Correlation Analysis Between Clinical Hypermobility Measurement and Radiographic Parameters of the Hallux Valgus Deformity.

The finding of "hypermobility" has conventionally been considered as a dichotomous categorical variable in both clinical practice and in the literature. In other words, it is defined as being either "present" or "absent" in patients with hallux valgus. Yet it might be far more likely that this represents a continuous variable described by a bell-shaped distribution. Therefore the objective of this investigation was to consider hypermobility as a continuous variable, and to compare the sagittal plane first ray motion to radiographic parameters commonly used in the evaluation of the hallux valgus deformity by means of correlation analyses. The radiographs and measurements of 86 feet were included and measurement of sagittal plane first ray motion was performed with the validated Klaue device. No statistically significant correlation was observed between the total first ray motion with the first intermetatarsal angle (Pearson correlation coefficient 0.106; p = .333), hallux valgus angle (Pearson correlation coefficient -0.106; p = .330), nor sesamoid position (Pearson correlation coefficient 0.155; p = .157). The results of this investigation uniquely consider measurement of hypermobility as a continuous variable, and find no correlation between first ray sagittal plane motion and radiographic parameters associated with the hallux valgus deformity. These results might indicate that although the concept of hypermobility has traditionally been coupled with presentation of the hallux valgus deformity, this might simply represent the result of a historical confirmation bias.