Knee ligament injuries combined with ipsilateral tibial and femoral diaphyseal fractures: the "floating knee".

The incidence of rupture of the knee ligaments was retrospectively studied in 47 patients with ipsilateral fractures of the femoral and tibial diaphyseal shaft. Fifteen patients proved to have an instability of the knee at the time of follow up. Disruption of the knee ligaments had not been recognised initially. At the time of initial treatment, injury of the knee ligaments had been diagnosed in only three cases. After stabilisation of both fractures in these cases, the knee ligaments had been repaired; at re-examination these patients had no complaints and their knees were perfectly stable. In view of the high incidence of missed cases, the possibility of disruption of the knee ligaments should be considered in all patients with fractures of both the femoral and tibial shaft. Meticulous examination of the knee at the time of injury is strongly advocated.