Intra-evaluator variability in the measurement of proximal articular set angle

In the evaluation of the distal articular orientation of the first metatarsal in hallux abducto valgus, one tool that can be employed is the radiographic measurement of the proximal articular set angle (PASA). Although it has been demonstrated that the inter-evaluator reliability of the measurement of PASA is suboptimal, the measurement may still retain usefulness. If intra-evaluator reliability is acceptable and the measurement is a valid predictor of the intraoperative condition, then the measurement retains clinical usefulness. The present study was designed to determine the intra-evaluator reliability of the measurement of PASA. Five evaluators were asked to make the measurement on five radiographs. Measurements were repeated approximately every 2 weeks until a total of 12 measurements on each radiograph were complied. A Chi-square distribution test of variance was utilized to analyze the data. The results demonstrated that the intra-evaluator reliability of the measurement of PASA was acceptable in three of the five evaluators, suggesting that some physicians can achieve satisfactory consistency in the measurement. It is unclear why the intra-evaluator reliability of the measurement of PASA is suboptimal for some physicians. Further study is required to address this issue, as well as the issue of the validity of the measurement.