37 patients (38 knees) undergoing multi-ligament reconstruction surgery for sub-acute and chronic knee dislocation were randomized to receive post-operative immobilization with either a hinged external fixator or rigid cast. The purpose of the study was to compare functional outcome and range of motion between groups. The external fixator allowed earlier performance of rehabilitative exercises compared to cast immobilization. External fixation was found to result in better Lysholm functional scores and lower loss of flexion in comparison to cast immobilization, but no differences in extension lag or IKDC stability test outcomes were observed between groups.