summary Multiple Epiphyseal Dysplasia is a congenital disorder caused most commonly by an autosomal mutation in cartilage oligomeric matrix protein on chromosome 19. Patients present with a form of dwarfism characterized by irregular, delayed ossification at multiple epiphyses. Diagnosis is made radiographically with presence of irregular, delayed ossification at multiple epiphyses. Treatment is usually physical therapy and pain management. Surgical osteotomies and arthroplasty are indicated in patients with progressive deformity or degenerative joint disease. Epidemiology Prevalence approximately 1:10000 Diagnosis presents between age 5-14 years of age Anatomic location caused by failure of formation of secondary ossification center (epiphysis) Etiology Pathophysiology delay of epiphyseal endochondral ossification lack of osseous support yields secondary articular cartilage deformity most commonly affects proximal femur and proximal humerus Genetics autosomal dominant is most common mutation in COMP (cartilage oligomeric matrix protein) gene on chromosome 19 (most common and most severe form) mutations type IX collagen COL9A1, COL9A2, COL9A3 causing type II collagen dysfunction because of type IX collagen acts as a link protein for type II collagen necessary for healthy articular cartilage Mutation in Matrillin 3 may also be autosomal recessive mutation in SLC26A2 (diastrophic dysplasia sulfate transporter gene) presents with at least one finding at birth clubfoot, cleft palate, clinodactyly up to half of patients with clinical diagnosis of MED do not have the typical genetic mutations Presentation Symptoms short-limbed, disproportionate dwarfism joint pain waddling gait Physical exam joint deformities from joint incongruity hips are most common joint involved valgus knee deformity common early OA joint contractures short, stubby fingers and toes normal neurologic exam normal intelligence spine is normal normal facies Imaging Radiographs general findings demonstrate irregular, delayed ossification at multiple epiphyses may also demonstrate multiple osteochondritis dissecans lesions hip may show bilateral proximal femoral epiphyseal defects distinguished from Legg-Calve-Perthes disease by its symmetric and bilateral presentation, early acetabular changes, and lack of metaphyseal cysts when bilateral Legg-Calve-Perthes is suspected, perform skeletal survey of other joints to rule out MED concurrent avascular necrosis of femoral head acetabular dysplasia knee valgus knee flattened femoral condyles double layer patella hand may show short, stunted metacarpals hyperextensible fingers foot short metatarsals Differential Spondyloepiphyseal dysplasia distinct in that it also involves the spine typically with a sharp curve atlantoaxial instability cervical myelopathy mutation in type II collagen Treatment Nonoperative NSAIDS and physical therapy indications early OA childhood hip deformities such as acetabular dysplasia often resolve by skeletal maturity Operative realigning osteotomy or hemiepiphysiodesis at the knee indications progressive genu varum or valgum total hip arthroplasty indications severe arthritis may present by age 30