In an experimental study on 20 cadaver knee joints we found examined t
he ventral translation of the tibial head, which is otherwise shown by
the Lachmann test, by dorsal sonography. These examinations were perf
ormed in knees in which arthroscopical examination had confirmed intac
t ACL. After endoscopical partial and complete rupture of the ACL the
examinations were repeated. Radiological examination was performed as
a reference method. In a sonographically standardized clinical study o
f 243 traumatized knee joints the ventral translation of the tibial he
ad was evaluated. In all knee joints examined an arthroscopy or arthro
tomy was performed, In 56% a rupture of the ACL was verified. There wa
s a positive correlation between translation of the tibial head by 3 m
m or more compared with the non-injured side and a rupture of the ACL
(sensitivity 0.95; specificity 0.98). The dynamic sonographic techniqu
e is a simple and highly sensitive specific diagnostic method that can
be used to quantify the results found on clinical examination.