Dysplasia Epiphysealis Hemimelica or Trevor Disease

Dysplasia epiphysealis hemimelica or Trevor disease rare, non-hereditary disease characterized by osteochondromas arising from the epiphyses.

The incidence is about 1 in 1 million. Males are three times more commonly affected than females.

The condition was first described in 1926 by Mouchet and Belot and then by Trevor in 1950. The term dysplasia epiphysealis hemimelica was coined by Fairbank in 1956.

It is thought to be a variant of osteochondroma arising from an epiphysis.

Though it is a benign disorder, in its natural history, the lesion continuously increases in size until skeletal maturity [Just like osteochondroma] leading to pain and arthrosis.

Typically, only one half of the epiphysis is involved bur involvement of the entire epiphysis is known. The medial side of the epiphysis is most commonly affected

It usually presents in young children. Lower extremity is more common than upper extremity and distal ends are more affected especially on the medial side. The distal femur and talus, navicular and first cuneiform joint are most commonly affected.

Classification

By Azouz et al

Classic Form

The distribution involves more than one bone or epiphysis within a single lower limb

Localized Form

Single bone is affected either on one side or both sides.

Generalized form

This type involves whole of the limb from pelvis to foot

Causes of Dysplasia Epiphysealis Hemimelica

The cause is uncertain but is thought to be congenital but is not genetically transmitted.

Presentation of Dysplasia Epiphysealis Hemimelica

Hard painless swelling or a mass on one side of a joint and stiffness are common complaints.

There would be deformity and muscle wasting in the area. Limb length discrepancy could be present. Sometimes, problem of joint locking can also be complained.

Differential Diagnoses

• Chondroblastoma
• Osteochondroma
• Enchondroma

Imaging

Xrays

Radiographs show an irregular mass with focal ossification arising from one side of the affected epiphysis. Widening of the joint may be noted.

CT

CT is able to define relation between the mass and its parent bone. It also is useful for evaluation of the articular cartilage and soft tissue.

MRI

MRI depicts the unossified cartilaginous mass and status of the articular cartilage in detail. It is able to differentiate abnormal epiphyseal growth from the main epiphysis.

Treatment of Dysplasia Epiphysealis Hemimelica

The treatment should be carried out if there is a deformity, pain, or interference with function. Excision of the mass and corrective osteotomy with preservation of joint is the usual treatment

No treatment is indicated if there is no symptom or mechanical block ..

In cases where surgery is not required ie. mild symptoms, supportive joint care, joint splintage and other measures to control symptom are taken.

Complications

Recurrence, degenerative osteoarthritis, fixed deformity, leg-length discrepancy, and loose bodies following fragmentation.

Outcome and Prognosis

Untreated dysplasia epiphysealis hemimelica involves joint and can cause considerable disability if not treated.

Recurrence is known.