A 98% sensitivity is pretty good, and a test doesn't have to be perfect to be useful.
Prior studies found the elbow extension test to be sensitive for fracture after acute trauma. Lack of full extension and presence of bony point tenderness or bruising were found to be 96% to 100% sensitive for fracture in several studies.
A recent study evaluated the ability of full extension and absence of point tenderness to rule out fracture. All patients had elbow x-rays.
There were 587 participants (233 children and 354 adults), of whom 59% had a fracture. In both adults and children, 98% of fractures were detected by inability to extend the elbow fully or presence of point tenderness. Only one patient with full extension and no tenderness required surgery.
Comment
There are two ways of evaluating this study.
1) These results show that the elbow extension test is not 100% accurate. (And we seem to strive for 100% all the time)
OR
2) If a patient can extend the elbow fully, has no significant point tenderness on palpation, and has no sign of overlying trauma such as laceration or bruising, the worst-case scenario is a 4% chance of fracture.
Consider documenting these clinical features and adding them to your sound clinical judgment
References
Jie KE et al. Extension test and ossal point tenderness cannot accurately exclude significant injury in acute elbow trauma. Ann Emerg Med 2014
