Metatarsal parallism in subtle Lisfranc's injuries. A new radiographic observation to aid diagnosis

IntroductionLisfranc joint injuries account for only 0.2% of all fractures but early diagnosis improves the chances of a better outcom]. Radiographic signs, such as diastasis (>2mm) of the 1–2 interspace, are subtle and. often missed, leading to a poorer outcome. We present a new radiographic sign, less likely to result in missed diagnoses. Null nypothesis: The intermetarsal angle remains unchanged in Lisfranc injuries.MethodA series of radiographs demonstrating Lisfranc injury were interspersed with normal and postoperative cases. Evidence of fixation was obscured. A selection of Foundation and Core Trainee medical staff measured the intermetatarsal angle (IMA) on two separate occasions. The measuring technique was demonstrated with no explanation for the reason behind the measurement.ResultsThe intra-class correlation (ICC) between observers was 0.96 and a mean 0.86 (range 0.69–0.96) for individual observers. IMA on comparative weight bearing AP views of injured and normal side, using Wilcoxon-signed ra...