Medial tenderness revisited: Is medial ankle tenderness predictive of instability in isolated lateral malleolus fractures?

•Pain with palpation over the deltoid ligament is associated with instability in isolated lateral malleolus fractures.•Strict reliance on the presence of medial tenderness alone to conclude instability would lead to an unacceptable number of false positives.•The 0.79 PPV of any medial tenderness for instability may be useful to cast doubt on equivocal stress radiography and prompt surgeons to repeat stress radiography or shorten the interval for radiographic follow up.