Achondroplasia - Genetic musculoskeletal disorders

Genetic musculoskeletal disorders

Achondroplasia

Definition

Achondroplasia is a form of osteochondroplasia in which the arms and legs are abnormally short.

Incidence

Commonest form of true dwarfism.

Age

Congenital, usually obvious by age 1.

Sex

M = F

Aetiology/pathophysiology

Inherited in an autosomal dominant fashion, most cases however are sporadic. The genetic mutation is within the fibroblast growth factor receptor âˆ’3 gene.

Clinical features

Disproportionate shortening of the long bones of the limbs with a normal trunk length. The head is large with a prominent forehead and a depressed bridge of the nose causing a saddle shaped nose. Intelligence is normal. There is a large lumbar lordosis, which causes prominent buttocks, flexed hips and bowed legs. A tri-dent deformity of the hands may be present.

Investigations

Skeletal survey allows accurate measurement of the long bones.

Management

Patients may develop neurological problems due to stenosis of the spinal canal; this may require surgical intervention. Leg lengthening procedures and genu varum correction may be considered.