Pretest

Introduction

Dysplasia epiphysealis hemimelica, also known eponymically as Trevor's disease, is a localized osteochondral overgrowth involving single or multiple epiphyses or ossification centers. (Slide) The condition can be thought of as an epiphyseal osteochondroma; however, it is not associated with osteochondromas of the metaphyses (the usual locations). The etiology is unknown, and there is no heritable tendency. Dysplasia epiphysealis hemimelica is a rare condition, with an incidence of approximately one per 1 million.

Slide

Signs and Symptoms

Growth is most commonly on the medial side of the epiphysis. Boys are more commonly affected than girls, and presentation is usually in childhood or early adolescence. If multiple epiphyseal osteochondromas occur, then they are usually ipsilateral. Patients present with painless swelling and a mass on one side of the joint. Decreased range of motion may be perceived as lacking full extension. If the osteochondral lesion expands one side of an epiphysis, then it may create an angular deformity. Patients frequently have a limp. Lower extremities are more often affected than upper extremities. The classic lesion, as described by Trevor, is located in the foot.

Imaging

Radiographs demonstrate a widened joint space. An irregular, multicentric, lobulated mass often protrudes directly from one side of the epiphysis. The mass has characteristics of cartilage. Magnetic resonance imaging is useful for showing the extent of the lesion and alteration in cartilage surface.

Histology

The lesion resembles an ostochondroma and, sometimes, a boundary of cartilage may separate the lesion from the epiphysis. Malignant degeneration has not been reported in this condition.

Treatment

If the clinical effects are mild, then the lesion may be treated by observation only. Surgery is necessary if the lesion is causing significant mechanical symptoms. Surgeons should aim to preserve the integrity of the joint as much as possible. Resection of an intra-articular wedge may be satisfactory.

Bibliography

1. MacKenzie W, Gabos P. In: Morrissy RT, Weinstein SL, eds. Lovell and Winter's Pediatric Orthopaedics. 5th ed. Philadelphia, Pa: Lippincott Williams and Wilkins; 2001:361-363.
   
2. Thacker JS. Dysplasia epiphysealis hemimelica of the tibial tubercle. Pediatr Radiol. 2005; 12:1-3.
   
3. Wenger DR. Evaluation, imaging, histology and operative treatment for dysplasia epiphysealis hemimelica (Trevor disease) of the acetabulum: A case report and review. Iowa Orthop J. 2005; 25:60-65. Review.