected to statistical analyses to determine whether there has been secular change in the size and shape of the knee and to determine if obesity is a significant causal factor. The results of these analyses indicate a secular trend in several of the dimensions, and that increases in BMI are contributing to changes in diaphyseal size (p = 0.000 to 0.009) and tibia lateral condyle shape (p = 0.040). The results of this study support a growing body of literature that indicates obesity has a significant effect on skeletal morphology.

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