We report about a 36 year old patient with thrombocytopenia due to Werlhof'
s disease, who had been diagnosed and treated as suffering from paraparesis
of both legs for 10 months. The real cause of his problem - a simultaneous
bilateral rupture of the quadriceps tendon - had not been detected. Only w
hen he underwent an ultrasound scan of both of his knees as part of the exa
mination in our outpatient department the diagnosis of a simultaneous bilat
eral rupture of the quadriceps tendon was made. The following operation con
firmed the sonographical findings. The sonographical evaluation of the quad
riceps tendon can clearly assess the extent of the lesion and lead to the n
ecessary therapeutical consequences.