Differences in the Lateral Compartment Joint Space Width After Anterior Cruciate Ligament Reconstruction: Response

Abstract

with great interest the article by Jones et al. 1 However, I have some concerns with the methods used and with the interpretation of the results. First, the confidence intervals of both groups with or without anterior cruciate ligament reconstruction showed significant overlapping, and the mean value of both groups is included in both confidence intervals. This might make the reader suspicious about the reality of the difference measured. Second, the differences observed were very small, and the mean difference was about 0.1 mm. To be able to accurately measure such a small difference, the accuracy and precision of the measuring process must be significantly smaller than 0.1 mm (eg, 0.05 mm). There is no doubt that a computer system may fulfill this requirement. However, I am not sure that the technique of taking radiographs does not involve an inherent inaccuracy that may flaw the measures. Actually, the authors did not report or quote any accuracy and precision analysis of their measurement process. For instance, I am not sure that 2 different radiographs taken from the same patient on the same day (repeatability) will not demonstrate a difference .0.1 mm. In that way, the results should be taken with great caution until this analysis has proven that both accuracy and precision of the whole measurement process are \0.1 mm.