Multiple epiphyseal dysplasia type 1 (MED 1) is a form of multiple epiphyseal dysplasia that is characterized by normal or mild short stature, pain in the hips and/or knees, progressive deformity of extremities and early-onset osteoarthrosis. Specific features to MED 1 include a more pronounced involvement of hip joints and gait abnormality and a shorter adult height. MED1 is allelic to pseudoachondroplasia with which it shares clinical and radiological features. The disease follows an autosomal dominant mode of transmission.

The term gait disturbance can refer to any disruption of the ability to walk. In general, this can refer to neurological diseases but also fractures or other sources of pain that is triggered upon walking. However, in the current context gait disturbance refers to difficulty walking on the basis of a neurological or muscular disease.