Complete dislocation of the knee is a relatively rare condition. When it occurs as a result of high-velocity injury, such as in a road traffic accident, associated vascular injury is generally suspected. In low-velocity injuries, however, distal pulses are often maintained throughout, and the possibility of vascular injury may erroneously be discounted. We report four cases of low-velocity dislocation of the knee, only one of which had an overt vascular disruption, but three of which had arterial damage. On the basis of our experiences, we recommend arteriography in all cases of complete dislocation of the knee.