Multiple epiphyseal dysplasia (MED), also known as dysplasia epiphysealis multiplex or Fairbank disease, refers to a group of skeletal dysplasias characterized by disorganized enchondral epiphyseal ossification in the long bones.

Epidemiology

The estimated prevalence of MED ranges from 1 in 20.000 to 1 in 10.000 ^1,2.

Clinical presentation

Although many forms of MED have different genetic and phenotypic expressions, most share the common presentation of joint pain, especially in the hips and knees. Mild to moderate short stature is common, but not mandatory. Muscular hypotonia indicates MED caused by the COMP (cartilage oligomeric matrix protein) gene mutation. Club feet are often associated with the recessive form of the disease (rMED) and are present in nearly a third of individuals with rMED ¹.

Pathology

Currently (c. 2024) there are six genetic mutations related to MED ²:

• COMP: autosomal dominant, ~50% of the cases

• DTDST (SCL26A2): autosomal recessive, ~25% of the cases

• MATN3: autosomal dominant

• COL9A2: autosomal dominant

• COL9A3: autosomal dominant

• COL9A1: autosomal dominant, very rare

Radiographic features

Given the genetic etiology of the disease, the findings are symmetric and include ^1,3:

• delayed appearance of epiphyseal ossification centers

• irregular, fragmented flattened epiphyses

• Widened joint spaces⁴

• delayed carpal ossification (COMP-MED)

• coxa vara (COMP-MED) or coxa valga (rMED)

• double-layered patella (often considered pathognomonic for MED, especially rMED)

• ‘snowcap’ appearance of the metacarpal epiphyses (rMED)

• brachydactyly (rMED)

Treatment and prognosis

The goal of treatment is to delay the development of early osteoarthritis. Adequate weight control and avoiding high-impact exercises are common measures to reduce stress on weight-bearing joints, which are the most affected ones. Surgical intervention may be considered in case of failure of non-operative management and progressive deformities. In early adulthood, total joint replacements, especially of the knees and hips, are usually indicated due to advanced osteoarthritis ^1-3.

Differential diagnosis

• Legg-Calvé-Perthes disease