Trevor disease (dysplasia epiphysealis hemimelica [DEH]) is a rare, intra-articular anomaly of cartilaginous overgrowth of the epiphysis. The usual presentation is on 1 side of the body and on 1 side of the epiphysis. The natural history of this disease is not clear because the lesions often are treated during childhood. Additionally, hip involvement is relatively uncommon; to our knowledge, total hip arthroplasty in a patient with DEH has not been reported previously. Our patient presented with previously untreated DEH of the hip joint, which had developed into a very unusual shape. He was treated with a total hip arthroplasty and had satisfactory functioning 2.5 years postsurgery.Conclusion:
Untreated DEH of the hip can lead to a very misshapen hip with a deformed femoral head and loss of the shape of the acetabulum, as well as stiffness due to an unusual shape and osteoarthritic changes. A total hip arthroplasty can give satisfactory functional results.