Hindfoot plantarflexion: a radiographic aid to the diagnosis of achilles tendon rupture.

Although tendo Achilles (TA) rupture is a clinical diagnosis, radiographs are sometimes taken to exclude bony injury. In equivocal clinical examination findings, an ultrasound examination is often performed. We investigated whether any radiographic signs of TA rupture existed that could help diagnose TA rupture in equivocal cases. We examined the case notes of 25 consecutive patients who had undergone repair for complete TA rupture. Their lateral radiographs were reviewed and the following angles were measured: calcaneal pitch, lateral talocalcaneal, and tibiocalcaneal. These were compared with a control group of patients who had undergone radiographic examination for ankle injuries resulting in a diagnosis of ankle sprain. The results were compared using an unpaired Student's t test. The mean tibiocalcaneal angle of the patients with complete TA rupture was 87.0 compared with 69.4 for the control group (p < .05). No significant difference was found with the other angles measured. The tibiocalcaneal angle can be a useful adjunct to the clinical examination in the diagnosis of TA rupture. It might also have a role in the evaluation of serial cast application after TA repair.