Title: Paper 113: The Medial Longitudinal Arch as a Possible Risk Factor For Ankle Sprains
Abstract: Introduction:The inversion sprain of the ankle joint is one of the most common injuries in sports medicine.However, understanding the mechanism of these injuries is difficult due to the complexity of the talocrural and talocalcaneal joints.The purpose of this study is to examine the movement of the ankle joint during a sprain simulation.Materials and Methods: Six female collegiate athletes, who had no complaint or previous history of an ankle sprain, joined this experiment.After receiving the subject?s informed consent and performing a general medical examination of the subjects, surface markers were secured to the skin directly over the malleoli.The subjects were asked to stand on a platform which would rapidly tilt 42 degrees laterally.After several practices, radiographs of an anteroposterior view of the ankle joint while tilting were taken using a high speed fluoroscopy (Philips INTEGRIS BH500).Inversion stress radiographs measured the normal talotibial angle within 5 degrees (Telos SE).The radiographs were digitized (NIH image 1.61) and analyzed to determine the change in inclination between the tibial and talar surfaces of the ankle joint, and the inclination between the surface markers on medial and lateral malleolus.Results: When the platform tilted, the subject's feet slid slightly and stopped causing their ankles to invert.The average inclination of the tibial and talar surface was 1.8 ϩ/Ϫ 0.9 degrees and 3.1 ϩ/Ϫ 1.9 degrees, respectively.This resulted in an average talotibial angle of 1.3 ϩ/Ϫ 0.9 degrees.However, the average inclination between the surface markers on the malleoli was 13.8 ϩ/Ϫ 7.9 degrees.Discussion: During this simulated ankle inversion sprain, the inclination of the tibial and talar surfaces remained almost horizontal.However, the inclination of the surface markers on the malleoli was largely influenced.This phenomenon was induced by many factors, including movement of the skin, subtalar articulation, shape of the subject?s foot, and laxity of the subject.Further investigation, including whether the movement is impaired in people with recurrent ankle inversion sprain, is needed.