Acromioclavicular joint

Cause, clinical and ultrasound findings

• This joint injury can result from either trauma or overuse in a degenerative shoulder.

• Clinically, the joint presents with pain at the end of passive range of motion, especially the cross-arm test (scarf or horizontal adduction). Resisted tests are usually strong and painless. Pain is usually point specific to the acromioclavicular joint, but it can radiate to the upper trapezius and anterior shoulder.

• Ultrasound findings include a thickened and bulging joint capsule, osteophytic lipping and cortical irregularities of the acromion and the clavicular ends of the joint. Occasionally, neovascularity of the joint capsule is found with power Doppler.

• Pain on dynamic assessment at the site of the probe.