Dislocation of Unicompartmental knee replacement (UKR) is extremely rare and surgical management in revision knee arthroplasty is challenging. Only very few cases, have been reported with this complication of the UKR with varying degrees of associated injury. We are reporting a traumatic dislocation of UKR at least five years after the primary operation in a 68 year old gentleman presented to the accident and emergency department with a swollen left knee after a crush injury. He had a medial Oxford Unicompartmental knee replacement previously for osteoarthritis. This was completely dislocated and impeded in the soft tissue of the knee. Finally this was revised to a total knee replacement successfully. The decision in this case to revise the UKR to a TKR was based on the clinical findings and the surgeon’s experience.