Multiple Epiphyseal Dysplasia [MED]
Multiple epiphyseal dysplasia is a condition characterized by a delay in the appearance of the epiphyses; irregular, symmetric epiphyseal formation; mild short stature; and early-onset osteoarthritis.
Multiple Epiphyseal Dysplasia is one of the most widely known, variable, and commonly occurring skeletal dysplasias.
MED is inherited by autosomal dominant transmission in the majority of cases; however, the autosomal recessive form also exists.
MED has been mapped to Chromosome 19, and its gene product is COMP, the same gene that is abnormal in pseudoachondroplasia.
Chromosome 1, the gene encoding for the α2 polypeptide chain of type IX collagen.
Gene that encodes matrilin-3, matrilin-3 another extracellular matrix protein.
Diastrophic dysplasia gene (DTDST).
The dysplasia is not recognizable at birth.
The first sign may be a delay in walking and often the diagnosis is not made until early adolescence.
Initial presenting complaints include joint stiffness or contractures, pain, a limp, or a waddling gait. As the child grows older, shorter stature becomes more evident. However, true dwarfism is not associated because many are above the third percentile for height.
The fingers and, to a lesser extent, the toes may be short and stubby.
Flexion contractures of the elbows and knees are common.
Genu valgum or varum may develop.
Pain from degenerative arthritis may be present in adolescence or early adulthood.
There are no associated neurologic findings. Intelligence is not affected.
The principal finding on radiographs is a delay in the appearance of the ossification centers. When the epiphyses do appear, they are small, fragmented, mottled, and flattened.
Coxa vara may occur with a short femoral neck. Other angular deformities, such as genu varum or valgum may be present. Lateral radiographs of the knee may demonstrate a peculiar finding, the double-layered patella. When this is present, it is characteristic of MED.
The spine is not affected.
Genetic testing can be performed to identify the mutations in MED; however, identification of the abnormality is possible in less than half of patients.
Orthopaedic treatment is rarely necessary in early childhood.
Once the diagnosis is established, maintenance of a range of motion is initiated.
The patient and parents should be cautioned regarding weight gain.
Growth manipulation by hemiepiphysiodesis or stapling may correct in some cases with lower extremity angular deformity.
Degenerative arthritis in children is treated symptomatically.
Osteoarthritis is present by 30 years of age – Total joint replacement in early adulthood is possible.