A new form of shoulder dysplasia in an 11-year-old boy.

Pain and impaired function in the shoulder can result from a variety of conditions. Dysplasias of the shoulder girdle are usually asymptomatic; previous literature reports on shoulder malformation have focused on glenoid dysplasia or complete agenesis of the clavicle. We report the case of an 11 year old patient with severe shoulder pain after strenuous physical exercise. Physical inspection showed a prominent clavicle and anteriorly displaced humerus. X-ray demonstrated an abnormally shortened clavicle and a hypoplastic acromion; MRI imaging revealed an elongated deltoid muscle leading over the humeral head. The patient recovered with analgesics and careful mobilization. This is the first reported case of a dysplasia of both the acromion and the clavicle. This developmental abnormality can lead to significant pain, but apparently responds well to conservative treatment. It is possible that this condition is underdiagnosed or represents significantly delayed development.