1. Positional Relationship of the Fibula Relative to the Tibia in Collegiate Athletes Katherine Lane Faculty Mentor: Alice Fazlollah, MS Department of Geography and Anthropology This research asses the relationship between the cross- sectional geometric (CSG) properties of the tibia and fibula. CSG properties can tell physical anthropologists about the kinds of activities individuals in past populations may have engaged in. Modern athletes can be used as a model to understand these relationships. Wolff’s Law states that bone form follows function, or that when stresses are placed on bone, the bone will remodel through either absorption or deposition in order to maintain optimal strain levels. The majority of research in cross-sectional bone geometry has been on the femur, and that which has been examining the lower leg usually focused only on the tibia. The fibula has managed to escape the focus of research due to the assumption of its lack of importance due to its lesser weight bearing capabilities. This study examines the correlation between the distance and angle between the tibia and fibula and tibial robusticity in different mobility groups. It was hypothesized that the greater the distance between the two bones would result in a less robust tibia, and, vice versus, the lesser the distance between the tibia and fibula would result in a more robust tibia. With the angle, it was hypothesized that the closer the fibula was positioned in a mediolateral plane results in a less robust tibia in the mediolateral aspect. 83 males between the ages of 18 and 30 years old and that have been participating in competitive sports since childhood/ early adolescence. Subgroups participated in the following activities: field hockey (15), distance runners (15), swimmers (15), cricketers (16), and non-athletes (20). pQCT scans were imported into ImageJ (http://rsb.info.nih.gov/ij/) and analyzed using BoneJ (http://bonej.org/).http://rsb.info.nih.gov/ij/http://bonej.org/ Distance and angle were examined against CSG properties. A positive correlation exists between distance and all cross-sectional geometric properties for both bones. For the tibia there was a positive correlation between angle and Iy (mediolateral rigidity), and for the fibula there was a positive correlation between angle and Iy and J (torsional rigidity). When examined by sporting groups, field hockey players and cricketers stood out. These two groups had no correlation between distance and Iy (while runners, swimmers, and controls had a positive correlation), and had a positive correlation between angle and Iy (while the other groups had no correlation). These results could be indicative of the different loading patterns of field hockey players and cricketers. These two groups have a more multidirectional, especially mediolateral, loading patterns versus the more anterior- posterior loading patterns of runners and swimmers. The results suggests that the fibula could help mediate the forces applied to the tibia especially when the fibula is aligned more in the mediolateral aspect. Further research on the relationship between the angle and cross-sectional geometric properties of the fibula and tibia would benefit from a study with larger sample sizes. Fig. 1 Example pQCT scan of the left tibia/ fibula at 50% of diaphyseal length. Fig. 2 Example screen shot of ImageJ program showing results. Introduction Materials and Methods Results Discussion Selected References Shaw CN, and Stock JT. 2009. Intensity, repetitiveness, and directionality of habitual adolescent mobility patterns influence the tibial diaphysis morphology of athletes. American Journal of Physical Anthropology 140(1):149-159. Marchi D & Shaw CN. 2011. Variation in fibular robusticity reflects variation in mobility patterns. Journal of Human Evolution 61(5):609-616 Goh JC, Mech AM, Lee EH, Ang EJ, Bayon P, and Pho PW. 1992. Biomechanical study on the load-bearing characteristics of the fibula and the effects of fibular resection. Clin Orthop Relat Res (279):223-228. Fig. 4 Hockey players and cricketers demonstrated significant positive correlation (P ≤ 0.05) between M-L bending rigidity & angle between centroids. Fig. 3 Controls and runners demonstrated significant positive correlation (P ≤ 0.05) between M-L bending rigidity and distance between the centroids.