Roentgenographic diagnoses of ruptured Achilles tendons.

In a prospective study, the roentgenographic features of the Achilles tendon were investigated in 60 patients with acute total rupture of the Achilles tendon. Sixty ankles without actual injuries, 60 patients with ankle fractures, and 60 patients with ankle sprains were selected as reference groups. At primary examination, 11 patients (18%) with Achilles tendon rupture were clinically estimated to have minor lesions in the Achilles tendon; all had a correct roentgenographic diagnosis. Kager's triangle was positive for rupture of the Achilles tendon in all 60 patients with operative verification of the rupture, seven (12%) had diminished Toygar's angle, and 29 (48%) had positive Arner's sign. Forty-seven patients with ruptured Achilles tendon had a thickness of the tendon compared with the opposite Achilles tendon. To lower the frequency of overlooked Achilles tendon rupture, any doubt as to whether a rupture of the Achilles tendon is present should result in a lateral roentgenographic examination of the ankle. Furthermore, the authors conclude that the presence or absence of Kager's triangle should be determined roentgenographically. If Kager's triangle is not identified on plain lateral roentgenographs of ankle, special soft tissue roentgenographs may be useful.