Fibular position in individuals with self-reported chronic ankle instability

Study Design: Case control study. Objectives: The purpose of this study was to assess the position of the distal fibula in individuals with chronic ankle instability (CAI). Background: Recent literature has suggested that a positional fault of the fibula on the tibia may contribute to CAI; however, there is a lack of objective scientific evidence to support this claim. Methods and Measures: Thirty subjects with unilateral CAI (mean ± SD age, 20.3 ± 1.3 years) and 30 subjects with no previous history of ankle injury (mean ± SD age, 21.3 ± 3.8 years) participated in this study. Subjects completed a pair of subjective functional scales and fluoroscopic lateral images of both the right and left ankles were recorded. The distance from the anterior margin of the distal tibia to the anterior margin of the distal fibula was measured in millimeters. Nonparametric statistics were used to assess the relationship between fibular position and CAI status. Results: There were significant differences between the CAI and control group ankles (P = .045) and within the involved and uninvolved sides of the CAI group (P = .006). Those with CAI had a significantly more anterior fibular position on their involved ankle in relation to their uninvolved limb, and the ankles of the control group. Conclusions: The fibula was positioned significantly more anterior in relation to the tibia in subjects with unilateral CAI. It is unclear if repetitive bouts of ankle instability caused the anterior fibular position or if the more anterior position was a predisposing factor to injury.