BACKGROUND: Our hypothesis was that patients treated with hinged external fixators as an adjunct to multiple-ligament reconstruction would have fewer reconstruction failures than patients treated without external fixation. METHODS: In this prospective randomized study, patients with a knee dislocation either underwent ligament reconstruction with placement of an external hinged knee brace following surgery (Group A) or underwent ligament reconstruction with placement of a hinged external fixator (Compass Knee Hinge) for six weeks instead of the brace (Group B). The patients were followed clinically and were evaluated with physical examination, Lysholm and International Knee Documentation Committee knee scores, visual analog scale pain scores, and status regarding return to work and activities. RESULTS: One hundred patients with 103 knee dislocations were enrolled. Seventy-seven patients with seventy-nine dislocations (thirty-two in Group A and forty-seven in Group B), with a minimum follow-up interval of twelve months, were available for evaluation. The mean duration of follow-up was thirty-nine months (range, twelve to eighty-six months). Nine patients (29%) in Group A had failed reconstructions compared with seven (15%) in Group B (p = 0.15). Group-A patients had twenty-two (21%) of 105 reconstructed individual ligaments fail compared with eleven (7%) of 157 reconstructed ligaments in Group B. The difference in ligament failure was significant (p < 0.001; power > 0.8), with more favorable results for the patients managed with the external fixation. CONCLUSIONS: Hinged external fixation as a supplement to reconstruction following knee dislocation was associated with fewer failed ligament reconstructions compared with external bracing. Patients presenting with highly unstable knee dislocations should be considered for hinged external fixation to supplement initial reconstructive procedures.